Wednesday, March 12, 2025

SPC Day 4 Outlook (For Saturday)



  The closer we get to this event, the more it looks like a tornado outbreak. 

ZCZC SPCSWOD48 ALL

   ACUS48 KWNS 120845

   SPC AC 120845


   Day 4-8 Convective Outlook  

   NWS Storm Prediction Center Norman OK

   0345 AM CDT Wed Mar 12 2025


   Valid 151200Z - 201200Z


   ...SEVERE WEATHER OUTBREAK POSSIBLE ON D4/SAT...


   ...DISCUSSION...

   ...Day 4/Sat - Central Gulf Coast States to the Ohio Valley...


   A strong large-scale upper trough is forecast to quickly move across

   the Plains to the MS Valley on Saturday. An intense jet streak will

   move across the Deep South into the OH Valley as this occurs. At the

   surface, a low secondary to the 980 mb low over the Upper Midwest is

   forecast to develop during the late morning/early afternoon across

   the mid-South. This will aid in further northward transport of rich

   Gulf moisture into portions of the Lower MS Valley and TN Valleys.

   Atop this moisture-primed boundary layer, cold 500 mb temperatures

   are forecast. This may support fairly steep lapse rates, which would

   foster moderate instability across portions of MS/AL amid supercell

   wind profiles. However, some uncertainty remains tied to the

   evolution of convection in the Day 3/Fri period into the morning

   hours of Saturday. Some forecast guidance suggests a relatively

   pristine warm sector will be maintained, or if only isolated

   convection develops overnight/early Saturday, recovery could occur.

   If this scenario unfolds, a concerning severe weather setup

   supporting all-hazard severe could unfold across portions of

   LA/MS/AL through the day and into evening, and eventually spreading

   east into GA overnight. Trends will be monitored closely over the

   coming days and further adjustments to the 30 percent/Enhanced risk

   area may be needed in future outlooks.


   With northward extent, instability will become more limited.

   Nevertheless, sufficient moisture amid intense deep-layer flow will

   support swaths of strong/damaging winds into the Ohio Valley and

   portions of the central Appalachians Saturday and Saturday night.

   Higher outlook probabilities may be needed in subsequent outlooks if

   confidence increases.


   ...Day 5/Sun - North Florida into the Carolinas and Mid-Atlantic...


   A strong upper trough will shift east across the Midwest and

   Southeast on Sunday. Strong deep-layer southwesterly flow ahead of

   the trough will overspread much of the eastern U.S. atop a moist

   boundary layer. Bands of convection will likely produce swaths of

   strong to severe gusts ahead of an eastward-advancing cold front. 


   ...Days 6-8/Mon-Wed...


   An upper trough will move offshore over the Atlantic on Monday,

   while a broad upper ridge spreads across the Plains in its wake.

   Another large-scale upper trough will move across the western U.S.

   on Tuesday, ejecting across the Plains and into the MS Valley on

   Wednesday. Some severe potential could return to parts of the

   central or south-central states toward the end of the period with

   this system, but current model forecasts suggest moisture return in

   the wake of the Day 4/5 system will remain poor. Trends will be

   monitored over the coming days.


   ..Leitman.. 03/12/2025


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SPC Day 4 Outlook (For Saturday)

  The closer we get to this event, the more it looks like a tornado outbreak.  ZCZC SPCSWOD48 ALL    ACUS48 KWNS 120845    SPC AC 120845    ...