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Day 1 Outlook Convective Tornado
Hail Wind
Categorical Day1 1200Z Outlook
Images courtesy of the NWS Storm Prediction Center
 Forecast Discussion

ACUS01 KWNS 180452
SPC AC 180451

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1151 PM CDT Thu Sep 17 2020

Valid 181200Z - 191200Z


Severe thunderstorms are not expected today.

...Pacific Northwest through northern Rockies region...

A large upper low currently offshore will advance slowly east and
will likely be centered over the northern Rockies by the end of this
period. Vorticity maxima will rotate through this feature and serve
to modulate thunderstorm coverage over the Pacific NW. The stronger
winds aloft accompanying the upper low will shift east of the richer
low-level moisture situated west of the Cascades. While a strong
storm or two cannot be ruled out, mainly across portions of WA and
OR where the surface layer destabilizes this afternoon and early
evening, the marginal thermodynamic environment should serve as a
limiting factor for severe storms.


A few thunderstorms will remain possible along coastal NC early in
this period and across south TX during the day in association with a
cutoff upper low circulation, but no severe weather is expected.

..Dial/Wendt.. 09/18/2020