ACUS01 KWNS 210041
SWODY1
SPC AC 210040

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0640 PM CST Wed Nov 20 2024

Valid 210100Z - 211200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
Severe thunderstorms are not expected tonight; although, a few
strong storms may be noted along the immediate Washington/Oregon
Coast this evening.

...01z Update...

Strong upper low off the BC/WA coast should gradually fill tonight
as it occludes offshore. As a result, mid-level heights will
gradually rise through sunrise, and onshore flow should weaken.
Until then, a few longer-lived showers/supercells developed about
100mi offshore and are now moving inland, especially over northwest
Pacific County WA. This convection was aided by marine-influenced
buoyancy, but this activity will quickly weaken as it encounters a
poor air mass inland. Some near-term risk for gusty winds, and
perhaps an offshore water spout, exist for the next few hours.
However, severe threat does not appear to be enough to warrant
severe probabilities overnight.

Downstream across the middle Atlantic, strong height falls will
spread across this region (180m in 12hr) ahead of a pronounced upper
low shifting southeast across the Great Lakes. A plume of modest
0-3km lapse rates developed across the Ohio Valley earlier this
afternoon which appeared to aid shallow convection across eastern OH
into western PA, where some localized damaging winds were noted.
However, this convection has spread well east of this steeper plume
and poor low-level lapse rates downstream do not support robust
updrafts overnight.

..Darrow.. 11/21/2024

$$

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