ACUS01 KWNS 031235
SWODY1
SPC AC 031234

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0734 AM CDT Tue Sep 03 2024

Valid 031300Z - 041200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN ROCKIES/GREAT BASIN AND ADJACENT HIGH PLAINS...

...SUMMARY...
Thunderstorms developing across the northern Rockies and adjacent
portions of the Great Basin this afternoon may produce occasional
strong to severe wind gusts, before spreading eastward toward the
northern High Plains this evening.

...Northern Great Basin/Rockies into the Adjacent High Plains...
An upper trough/low over the Pacific Northwest this morning will
continue moving eastward today across the northern Rockies. This
feature is forecast to gradually weaken through the period, but
enhanced mid-level west-southwesterly flow will persist across parts
of the northern Great Basin into the northern Rockies and adjacent
High Plains. As large-scale ascent associated with the upper trough
overspreads the northern Rockies, thunderstorms should develop over
the higher terrain through early afternoon in tandem with daytime
heating.

Latest surface observations show somewhat greater low-level moisture
across this region, with surface dewpoints generally in the mid 40s
to low 50s across central ID into southwest MT. Although instability
is forecast to remain fairly modest this afternoon, deep-layer shear
around 25-35 kt should be sufficient to support organized
convection, including the potential for a couple of marginal
supercells initially with associated hail/wind threat. With
steepened low/mid-level lapse rates present, this activity should
continue to pose some threat for isolated strong to severe wind
gusts as it congeals and spreads east-northeastward across parts of
the northern High Plains through this evening.

Somewhat more limited low-level moisture should be present this
afternoon farther south into WY and northern UT. Even so, diurnal
heating will aid in a deeply mixed boundary layer by this afternoon,
and steep mid-level lapse rates are also expected to remain over
this region. The net result will be high-based thunderstorms capable
of producing isolated strong to severe winds initially developing
across northern UT into far eastern ID, and subsequently moving
east-northeastward over WY through the evening. Confidence in a more
concentrated corridor of severe winds remains generally low at this
time given the weak instability and modest deep-layer shear
forecast, especially with southward extent into the northern Great
Basin and WY.

..Gleason/Leitman.. 09/03/2024

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