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 %
209,025
10,660,428
Minneapolis, MN...St. Paul, MN...Madison, WI...Sioux Falls, SD...Cedar Rapids, IA...
Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point.
Day 1 Hail Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
15 %
87,235
2,062,776
Sioux Falls, SD...Fargo, ND...St. Cloud, MN...Grand Forks, ND...Moorhead, MN...
5 %
115,358
5,767,776
Minneapolis, MN...St. Paul, MN...Rochester, MN...Duluth, MN...Sioux City, IA...
SPC AC 090520
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1220 AM CDT Sun Aug 09 2020
Valid 091200Z - 101200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER
MIDWEST...
...SUMMARY...
Strong to severe thunderstorms are expected across parts of the
Upper Midwest this afternoon and evening. Large hail and wind
damage will be the primary threats.
...Upper Midwest...
Strong short-wave trough, currently located over AB, is forecast to
dig southeast toward the upper Red River Valley by the end of the
period. This feature will induce large-scale height falls across the
upper Midwest during the day which should encourage a reasonable
mass response, and frontal surge across the northern Plains by early
afternoon. Latest model guidance suggests a pronounced surface front
should extend from southeast AB-eastern ND-central SD at 18z, then
progress into central MN-southeast SD by 10/00z. This boundary will
likely serve as the focus for potentially strong/severe
thunderstorms.
One caveat that could complexify the convective evolution will be
the early-day disturbance that will eject from southeast SD, across
southern MN into western WI by early evening. This disturbance
currently is responsible for substantial convection across southern
SD/northern NE. Remnants of the MCS will be ongoing at daybreak,
likely over southwest MN. Some of this convection could produce
hail/wind early in the period. Depending on the cloud canopy and its
influence on boundary-layer heating, intensification is possible
downstream. Forecast soundings ahead of this feature are quite
unstable and there appears to be sufficient shear for sustained
updrafts. However, multi-cell/MCS storm mode may be established
early which would limit any supercell potential.
Later in the day, strong surface heating across the central High
Plains into southeast SD should result in convective temperatures
being breached. Prior to this, thunderstorms will likely initiate
along the front across AB into northern ND. This activity will be
encouraged by aforementioned large-scale forcing for ascent ahead of
the short wave. By late afternoon this activity should develop south
along the wind shift into eastern SD. With time an elongated
corridor of strong/severe frontal convection should spread southeast
across much of MN. Hail and wind are expected with this activity.
..Darrow/Squitieri.. 08/09/2020
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
| 
)
