SPC AC 291228
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0628 AM CST Sat Jan 29 2022
Valid 291300Z - 301200Z
...NO THUNDERSTORM AREAS FORECAST...
...SUMMARY...
Thunderstorm areas are not forecast today over the contiguous U.S.
...Synopsis/Discussion...
The mid/upper-level pattern will remain characterized by mean
troughing in the East and ridging in the West. Within the large
area of cyclonic flow in the eastern CONUS, a basal trough initially
over parts of GA and the Carolinas will eject northeastward offshore
from the Mid-Atlantic and New England today. By 00Z, a compact
cyclone should form at 500 mb near Cape Cod and move northeastward
to southern New Brunswick by 06Z. An intense surface low --
analyzed at 11Z roughly east of the southern Delmarva Peninsula and
south of ACK, will eject northeastward parallel to the 500-mb low,
but farther east across Nova Scotia.
Among short-term progs, the RAP most aggressively destabilizes
mid/upper-level lapse rates in some of the elevated conveyor today
near Cape Cod and parts of the ME coast. That strongest UVV
scenario results in minor buoyancy (MUCAPE of about 75 J/kg or less)
astride the -20 C isotherm, and rooted between 550-600 mb. While
brief/isolated lightning (and associated thundersnow) cannot be
ruled out in the most vigorously convective portions of the conveyor
northwest of the surface low, overall lightning potential appears
too low, isolated and conditional to warrant a 10%/general thunder
area at this time.
A southern-stream perturbation aloft, with an accompanying broad,
weak, closed 500-mb cyclone now off the CA coastline, will move
across southern CA this evening and overnight, reaching southwestern
AZ by 12Z tomorrow. Very elevated/midlevel destabilization above a
moist layer, with weak buoyancy, also is evident in a few forecast
soundings late this afternoon into this evening around 500 mb, near
the SAN-YUM corridor. However, a deep, very dry layer will exist
below any shallow midlevel convection, and thunder potential appears
too minimal for an outlook area.
..Edwards/Goss.. 01/29/2022
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