SPC Nov 21, 2024 1730 UTC Day 2 Convective Outlook

SPC 1730Z Day 2 Outlook

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1121 AM CST Thu Nov 21 2024

Valid 221200Z - 231200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
A few thunderstorms are possible along the Pacific Northwest Coast
Friday. Severe storms are not expected.

...Synopsis...
Amplified mid-level flow is likely over much of the CONUS Friday,
with a deep upper low off the East Coast and a similarly deep trough
off the West Coast. Between the two lows, a shortwave ridge will
slowly migrate eastward over the central Plains. At the surface, a
low and trailing cold front will steadily move offshore through the
day over the East. High pressure and offshore flow are likely over
the central CONUS. While along the West Coast, a pronounced low and
onshore flow will continue.

As the upper trough continues to shift eastward, cool and stable
offshore flow should limit buoyancy and deep convection over the
eastern 2/3rds of the CONUS. The only exception to this could be
brief, low-topped storms near Cape Cod. A few deeper convective
elements embedded within broad stratiform could produce sporadic
lightning before stronger offshore flow shifts any lingering
buoyancy completely offshore by midday.

Across the Pacific Northwest, continuous onshore flow is likely as
the cold core of the upper trough (-28 to -30 C 500 mb temps) moves
onshore late in the day and overnight. Scattered low-topped
convection will be most likely over the ocean overnight, but a few
thunderstorms with sporadic lightning could move inland. With very
weak MUCAPE (100-200 J/kg) any stronger updrafts will likely be
brief. Strong deep-layer shear could briefly overlap with the
buoyancy supporting a sporadic strong wind gust near the coast.
However, the transient nature of the updrafts should keep the severe
risk negligible.

..Lyons.. 11/21/2024

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