round four… is spring any nearer?...the ahps outlook process is “considering” some upcoming...
TRANSCRIPT
Round Four… is Spring any Nearer?
Some Area Weather, Water, and Climate Observations...
And Prospects for the 2020 Spring Flood…
Jim Kaiser Gregory GustLead Meteorologist Warning Coordination MeteorologistNOAA, NWS Grand Forks ND NOAA, NWS Grand Forks ND
Red River and Devils Lake Basin 2020 Spring Flood Outlook - March 12, 2020
Bottom Line up Front:• Good News… Flood risk hasn’t changed much since earlier outlooks.
– No big storms since mid-January
– Snowfall/SWE since January 18th is below normal (~ 0.50 to 0.75 inches low)
– Mild conditions through mid-winter with frost depth shallower than normal
• Bad News… Risk for significant flooding (Mod/Major) still very high. – Fall thru mid winter precipitation was a record (Sept, Oct, Nov, Dec, Jan, Feb)
– Soils are still really, really wet (though frozen)
– Still near to above normal snowpack/snow-water with high runoff potential
• Latest Climate outlooks show no clear signal: wet, dry, or normal.
• This Spring: Risks levels are still in Top 10 to Top 5 flood territory.
Flood Risk by Category at River Forecast Points
MN: Bumped Roseau up into Minor Flood Risk category. Rest of forecast points remain in similar risk categories since Feb 27th outlook.
• Looking just at winter snow amounts… recall that October saw an “historic” snowfall episode across a large part of central and eastern ND.
• All that snow melted before the classic winter freeze-up, and doesn’t show up in current snowfall analyses but is still partially available for runoff.
NOAA/NWS (CPC) Climate Prediction Center Analysis
This excessively wet soil is a consequence of record Sep-Nov precipitation, both rain and snow.
By the numbers…
As of Mar 10th, the Fargo area hasdropped to 9th wettest on recordfor Fall-Early Winter precipitation
(9/1/19 through 3/10/20)
Only 0.21” since Jan 20th(~0.61 inches below average since Jan 20)
While the Grand Forks area →is soundly in 1st place!
Only 0.14” since Jan 20th(~0.65 inches below average since Jan 20)
Data from NOAA/NCEI, via the XMACIS2 system,with long term records back through the 1890s.
In general, flow at freeze-up was nearing record high levels for the time of year for much of the Northern Plains/Midwest…
The first 2 of 7 keyflood ingredients
are well met [both at or near
record]
The 2009, 2010, and 2011 “historic”
spring flood years also had our
previous “historic” fall season flood
crests (falls of 2008, 2009, and 2010)
So what’s next?
So what’s next?The first 2 of 7 keyflood ingredients
are well met [both at or near
record]
The 2009, 2010, and 2011 “historic”
spring flood years also had our
previous “historic” fall season flood
crests (falls of 2008, 2009, and 2010)
3. Frost Depths are running Below Normal… less deep than last year (0 to 30 inches)4. Winter Snowpack is Near to Above Normal… except for the far northern basin 5. Snow Water Equivalent (SWE) is High… near typical winter season values already
29” 15”
27” 6”
9”
24”
33”
39”31”
49”
1”
Data courtesy of NDAWN, NRCS SCAN, and other government sites
Frost Depth Analysis as of February 24, 2020(no significant change since January 23rd outlook)
“Shallow Frost”
7”
11”
Snow Depth Analysis as of March 11, 2020(continuing to compress since January 23rd outlook, only slight additions)
Snow Water Equivalent Analysis as of March 11, 2020(some water coming out since February 27th outlook)
Compare: Snow Water Equivalent Analysis as of March 11, 2019(note: there was a lot more snow in February and early March!)
Also… in march od 2019, soils were a lot drier underneath all that snow!
A 10-20 percent reduction overall in SWE in past 2 weeks.
Some into ditch network, some into “skin layer” of soil.
*Skin Layer refers to stored at top of soil, not yet soaked into frozen ground.
So what’s next?The first 2 of 7 keyflood ingredients
are well met [both at or near
record]
The 2009, 2010, and 2011 “historic”
spring flood years also had our
previous “historic” fall season flood
crests (falls of 2008, 2009, and 2010)
3. Frost Depths are running Below Normal… less deep than last year (0 to 30 inches)4. Winter Snowpack is Near to Above Normal… except for the far northern basin 5. Snow Water Equivalent (SWE) is High… near typical winter season values already6. To be determined!7. To be determined!
Some early rain/snow occurred on Mar 12th, 2020.
Week 1 forecast precipitation: 0.25 to 0.50 inches
(Today through next Thursday)
Potential Sun-MonWinter Storm
The AHPS Outlook Process is “considering” some upcoming Precipitation and Temperatures.
As mentioned in the March 12th, 10:30am briefing:
• From mid March through April a weekly amount of precipitation of from 0.25 to 0.50 inches would be considered “normal”.
• Should this occur, the probabilities would best reflect this near the 50th percentile level.
• Higher or lower precipitation amounts would steer towards the lower (45th to 25th) or higher (55th to 75th) risk percentiles, respectively.
• Likewise, a colder or warmer temperature regime may increase or decrease risk levels in any one sub-basin.
High Risk Level : Low Risk PercentileLow Risk Level : High Risk Percentile
Week 2: Below Norm Temps, nr Norm Precip
Week 2 (8-14 day) Outlook - issued March 11th
March, April, May Outlook - issued February 20th
No Clear Climate Signal as we head into Spring
Spring Snowmelt Timing?
Highly dependent on the temperature forecast!
Last week’s ideas… maybe an early thaw
This week’s ideas… now looking like a late thaw
Flood Risk by Category at River Forecast Points
MN: Bumped Roseau up into Minor Flood Risk category. Rest of forecast points remain in similar risk categories since Feb 27th outlook.
Eg: Red River at Fargo-Moorhead: mid-hi Major(floodwalls installed, some bridges closed)
New! Probabilistic Flood Outlook Summary (PFOS)
https://www.weather.gov/fgf/PFOS
An Experimental Product
Now for all Red River mainstem and tributary locations
At a glance, relates current risk to:
• flood stages
• recent years
• floods of record
Let us know what you think!
Devils Lake: 1.8 to 2.6 ft rise expected(rise back to levels last seen 2015-2016)
1450.8 to 1451.6 ft.
Current level: ~1449.0
Bottom Line up Front:• Good News… Flood risk hasn’t changed much since earlier outlooks.
– No big storms since mid-January
– Snowfall/SWE since January 18th is below normal (~ 0.50 to 0.75 inches low)
– Mild conditions through mid-winter with frost depth shallower than normal
• Bad News… Risk for significant flooding (Mod/Major) still very high. – Fall thru mid winter precipitation was a record (Sept, Oct, Nov, Dec, Jan, Feb)
– Soils are still really, really wet (though frozen)
– Still near to above normal snowpack/snow-water with high runoff potential
• Latest Climate outlooks show no clear signal: wet, dry, or normal.
• This Spring: Risks levels are still in Top 10 to Top 5 flood territory.
Flood Risk by Category at River Forecast Points
MN: Bumped Roseau up into Minor Flood Risk category. Rest of forecast points remain in similar risk categories since Feb 27th outlook.
Flood Risk by Category at River Forecast Points
Summary:
Widespread Runoff
Road Closures
Floodwalls Closed
As Bad or Worse than Spring 2019?
Possible Top 5 Flood?
Exposure to Late March and April Weather Worries[translation: a late spring runoff has more risk from potential heavy rain events]
CRED Flood Reporter - relaunched in 2019!
Future 2020 Probabilistic Outlooks:None Scheduled ATTM
Contact the NWS Grand Forks office 24/7:Email: [email protected]
Phone: (701) 795-5127
Jim Kaiser Gregory GustLead Meteorologist Warning Coordination [email protected] [email protected]