SPC Nov 21, 2024 1930 UTC Day 3 Severe Thunderstorm Outlook

SPC 1930Z Day 3 Outlook

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0129 PM CST Thu Nov 21 2024

Valid 231200Z - 241200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms appear unlikely across the CONUS Saturday.

...Synopsis...
Mid-level flow across the CONUS is forecast to become more zonal
with time as prominent troughing on either coast gradually
deamplifies. Ridging over the central CONUS will weaken and shift
eastward as the East Coast trough moves offshore. To the west,
strong mid-level flow will move inland across the Pacific Northwest
and northern Rockies as the upper low cuts off southwest of BC. A
weak surface low and cold front will move across the northern
Rockies and intensify over the High Plains. High pressure over the
eastern US will favor cool, dry and stable offshore flow across the
eastern half of the country.

...Northwest and Northern Rockies...
As the broad upper-level cyclone over the Pacific Northwest
gradually devolves, a lead shortwave trough embedded within the
stronger zonal flow will quickly eject eastward over the Northern
Rockies. A weak surface low and trailing cold front will also move
east with the stronger flow aloft. Area model soundings show weak
destabilization is possible over parts of eastern OR and southern ID
as forcing for ascent increases and low-level lapse rates steepen
ahead of the front.  While very limited, enough buoyancy (MUCAPE
~100-200 J/kg) may develop for a few lightning flashes with
low-topped, mixed-phase, convective elements. Additionally,
low-topped storms may approach near shore areas of OR/WA and
northern CA. However, cool inland surface temperatures and weakening
large-scale ascent should limit lightning chances inland.

..Lyons.. 11/21/2024

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