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ACUS01 KWNS 272002

SWODY1

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.



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