SPC AC 042203

   Day 1 Convective Outlook CORR 1
   NWS Storm Prediction Center Norman OK
   0403 PM CST Mon Mar 04 2024

   Valid 042000Z - 051200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER A LARGE
   AREA FROM CENTRAL/EAST TEXAS INTO MOST OF THE MISSISSIPPI VALLEY...

   CORRECTED FOR TYPO

   ...SUMMARY...
   Isolated strong to severe thunderstorms will be possible this
   afternoon into tonight from parts of central Texas into the lower
   Mississippi Valley, as well as from the Ozarks into the Midwest.
   Large hail is expected to be the main threat, but strong/gusty winds
   and even a tornado may also occur.

   ...20Z Update...

   ...Eastern IA/Northern MO/Northern IL...
   Recent surface analysis places a low just south of the IL/WI/IA
   border intersection. A cold front extends southwestward from this
   low across northern MO and eastern KS, while a warm front extends
   eastward across northern IL and then arcs sharply northeastward over
   southern Lake Michigan. A few elevated storms have been noted near
   the surface low, with some deepening warm sector cumulus also
   ongoing from central MO into northern/central IL. As mentioned in
   MCD #0189, additional thunderstorm development is still expected
   along and just ahead of cold front from far eastern IA into
   northwest Illinois and northeast Missouri in the next 1-3 hours.
   Front-parallel orientation to the deep-layer vertical shear will
   likely lead to an undercutting of these storms, with a predominantly
   elevated storm mode anticipated. Even so, steep lapse rates will
   support some stronger updrafts capable of hail. Some damaging gusts
   are possible as well, particularly as cells interact with the cold
   front.

   ...East TX/LA/Western MS this afternoon and evening...
   Scattered thunderstorms are currently ongoing from East TX across
   much of LA, supported by southwesterly flow aloft and resultant
   warm-air advection. General expectation is for these storms to
   gradually shift northeastward into more of western MS over time, in
   tandem with the zone of most favorable warm-air advection. Modest
   vertical shear remains favorable for transient supercell structures
   and the threat for hail and damaging gusts.

   ...Eastern OK into Mid MS Valley this evening and overnight...
   Thunderstorm development along the front later this evening along
   the from southern MO into eastern OK remains uncertain, given the
   potential for warm mid-level temperatures and resulting capping.
   Additionally, vertical shear will be modest, with a resultant
   potential for the front to undercutting development. Even so, the
   warm and moist low-levels combined with steep mid-level lapse rates
   will support a conditional risk for severe hail.

   ..Mosier.. 03/04/2024

   .PREV DISCUSSION... /ISSUED 1000 AM CST Mon Mar 04 2024/

   ...East TX/LA/Western MS Today...
   Moderately strong southern-stream mid-level flow is present today
   across the southern states, with several weak perturbations
   affecting the area.  A warm and moist surface air mass is in place
   across east TX into LA, where dewpoints in the upper 60s and 70s
   will yield afternoon MLCAPE of 1500-2000 J/kg.  Weak low-level warm
   advection is expected to result in increasing thunderstorm
   development this morning through the afternoon as storms spread
   eastward toward southwest MS.  Deep-layer shear is sufficient for at
   least transient supercell structures, but relatively weak low-level
   winds suggest the main threats will be hail and gusty winds with the
   strongest cells.

   ...Eastern IA/Northern MO/Northern IL...
   A strong surface cold front is sagging southeastward across IA this
   morning into a marginally moist and unstable air mass.  All 12z
   model guidance agrees on the development of showers and
   thunderstorms along the front by early afternoon, although many
   solutions suggest most of the activity will be behind the front and
   slightly elevated.  Nevertheless, cool temperatures aloft and steep
   mid-level lapse rates will promote hail in the stronger cores. 
   Storms that can form and persist ahead of the front would have some
   marginal concern for gusty winds and perhaps a brief tornado as
   well.

   ...Eastern OK into Mid MS Valley...
   Morning model guidance is quite diverse in the development of
   thunderstorms across this region, with low confidence in any
   particular area.  Will maintain the ongoing MRGL area as a
   conditional risk if storms can form - mainly due to unseasonably
   warm and moist conditions and sufficient CAPE for some risk of hail.
    However, considerably uncertainty exists.

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