drought history for texas' 10 regions - south …...drought history for texas’ 10 regions...

DroughtHistoryforTexas’10Regions

PreparedbytheSouthCentralClimateScienceCenterinNorman,Oklahoma

May28,2013UpdatedJanuary12,2018

http://southcentralclimate.org/

[email protected]

http://southcentralclimate.org

mailto:[email protected]

Whatisdrought? 3

Whybepreparedfordrought? 3

The“Droughts-of-Record”inTexas 3

Howtobepreparedfordrought? 4

Howisdroughtmeasured? 4

HasTexasexperienceddrought? 6

TheClimateofTexas 6

Region1:HighPlains 7

Region2:LowRollingPlains 12

Region3:North-CentralTexas 17

Region4:EastTexas 22

Region5:TransPecosofTexas 27

Region6:EdwardsPlateauofTexas 32

Region7:SouthCentralTexas 37

Region8:UpperCoast 42

Region9:SouthTexas 47

Region10:LowerValley 52

Acknowledgments 58

Bibliography 58

HighPlainsofTexas Page�2

Whatisdrought?DeNiningdroughtcanbedifNicultbecausetheimpactsassociatedwithdroughtareoftenfar-reachinganddevastating.Ameteorologicaldroughtisaprolongedperiodwhenprecipitationisbelow“normal”forthelocation(Heim2002).Anagriculturaldroughtoccurswhensoilsaretoodrytogrowhealthyvegetation,particularlycropsorforests.Aswaterbecomesscarceinrivers,lakes,andotherwaterbodies,ahydrologicaldroughtdevelops.If,atanytime,thewaterdemandsofsociety(e.g.,waterfordrinking,maintaininglawnsandgardens,washingclothes)exceedtheavailabilityofgood-qualitywater,thenasocioeconomicdroughthasoccurred.Asocioeconomicdroughtmayariseevenduringtimesofnormalprecipitationbecauseofincreasedwaterdemandfromagrowingpopulation,increasedtemperaturesandwindspeeds,newbusinesses,orothersocietalchanges.

Whybepreparedfordrought?Since2000,theNationalOceanicandAtmosphericAdministrationhasidentiNiedninedroughtsnationwideasbillion-dollarweatherdisastersbasedonbothdamagesandcosts,suchasfromcroploss.The2012drought,whichatitsheightaffectedover80%ofthecontiguousU.S.,resultedinestimateddamagesandcostsofover$50billionfrombothdirectandindirectimpacts.Droughtcanresultincrop,pasture,andforestdamage;increasedlivestockandwildlifemortality;increasedNirehazard;threatstoaquaticandwildlifehabitats;increasedwaterdemand;andreducedwatersupplies.

Propermanagementofwaterresourcesisnecessarytoprotectsuppliesfordrinkingwater,sanitation,andNireprotectionaswellastomaintaineconomicactivityandenvironmentalsustainability.Becausedisastersaffectfamilies,neighbors,andbusinesseslocally,community-levelplanningisnecessarytoreducethevulnerabilitytodroughtinTexas.

The“Droughts-of-Record”inTexasForpurposeofplanning,weconsiderthe“drought-of-record”tobethedroughtwiththeworstenvironmentalconditionsratherthanthedroughtwiththeworstrecordedimpactsontheHighPlainsofTexas.Hence,ashorterandlessseveredroughtwithhighmonetarylossesinourrecentpast(e.g.,during2011)willnotoutweighalongandseveredroughtinourearlyhistory,whenfewerpeoplelivedintheregion.Wechoosetopreparefortheworst.

WecomparedPalmerDroughtSeverityIndicesforthesedroughts,aswellasthemostrecent(hence,memorable)droughtof2011topresent(December2012)inTables1-9.Usingtheseindices,thedroughtofthe1950sexceedsthedurationandintensityofallotherdroughts.


Howtobepreparedfordrought?LocalofNicialsandotherkeystakeholdersinTexaswillbebetterpreparedfordroughtwhentheycompletethefollowing:(1)haveassessedtheirvulnerabilitytodrought,(2)understandpastdroughtsandthelocalclimate,(3)monitordrought,(4)prepareathoroughsetofactionstobetakenbefore,during,andafteradrought,and(5)educatecitizensonthisplan.

Havingaplaninplacewillenabletheseindividualstounderstandkeyfactorstomonitorsotheymayrespondproactivelytodroughtconditionsearly.Followingthisplanhelpsreducetherisksuchthat,whendroughtconditionsoccur,waterresourcesdonotrunout.ThisreportwillhelpgovernmentofNicialsandresourcemanagersbyoverviewingtheclimateanddroughthistoryinTexassincerecord-keepingbeganinthelate19thcentury.

Howisdroughtmeasured?Toquantifydroughtseverity,thescientiNiccommunityhasdevelopedseveralmethodstoassessdrought,includingdeparturefromnormalprecipitation,thePalmerDroughtSeverityIndex,andtheStandardizedPrecipitationIndex.Allthreeuseweatherobservationstodiagnosedroughtconditions.Thesimplestoftheseistheannualdeparturefromnormalprecipitation,whichistheactualprecipitationtotalfortheyearsubtractedfromtheannualnormal.LargenegativevaluesindicateaprecipitationdeNicitforthatyear.

ThePalmerDroughtSeverityIndexusesobservationsorestimatesofprecipitation,temperature,andsoilwatercontent.Valuestypicallyrangefrom+4representingextremelywetconditionsto–4representingextremelydryconditions.Valueslessthan–1indicatesomelevelofdrought,andthevaluesbecomemorenegativewithlessrainfallandhottertemperatures.

ThePalmerDroughtSeverityIndexhelpstodiagnoseagriculturaldroughtbecauseitissensitivetosoilmoistureconditionsandworkswellatrelativelylongtimescales.TheindexdoesnotaccountforreservoirlevelsandstreamNlow,soithasdrawbacksfordiagnosinghydrologicaldrought.

TheStandardizedPrecipitationIndexisbasedsolelyonprecipitationbuthastheadvantageofmultipletimescales(e.g.,3months,6months,1year)tobetterhighlightshort-termversuslong-termdroughts.Valuestypicallyrangefrom+2asextremelywetto–2asextremelydry,withvalueslessthan–1representingdrought.

AmorerecentmethodtomeasuredroughtintensityistheU.S.DroughtMonitor(Figure1).ThisproductdepictsweeklydroughtconditionsfortheUnitedStatesonadroughtintensityscaleofD0toD4,withD0representingareasthatareabnormallydryandD4representingareasofexceptionaldrought.Althoughthelevelsaresubjectivelydetermined,theyareestablishedthroughexpertreviewofweatherandwaterdata,includinglocalobservations,


aswellasreportsofdroughtimpactsfromlocal,tribal,state,andfederalofNicialsaswellasthepublicandmedia.Figure1displaystheweeklypercentageofeachofTexas’regionsaffectedbyD0throughD4droughtsince2000 .1

� Figure1.ExamplemapoftheU.S.DroughtMonitorfromthedroughtassessmentissuedfortheweekprecedingSeptember27,2011.Thecolorscale(yellowtodarkred)displaysthelevelofdroughtfromD0(abnormallydry)toD4(exceptionaldrought).SigniLicantregionalimpactsonagriculturearedesignatedwithan“S”andregionalimpactsonwatersupplyaredesignatedwithan“L”.ThemapsarereleasedeachThursdayat8:30a.m.EasternTime.CourtesyoftheNationalDroughtMitigationCenter.

Data provided by the National Drought Mitigation Center.1


HasTexasexperienceddrought?DroughtisarecurringconditioninTexas,andispartofourclimate.Ourclimatehistorycanprovideusinsightintowhatwemayseeinthefuture.Being“droughtready”means,inpart,thatwerecognizehowourclimatehaschangedovertime.Let’sexamineourpast.

TheClimateofTexasTemperatureandprecipitationarethetwomainelementsofourclimate.BecauseTexasislocatedinthemiddlelatitudes,andnorthwestoftheGulfofMexico,itscitizensexperienceawiderangeofweatherconditions.Hence,ourclimateishighlyvariable,fromyeartoyear,seasontoseason,andmonthtomonth.

Figure2.MapoftheclimatedivisionsofTexas.


Climate Divisions1 - High Plains2 - Low Rolling Plains3 - North Central 4 - East5 - Trans Pecos6 - Edwards Plateau7 - South Central 8 - Upper Coast9 - South 10 - Lower Valley

Region 1: High Plains

Texas’HighPlainsregionhasexperiencedawiderangeoftemperaturesandprecipitationoverthepastseveraldecades.Abnormallyhotanddryconditionshaveoccurredmultipletimessincetheearly1900s.Figure3showstheannualtemperature(top)andannualprecipitation(bottom)intheHighPlainsofTexassince1895. Theannualtemperaturefor2

theHighPlainsofTexasaverages58.4degreesFahrenheit,whileprecipitationaverages18.81inches.Warmer-than-averageperiodshavespannedthe1930s,the1950s,andthelate1990sthroughtheearly2010s.SigniNicantperiodsofdrier-than-averageconditionsincludetheearly1910s,the1930s,the1950s,the1960s,andtheearly2010s.


Figure3.Theaverageannualtemperature(topgraph)andtotalannualprecipitation(bottomgraph)intheHighPlainsofTexasfrom1895to2012.Tohighlightwarmer,cooler,wetter,ordrierperiods,5-yearmovingaveragesareshaded.Onthetopgraph,redshading(abovethehorizontalline)indicateswarmerperiodsandblueshading(belowtheline)notescoolerperiodsthanaverage.Similarly,onthebottomgraph,greenshading(abovethehorizontalline)highlightswetterperiodsandbrownshading(belowtheline)highlightsdrierperiodsthanaverage.Extendedperiodsofrelativelywarmtemperaturesorlowprecipitationareoutlinedinredboxes.

Optionsforthedrought-of-recordfortheregionincludethedroughtsinthe1930sandthe1950s.Thelongestperiodofdryconditionswasundoubtablywasduringthe1950s.Table1comparesPalmerDroughtSeverityIndicesforthesedroughtsandothers.Usingtheseindices,thedroughtofthe1950sexceedsthedurationandintensityofallotherdroughts;hence,theperiodfromJanuary1950toFebruary1957isthedrought-of-recordfortheHighPlainsofTexas.

BecauseofitsintenseheatcombinedwithaperiodofPDSIlessthan-4,June1933toOctober1940comesinsecondforthedrought-of-recordfortheHighPlainsofTexas.

Table1:ComparisonofPalmerDroughtSeverityIndices(PDSI)forSeveralDroughtsAffectingtheHighPlainsofTexas

*Note:DataonlyavailablethroughDecember2012;droughtconditionsmayhavecontinuedpastthisdate.

Time PeriodMonths with PDSI

less than –1Months with PDSI

less than –4Lowest

PDSI Value

February1909–June1911 29(of29months) 10consecutiveplus1

other –5.31

June1933–October1940 62(of89months) 10consecutive –5.01

January1950–February1957 77(of86months) 10consecutiveplus12

others –5.86

March1963–July1971 64(of101months) 1 -4.19

December2010–December2012* 25(of25months) 8consecutiveplus7

consecutive -6.79


TounderstandwhenthereisthegreateststressonwateravailabilityfortheHighPlainsofTexas,theaveragemonthlytemperatureandprecipitation,aswellastheiraveragehighestandlowestmonthlyvalues,areshowninFigure4.Warmertemperaturesresultingreaterwaterlossbyevaporationandtranspiration.ThewarmesttemperaturestypicallyoccurduringJune,July,andAugust(topofFigure4).

�

� Figure4.Topgraph:Themonthlyaveragetemperature(indegreesFahrenheit)acrosstheHighPlainsofTexasusingdatafrom1895to2012.Thered(middle)lineistheaverageofallclimate-divisionaveragetemperaturesforthattimeperiod.Theblue(top)lineisthehighestmonthlyaverageandthegreen(bottom)lineisthelowest.Bottomgraph:Theaveragetotalprecipitation(ininches)bymonthacrosstheHighPlainsofTexasusingdatafrom1895to2012.Theblue(leftmostofeachmonthlycluster)baristhehighestmonthlyprecipitation;thegreen(middleofthecluster)istheaverageprecipitationtotalrecordedforthatmonth;thegold(rightmost)isthelowestprecipitationtotalrecordedforthatmonth.[NotethatzeroprecipitationhasoccurredatleastonceduringJanuary,February,March,September,October,November,andDecember.]ThepeakprecipitationinMayisclearlyvisible.

Average Temperature by Month in the High Plains of Texas

Tem

pera

ture

(in

Fahr

enhe

it)

2030405060708090

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

HighestAverageLowest

Total Precipitation by Month in the High Plains of Texas

Prec

ipita

tion

(in in

ches

)

02468

10121416




TheHighPlainsofTexashasexperiencedlongandextremedroughtsinitspast.Figure5displaysthedeparturefromnormalprecipitation,andPalmerDroughtSeverityIndex,fortheHighPlainsofTexasfrom1895to2012.Redboxesoutlinethesamedrier-than-averageperiodshighlightedinFigure3.

Figure5a.Annualdeparturefromnormalprecipitation(actualprecipitationtotalfortheyearsubtractedfromtheannualnormal)fortheHighPlainsofTexasfrom1895to2012.

Figure5b.PalmerDroughtSeverityIndexfortheHighPlainsofTexasfrom1895to2012.


Annual Departure from Normal Precipitation for the High Plains of Texas

Prec

ipita

tion

Dep

artu

re (i

n in

ches

)

-15

-10

-5

0

5

10

15

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Palmer Drought Severity Index for the High Plains of Texas

-6

-4

-2

0

2

4

6

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Theregionhasexperienceddryconditionsfrom2000to2013.InFigure6welookatdroughtdesignationintheHighPlainsofTexasandseethatfrom2000-2004abnormallydrytoextremeconditionscoveredupto100%oftheregion.In2011to2013theregionexperiencedextremetoexceptionaldroughtalsocovering25tonearly100%ofregion.

�

Figure6DroughthistoryfortheHighPlainsofTexasasdesignatedbytheU.S.DroughtMonitor.ThecolorscaleisidenticaltothatinFigure1.NotethattheHighPlainsofTexaswasexperiencingextreme(brightred)toexceptionaldrought(darkred)acrossmostoftheclimatedivisionduringmuchof2006and2011topresent(datathroughMarch2013).DatacourtesyoftheNationalDroughtMitigationCenter.

Percent of the High Plains of Texas Covered by a Drought Designation

Perc

ent C

over

age

0

25

50

75

100

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

201

1

2012

2013


Formoreinformationonthesourcesofdroughtinformation,seeTable11onpage57.

Region2:LowRollingPlainsTheLowRollingPlainsregionofTexashasexperiencedawiderangeoftemperaturesandprecipitationoverthepastseveraldecades.Abnormallyhotanddryconditionshaveoccurredmultipletimessincetheearly1900s.Figure7showstheannualtemperature(top)andannualprecipitation(bottom)intheLowRollingPlainsofTexassince1895. The3

annualtemperaturefortheLowRollingPlainsofTexasaverages62.8degreesFahrenheit,whileprecipitationaverages23.5inches.Warmer-than-averageperiodshavespannedthe1920s,the1930s,the1950s,andthelate1990sthroughthe2000s.SigniNicantperiodsofdrier-than-averageconditionsincludethe1910s,themid-1920sthroughtheearly1940s,the1950s,themid-1960s,andtheearly2010s.

LowRollingPlainsofTexas Page�12

Figure7.Theaverageannualtemperature(topgraph)andtotalannualprecipitation(bottomgraph)intheLowRollingPlainsofTexasfrom1895to2012.Tohighlightwarmer,cooler,wetter,ordrierperiods,5-yearmovingaveragesareshaded.Onthetopgraph,redshading(abovethehorizontalline)indicateswarmerperiodsandblueshading(belowtheline)notescoolerperiodsthanaverage.Similarly,onthebottomgraph,greenshading(abovethehorizontalline)highlightswetterperiodsandbrownshading(belowtheline)highlightsdrierperiodsthanaverage.Extendedperiodsofrelativelywarmtemperaturesorlowprecipitationareoutlinedinredboxes.

Optionsforthedrought-of-recordfortheregionincludethedroughtsinthe1910s,the1930s,andthe1950s.Thelongestperiodofdryconditionsundoubtablywasduringthe1950s.Table2comparesPalmerDroughtSeverityIndicesforthesedroughts.Usingtheseindices,thedroughtofthe1950sexceedsthedurationandintensityofallotherdroughts;hence,theperiodfromJanuary1950toFebruary1957isthedrought-of-recordfortheLowRollingPlainsofTexas.

Becauseofitsintenseheatcombinedwithnon-stopdryconditions,February1909toAugust1913comesinsecondforthedrought-of-recordfortheLowRollingPlainsofTexas.

Table2:ComparisonofPalmerDroughtSeverityIndices(PDSI)forSeveralDroughtsAffectingtheLowRollingPlainsofTexas





PDSI Value

February1909–August1913 53(of55months) 10consecutiveplus3

other –5.66

June1933–October1940 62(of89months) 10consecutive –5.01

January1950–February1957 77(of86months) 10consecutiveplus12

others –5.86

March1963–July1971 64(of101months) 1 -4.19

December2010–December2012* 25(of25months) 8consecutiveplus7

consecutive -6.79


TounderstandwhenthereisthegreateststressonwateravailabilityfortheLowRollingPlainsofTexas,theaveragemonthlytemperatureandprecipitation,aswellastheiraveragehighestandlowestmonthlyvalues,areshowninFigure8.Warmertemperaturesresultingreaterwaterlossbyevaporationandtranspiration.ThewarmesttemperaturestypicallyoccurduringJune,July,andAugust(topofFigure8).

�

� Figure8.Topgraph:Themonthlyaveragetemperature(indegreesFahrenheit)acrosstheLowRollingPlainsofTexasusingdatafrom1895to2012.Thered(middle)lineistheaverageofallclimate-divisionaveragetemperaturesforthattimeperiod.Theblue(top)lineisthehighestmonthlyaverageandthegreen(bottom)lineisthelowest.Bottomgraph:Theaveragetotalprecipitation(ininches)bymonthacrosstheLowRollingPlainsofTexasusingdatafrom1895to2012.Theblue(leftmostofeachmonthlycluster)baristhehighestmonthlyprecipitation;thegreen(middleofthecluster)istheaverageprecipitationtotalrecordedforthatmonth;thegold(rightmost)isthelowestprecipitationtotalrecordedforthatmonth.[NotethatzeroprecipitationhasoccurredatleastonceduringJanuary,February,September,October,November,andDecember.]Thetwopeaksinprecipitation,LirstinMay,theninSeptember,isclearlyvisible.

Average Temperature by Month for the Low Rolling Plains of Texas

Tem

pera

ture

(in

Fahr

enhe

it)

2535455565758595



Total Precipitation by Month for the Low Rolling Plains of Texas

Prec

ipita

tion

(in in

ches

)

02468

10121416




TheLowRollingPlainsofTexashasexperiencedlongandextremedroughtsinitspast.Figure9displaysthedeparturefromnormalprecipitation,andPalmerDroughtSeverityIndexfortheLowRollingPlainsofTexasfrom1895to2012.Redboxesoutlinethesamedrier-than-averageperiodshighlightedinFigure7.

Figure9a.Annualdeparturefromnormalprecipitation(actualprecipitationtotalfortheyearsubtractedfromtheannualnormal)fortheLowRollingPlainsofTexasfrom1895to2012.

Figure9b.PalmerDroughtSeverityIndexfortheLowRollingPlainsofTexasfrom1895to2012.


Annual Departure from Normal Precipitation for the Low Rolling Plains of Texas

Prec

ipita

tion

Dep

artu

re (i

n in

ches

)

-15

-10

-5

0

5

10

15

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Palmer Drought Severity Index for the Low Rolling Plains of Texas

-6

-4

-2

0

2

4

6

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Theregionhasexperienceddryconditionsfrom2000to2013.InFigure10welookatdroughtdesignationintheLowRollingPlainsofTexasandseethatfrom2000-2004abnormallydrytoextremeconditionscoveredupto100%oftheregion.In2011to2013theregionexperiencedextremetoexceptionaldroughtalsocovering25tonearly100%ofregion.

�

Figure10.DroughthistoryfortheLowRollingPlainsofTexasasdesignatedbytheU.S.DroughtMonitor.ThecolorscaleisidenticaltothatinFigure1.NotethattheLowRollingPlainsofTexaswasexperiencingextreme(brightred)toexceptionaldrought(darkred)acrossmostoftheclimatedivisionduringmuchof2006and2011topresent(datathroughMarch2013).DatacourtesyoftheNationalDroughtMitigationCenter.

Percent of the Low Rolling Plains of Texas Covered by a Drought Designation

Perc

ent C

over

age

0

25

50

75

100

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

201

1

2012

2013



Region3:North-CentralTexasNorth-CentralTexashasexperiencedawiderangeoftemperaturesandprecipitationoverthepastseveraldecades.Abnormallyhotanddryconditionshaveoccurredmultipletimessincetheearly1900s.Figure11showstheannualtemperature(top)andannualprecipitation(bottom)innorth-centralTexassince1895. Theannualtemperaturefor4

north-centralTexasaverages65.0degreesFahrenheit,whileprecipitationaverages32.3inches.Warmer-than-averageperiodshavespannedthelate1900s,the1920sthroughthe1930s,the1950s,andthelate1990sthroughtheearly2010s.SigniNicantperiodsofdrier-than-averageconditionsincludethe1910s,the1930s,the1950s,thelate1970s,andtheearly2010s.

North-CentralTexas Page�17

Figure11.Theaverageannualtemperature(topgraph)andtotalannualprecipitation(bottomgraph)innorth-centralTexasfrom1895to2012.Tohighlightwarmer,cooler,wetter,ordrierperiods,5-yearmovingaveragesareshaded.Onthetopgraph,redshading(abovethehorizontalline)indicateswarmerperiodsandblueshading(belowtheline)notescoolerperiodsthanaverage.Similarly,onthebottomgraph,greenshading(abovethehorizontalline)highlightswetterperiodsandbrownshading(belowtheline)highlightsdrierperiodsthanaverage.Extendedperiodsofrelativelywarmtemperaturesorlowprecipitationareoutlinedinredboxes.

Optionsforthedrought-of-recordfortheregionincludethedroughtsinthe1910s,late1930s,andmid-1950s.Thelongestperiodofdryconditionsundoubtablywasduringthe1950s.Table3comparesPalmerDroughtSeverityIndicesforthesedroughts,..Usingtheseindices,thedroughtofthe1950sexceedsthedurationandintensityofallotherdroughts;hence,theperiodfromNovember1950toFebruary1957isthedrought-of-recordfornorth-centralTexas.

Becauseofitsintenseheatcombinedwithnon-stopdryconditions,January1909toAugust1918comesinsecondforthedrought-of-recordfornorth-centralTexas.

Table 3: Comparison of Palmer Drought Severity Indices (PDSI) for Several Droughts Affecting North-Central Texas

*Note: Data only available through December 2012; drought conditions may have continued past this date.




PDSI Value

January1909–August1918 81(of116months) 15consecutiveplus1

other –6.03

November1950–February1957 76(of76months) 12consecutiveplus11

others –6.92

February1963–August1967 32(of43months) 4 –4.56

November1975–February1981 35(of64months) 1 -4.24

June2010–December2012* 19(of31months) 3consecutive -5.28


Tounderstandwhenthereisthegreateststressonwateravailabilityfornorth-centralTexas,theaveragemonthlytemperatureandprecipitation,aswellastheiraveragehighestandlowestmonthlyvalues,areshowninFigure12.Warmertemperaturesresultingreaterwaterlossbyevaporationandtranspiration.ThewarmesttemperaturestypicallyoccurduringJulyandAugust(topofFigure12).

�

� Figure12.Topgraph:Themonthlyaveragetemperature(indegreesFahrenheit)acrossnorth-centralTexasusingdatafrom1895to2012.Thered(middle)lineistheaverageofallclimate-divisionaveragetemperaturesforthattimeperiod.Theblue(top)lineisthehighestmonthlyaverageandthegreen(bottom)lineisthelowest.Bottomgraph:Theaveragetotalprecipitation(ininches)bymonthacrossnorth-centralTexasusingdatafrom1895to2012.Theblue(leftmostofeachmonthlycluster)baristhehighestmonthlyprecipitation;thegreen(middleofthecluster)istheaverageprecipitationtotalrecordedforthatmonth;thegold(rightmost)isthelowestprecipitationtotalrecordedforthatmonth.[NotethatzeroprecipitationhasoccurredatleastonceduringDecember.]ThepeakinprecipitationinAprilisclearlyvisible.

Average Temperature by Month for North Central Texas

Tem

pera

ture

(in

Fahr

enhe

it)

30405060708090

100



Total Precipitation by Month for North Central Texas

Prec

ipita

tion

(in in

ches

)

02468

10121416




North-centralTexashasexperiencedlongandextremedroughtsinitspast.Figure13displaysthedeparturefromnormalprecipitation,andPalmerDroughtSeverityIndexfornorth-centralTexasfrom1895to2012.Redboxesoutlinethesamedrier-than-averageperiodshighlightedinFigure11.

Figure13a.Annualdeparturefromnormalprecipitation(actualprecipitationtotalfortheyearsubtractedfromtheannualnormal)fornorth-centralTexasfrom1895to2012.

Figure13b.PalmerDroughtSeverityIndexfornorth-centralTexasfrom1895to2012.


Annual Departure from Normal Precipitation for North Central Texas

Prec

ipita

tion

Dep

artu

re (i

n in

ches

)

-15

-10

-5

0

5

10

15

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Palmer Drought Severity Index for North Central Texas

-5-4-3-2-1012345

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Theregionhasexperienceddryconditionsfrom2000to2013.InFigure14welookatdroughtdesignationinnorth-centralTexasandseethatfrom2005-20027severetoextremeconditionscoveredupto100%oftheregion.In2011to2013theregionexperiencedseveretoexceptionaldroughtcoveringnearly100%ofregion.

Figure14.Droughthistoryfornorth-centralTexasasdesignatedbytheU.S.DroughtMonitor.ThecolorscaleisidenticaltothatinFigure1.Notethatnorth-centralTexaswasexperiencingextreme(brightred)toexceptionaldrought(darkred)acrossmostoftheclimatedivisionduringmuchof2005through2006and2011topresent(datathroughMarch2013).DatacourtesyoftheNationalDroughtMitigationCenter.


Percent of North Central Texas Covered by a Drought Designation

Perc

ent C

over

age

0

25

50

75

100

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

201

1

2012

2013


Region4:EastTexasNortheastOklahomahasexperiencedawiderangeoftemperaturesandprecipitationoverthepastseveraldecades.Abnormallyhotanddryconditionshaveoccurredmultipletimessincetheearly1900s.Figure15showstheannualtemperature(top)andannualprecipitation(bottom)ineasternTexassince1895. Theannualtemperatureforeastern5

Texasaverages65.8degreesFahrenheit,whileprecipitationaverages46.32inches.Warmer-than-averageperiodshavespannedthelate1900sthroughtheearly1910s,the1920sthroughthelate1950s,andthelate1990sthroughtheearly2010s.SigniNicantperiodsofdrier-than-averageconditionsincludethelate1890sthroughtheearly1900s,the1910s,the1930s,the1950s,the1960sthroughtheearly1970s,andtheearly2010s.

EastTexas Page�22

Figure15.Theaverageannualtemperature(topgraph)andtotalannualprecipitation(bottomgraph)ineasternTexasfrom1895to2012.Tohighlightwarmer,cooler,wetter,ordrierperiods,5-yearmovingaveragesareshaded.Onthetopgraph,redshading(abovethehorizontalline)indicateswarmerperiodsandblueshading(belowtheline)notescoolerperiodsthanaverage.Similarly,onthebottomgraph,greenshading(abovethehorizontalline)highlightswetterperiodsandbrownshading(belowtheline)highlightsdrierperiodsthanaverage.Extendedperiodsofrelativelywarmtemperatures orlowprecipitationareoutlinedinredboxes.

Optionsforthedrought-of-recordfortheregionincludethedroughtsinthe1910s,thelate1930s,andthemid-1950s.Thelongestperiodofdryconditionsundoubtablywasduringthe1950s.Table4comparesPalmerDroughtSeverityIndicesforthesedroughts.Usingtheseindices,thedroughtofthe1950sexceedstheintensityofmostotherdroughts;hence,theperiodfromNovember1950toFebruary1957isthedrought-of-recordforeasternTexas.

Table4:ComparisonofPalmerDroughtSeverityIndices(PDSI)forSeveralDroughtsAffectingEastTexas





PDSI Value

May1896–August1902 48(of88months) 0 –3.82

December1915–September1918 27(of35months) 10consecutive –5.99

November1950–February1957 49(of76months) 6consecutiveplus2

others -4.54

December1962–May1972 77(of114months) 0 -3.78

May2010-December2012* 29(of29months) 11consecutive -6.5

EastTexas Page�23

TounderstandwhenthereisthegreateststressonwateravailabilityforeasternTexas,theaveragemonthlytemperatureandprecipitation,aswellastheiraveragehighestandlowestmonthlyvalues,areshowninFigure16.Warmertemperaturesresultingreaterwaterlossbyevaporationandtranspiration.ThewarmesttemperaturestypicallyoccurduringAugustineasternTexas(topofFigure16).

�

� Figure16.Topgraph:Themonthlyaveragetemperature(indegreesFahrenheit)acrosseasternTexasusingdatafrom1895to2012.Thered(middle)lineistheaverageofallclimate-divisionaveragetemperaturesforthattimeperiod.Theblue(top)lineisthehighestmonthlyaverageandthegreen(bottom)lineisthelowest.Bottomgraph:Theaveragetotalprecipitation(ininches)bymonthacrosseasternTexasusingdatafrom1895to2012.Theblue(leftmostofeachmonthlycluster)baristhehighestmonthlyprecipitation;thegreen(middleofthecluster)istheaverageprecipitationtotalrecordedforthatmonth;thegold(rightmost)isthelowestprecipitationtotalrecordedforthatmonth.[NotethatzeroprecipitationhasoccurredatleastonceduringJulyandOctober]Thethreepeaksofprecipitation,LirstinMay,theninOctober,andLinallyinNovember,isclearlyvisible.

Average Temperature by Month for East Texas

Tem

pera

ture

(in

Fahr

enhe

it)

30405060708090

100



Total Precipitation by Month for East Texas

Prec

ipita

tion

(in in

ches

)

02468

10121416



EastTexas Page�24

EasternTexashasexperiencedlongandextremedroughtsinitspast.Figure17displaysthedeparturefromnormalprecipitation,andPalmerDroughtSeverityIndexforeasternTexasfrom1895to2012.Redboxesoutlinethesamedrier-than-averageperiodshighlightedinFigure15.

Figure17a.Annualdeparturefromnormalprecipitation(actualprecipitationtotalfortheyearsubtractedfromtheannualnormal)foreasternTexasfrom1895to2012.

Figure17b.PalmerDroughtSeverityIndexforeasternTexasfrom1895to2012.

EastTexas Page�25

Annual Departure from Normal Precipitation for East Texas

Prec

ipita

tion

Dep

artu

re (i

n in

ches

)

-20-15-10-505

101520

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Palmer Drought Severity Index for East Texas

-5-4-3-2-1012345

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Theregionhasexperienceddryconditionsfrom2000to2013.InFigure18welookatdroughtdesignationineastTexasandseethatfrom2005-2007abnormallydrytoextremeconditionscovered15to100%oftheregion.In2011to2013theregionexperiencedextremetoexceptionaldroughtalsocovering25tonearly100%ofregion.

�

Figure18.DroughthistoryforeasternTexasasdesignatedbytheU.S.DroughtMonitor.ThecolorscaleisidenticaltothatinFigure1.NotethateasternTexaswasexperiencingextreme(brightred)toexceptionaldrought(darkred)acrossmostoftheclimatedivisionduringmuchof2005through2006and2011topresent(datathroughMarch2013).DatacourtesyoftheNationalDroughtMitigationCenter.

Percent of East Texas Covered by a Drought Designation

Perc

ent C

over

age

0

25

50

75

100

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

201

1

2012

2013

EastTexas Page�26


Region5:TransPecosofTexasTheTransPecosregionofTexashasexperiencedawiderangeoftemperaturesandprecipitationoverthepastseveraldecades.Abnormallyhotanddryconditionshaveoccurredmultipletimessincetheearly1900s.Figure19showstheannualtemperature(top)andannualprecipitation(bottom)intheTransPecosofTexassince1895. The6

annualtemperaturefortheTransPecosofTexasaverages63.8degreesFahrenheit,whileprecipitationaverages12.42inches.Warmer-than-averageperiodshavespannedthe1900s,andthemid-1990sthroughtheearly2010s.SigniNicantperiodsofdrier-than-averageconditionsincludetheearly1910s,themid-1920stothemid-1930s,themid-1940sthroughthelate1960s,themid-1990sthroughthemid-2000s,andtheearly2010s.

TransPecosofTexas Page�27

Figure19Theaverageannualtemperature(topgraph)andtotalannualprecipitation(bottomgraph)intheTransPecosofTexasfrom1895to2012.Tohighlightwarmer,cooler,wetter,ordrierperiods,5-yearmovingaveragesareshaded.Onthetopgraph,redshading(abovethehorizontalline)indicateswarmerperiodsandblueshading(belowtheline)notescoolerperiodsthanaverage.Similarly,onthebottomgraph,greenshading(abovethehorizontalline)highlightswetterperiodsandbrownshading(belowtheline)highlightsdrierperiodsthanaverage.Extendedperiodsofrelativelywarmtemperaturesorlowprecipitationareoutlinedinred boxes.

Optionsforthedrought-of-recordfortheregionincludethedroughtsinthe1920stothe1930s,the1940stothe1960s,andthe1990stotheearly2000s.Thelongestperiodofdryconditionsundoubtablywasduringthe1940sthroughthe1960s.Table5comparesPalmerDroughtSeverityIndicesforthesedroughts.Usingtheseindices,thedroughtofthe1940sthroughthe1960swellexceedsthedurationandintensityofallotherdroughts;hence,theperiodfromFebruary1943toNovember1967isthedrought-of-recordfortheTransPecosofTexas.

Becauseofitsintenseheatcombinedwithnon-stopdryconditions,October1992throughDecember2003comesinsecondforthedrought-of-recordfortheTransPecosofTexas.

Table5:ComparisonofPalmerDroughtSeverityIndices(PDSI)forSeveralDroughtsAffectingtheTransPecosofTexas





PDSI Value

March1907–August1913 40(of78months) 3consecutiveplus1

other –4.49

February1921–August1936 102(of187months) 9consecutive –5.38

February1943–November1967 185(of298months) 10consecutiveplus6

consecutive -5.1

October1992–December2003 108(of135months) 7 -5.12

October2010-December2012* 27(of27months) 12consecutive -6.47


TounderstandwhenthereisthegreateststressonwateravailabilityfortheTransPecosofTexas,theaveragemonthlytemperatureandprecipitation,aswellastheiraveragehighestandlowestmonthlyvalues,areshowninFigure20.Warmertemperaturesresultingreaterwaterlossbyevaporationandtranspiration.ThewarmesttemperaturestypicallyoccurduringJune,July,andAugust(topofFigure20).

�

� Figure20.Topgraph:Themonthlyaveragetemperature(indegreesFahrenheit)acrosstheTransPecosofTexasusingdatafrom1895to2012.Thered(middle)lineistheaverageofallclimate-divisionaveragetemperaturesforthattimeperiod.Theblue(top)lineisthehighestmonthlyaverageandthegreen(bottom)lineisthelowest.Bottomgraph:Theaveragetotalprecipitation(ininches)bymonthacrosstheTransPecosofTexasusingdatafrom1895to2012.Theblue(leftmostofeachmonthlycluster)baristhehighestmonthlyprecipitation;thegreen(middleofthecluster)istheaverageprecipitationtotalrecordedforthatmonth;thegold(rightmost)isthelowestprecipitationtotalrecordedforthatmonth.[NotethatzeroprecipitationhasoccurredatleastonceduringJanuary,February,March,April,November,andDecember.]ThepeakprecipitationinSeptemberisclearlyvisible.

Average Temperature by Month for the Trans Pecos of Texas

Tem

pera

ture

(in

Fahr

enhe

it)

304050

607080

90



Total Precipitation by Month for the Trans Pecos of Texas

Prec

ipita

tion

(in in

ches

)

02468

10121416




TransPecosofTexashasexperiencedlongandextremedroughtsinitspast.Figure21displaysthedeparturefromnormalprecipitation,andPalmerDroughtSeverityIndexfortheTransPecosofTexasfrom1895to2012.Redboxesoutlinethesamedrier-than-averageperiodshighlightedinFigure19.

Figure21a.Annualdeparturefromnormalprecipitation(actualprecipitationtotalfortheyearsubtractedfromtheannualnormal)fortheTransPecosofTexasfrom1895to2012.

Figure21b.PalmerDroughtSeverityIndexfortheTransPecosofTexasfrom1895to2012.


Annual Departure from Normal Precipitation for the Trans Pecos of Texas

Prec

ipita

tion

Dep

artu

re (i

n in

ches

)

-10

-5

0

5

10

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Palmer Drought Severity Index for the Trans Pecos of Texas

-5-4-3-2-1012345

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Theregionhasexperienceddryconditionsfrom2000to2013.InFigure22welookatdroughtdesignationintheTransPecosofTexasandseethatfrom2000-2004abnormallydrytoextremeconditionscoveredupto100%oftheregion.In2011to2013theregionexperiencedextremetoexceptionaldroughtalsocoveringnearly60to100%ofregion.

Figure 22. Drought history for the Trans Pecos of Texas as designated by the U.S. Drought Monitor. The color scale is identical to that in Figure 1. Note that the Trans Pecos of Texas was experiencing extreme (bright red) to exceptional drought (dark red) across most of the climate division during much of 2001, 2003, and 2011 to present (data through March 2013). Data courtesy of the National Drought Mitigation Center.

EdwardsPlateauofTexas Page�31

Percent of the Tran Pecos of Texas Covered by a Drought Designation

Perc

ent C

over

age

0

25

50

75

100

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

201

1

2012

2013


Region6:EdwardsPlateauofTexas

TheEdwardsPlateauhasexperiencedawiderangeoftemperaturesandprecipitationoverthepastseveraldecades.Abnormallyhotanddryconditionshaveoccurredmultipletimessincetheearly1900s.Figure23showstheannualtemperature(top)andannualprecipitation(bottom)intheEdwardsPlateauofTexassince1895. Theannual7

temperaturefortheEdwardsPlateauofTexasaverages66.0degreesFahrenheit,whileprecipitationaverages25.24inches.Warmer-than-averageperiodshavespannedthelate1900sthroughthemid-1910s,the1920sthroughthe1930s,themid-1950s,themid-1990sthroughtheearly2000s,andtheearly2010s.SigniNicantperiodsofdrier-than-averageconditionsincludetheearly1910s,thelate1910s,the1950s,the1960s,andtheearly2010s.


Figure23.Theaverageannualtemperature(topgraph)andtotalannualprecipitation(bottomgraph)intheEdwardsPlateauofTexasfrom1895to2012.Tohighlightwarmer,cooler,wetter,ordrierperiods,5-yearmovingaveragesareshaded.Onthetopgraph,redshading(abovethehorizontalline)indicateswarmerperiodsandblueshading(belowtheline)notescoolerperiodsthanaverage.Similarly,onthebottomgraph,greenshading(abovethehorizontalline)highlightswetterperiodsandbrownshading(belowtheline)highlightsdrierperiodsthanaverage.Extendedperiodsofrelativelywarmtemperaturesorlowprecipitationareoutlinedinredboxes.

Optionsforthedrought-of-recordfortheregionincludethedroughtsinthemid-1910sand1950s.Theperiodwiththelongestdurationisundoubtablythe1950s.Table6comparesPalmerDroughtSeverityIndicesforthesedroughtsandothers.Usingtheseindices,thedroughtofthe1950swellexceedsintensityofallotherdroughts;hence,theperiodfromOctober1950toFebruary1957isthedrought-of-recordfortheEdwardsPlateauofTexas.

Becauseofitsnon-stopdryconditionscombinedwithaperiodofPDSIlessthan-4,January1916toOctober1918comesinsecondforthedrought-of-recordfortheEdwardsPlateauofTexas.

Table6:ComparisonofPalmerDroughtSeverityIndices(PDSI)forSeveralDroughtsAffectingtheEdwardsPlateauofTexas





PDSI Value

January1909-August1913 53(of56months) 3consecutive –4.23

January1916-October1918 33(of33months) 14consecutiveplus1

other –5.25

October1950-February1957 77(of77months)

11consecutive,7consecutive,plus11

other–6.08

January1962-July1964 31(of31months) 4consecutive –4.54

November2010-December2012* 26(of26months) 8consecutive –6.13


TounderstandwhenthereisthegreateststressonwateravailabilityfortheEdwardsPlateauofTexas,theaveragemonthlytemperatureandprecipitation,aswellastheiraveragehighestandlowestmonthlyvalues,areshowninFigure24.Warmertemperaturesresultingreaterwaterlossbyevaporationandtranspiration.ThewarmesttemperaturestypicallyoccurduringJulyandAugust(topofFigure24).

�

�Figure24.Topgraph:Themonthlyaveragetemperature(indegreesFahrenheit)acrosstheEdwardsPlateauofTexasusingdatafrom1895to2012.Thered(middle)lineistheaverageofallclimate-divisionaveragetemperaturesforthattimeperiod.Theblue(top)lineisthehighestmonthlyaverageandthegreen(bottom)lineisthelowest.Bottomgraph:Theaveragetotalprecipitation(ininches)bymonthacrosstheEdwardsPlateauofTexasusingdatafrom1895to2012.Theblue(leftmostofeachmonthlycluster)baristhehighestmonthlyprecipitation;thegreen(middleofthecluster)istheaverageprecipitationtotalrecordedforthatmonth;thegold(rightmost)isthelowestprecipitationtotalrecordedforthatmonth.[NotethatzeroprecipitationhasoccurredatleastonceduringJanuary,February,August,November,andDecember]Thetwopeaksofprecipitation,LirstinMay,theninSeptember,areclearlyvisible.

Average Temperature by Month for the Edwards Plateau of TX

Tem

pera

ture

(in

Fahr

enhe

it)

30

405060

708090



Total Precipitation by Month for the Edwards Plateau of TX

Prec

ipita

tion

(in in

ches

)

02468

10121416




TheEdwardsPlateauofTexashasexperiencedlongandextremedroughtsinitspast.Figure25displaysthedeparturefromnormalprecipitation,andPalmerDroughtSeverityIndexfortheEdwardsPlateauofTexasfrom1895to2012.Redboxesoutlinethesamedrier-than-averageperiodshighlightedinFigure23.

Figure25a.Annualdeparturefromnormalprecipitation(actualprecipitationtotalfortheyearsubtractedfromtheannualnormal)fortheEdwardsPlateauofTexasfrom1895to2012.

Figure25b.PalmerDroughtSeverityIndexfortheEdwardsPlateauofTexasfrom1895to2012.


Annual Departure from Normal Precipitation for the Edwards Plateau of TX

Prec

ipita

tion

Dep

artu

re (i

n in

ches

)

-20

-15

-10

-5

0

5

10

15

20

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Palmer Drought Severity Index for the Edwards Plateau of Texas

-6

-4

-2

0

2

4

6

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Theregionhasexperienceddryconditionsfrom2000to2013.InFigure26welookatdroughtdesignationintheEdwardsPlateauofTexasandseethatfrom2000-2001severetoextremeconditionscoveredupto100%oftheregion.2006to2007aswellas2011to2013theregionexperiencedextremetoexceptionaldroughtalsocovering25to100%ofregion.

Figure26.DroughthistoryfortheEdwardsPlateauofTexasasdesignatedbytheU.S.DroughtMonitor.ThecolorscaleisidenticaltothatinFigure1.NotethattheEdwardsPlateauofTexaswasexperiencingextreme(brightred)toexceptionaldrought(darkred)acrossmostoftheareaduringmuchof2006,2008through2009,and2011topresent(datathroughMarch2013).DatacourtesyoftheNationalDroughtMitigationCenter.


Percent of the Edwards Plateau of Texas Covered by a Drought Designation

Perc

ent C

over

age

0

25

50

75

100

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

201

1

2012

2013


Region7:SouthCentralTexasSouthCentralTexashasexperiencedawiderangeoftemperaturesandprecipitationoverthepastseveraldecades.Abnormallyhotanddryconditionshaveoccurredmultipletimessincetheearly1900s.Figure27showstheannualtemperature(top)andannualprecipitation(bottom)insouth-centralTexassince1895. Theannualtemperaturefor8

south-centralTexasaverages69.4degreesFahrenheit,whileprecipitationaverages34.54inches.Warmer-than-averageperiodshavespannedthelate1900sthroughthemid-1910s,the1920s,the1950s,andthelate1990sthroughtheearly2010s.SigniNicantperiodsofdrier-than-averageconditionsincludethelate1910s,the1950s,the1960s,andtheearly2010s.

SouthCentralTexas Page�37

Figure 27. The average annual temperature (top graph) and total annual precipitation (bottom graph) in south-central Texas from 1895 to 2012. To highlight warmer, cooler, wetter, or drier periods, 5-year moving averages are shaded. On the top graph, red shading (above the horizontal line) indicates warmer periods and blue shading (below the line) notes cooler periods than average. Similarly, on the bottom graph, green shading (above the horizontal line) highlights wetter periods and brown shading (below the line) highlights drier periods than average. Extended periods of relatively warm temperatures or low precipitation are outlined in red boxes.

Optionsforthedrought-of-recordfortheregionincludethedroughtsinthemid-1910sand1950s.Theperiodwiththelongestdurationisundoubtablythe1950s.Table7comparesPalmerDroughtSeverityIndicesforthesedroughtsandothers.Usingtheseindices,thedroughtofthe1950swellexceedsintensityofallotherdroughts;hence,theperiodfromJanuary1951toFebruary1957isthedrought-of-recordforsouth-centralTexas.

Becauseofitsnon-stopdryconditionscombinedwithaperiodofPDSIlessthan-4,June1915toSeptember1918comesinsecondforthedrought-of-recordforsouth-centralTexas.

Table7:ComparisonofPalmerDroughtSeverityIndices(PDSI)forSeveralDroughtsAffectingSouth-CentralTexas





PDSI Value

January1909-December1911 36(of36months) 4consecutive –4.91

June1915-September1918 39(of40months) 20consecutive –6.16

January1951-February1957 74(of74months) 32consecutiveplus4

other –6.67

February1962-December1964 35(of35months) 7consecutive –5.04

December2010-December2012* 24(of25months) 7consecutive –5.75


Tounderstandwhenthereisthegreateststressonwateravailabilityforsouth-centralTexas,theaveragemonthlytemperatureandprecipitation,aswellastheiraveragehighestandlowestmonthlyvalues,areshowninFigure28.Warmertemperaturesresultingreaterwaterlossbyevaporationandtranspiration.ThewarmesttemperaturestypicallyoccurduringJulyandAugust(topofFigure28).

�

�Figure28.Topgraph:Themonthlyaveragetemperature(indegreesFahrenheit)acrosssouth-centralTexasusingdatafrom1895to2012.Thered(middle)lineistheaverageofallclimate-divisionaveragetemperaturesforthattimeperiod.Theblue(top)lineisthehighestmonthlyaverageandthegreen(bottom)lineisthelowest.Bottomgraph:Theaveragetotalprecipitation(ininches)bymonthacrosssouth-centralTexasusingdatafrom1895to2012.Theblue(leftmostofeachmonthlycluster)baristhehighestmonthlyprecipitation;thegreen(middleofthecluster)istheaverageprecipitationtotalrecordedforthatmonth;thegold(rightmost)isthelowestprecipitationtotalrecordedforthatmonth.[NotethatzeroprecipitationhasoccurredatleastonceduringFebruary,July,andAugust]Thethreepeaksofprecipitation,LirstinJuly,theninSeptember,andLinallyinDecember,areclearlyvisible.

Average Temperature by Month for South Central Texas

Tem

pera

ture

(in

Fahr

enhe

it)

40

50

60

70

80

90



Total Precipitation by Month for South Central Texas

Prec

ipita

tion

(in in

ches

)

02468

10121416




South-centralTexashasexperiencedlongandextremedroughtsinitspast.Figure29displaysthedeparturefromnormalprecipitation,andPalmerDroughtSeverityIndexforsouth-centralTexasfrom1895to2012.Redboxesoutlinethesamedrier-than-averageperiodshighlightedinFigure27.

Figure29a.Annualdeparturefromnormalprecipitation(actualprecipitationtotalfortheyearsubtractedfromtheannualnormal)forsouth-centralTexasfrom1895to2012.

Figure29b.PalmerDroughtSeverityIndexforsouth-centralTexasfrom1895to2012.


Annual Departure from Normal Precipitation for South-Central Texas

Prec

ipita

tion

Dep

artu

re

(in in

ches

)

-20-15-10-505

101520

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Palmer Drought Severity Index for South-Central Texas

-5-4-3-2-1012345

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Theregionhasexperienceddryconditionsfrom2000to2013.InFigure30welookatdroughtdesignationintheSouthCentralTexasandseethatfrom2008-20010theregionsexperiencedextremetoexceptionalconditionscoveringupto100%oftheregion.In2011to2013theregionexperiencedthesameconditionsspanninglongerperiodsoftime.

Figure30.Droughthistoryforsouth-centralTexasasdesignatedbytheU.S.DroughtMonitor.ThecolorscaleisidenticaltothatinFigure1.Notethatsouth-centralTexaswasexperiencingextreme(brightred)toexceptionaldrought(darkred)acrossmostoftheareaduringmuchof2006,2008through2009,and2011topresent(March2013).DatacourtesyoftheNationalDroughtMitigationCenter.


Percent of South Central Texas Covered by a Drought Designation

Perc

ent C

over

age

0

25

50

75

100

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

201

1

2012

2013


Region8:UpperCoast

TheUpperCoastofTexashasexperiencedawiderangeoftemperaturesandprecipitationoverthepastseveraldecades.Abnormallyhotanddryconditionshaveoccurredmultipletimessincetheearly1900s.Figure31showstheannualtemperature(top)andannualprecipitation(bottom)intheUpperCoastofTexassince1895. Theannualtemperaturefor9

theUpperCoastofTexasaverages69.5degreesFahrenheit,whileprecipitationaverages47.67inches.Warmer-than-averageperiodshavespannedthelate1900sthroughtheearly1910s,the1920s,the1950s,andthelate1990sthroughtheearly2010s.SigniNicantperiodsofdrier-than-averageconditionsincludethelate1910s,the1950s,the1960s,andtheearly2010s.

UpperCoastTexasofTexas Page�42

Figure31.Theaverageannualtemperature(topgraph)andtotalannualprecipitation(bottomgraph)intheUpperCoastofTexas.from1895to2012.Tohighlightwarmer,cooler,wetter,ordrierperiods,5-yearmovingaveragesareshaded.Onthetopgraph,redshading(abovethehorizontalline)indicateswarmerperiodsandblueshading(belowtheline)notescoolerperiodsthanaverage.Similarly,onthebottomgraph,greenshading(abovethehorizontalline)highlightswetterperiodsandbrownshading(belowtheline)highlightsdrierperiodsthanaverage.Extendedperiodsofrelativelywarmtemperaturesorlowprecipitationareoutlinedinred boxes.

Optionsforthedrought-of-recordfortheregionincludethedroughtsinthemid-1910sand1950s.TheperiodwiththelongestdurationofPDSIlessthan-4isundoubtablythemid-1910s.Table8comparesPalmerDroughtSeverityIndicesforthesedroughtsandothers.Usingtheseindices,thedroughtofthemid-1910swellexceedsintensityofallotherdroughts;hence,theperiodfromJune1915toSeptember1918isthedrought-of-recordfortheUpperCoastofTexas.

Becauseofitsintenseheatcombinedwithnon-stopdryconditions,October1950toJuly1957comesinsecondforthedrought-of-recordfortheUpperCoastofTexas.

Table8:ComparisonofPalmerDroughtSeverityIndices(PDSI)forSeveralDroughtsAffectingtheUpperCoastofTexas





PDSI Value

June1915-September1918 40(of40months) 13consecutiveplus1

other –5.91

October1950-July1957 69(of83months) 10consecutiveplus2

other –5.45

February1962-November1965 46(of46months) 2 –5.09



TounderstandwhenthereisthegreateststressonwateravailabilityfortheUpperCoastofTexas,theaveragemonthlytemperatureandprecipitation,aswellastheiraveragehighestandlowestmonthlyvalues,areshowninFigure32.Warmertemperaturesresultingreaterwaterlossbyevaporationandtranspiration.ThewarmesttemperaturestypicallyoccurduringJune,JulyandAugust(topofFigure32).

�

� Figure32.Topgraph:Themonthlyaveragetemperature(indegreesFahrenheit)acrosstheUpperCoastofTexasusingdatafrom1895to2012.Thered(middle)lineistheaverageofallclimate-divisionaveragetemperaturesforthattimeperiod.Theblue(top)lineisthehighestmonthlyaverageandthegreen(bottom)lineisthelowest.Bottomgraph:Theaveragetotalprecipitation(ininches)bymonthacrosstheUpperCoastofTexasusingdatafrom1895to2012.Theblue(leftmostofeachmonthlycluster)baristhehighestmonthlyprecipitation;thegreen(middleofthecluster)istheaverageprecipitationtotalrecordedforthatmonth;thegold(rightmost)isthelowestprecipitationtotalrecordedforthatmonth.[NotethatzeroprecipitationhasoccurredatleastonceduringJulyandOctober]Thethreepeaksofprecipitation,LirstinJuly,theninSeptember,andLinallyinOctober,areclearlyvisible.

Average Temperature by Month for the Upper Coast of TX

Tem

pera

ture

(in

Fahr

enhe

it)

40

50

60

70

80

90



Total Precipitation by Month for the Upper Coast of TX

Prec

ipita

tion

(in in

ches

)

0358

1013151820




Figure33displaysthedeparturefromnormalprecipitation,PalmerDroughtSeverityIndex,andtwo-yearStandardizedPrecipitationIndexfortheUpperCoastofTexasfrom1895to2012.Redboxesoutlinethesamedrier-than-averageperiodshighlightedinFigure31.ItisevidentfromthesethreedroughtindicatorsthattheUpperCoastofTexashasexperiencedlongandextremedroughtsinitspast.

Figure33a.Annualdeparturefromnormalprecipitation(actualprecipitationtotalfortheyearsubtractedfromtheannualnormal)fortheUpperCoastofTexasfrom1895to2012.

Figure33b.PalmerDroughtSeverityIndexfortheUpperCoastofTexasfrom1895to2012.


Annual Departure from Normal Precipitation for the Upper Coast of Texas

Prec

ipita

tion

Dep

artu

re

(in in

ches

)

-25-20-15-10-505

10152025

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Palmer Drought Severity Index for the Upper Coast of Texas

-5-4-3-2-1012345

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Theregionhasexperienceddryconditionsfrom2000to2013.InFigure34welookatdroughtdesignationintheuppercoastofTexasandseethatfrom2008-2010abnormallydrytoextremeconditionscovered25-100%oftheregion.In2011to2013theregionexperiencedextremetoexceptionaldroughtalsocovering50-100%ofregion.

Figure34.DroughthistoryfortheUpperCoastofTexasasdesignatedbytheU.S.DroughtMonitor.ThecolorscaleisidenticaltothatinFigure1.NotethattheUpperCoastofTexaswasexperiencingextreme(brightred)toexceptionaldrought(darkred)acrossmostoftheareaduringmuchof2006,2009,and2011topresent(datathroughMarch2013).DatacourtesyoftheNationalDroughtMitigationCenter.


Percent of the Upper Coast Covered by a Drought Designation

Perc

ent C

over

age

0

25

50

75

100

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

201

1

2012

2013


Region9:SouthTexas

SouthTexashasexperiencedawiderangeoftemperaturesandprecipitationoverthepastseveraldecades.Abnormallyhotanddryconditionshaveoccurredmultipletimessincetheearly1900s.Figure35showstheannualtemperature(top)andannualprecipitation(bottom)insouthTexassince1895. TheannualtemperatureforsouthTexasaverages10

71.9degreesFahrenheit,whileprecipitationaverages23.29inches.Warmer-than-averageperiodshavespannedthelate1900sthroughtheearly1910s,thelate1910sthroughthe1920s,the1950s,andthemid-1990sthroughtheearly2010s.SigniNicantperiodsofdrier-than-averageconditionsincludetheearly1910s,thelate1910s,themid-1940sthroughthe1950s,the1960s,andtheearly2010s.

SouthTexas Page�47

Figure35.Theaverageannualtemperature(topgraph)andtotalannualprecipitation(bottomgraph)insouthTexasfrom1895to2012.Tohighlightwarmer,cooler,wetter,ordrierperiods,5-yearmovingaveragesareshaded.Onthetopgraph,redshading(abovethehorizontalline)indicateswarmerperiodsandblueshading(belowtheline)notescoolerperiodsthanaverage.Similarly,onthebottomgraph,greenshading(abovethehorizontalline)highlightswetterperiodsandbrownshading(belowtheline)highlightsdrierperiodsthan average.Extendedperiodsofrelativelywarmtemperaturesor lowprecipitationare outlined in red boxes.

Optionsforthedrought-of-recordfortheregionincludethedroughtsinthemid-1910sandthe1950s.Theperiodwiththelongestdurationisundoubtablythe1950s.Table9comparesPalmerDroughtSeverityIndicesforthesedroughtsandothers.Usingtheseindices,thedroughtofthe1950swellexceedsintensityofallotherdroughts;hence,theperiodfromFebruary1950toFebruary1956isthedrought-of-recordforsouthTexas.

Becauseofitsnon-stopdryconditionscombinedwithaperiodofPDSIlessthan-4,January1916toOctober1918comesinsecondforthedrought-of-recordforsouthTexas.

Table9:ComparisonofPalmerDroughtSeverityIndices(PDSI)forSeveralDroughtsAffectingSouthTexas





PDSI Value

January1909-August1913 55(of56months) 0 –4.00

January1916-October1918 34(of34months) 8consecutive –4.43

February1950-February1957 85(of85months)

8consecutive,6consecutive,plus6

other–4.55

October1961-September1965 45(of48months) 0 –3.91



TounderstandwhenthereisthegreateststressonwateravailabilityforsouthTexas,theaveragemonthlytemperatureandprecipitation,aswellastheiraveragehighestandlowestmonthlyvalues,areshowninFigure36.Warmertemperaturesresultingreaterwaterlossbyevaporationandtranspiration.ThewarmesttemperaturestypicallyoccurduringJune,JulyandAugust(topofFigure36).

�

� Figure36.Topgraph:Themonthlyaveragetemperature(indegreesFahrenheit)acrosssouthTexasusingdatafrom1895to2012.Thered(middle)lineistheaverageofallclimate-divisionaveragetemperaturesforthattimeperiod.Theblue(top)lineisthehighestmonthlyaverageandthegreen(bottom)lineisthelowest.Bottomgraph:Theaveragetotalprecipitation(ininches)bymonthacrosssouthTexasusingdatafrom1895to2012.Theblue(leftmostofeachmonthlycluster)baristhehighestmonthlyprecipitation;thegreen(middleofthecluster)istheaverageprecipitationtotalrecordedforthatmonth;thegold(rightmost)isthelowestprecipitationtotalrecordedforthatmonth.[NotethatzeroprecipitationhasoccurredatleastonceduringJanuary,February,July,August,October,November,andDecember]Thetwopeaksofprecipitation,LirstinJuly,theninSeptemberareclearlyvisible.

Average Temperature by Month for South Texas

Tem

pera

ture

(in

Fahr

enhe

it)

45

55

65

75

85

95



Total Precipitation by Month for South Texas

Prec

ipita

tion

(in in

ches

)

02468

10121416




SouthTexashasexperiencedlongandextremedroughtsinitspast.Figure37displaysthedeparturefromnormalprecipitation,PalmerDroughtSeverityIndex,andtwo-yearStandardizedPrecipitationIndexforsouthTexasfrom1895to2012.Redboxesoutlinethesamedrier-than-averageperiodshighlightedinFigure35.Itisevidentfromthesethreedroughtindicatorsthat.

Figure37a.Annualdeparturefromnormalprecipitation(actualprecipitationtotalfortheyearsubtractedfromtheannualnormal)forsouthTexasfrom1895to2012.

Figure37b.PalmerDroughtSeverityIndexforsouthTexasfrom1895to2012.


Annual Departure from Normal Precipitation for South Texas

Prec

ipita

tion

Dep

artu

re

(in in

ches

)

-20-15-10-505

101520

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Palmer Drought Severity Index for South Texas

-6

-4

-2

0

2

4

6

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Theregionhasexperienceddryconditionsfrom2000to2013.InFigure38welookatdroughtdesignationinsouthTexasandseethatabnormallydrytoexceptionallydryconditionscoveredmorethan25%oftheregionin2006,2009,and2011.

Figure38.DroughthistoryforsouthTexasasdesignatedbytheU.S.DroughtMonitor.ThecolorscaleisidenticaltothatinFigure1.NotethatsouthTexaswasexperiencingextreme(brightred)toexceptionaldrought(darkred)acrossmostoftheareaduringmuchof2006,2008through2009,and2011topresent(datathroughMarch2013).DatacourtesyoftheNationalDroughtMitigationCenter.


Percent of South Texas Covered by a Drought Designation

Perc

ent C

over

age

0

25

50

75

100

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

201

1

2012

2013


Region10:LowerValleyTheLowerValleyofTexashasexperiencedawiderangeoftemperaturesandprecipitationoverthepastseveraldecades.Abnormallyhotanddryconditionshaveoccurredmultipletimessincetheearly1900s.Figure39showstheannualtemperature(top)andannualprecipitation(bottom)intheLowerValleyofTexassince1895. Theannualtemperature11

fortheLowerValleyofTexasaverages74.0degreesFahrenheit,whileprecipitationaverages24.86inches.Warmer-than-averageperiodshavespannedthelate1900sthroughtheearly1910s,thelate1910sthroughthe1920s,themid-1940sthroughthe1950s,andthemid-1990sthroughtheearly2010s.SigniNicantperiodsofdrier-than-averageconditionsincludethemid-1940sthroughthe1950s,theearly1960sthroughthemid-1960s,andtheearly2010s.

LowerValleyofTexas Page�52

Figure 39. The average annual temperature (top graph) and total annual precipitation (bottom graph) in the Lower Valley of Texas from 1895 to 2012. To highlight warmer, cooler, wetter, or drier periods, 5-year moving averages are shaded. On the top graph, red shading (above the horizontal line) indicates warmer periods and blue shading (below the line) notes cooler periods than average. Similarly, on the bottom graph, green shading (above the horizontal line) highlights wetter periods and brown shading (below the line) highlights drier periods than average. Extended periods of relatively warm temperatures or low precipitation are outlined in red boxes.

Anoptionforthedrought-of-recordintheregionincludesthedroughtinthemid-1940sthroughthe1950s.Theperiodwiththelongestdurationisundoubtablythisperiodat152months.Table10comparesPalmerDroughtSeverityIndicesforthisdroughtandothers,aswellasthemostrecent(hence,memorable)droughtof2011to2012.Usingtheseindices,thedroughtofthemid-1940sthroughthe1950swellexceedsintensityofallotherdroughts;hence,theperiodfromMarch1945toOctober1957isthedrought-of-recordfortheLowerValleyofTexas.

Table10:ComparisonofPalmerDroughtSeverityIndices(PDSI)forSeveralDroughtsAffectingtheLowerValleyofTexas





PDSI Value

March1945-October1957 133(of152months) 3consecutiveplus2

other –4.89

November1999-August2002 34(of34months) 2 –4.23

November2010-December2012* 26(of26months) 3consecutive,plus2

other –4.43


TounderstandwhenthereisthegreateststressonwateravailabilityfortheLowerValleyofTexas,theaveragemonthlytemperatureandprecipitation,aswellastheiraveragehighestandlowestmonthlyvalues,areshowninFigure40.Warmertemperaturesresultingreaterwaterlossbyevaporationandtranspiration.ThewarmesttemperaturestypicallyoccurduringJune,JulyandAugust(topofFigure40).

�

� Figure40.Topgraph:Themonthlyaveragetemperature(indegreesFahrenheit)acrosstheLowerValleyofTexasusingdatafrom1895to2012.Thered(middle)lineistheaverageofallclimate-divisionaveragetemperaturesforthattimeperiod.Theblue(top)lineisthehighestmonthlyaverageandthegreen(bottom)lineisthelowest.Bottomgraph:Theaveragetotalprecipitation(ininches)bymonthacrosstheLowerValleyofTexasusingdatafrom1895to2012.Theblue(leftmostofeachmonthlycluster)baristhehighestmonthlyprecipitation;thegreen(middleofthecluster)istheaverageprecipitationtotalrecordedforthatmonth;thegold(rightmost)isthelowestprecipitationtotalrecordedforthatmonth.[NotethatzeroprecipitationhasoccurredatleastonceduringApril,May,July,August,October,andDecember]Thethreepeaksofprecipitation,LirstinJuly,theninSeptember,theninOctober,areclearlyvisible.

Average Temperature by Month for the Lower Valley of TX

Tem

pera

ture

(in

Fahr

enhe

it)

50

60

70

80

90



Total Precipitation by Month for the Lower Valley of TX

Prec

ipita

tion

(in in

ches

)

02468

10121416




LowerValleyofTexashasexperiencedlongandextremedroughtsinitspast.Figure41displaysthedeparturefromnormalprecipitation,andPalmerDroughtSeverityIndexfortheLowerValleyofTexasfrom1895to2012.Redboxesoutlinethesamedrier-than-averageperiodshighlightedinFigure2.

Figure41a.Annualdeparturefromnormalprecipitation(actualprecipitationtotalfortheyearsubtractedfromtheannualnormal)fortheLowerValleyofTexasfrom1895to2012.

Figure41b.PalmerDroughtSeverityIndexfortheLowerValleyofTexasfrom1895to2012.


Annual Departure from Normal Precipitation for the Lower Valley of Texas

Prec

ipita

tion

Dep

artu

re

(in in

ches

)

-20-15-10-505

101520

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Palmer Drought Severity Index for the Lower Valley of Texas

-5-4-3-2-1012345

1895

1900

1905

1910

1915

1920

1925

1930

1935

1940

1945

1950

1955

1960

1965

1970

1975

1980

1985

1990

1995

2000

2005

2010

Theregionhasexperienceddryconditionsfrom2000to2013.InFigure42welookatdroughtdesignationintheLowerValleyregionofTexasandseethatfrom2000-2002moderatelydrytoextremeconditionscoveredupto100%oftheregion.In2011to2013theregionexperiencedextremetoexceptionaldroughtcovering25to100%ofregion.

Figure42.DroughthistoryfortheLowerValleyofTexasasdesignatedbytheU.S.DroughtMonitor.ThecolorscaleisidenticaltothatinFigure1.NotethattheLowerValleyofTexaswasexperiencingextreme(brightred)toexceptionaldrought(darkred)acrossmostoftheareaduringmuchof2002,2006,2009,and2011topresent(datathroughMarch2013).DatacourtesyoftheNationalDroughtMitigationCenter.


Percent of the Lower Valley Covered by a Drought Designation

Perc

ent C

over

age

0

25

50

75

100

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

201

1

2012

2013


DroughtResourcesThereareseveralexcellentsourcesofinformationfordroughtmonitoringandreporting,rangingfromnationaltolocal(Table10).Theseresourcesaredesignedtohelpyoupanandpreparefordroughtconditionsinyouregion.

Table11summarizesseveralexcellentsourcesofinformationfordroughtmonitoringandreporting,rangingfromnationaltolocal.

Table11:SourcesofDroughtInformation&Tools

Source Web Address Uses

MajorSourcesofInformation

NationalIntegratedDroughtInformationSystem

www.drought.gov

Consolidatedsourceofdroughtinformation,monitoring&reportingtools,includingmanyoftheothersourceslistedbelow

NationalDroughtMitigationCenter drought.unl.edu

Consolidatedsourceofdroughtinformation,includingdroughtplanning,monitoringreporting,risks,andimpacts

StateClimateOfNice-Texas climatexas.tamu.edu ConsolidatedsourceofTexasclimate

information

WestTexasMesonet www.mesonet.ttu.edu/ RegionalweatherobservingnetworkspeciNictowestTexas

Speci[icDrought-RelatedTools

U.S.DroughtMonitor:NationalDroughtMitigationCenter

droughtmonitor.unl.edu/Currentandpastdiagnosesofdroughtconditions,bothnearbyandacrosstheUnitedStates

TexasDroughtMonitoringWebsite:OfLiceoftheStateClimatologist

climatexas.tamu.edu/index.php/drought

CurrentdroughtconditionsandresearchonpreviousdroughtimpactswithinTexas

U.S.SeasonalDrought&PrecipitationOutlooks:ClimatePredictionCenter

www.cpc.noaa.gov

Large-scaletrendsindroughtacrosstheU.S.forthenextfewmonths;Expertassessments(notforecasts)ofpossiblechangesinprecipitationconditionsoverarangeoftimes(6-10days,8-14days,1month,&3months)

DroughtResources Page�57

http://www.drought.gov

http://drought.unl.edu

http://www.mesonet.ttu.edu

http://climatexas.tamu.edu/index.php/drought

http://www.cpc.noaa.gov

TheSouthernClimateImpactsPlanningProgramprovidesadroughtmonitoringwebsiteathttp://www.southernclimate.org/data.php.TheproductsonthissitedepictchangesinprecipitationandtemperatureacrosstheSouthernUnitedStates(includingTexas).Tablessummarizethecurrentprecipitationtotalstopastyearsacrossavarietyoftimescales(e.g.,last30days,last90days),asshowninFigure43.

Figure43.ExampleofadroughtmonitoringproductfromtheSouthernClimateImpactsPlanningProgram(http://www.southernclimate.org/).Thisexampleprovidesanassessmentofthepast30daysendingonMay26,2013andincludesthefollowinginformation:totalrainfallfortheperiod,departure(difference)fromnormalrainfallfortheperiod,thepercentageofnormalprecipitationfortheperiod,howwetordrytheperiodhasbeencomparedtopreviousyears,theprecipitationamountforthedriestsimilarperiodonrecord(anditsyear),andtheprecipitationamountforthewettestsimilarperiodonrecord(anditsyear).

AcknowledgmentsWeeklyU.S.DroughtMonitordatawereprovidedbyBrianFuchsoftheNationalDroughtMitigationCenter,andclimatedivisiondataweresuppliedbyMonicaDemingoftheOklahomaClimatologicalSurvey.TexasdroughtphotoscourtesyoftheSanAngelo,TXNationalWeatherServiceWeatherForecastOfNice(http://www.srh.noaa.gov/sjt/?n=drought).

BibliographyHeim,R.R.,2002:AReviewofTwentieth-CenturyDroughtIndicesUsedintheUnitedStates.

BulletinoftheAmericanMeteorologicalSociety,83,1149-1165.

DroughtResources Page�58

http://www.southernclimate.org/data.php

http://www.southernclimate.org/

http://www.srh.noaa.gov/sjt/?n=drought

drought history for texas' 10 regions - south …...drought history for texas’ 10 regions...

Documents