SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1115 AM CST Sun Dec 04 2022
Valid 051200Z - 061200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
...SUMMARY...
The risk for severe thunderstorms appears negligible across the
U.S., Monday through Monday night.
...Synopsis...
Higher latitude blocking, including one prominent mid-level ridge
across the Greenland vicinity, likely will be maintained through
this period and beyond. To the southwest of this ridge, a broad
mid-level low continues to evolve across much of Canada and the
northern tier of the U.S. (to the east of the Rockies), with some
retrogression of its deep center to the west-northwest of Hudson Bay
forecast through Monday/Monday night. As this occurs, models
indicate that cold surface ridging will build and begin to nose
southward to the lee of the Canadian Rockies, preceded by a more
modest cold intrusion across much of the Upper Midwest, upper
Mississippi Valley and northern into central Great Plains by 12Z
Tuesday.
A prior cold front is now in the process of stalling across the
south Atlantic and Gulf Coast vicinity, and is forecast to weaken/
retreat northward beneath a modestly amplified belt of westerlies
emanating from the mid-latitude eastern Pacific. By late Monday
into Monday night, it appears that this will include building
mid-level ridging across the Southeast (to the north of a prominent
subtropical high centered near the Yucatan Peninsula) and digging,
positively tilted large-scale troughing near and to the west of
California and Baja California.
Downstream of this troughing, a plume of lower/mid-tropospheric
moist return flow, which has developed off the lower latitude
eastern Pacific, may become suppressed south of the Southwestern
international border vicinity by 12Z Monday. But mid-level moisture
return will continue around the western/northwestern periphery of
the downstream ridging, across Texas and the lower Mississippi
Valley into the western slopes of the southern Appalachians and
surrounding Southeast. At the same time, it appears that modest
ongoing low-level moisture return, emanating from the western Gulf
of Mexico, will gradually spread from southern/eastern Texas through
much of the Mid South and Tennessee Valley vicinity, while also
increasing off the northwestern Gulf into the central Gulf Coast
states.
...Gulf Coast/Southeast...
Warming mid-level temperatures probably will cap weak surface-based
(or near surface-based) destabilization across much of the Gulf
coastal plain Monday through Monday night. However, despite
generally weak mid-level lapse rates, elevated moisture return
farther north may contribute to weak destabilization and convection
rooted within a developing persistent lower/mid tropospheric warm
advection regime, across the Mid South into southern Appalachians
vicinity. This may include occasional embedded thunderstorm
development, aided by mid/upper provided by weak perturbations
migrating around the periphery of the subtropical ridge.
...Northern California vicinity...
Weak instability beneath the mid-level cold core of a remnant
digging cyclonic circulation will contribute to the risk for
convection occasionally capable of producing lightning, from near
coastal areas into the Sierra Nevada.
..Kerr.. 12/04/2022
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