Aug 31, 2021 0100 UTC Day 1 Convective Outlook
Updated: Tue Aug 31 00:39:58 UTC 2021 (20210831 0100Z Day 1 shapefile | 20210831 0100Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20210831 0100 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
SLIGHT 168,051 3,836,499 Omaha, NE...Lincoln, NE...Montgomery, AL...Sioux City, IA...Tuscaloosa, AL...
MARGINAL 183,731 17,403,572 Kansas City, MO...Virginia Beach, VA...Atlanta, GA...Norfolk, VA...Birmingham, AL...
Probabilistic Tornado Graphic
20210831 0100 UTC Day 1 Tornado Probabilities 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
5 % 23,540 1,157,886 Montgomery, AL...Tuscaloosa, AL...Meridian, MS...Prattville, AL...Enterprise, AL...
2 % 193,451 13,823,305 Atlanta, GA...Omaha, NE...Lincoln, NE...Birmingham, AL...Mobile, AL...
Probabilistic Damaging Wind Graphic
20210831 0100 UTC Day 1 Damaging Wind Probabilities 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
SIG SEVERE 61,586 1,610,379 Omaha, NE...Lincoln, NE...Council Bluffs, IA...Bellevue, NE...Grand Island, NE...
15 % 137,075 2,595,064 Omaha, NE...Lincoln, NE...Sioux City, IA...Rapid City, SD...Council Bluffs, IA...
5 % 96,564 5,865,007 Kansas City, MO...Virginia Beach, VA...Norfolk, VA...Chesapeake, VA...Durham, NC...
Probabilistic Large Hail Graphic
20210831 0100 UTC Day 1 Large Hail Probabilities 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
SIG SEVERE 79,205 459,187 Rapid City, SD...Bismarck, ND...North Platte, NE...Mandan, ND...Pierre, SD...
15 % 132,657 2,498,326 Omaha, NE...Lincoln, NE...Sioux City, IA...Rapid City, SD...Council Bluffs, IA...
5 % 80,036 1,292,511 St. Joseph, MO...Leavenworth, KS...Liberty, MO...Scottsbluff, NE...Excelsior Springs, MO...
   SPC AC 310039

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0739 PM CDT Mon Aug 30 2021

   Valid 310100Z - 311200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
   NORTHERN/CENTRAL PLAINS AND ACROSS PORTIONS OF THE CENTRAL GULF
   COAST REGION...

   ...SUMMARY...
   A few tornadoes remain possible tonight across extreme eastern
   Mississippi and southern/central Alabama in association with
   Tropical Cyclone Ida. Scattered severe storms with very large hail
   and significant damaging winds are also possible across portions of
   the northern and central Plains.

   ...Northern/Central Plains...

   LLJ has yet to increase significantly across the central Plains but
   is expected to strengthen over the next few hours from northwest KS
   into north-central NE. Multiple thunderstorm clusters are
   propagating slowly south across the western Dakotas and this
   activity should gradually increase in areal coverage as boundary
   layer decouples. Over the last hour or so, agitated Cu field over
   Cherry County NE has yielded deeper updrafts, and new thunderstorm
   activity is likely across this region after sunset. 00z sounding
   from LBF exhibited a bit of inhibition which partially explains the
   sparsity of thunderstorms across this region. Even so, low-level
   warm advection later this evening should contribute to an MCS that
   will track southeast with the potential for large hail/damaging
   winds.

   ...Gulf Coast Region...

   Remnants of Tropical Cyclone Ida continue lifting northeast across
   northern MS. Low-level flow is beginning to veer along the central
   Gulf Coast suggesting the greater probabilities for brief tornadoes
   will also gradually shift north. Have adjusted the outlook to
   reflect this trend.

   ...Southern Delmarva/northeast NC...

   Pocket of yet-to-be overturned air remains across extreme southeast
   VA into eastern NC. Scattered thunderstorms trailing across the
   southern Delmarva along the VA/NC border will gradually spread into
   this pocket of buoyancy. Gusty winds may accompany the strongest
   storms for the next few hours before nocturnal cooling weakens
   instability.

   ..Darrow.. 08/31/2021

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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z