Apr 21, 2024 2000 UTC Day 1 Convective Outlook
Updated: Sun Apr 21 19:45:34 UTC 2024 (20240421 2000Z Day 1 shapefile | 20240421 2000Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20240421 2000 UTC Day 1 Outlook Graphic
Day 1 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
MARGINAL 22,991 2,785,681 Jacksonville, FL...Gainesville, FL...Valdosta, GA...Lakeside, FL...Hinesville, GA...
Probabilistic Tornado Graphic
20240421 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
20240421 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 % 23,001 2,772,183 Jacksonville, FL...Gainesville, FL...Valdosta, GA...Lakeside, FL...Hinesville, GA...
Probabilistic Large Hail Graphic
20240421 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
5 % 23,462 2,816,578 Jacksonville, FL...Gainesville, FL...Ocala, FL...Valdosta, GA...Palm Coast, FL...
   SPC AC 211945

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0245 PM CDT Sun Apr 21 2024

   Valid 212000Z - 221200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SOUTHEAST
   GEORGIA INTO NORTHERN FLORIDA...

   ...SUMMARY...
   Isolated damaging gusts and marginally severe hail remain possible
   for a few hours this afternoon/evening across southeast Georgia and
   north Florida.

   ...Southeast Georgia and northern Florida...
   Within the past few hours, a transient supercell on the northern
   fringe of the effective warm sector along the SC coast produced a
   measured severe (58 mph) wind gust, indicating that the environment
   across northern FL into southeast GA remains conducive for severe
   storms. However, convection has struggled to maintain intensity over
   the past few hours despite steadily diminishing MLCIN - possibly
   owing to a temporal displacement between the initial storms and the
   more favorable thermodynamic environment that is currently becoming
   established. Renewed attempts at convective initiation along the
   cold front are noted across south-central GA, so a severe wind/hail
   risk should persist for the next several hours (see forthcoming MCD
   #504 for details). Latest CAM guidance suggests this potential will
   be maximized between 21-00 UTC across southeast GA into far northern
   FL before the front moves off the GA coast and nocturnal cooling
   begins to hinder surface-based convection further south into the FL
   peninsula.

   ..Moore.. 04/21/2024

   .PREV DISCUSSION... /ISSUED 1124 AM CDT Sun Apr 21 2024/

   ...North FL/south GA this afternoon/evening...
   Visible satellite imagery late this morning shows a cumulus field
   and a destabilizing airmass to the east of an ongoing band of
   convection near a southwest-northeast oriented front.  Ample heating
   over the area to the east of patchy cirrus will promote temperatures
   warming into the lower 80s deg F.  12z model guidance so far has a
   negative bias on surface dewpoints across north FL compared to
   observations (3-6 deg F too dry).  This is partially explained by a
   richer moist profile observed through almost 850 mb via the 12z
   Tallahassee raob.  As a result, slightly higher dewpoints (upper 60s
   deg F) and greater buoyancy (1000-1500 J/kg MLCAPE) are expected
   than previously forecast.  Water-vapor imagery shows a lead
   disturbance moving east across the central Gulf Coast, and it will
   reach the northeast Gulf by late this afternoon/early evening. 
   Ascent and some strengthening in flow will aid in some storm
   organization (reference 50-kt 2-6 km flow at Tallahassee on the 88D
   VAD).  Limited low-level convergence and a warm layer near 800 mb
   may act to hinder an otherwise more organized potential severe
   setup.  Regardless, isolated 50-65 mph gusts and marginally severe
   hail are possible with the stronger storms this afternoon into the
   early evening.

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