Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Day 1 Tornado Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Day 1 Wind Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
15 %
33,780
1,805,158
Cedar Rapids, IA...Rochester, MN...Waterloo, IA...Lakeville, MN...Cedar Falls, IA...
SPC AC 051629
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1129 AM CDT Sat Sep 05 2020
Valid 051630Z - 061200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVERNIGHT
ACROSS PARTS OF SOUTHWEST AND SOUTH CENTRAL MN...
...SUMMARY...
Scattered thunderstorms capable of very large hail and isolated wind
damage are expected tonight across parts of the Upper Midwest.
...Southern MN/IA vicinity overnight...
An embedded mid-upper speed max near the AB/MT border will crest the
Great Basin upper ridge and then progress east-southeastward over
the Dakotas/MN tonight, in advance of an amplifying northern-stream
trough. In response, cyclogenesis is expected in the lee of the
northern Rockies, and a cyclone will subsequently develop eastward
across the Dakotas tonight. This will induce a 40-50 kt
southwesterly low-level jet from the central Plains toward the upper
MS Valley, which will transport low-level moisture (now across KS)
northeastward to IA/southern by tonight. The moistening will occur
beneath the eastern extent of steep midlevel lapse rates (8-9 C/km)
with an elevated mixed layer, resulting in moderate-strong buoyancy
(MUCAPE of 2000-3000 J/kg).
Strong warm advection on the nose of the low-level jet will likely
support elevated thunderstorm development tonight (03-06z) near the
SD/MN border as low-level moisture/buoyancy increase. Strong
deep-layer vertical shear and the low-level warm advection will
result in long, curved hodographs that favor elevated supercells
with the initial storm development, when very large hail is most
probable. Upscale growth into clusters appears likely overnight as
the storms spread southeastward from MN toward northeast IA.
Despite the convection being rooted above the surface, there will be
some potential for strong downdrafts to reach the surface, with an
attendant threat for a few damaging gusts.
..Thompson/Moore.. 09/05/2020
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NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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