SPC AC 272000

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0300 PM CDT Sat Apr 27 2024

   Valid 272000Z - 281200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
   THE SOUTHERN AND CENTRAL PLAINS...

   ...SUMMARY...
   Severe thunderstorms are likely today and tonight across the
   southern and central Plains into the lower to mid Missouri Valley.
   The most numerous/intense storms are expected from north Texas into
   Oklahoma and southeast Kansas, where strong tornadoes, very large
   hail of 2-3 inches in diameter and damaging winds of 60-80 mph are
   all possible.

   ...20z Update...
   The previous forecast remains on track for a regional outbreak of
   severe storms with strong, potentially long-track tornadoes, very
   large hail and damaging winds. Numerous storms have initiated within
   the warm sector ahead of the dryline over central KS and much of OK.
   Numerous supercells are present, but storm organization has been
   slow thus far. As the boundary-layer slowly deepens from strong
   southerly warm air advection and muted diurnal heating, an
   increasingly strong low-level jet will gradually expand low-level
   hodographs. Multiple rounds of convection appear likely through
   tonight as the main trough is still forecast to overspread the
   southern Plains from 21-06z. While some uncertainty about storm mode
   and interactions limits predictability for higher tornado probs, the
   environment remains favorable for strong and potentially long-track
   tornadoes and very large hail with the more discrete supercells into
   tonight.

   ...Northern KS and southern NE into MO and IA...
   The cold front/effective boundary has trended farther south than the
   most recent guidance. Additional storm development to the south
   should further reinforce this boundary through the day. Hail and a
   few tornadoes appear likely with supercells along the warm side of
   the front. Have adjusted the ENH southward to better account for
   ongoing storms.

   Farther east, clear skies and strong low-level moisture advection
   have allowed for substantial destabilization over parts of northern
   MO and southern IA. South of the effective front, additional storm
   development into lines and clusters appears likely into the
   afternoon. Damaging winds and a few tornadoes are likely.

   ..Lyons.. 04/27/2024

   .PREV DISCUSSION... /ISSUED 1125 AM CDT Sat Apr 27 2024/

   ...A regional outbreak of severe thunderstorms is forecast for this
   afternoon and evening across parts of KS/OK.  Very large hail and
   strong tornadoes are possible..

   ...OK/northwest TX/south-central KS...
   Water vapor imagery shows the main upper trough is still back over
   southern AZ, with a rapidly ejecting mid/upper level jet streak
   nosing into OK/TX.  This lead feature has aided in the development
   of severe storms this morning over parts of west TX/OK.  Storms will
   develop northeastward through the afternoon into central KS, despite
   an expansive anvil shield from the morning convection.  These storms
   will pose a risk of very large hail and a few tornadoes through the
   afternoon and early evening.

   Farther south, the air mass across much of central/western OK and
   northwest TX continues to warm/destabilize as temperatures rise
   through the mid/upper 70s - eliminating CINH.  Only weak upper
   forcing through the afternoon will result in chaotic development of
   discrete supercells in a very strongly sheared and very unstable
   environment.  Forecast soundings show very steep mid-level lapse
   rates, ample low-level moisture, and strong/increasing shear
   profiles through the day.  Details of timing and location are
   nebulous, but those storms that develop will pose a risk of very
   large hail and strong and possibly long-track tornadoes.  The
   stronger large-scale forcing will arrive around/after dark, with a
   greater eastward surge of storms across central OK expected.  This
   activity may organize upscale in bowing segments will an increasing
   risk of damaging winds along with hail and tornadoes into southeast
   KS and northeast OK tonight.

   ...Southeast CO into northern KS...
   A rather strong surface boundary extends from southeast CO across
   much of northern KS.  Relatively strong heating along this boundary
   and moderate instability will lead to scattered thunderstorm
   development by mid-afternoon along the entire corridor.  Steep
   mid-level lapse rates, strong deep-layer shear, and favorable
   low-level wind profiles in vicinity of the boundary will pose a risk
   of very large hail and a few tornadoes through the afternoon and
   early evening.  This activity is expected to build eastward this
   evening along the same boundary into parts of southern IA/northern
   MO, with a continued risk of large hail along with an increasing
   threat of damaging winds.

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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