SPC AC 011943

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0243 PM CDT Tue Apr 01 2025

   Valid 012000Z - 021200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING
   AND OVERNIGHT ACROSS PARTS OF OKLAHOMA AND KANSAS....

   ...SUMMARY...
   Rapid, intense thunderstorm development should occur this evening
   over parts of the central/southern Plains. A few supercells with a
   risk for very large hail and strong tornadoes appear possible,
   particularly across central Oklahoma into eastern Kansas. A line of
   thunderstorms should also develop and pose a threat for
   severe/damaging winds across eastern Kansas into western Missouri
   tonight.

   No changes have been made to the ongoing convective outlook severe
   risk areas.  Low-level moisture is streaming northward, roughly in
   line with model guidance.  This will lead to a corridor of strong
   instability and only weak cap by late afternoon to the east of the
   surface dryline.  Widely scattered intense supercells are expected
   to develop by early evening along the dryline from central KS into
   central OK.  Very favorable thermodynamic and kinematic parameters
   suggest all severe hazards are possible with these storms, including
   very large hail and a strong tornado or two.

   Overnight, the primary upper trough and associated 100 knot
   mid-level jet max will move into the Plains states, leading to the
   development of another round thunderstorms over eastern KS/OK before
   12z. These storms will also pose a risk of large hail and a few
   tornadoes.

   ..Hart.. 04/01/2025

   .PREV DISCUSSION... /ISSUED 1135 AM CDT Tue Apr 01 2025/

   ...OK-TX...
   Visible-satellite imagery shows stratus and moisture streaming
   northward through TX into OK on strengthening southerly low-level
   flow.  Increasingly rich moisture around 850 mb layer will mix
   downward beneath an initially strong capping inversion sampled on 12
   UTC area observed soundings.  Heating of an increasingly moist and
   destabilizing boundary layer will result in a very unstable airmass
   late this afternoon into the early evening.  Models show lower 60s
   dewpoints reaching I-40 by early evening.  Very strong and favorable
   wind profiles for supercells will support rapid supercell
   development if storms initiate (22-01 UTC).  Models differ on the
   diurnal storm coverage casting considerable uncertainty---but some
   guidance has trended towards at least one to a few dryline discrete
   supercells across the southern Great Plains.  Very large hail and
   tornadoes would be the primary hazards.  Enlarged and elongated
   hodographs would support the potential for strong tornadoes provided
   a sustained supercell develops late this afternoon/evening.  Later
   tonight, models show richer moisture with a very unstable airmass
   being maintained.  Of particular note is forcing for ascent
   perturbing the airmass from north-central TX into OK near and ahead
   of the front.  A nocturnal risk for renewed supercell development
   capable of all hazards would be strongly favored with any activity
   not undercut by the front---mainly during the 08-12 UTC period.  

   ...Central Plains into Missouri...
   Not much change in thinking from the prior forecast.  The cap is
   forecast to erode on the northern periphery of more appreciable
   moisture over the central High Plains by late afternoon or early
   evening.  At least isolated thunderstorms are expected to develop
   near the triple point in the south-central KS/north-central OK
   vicinity, and subsequently spread quickly northeastward.  Moderate
   to locally strong instability, coupled with 50-60 kt of effective
   bulk shear, will easily support supercells, with an associated
   threat for very large hail (up to 2-3 inches in diameter).  As the
   southerly low-level jet markedly increases this evening, hodographs
   will enlarge and become elongated, with ample effective SRH to
   support tornadoes with any sustained supercells. Given the strength
   of the low-level flow expected (50-60+ kt southerly jet at 850 mb)
   and degree of low-level shear forecast, strong tornadoes appear
   possible.  A line of convection should also erupt along the cold
   front in north-central to northeast KS tonight, and spread eastward
   into parts of western MO through early Wednesday morning. Even with
   the time of night, the overall environment appears quite favorable
   for severe/damaging winds, including the potential for isolated 75+
   mph gusts. 

   ...Central Valley of California...
   With cold air aloft associated with the upper trough over the
   western CONUS, weak instability could develop by peak afternoon
   heating to support isolated strong thunderstorms. These could pose a
   risk for small hail, gusty winds, and perhaps a brief tornado
   across portions of the Central Valley in CA.

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