SPC AC 250723
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0223 AM CDT Mon Sep 25 2017
Valid 271200Z - 281200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
The severe weather threat across the continental U.S. is expected to
be low on Wednesday.
A cut-off low across the Southwest will remain nearly stationary
throughout the forecast period. Farther east, mid-level flow will
strengthen across the Great Lakes and vicinity in response to a
series of amplifying troughs migrating eastward across Ontario and
Quebec. A ridge will also remain nearly stationary across Texas and
At the surface, an expansive ridge will overspread much of the
CONUS, including the Rockies, Plains, and western Great Lakes. This
ridge will result in a cooler, drier airmass in many areas northwest
of a front located from south Texas through Arkansas and into Ohio.
With deeper boundary layer moisture displaced from areas of
mid-level flow, the severe threat across much of the country (except
for the Southwest) will be fairly low.
Across the Southwest, models are consistent in depicting scattered
convection during the afternoon on the east side of the cutoff low.
Deep shear profiles will encourage some organization and the
expected steep lapse rates that will exist by mid to late afternoon
may support isolated downburst winds approaching severe limits.
Models are not consistent regarding the amount of destabilization
across the region - with these inconsistencies primarily tied to the
amount of mid-level cooling across portions of eastern Arizona and
western New Mexico. At this time, the severe risk is expected to be
too isolated to merit severe probabilities, although the region will
be monitored in later outlooks.
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