spc ac 181712
day 2 convective outlook
nws storm prediction center norman ok
1112 am cst mon jan 18 2021
valid 191200z - 201200z
...no severe thunderstorm areas forecast...
a few thunderstorms will be possible tuesday afternoon and evening
across a portion of south texas as well as near the coast of
low-amplitude shortwave ridging aloft will gradually build across tx
tuesday. a weak vorticity maximum may move through the upper ridge
during the evening. a cold front initially from the lower ms valley
through south central and southwest tx will advance slowly south.
partially modified gulf air with dewpoints generally in the low 60s
f will advect through the pre-frontal warm sector. scattered showers
are expected to develop, primarily in the frontal zone. forecast
soundings indicate presence of a capping inversion near 700 mb which
will serve as a limiting factor for deeper convection, especially
given weak forcing aloft and tendency for the ridge to build.
nevertheless a few deeper updrafts with potential for isolated
lightning flashes cannot be ruled out, especially during the
...southern california coast...
an upper low will move southward from nv and southern ca early
tuesday to off the southern ca coast during the evening. cool
temperatures aloft promoting 7-7.5 mid-level lapse rates and
vorticity maxima rotating through the upper low circulation will
promote the development of mid-level convection. some of these
updrafts might become deep enough for a few lightning flashes near
the coast, but most thunderstorm activity will remain offshore.
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note: the next day 2 outlook is scheduled by 0700z