SPC Apr 12, 2025 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0237 PM CDT Sat Apr 12 2025

Valid 122000Z - 131200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHERN MONTANA INTO NORTHERN WYOMING AND FAR WESTERN SOUTH
DAKOTA...

...SUMMARY...
Thunderstorms with isolated severe gusts are possible across parts
of southern Montana/northern Wyoming to the Black Hills this
afternoon and evening.

...20Z Update...
The forecast remains on track, and no changes were made with this
update. For details, see the previous discussion below.

..Weinman.. 04/12/2025

.PREV DISCUSSION... /ISSUED 1112 AM CDT Sat Apr 12 2025/

...Southern Montana into Northern Wyoming and Far Western South
Dakota...
A mid-level shortwave trough over WA/OR will move eastward over
ID/MT/WY by tonight, with downstream lee cyclogenesis occurring
across the central High Plains. Low-level moisture will remain very
limited across the northern Rockies and adjacent High Plains, with
surface dewpoints generally in the 30s. But, forcing for ascent and
mid-level moisture should be sufficient for high-based thunderstorms
to develop this afternoon/evening across parts of northern WY and
southern MT. Forecast soundings show inverted-v profiles with weak
instability and some increase in mid-level winds, which could
support isolated strong to severe wind gusts with this convection as
it spreads eastward.

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