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ACUS01 KWNS 231957

SWODY1

SPC AC 231956



Day 1 Convective Outlook  

NWS Storm Prediction Center Norman OK

0256 PM CDT Tue Apr 23 2024



Valid 232000Z - 241200Z



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

TEXAS...



...SUMMARY...

Isolated severe thunderstorms capable of producing large hail

(potentially 2+ inch diameter) and gusts to 65 mph will be possible

this afternoon and evening across northwest Texas.



...20Z Update...

Overall forecast outlined in the previous discussion (appended

below) remains valid. As mentioned in recently issued MCD 506, a

supercell or two should develop across a portion of western North

Texas through late afternoon, with large hail of 1.5 to 2.5 inches

in diameter and localized severe gusts of 60-70 mph possible. An

isolated storm or two is also possible farther south in the Texas

Trans Pecos vicinity. Marginally severe hail (i.e. around 1" in

diameter) and damaging gusts are possible here as well.



Farther north, isolated thunderstorms are still anticipated from

northern IL into Lower MI ahead of an approaching shortwave trough

and associated cold front. A few strong to severe storms are

possible with small to marginally severe hail and damaging winds as

the primary hazards (as mentioned in recently issued MCD 507).



...Early tomorrow morning from TX Panhandle into

north-central/central OK...

Elevated thunderstorms may develop from the northeast TX/eastern OK

Panhandles into central/north-central OK within the warm-air

advection regime along the northeastern edge of the returning

low-level moisture. Steep mid-level lapse rates and favorable

cloud-bearing layer shear could support an isolated instance or two

of hail with initial development. However, severe coverage is

currently expected to remain less than 5%, precluding the

introduction of any outlook areas.



..Mosier.. 04/23/2024



.PREV DISCUSSION... /ISSUED 1123 AM CDT Tue Apr 23 2024/



...Northwest TX...

Visible satellite imagery and surface analysis this morning indicate

the initial stage of moisture return is occurring across the

southern Great Plains in the wake of a frontal intrusion into the

Gulf a few days ago.  A mid-level ridge will increasingly become

established across the central/southern Rockies and adjacent High

Plains as a Great Lakes disturbance gradually becomes more displaced

from the region.  An associated cold front will move southward

across KS/OK before eventually stalling tonight across southeast OK

and northwest TX.  Weak lee cyclogenesis will aid in maintaining a

southerly low-level fetch across central into west TX as strong

heating results in a sharpening dryline by late afternoon.  Isolated

thunderstorm development will be most probable near the triple point

20-22Z.  Steep lapse rates coupled with adequate moisture (1500-2000

J/kg MLCAPE) and veering flow beneath moderate westerlies, will

support an initial supercell mode.  Isolated very large hail of

2-2.5 inches in diameter will be the main threat, along with a few

55-65 mph gusts.



...Northern IL/southeast WI/Lower MI late this afternoon/evening...

Have not changed the existing outlook for this region due primarily

to consistency in model data and the forecast conceptual model not

deviating.  Water-vapor imagery this morning shows a mid-level

trough over the Upper Midwest and this will continue southeast into

the central Great Lakes by mid evening.  An associated surface

trough will likewise move southeastward, and this trough will be

preceded by a band of rain with minimal buoyancy.  Behind the rain

band, surface heating with steepening low-level lapse rates and

cooling midlevel temperatures will support weak surface-based

buoyancy just ahead of a secondary frontal surge.  Some low-topped

convection will be possible late this afternoon through late evening

from northern IL/southeast WI into Lower MI.  The stronger storms

could yield a localized marginal hail/damaging wind threat.



$$