Subj : DAY2SVR: Nws Storm Predic
To   : All
From : Mike Powell
Date : Mon Nov 13 2023 10:42:00

ACUS02 KWNS 130632
SWODY2
SPC AC 130631

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1231 AM CST Mon Nov 13 2023

Valid 141200Z - 151200Z

....NO SEVERE THUNDERSTORM AREAS FORECAST...

....SUMMARY...
Non-severe thunderstorms are possible from portions of the upper
Texas coast to southern Louisiana and coastal Mississippi.

....Synopsis/Discussion...
In mid/upper levels, a mean trough will be maintained through day 2
off the West Coast, but with a split-flow configuration developing
day 1, as a cyclone breaks southward off the one now located over
and westward from the BC coastline.  The northern-stream portion
will move eastward over BC and the Canadian Rockies as an open-wave
trough, while the basal cyclone digs southward and becomes cut off
well west of CA.  By this period, a series of northern-stream
shortwave troughs across western and central Canada will render a
regime of progressive ridging, moving eastward from the upper
Mississippi Valley across the Great Lakes to the northern
Appalachians.

Farther south, a shortwave trough was apparent in moisture-channel
imagery over Chihuahua.  As heights fall across the central/northern
Plains from the northern-stream perturbations, the southern-stream
trough is forecast to move eastward to northwest, central and
south-central TX by the start of day-2, 14/12Z.  It then should
proceed eastward, maintaining nearly neutral tilt, and reaching from
northern LA to the west-central Gulf by 15/12Z.  Cyclogenesis in
low/middle levels (surface-700 mb) is forecast in response over the
northwestern Gulf, including a frontal-wave surface low that should
move eastward while remaining offshore from TX and LA.  The surface
warm front likewise should stay south of the coast, though
conditional on precip effects to its north, the boundary may impinge
on the area near the mouth of the Mississippi River overnight.

An extensive warm-advection/moisture-transport regime northeast of
the low will spread/expand eastward through the period.  The related
increase of low-level theta-e north of the front should offset
modest mid/upper-level lapse rates enough to foster around 100-500
J/kg MUCAPE over coastal areas, extending into icing layers suitable
for lightning.  Overall overland thunderstorm coverage appears
isolated to widely scattered in this scenario.

...Edwards.. 11/13/2023

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