SPC AC 030556
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1156 PM CST Tue Jan 02 2018
Valid 031200Z - 041200Z
...NO SEVERE THUNDERSTORM AREAS FORECAST...
A few thunderstorms are expected across the central and northern
California coastal areas late this afternoon and evening.
Other/ongoing showers and a couple of thunderstorms may persist
early along a portion of the east Florida coast.
Slow progression of the highly amplified upper flow field over the
U.S. will continue today, with both the western ridge and eastern
trough advancing gradually eastward. Within the longer-wavelength
flow, two faster-moving short-wave troughs are evident that will
affect the convective forecast. One, approaching the lower
Mississippi Valley at this time, will sweep quickly east across the
northern Gulf of Mexico and across the Florida peninsula during the
afternoon. A second -- moving northeast across the eastern Pacific,
will affect the West Coast mainly during the second half of the
At the surface, a clipper-type front will cross the Great Lakes
region, while low pressure develops early in the period off eastern
Florida ahead of the upper trough. With time, this low is forecast
to move northward along the Gulf Stream and deepen rapidly.
Elsewhere across the U.S., high pressure will largely prevail.
...Coastal central California...
Showers -- possibly with occasional/embedded lightning -- will
approach, and then reach, portions of coastal central California by
late afternoon, and then expand northward overnight, in conjunction
with passage of the aforementioned upper trough.
...Coastal eastern Florida...
Showers -- and possibly a couple of thunderstorms, may affect
portions of eastern Florida, mainly early in the period. Greater
coverage of convection should, however, remain offshore, with any
inland threat likely ending by mid afternoon at the latest.
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