MET4300/5355SevereWeather

Lecture 1 Introduction

CourseOrganization• Tu/Th11:00AM-12:15 PM,AHC5Rm357•HaiyanJiang,305-348-2984,AHC5Rm371,haiyan.jiang@fiu.edu

•OfficeHoursTu12:15-1:15PM,orbyappointment•PreviousGeneralorIntroductiontoMETcourse.•On-linecoursematerialsat:http://faculty.fiu.edu/~hajian/MET4300/MET4300.html

•WxChallenge:LocalmanagerRigobertoOlivera(roliv053@fiu.edu),signupbeforeJan20,2019)

Grades:

Grading Factors

Participation(in-class excises) 10%

Term-paper (Graduate) 10%

Exam #1 20%

Exam #2 20%

Final 50%(Under)40% (Graduate)

Total 100%

Absence:

• Needavalidexcuse(in-classexercisesarecountedtowardyourgrade)

Text:

• Severe&HazardousWeather--Anintroduction toHighImpactMeteorology,5th Edition,byRobertRauber, JohnWalsh,andDonnaCharlevoix,Kendall-Hunt,2017. ISBN:9781524931667.Textbookinformationathttps://he.kendallhunt.com/product/severe-and-hazardous-weather-introduction-high-impact-meteorology-0

Textbook:• 27chapters:we’llcover22ofthem

• Specialsections:

1).ListoflearningObjectives2).Checkyourunderstanding3).Testyourunderstanding4).Testyourproblemsolvingskills5).Focusbox(case,advancedtopics,etc.)

Suggestions

• Previewthechapter

• Readthetext,startwithlearningobjectives

• Payattentionto“checkyourunderstanning”questionswhilereading

• ”Answer“Testyourunderstanding”questionsafterreadingthechapter

• “Testyourproblem-solvingskills”

ClassActivities:

• From“ActiveLearningExercises”bookortextbook“testyourproblemsolvingskill”questions

• Dueinclass,counting10%ofyourtotalgrade• NoMake-ups

Exams:

• Total3exams:Exam1,2,andfinal

• Exam1:Feb.7

• Exam2:Mar.28

• Finalexam:Apr.23

• Yourinputaboutexamtime?

CourseFocus:Severe&HazardousWeather

CourseTopics•1/3ofthewholecoursewillcoversomeverybasicmeteorologyconcept(lec1-11;textbookCH1-9)

• Therest:differenttypesofsevere&hazardousweatherincludingleecyclone,northeasters,icestorms,lake-effectsnow,coldwaves,blizzards,mountainsnowstorms,mountainwindstorms,thunderstorms,tornadoes,hailstorms,lightning,anddownbursts.

Whatissevereweather?

• Large,damaginghail(diameter>=1inch)

•Damagingwinds(>=60mph,50kt,or25ms-1)

• Tornado•Oralloftheabove• Strongupdrafts!

SevereWeather=“MESOSCALE”Weather

•Meso=Middle,betweenMacro- andMicro- scale•Orbetween“Synoptic”and“Convective”•ActuallyincludesConvectivescale,too.•Horizontalscaleisdeterminedbysurfacepropertiesornaturalscalesofconvectivesystems

•Verticalscaleisdefinedbythedepthofthetroposphere.

WhatisHazardousWeather?

• Thedefinitionismuchbroaderthansevereweather.•Hazardousweatherincludesalltypesofweatherthathashazardousimpacts.

• Itincludesalmostallscalesofweathersystems,notonlymesoscale.

ScalesofAtmosphericMotion

Scale Length Time

Planetary ~6000 km (Re) Weeks

Synoptic ~ 2000 km days to a week

Meso-α 2000-200 km A day or two

Meso-β 200-20 km A day-hours

Meso-γ 20-2 km Hours-minutes

Convective 5 km – 500m Minutes

Micro < 2 km Minutes-seconds

Orlanski, 1975

METSCALES

PlanetaryWaves

Synoptic-ScaleWeatherin1863

Synoptic-ScaleWeather

Meso- β

Radar, which maps hydrometeors (primarily rainfall) is a key instrument for understanding the mesoscale

Meso-Anticyclone

GustFront

Gustfront:theleadingedgeofcoolairrushingdownandoutfromathunderstorm.

Downslopewind(Chinook,snoweater) isawinddirecteddownaslope,oftenusedtodescribewindsproducedbyprocesseslargerinscalethantheslope.

Suctionvortex arereallysubstructuresofmany,perhapsall,tornadoesbutarenotalwayseasilyvisible.Theseoccur,usually,atthebaseofthetornadovortexwherethetornadomakescontactwiththesurface.

Dustdevil isastrong,well-formed,andrelativelylong-livedwhirlwind,rangingfromsmall(halfametrewideandafewmetrestall)tolarge(morethan10 metreswideandmorethan1000 metrestall).Theprimaryverticalmotionisupward.Dustdevilsareusuallyharmless.

Summary

• Severeweather• Large,damaginghail(20mm,or¾in)• Damagingwinds(50kt,or25ms-1)• Tornado• Oralloftheabove

• Hazardousweather:includeallscalesofweather• Scalesofmotion

• Planetary&synoptic—balanced>2000km• Mesoscale---nonbalanced,2000-2km• Convective—buoyantmotions,5-0.5km(scaleheight)• Microscale---nearsurface<1km