Memphis, TN...Birmingham, AL...Lubbock, TX...Montgomery, AL...Little Rock, AR...
Probabilistic Tornado Graphic
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
2 %
27,985
175,307
Rapid City, SD...Pierre, SD...Rapid Valley, SD...
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 %
46,424
142,564
Pierre, SD...Rapid Valley, SD...
5 %
361,622
12,447,528
Memphis, TN...Birmingham, AL...Lubbock, TX...Montgomery, AL...Little Rock, AR...
Probabilistic Large Hail Graphic
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 %
29,786
62,412
No Major Population Center in Risk Area
5 %
133,276
1,192,238
Sioux Falls, SD...Rapid City, SD...Bismarck, ND...North Platte, NE...Aberdeen, SD...
SPC AC 111218
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0718 AM CDT Tue Aug 11 2020
Valid 111300Z - 121200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER WESTERN SOUTH
DAKOTA...WESTERN NEBRASKA...AND VICINITY...
...SUMMARY...
Scattered strong/severe convection is expected across portions of
the Plains from late afternoon into the overnight hours, especially
across portions of South Dakota and Nebraska. Hail and wind are the
primary threats. Marginally severe storms are also possible across
parts of the mid-South and Northeast.
...Northern Plains...
Morning water vapor imagery shows multiple weak shortwave troughs
moving across WY. These features will track eastward and impact
portions of the Dakotas into NE later today. Strong heating along
the western edge of deeper moisture over eastern CO/NE Panhandle
will lead to scattered afternoon thunderstorms. This activity will
move/build eastward, posing a risk of locally damaging wind gusts
and some hail. Other storms may develop farther north across
portions of southwest ND and western SD by early evening, capable of
damaging winds and hail. One or more clusters of storms may persist
well after midnight, posing a marginal risk of strong winds eastward
across SD.
...AR into Central Gulf Coast states...
A weakening MCS over OK has resulted in a diffuse MCV. This feature
will move slowly eastward into AR this afternoon, likely aiding in
the development of scattered thunderstorms. A corridor of strong
instability is forecast to extend from AR into parts of MS/AL/FL,
with afternoon SBCAPE values over 3000 J/kg. Vertical shear
profiles are weak throughout this area, but high CAPE and ample
moisture may result in locally intense downdrafts in the strongest
cells this afternoon and evening.
...Eastern NY into northern New England...
The shortwave trough that helped to organized the significant severe
weather event yesterday is now moving across Ontario. The
re-development of scattered thunderstorms is expected this afternoon
along a cold front extending from southern Quebec into eastern NY.
Convergence along the front is weak, and confidence in convective
initiation/longevity is not particularly high. Nevertheless, those
storms that can develop will pose a risk of locally damaging wind
gusts.
..Hart/Mosier.. 08/11/2020
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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