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 060036
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0736 PM CDT Sat Sep 05 2020
Valid 060100Z - 061200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHWEST AND SOUTHERN MINNESOTA...
...SUMMARY...
Scattered thunderstorms capable of very large hail and isolated wind
damage are expected tonight across parts of the Upper Midwest.
...Upper Midwest...
Water vapor imagery shows northwest mid-level flow in place over the
north-central U.S. with a subtle shortwave trough located in the
northern Plains. This feature will move southeastward into the upper
Mississippi Valley this evening. Ahead of the shortwave trough,
moisture advection will continue across the north-central states as
a northwest-to-southeast axis of moderate instability becomes
reinforced from eastern South Dakota to northern Missouri. As a
low-level jet strengthens and large-scale ascent increases,
thunderstorms are forecast to initiate in far northeastern South
Dakota and southwest Minnesota from 03Z to 04Z with convection
rapidly expanding in coverage. This convection will form into a
large cluster of strong thunderstorms, moving east-southeastward
across southern Minnesota and northern Iowa late this evening. The
cluster of storms should reach the Mississippi River late tonight.
RAP forecast sounding across southwestern Minnesota this evening
have a sharp temperature inversion from the surface to 700 mb.
Instability above 700 mb is forecast to steadily increase as MUCAPE
reaches the 2500 to 3000 J/kg range. Lapse rates above the inversion
near 8.0 C/km and strong effective shear of 70 to 80 kt will be
favorable for supercells with large hail. The more intense supercell
updrafts may be able to produce hailstones of greater than 2 inches
in diameter, mainly in southwestern Minnesota where parameters
appear most favorable. The surface inversion is not forecast to be
as steep further to the southeast across southeast Minnesota and
northeast Iowa. For this reason, isolated damaging wind gusts will
be possible as the cluster of storms organizes and moves
southeastward. The severe threat will become marginal as the cluster
of storms approaches the Mississippi River in the 08Z to 10Z
timeframe.
..Broyles.. 09/06/2020
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z
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