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ACUS01 KWNS 230514

SWODY1

SPC AC 230513



Day 1 Convective Outlook  

NWS Storm Prediction Center Norman OK

1213 AM CDT Tue Apr 23 2024



Valid 231200Z - 241200Z



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

NORTHWEST TEXAS...



...SUMMARY...

A few severe thunderstorms capable of producing large hail (2+ inch

diameter) and gusts to 65 mph will be possible this afternoon and

evening across northwest Texas. Additional strong storms producing

hail to near 1 inch diameter and 60 mph gusts are possible from

southeast Wisconsin and northern Illinois into Lower Michigan.



...Synopsis...



An upper shortwave trough will pivot eastward across the Upper Great

Lakes to the Northeast today. Meanwhile, upper ridging will be

focused over the Rockies. At the surface, an area of elongated low

pressure is forecast from Quebec to the Upper MS Valley. A secondary

surface low is forecast to develop over the TX Panhandle/South

Plains. A cold front will link between these two areas of low

pressure, extending from southwest WI to central OK and the TX

Panhandle by early/mid afternoon. A prior cold frontal intrusion

into the Gulf of Mexico and surface high pressure over the Southeast

will limit boundary-layer moisture. However, east/southeasterly

low-level trajectories into TX become more south/southwest into OK

and the along the surface trough into the Upper Great Lakes will

allow for low 60s F dewpoints south (southern Plains) to 40s F

dewpoints north (Great Lakes).



...Upper Great Lakes...



Stronger large-scale ascent will be focused across WI/Lower MI and

vicinity during the afternoon ahead of the surface front and upper

shortwave trough. While boundary-layer moisture will remain modest,

temperatures aloft are forecast to be quite cool, resulting in very

steep midlevel lapse rates. This will foster MLCAPE values generally

less than 750 J/kg amid modest effective shear magnitudes greater

than 30 kt. This should support isolated strong to severe storms

during the afternoon/evening from southeast WI into northern IL/IN

and parts of Lower MI. Elongated hodographs and mainly elevated

instability coupled with the cold temperatures aloft may support

hail to near 1 inch diameter. Steep low-level lapse rates amid a dry

boundary-layer also may support locally strong gusts. 



...Northwest TX/Southwest OK vicinity...



Large-scale ascent will be somewhat nebulous over the region today,

but subtle northwest flow aloft amid veering low-level wind profiles

will result in 40+ kt effective shear magnitudes. Strong heating in

the vicinity of a surface low/triple point and dryline, coupled with

steep midlevel lapse rates, will aid in moderate destabilization

(MLCAPE around 1500-2000 J/kg possible). This should support a few

organized cells during the late afternoon/evening. Elongated

forecast hodographs and modest vertical shear through 3 km suggests

supercells capable of large hail (2+ inch diameter) are possible.

Weak low-level flow and mixing to around 850 mb also indicates some

potential for locally strong/severe gusts. While storm coverage is

expected to remain isolated, given potential for significant hail

(2+ inch diameter), a Slight (level 2 of 5) risk has been included.



..Leitman/Weinman.. 04/23/2024



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