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ACUS01 KWNS 041959

SWODY1

SPC AC 041958



Day 1 Convective Outlook  

NWS Storm Prediction Center Norman OK

0258 PM CDT Sat May 04 2024



Valid 042000Z - 051200Z



...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR WEST

TEXAS...



...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF

NORTHWEST/WEST-CENTRAL ILLINOIS...



...SUMMARY...

Scattered severe thunderstorms are expected across parts of the

southern High Plains into the Hill Country of central Texas this

afternoon and evening. Several storms may produce very large hail,

and a couple strong tornadoes are possible.



...20Z Update...



...Far West Texas into TX Hill Country/Central TX...

Outflow-augmented cold front continues to surge southward across the

Permian Basin. Development along the front has been relatively

short-lived thus far, primarily due to the undercutting of the

updrafts. Even so, buoyancy is building north of the front, so more

storm maturation and increasing severe potential appears possible

north of the front. A more thermodynamically favorable environment

exists south of the surging cold front, where there is a greater

potential for surface-based storms capable of all severe hazards,

including tornadoes. 



This initially more discrete activity will likely increase in

coverage later this evening as the shortwave trough currently moving

through northern Mexico reaches Far West Texas. Some potential for

upscale growth exists as forcing increasing, with the resulting MCS

then pushing eastward through the Hill Country. Damaging wind gusts

will be the primary hazards with this convective line. However,

ample low-level moisture and veering low-level flow could support a

few line-embedded QLCS tornadoes.  



...Western Illinois...

As mentioned in recently issued MCD #630, the airmass ahead of the

southeastward-progressing cold front will continue to destabilize as

dewpoints climb into the mid-60s and temperatures warm into the low

80s. Substantial instability (~1500-2000 J/kg MLCAPE) and modest

deep-layer shear will lead to some loosely organized multicell

thunderstorms capable of isolated hail and damaging gusts along and

ahead of the front later this afternoon.



..Mosier.. 05/04/2024



.PREV DISCUSSION... /ISSUED 1142 AM CDT Sat May 04 2024/



...TX/southern OK/extreme southeastern NM...

Not much change for this outlook update other than a minor southward

shift of severe probabilities across far southeast NM and West TX to

account for the projected cold front position by mid afternoon. 

Still expecting widely scattered to scattered thunderstorms to form

this afternoon along and behind the cold front over west TX and

southeastern NM, as well as ahead of the cold front, near the

dryline and over strongly heated, relatively high elevations west of

the Pecos Valley.  The stronger updrafts will attain supercell

characteristics and pose a large-hail threat on both sides of the

front, with severe-wind and tornado potential more prevalent to its

south.  Forecast soundings south of the front indicate veering and

increasing flow with height which will become very favorable for

supercells.  It still appears one or two dominant, prefrontal,

mid/late-afternoon supercells may evolve and remain south of the

front.  The potential for a strong tornado in addition to giant hail

will be the primary hazards with these warm sector supercells. 

Additional storm development is expected by early evening with an

amassing of cold pools eventually expected, as southeasterly 850mb

flow strengthens.  A severe MCS will likely evolve during the

evening and probably persist into the overnight as it moves east

across portions of the Edwards Plateau and central TX.  Have

expanded wind probabilities farther east to account for a lingering

threat for severe gusts and perhaps a localized risk for a tornado

late as this activity moves east of I-35.



...North/northeast TX to mid Mississippi Valley/western Great Lakes

vicinity...

A diurnal intensification of isolated to scattered thunderstorms is

expected this afternoon within this general corridor from the Red

River Valley northeastward into the IL/WI vicinity.  With much of

this region located in between larger-scale mid-level waves, modest

kinematic fields will tend to limit overall storm organization and

severe potential.  Nonetheless, heating of a moist boundary layer

will facilitate the development of moderate instability by early to

mid afternoon.  Mainly semi-organized bands of multicells and

clusters thereof will occasionally result in sporadic potential for

wind damage and large hail.  It appears perhaps a corridor for

greater wind damage potential may occur immediately ahead/downstream

of an MCV moving east across the mid MS Valley.  Model guidance

indicates slightly greater organized line segments and wind

potential later this afternoon from central into northern portions

of IL.  Have also expanded the MRGL northward into portions of WI

where sufficient destabilization will occur ahead of a front and

associated mid-level disturbance over the Upper Midwest.



$$