Aug 28, 2023 2000 UTC Day 1 Convective Outlook
Updated: Mon Aug 28 19:45:50 UTC 2023 (20230828 2000Z Day 1 shapefile | 20230828 2000Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20230828 2000 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MARGINAL 151,343 25,729,864 Charlotte, NC...New Orleans, LA...Atlanta, GA...Raleigh, NC...Birmingham, AL...
Probabilistic Tornado Graphic
20230828 2000 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
No Risk Areas Forecast
Probabilistic Damaging Wind Graphic
20230828 2000 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
5 % 151,958 25,813,797 Charlotte, NC...New Orleans, LA...Atlanta, GA...Raleigh, NC...Birmingham, AL...
Probabilistic Large Hail Graphic
20230828 2000 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
No Risk Areas Forecast
   SPC AC 281945

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0245 PM CDT Mon Aug 28 2023

   Valid 282000Z - 291200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
   ACROSS PORTIONS OF THE SOUTHEAST...

   ...SUMMARY...
   Isolated storms capable of strong and gusty winds are possible
   across the Southeast this afternoon.

   ...20Z Update...

   ...Southeast...
   18Z soundings sampled a moist, moderately buoyant, and weakly
   sheared environment across the region. This matches the overall
   expectation outlined in the previous outlook (appended below), with
   a predominantly disorganized multicellular storm mode anticipated.
   Isolated water-loaded downbursts remain possible, particularly from
   southern MS and across much of AL where the highest storm coverage
   is anticipated.

   ...Central/Southern High Plains...
   Convective initiation has already occurred across the high terrain,
   with southeastward motion still expected to take these storms into
   the High Plains. Mesoanalysis estimated effective bulk shear is
   already 20 to 25 kt across the region, with some additional increase
   anticipated throughout the afternoon. As such, some organization is
   possible, with an attendant threat for a strong gust or two. Overall
   coverage is still expected to remain too low for an outlook area.

   ..Mosier.. 08/28/2023

   .PREV DISCUSSION... /ISSUED 1126 AM CDT Mon Aug 28 2023/

   ...Southeast this afternoon...
   A weak midlevel trough persists from the northern Gulf of Mexico to
   the southern Appalachians with multiple embedded vorticity maxima. 
   Vertical shear is very weak across the Southeast, and thermodynamic
   profiles are less favorable for strong downdrafts compared to
   previous days.  Thus, scattered pulse-type storms are expected this
   afternoon along a combination of a stalled synoptic front, weak
   differential heating zones and local sea breeze circulations.  The
   wind-damage threat appears to be on the lower margins for an outlook
   area, but will maintain the 5% area for the possibility of isolated
   downbursts.

   ...Central/southern High Plains this afternoon/evening...
   Similar to yesterday, a few storm clusters will form this afternoon
   and move south-southeastward from southeast WY across eastern CO
   into eastern NM through this evening.  Effective bulk shear of 25-30
   kt will support semi-organized storms, a few of which could produce
   gusty outflow winds and small hail.  However, the storms will be
   relatively low topped for late summer and the severe threat appears
   too marginal to add an outlook area.

   ...Tropical cyclone Idalia and FL...
   Tropical storm Idalia is expected to become a hurricane later today
   into tonight while moving northward toward the southeast Gulf of
   Mexico (please refer to latest NHC advisories for additional
   information).  The stronger wind profiles and associated supercell
   threat will likely be delayed in FL until Tuesday during the day, so
   will not add any tornado probabilities in this update.

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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z