SPC AC 030620
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1220 AM CST Fri Dec 03 2021
Valid 041200Z - 051200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Severe thunderstorms appear unlikely across the contiguous United
States on Saturday.
...Synopsis and Discussion...
The primary mid-level westerly jet should remain confined to the
northern tier of the CONUS on Saturday, while gradual amplification
occurs over the northwestern/north-central states by the end of the
period as a shortwave trough strengthens over this region. A subtle
southern-stream shortwave trough is forecast to advance eastward
across the lower MS Valley and parts of the Southeast through the
day, while another upper trough/low moves slowly eastward across
Baja California and portions of the Southwest. At the surface, a
cold front should make only slow southward progress Saturday across
the Mid-South/TN Valley as high pressure shifts from the
northern/central Plains and Midwest towards the Atlantic Coast by
early Sunday morning. An area of weak low pressure may exist along
the Red River (OK/TX border vicinity), with a dryline extending
southward from this low across central TX.
Isolated thunderstorms may be ongoing Saturday morning from portions
of northeast TX towards the lower MS Valley in association with the
weak southern-stream shortwave trough described above. Additional
convective development through the day appears uncertain, as
large-scale ascent behind the departing shortwave trough is expected
to remain nebulous. Modest capping across the warm sector may also
tend to inhibit thunderstorm development through much of the day.
Still, there appears to be some chance for at least isolated
thunderstorms to develop by Saturday evening along/east of the weak
surface low across parts of north-central/northeast TX and eastern
OK. Short-term guidance continues to show variability regarding the
quality and northward extent of low-level moisture return across
these areas, which impacts the degree of boundary-layer instability
that may develop. Regardless, deep-layer shear is forecast to remain
fairly weak, which should generally limit the potential for
organized severe thunderstorms. Additional convection may develop
Saturday night from the southern Plains into the lower MS Valley and
Mid-South as a southwesterly low-level jet slowly strengthens,
although this activity will likely remain elevated.
..Gleason.. 12/03/2021
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