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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.

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O'Hare International Airport KORD (Arlington Heights South)
Chicago Executive Airport KPWK (Arlington Heights North)

Thursday, September 18, 2025

SPC Sep 18, 2025 0600 UTC Day 1 Convective Outlook

LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook


Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1159 PM CDT Wed Sep 17 2025

Valid 181200Z - 191200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS CENTERED FROM
OKLAHOMA INTO MISSOURI...AND INCLUDING PORTIONS OF SURROUNDING
STATES...

...SUMMARY...
Strong to locally severe storms are possible from late afternoon
into tonight from parts of Oklahoma into Missouri and over small
parts of adjacent states.

...Discussion...
An upper trough will remain over much of the central and northern
Plains, with cool midlevel temperatures extending as far south as
northern TX. An upper disturbance will move across OK and KS during
the day, pivoting into IA/MO/AR during the evening. Cooling
aloft/height falls associated with this feature should aid daytime
destabilization.

At the surface, a weak boundary should extend from the TX Panhandle
into northern OK, and into the eastern KS/western MO vicinity.
Daytime heating will combine with the cool air aloft and a
marginally moist boundary layer to produce MLCAPE on the order of
1500 J/kg. Early day rain/storms may occur over KS beneath midlevel
cold pocket, and some of this activity could eventually produce
small hail.

By late afternoon and as the low-level lapse rate plume is
established, renewed development is expected from eastern KS into
OK, with activity pushing into western MO and northwest AR through
evening. Overall, deep layer shear will be marginal, however, strong
high-level flow may support a greater chance of hail from the TX
Panhandle into OK, while the coldest midlevel temperatures also
support hail from eastern KS into MO.

..Jewell.. 09/18/2025


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