Subj : DAY1SVR: Day 1 Convective
To   : All
From : Mike Powell
Date : Mon Dec 04 2023 09:53:00

ACUS01 KWNS 041256
SWODY1
SPC AC 041254

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0654 AM CST Mon Dec 04 2023

Valid 041300Z - 051200Z

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

....SUMMARY...
Severe thunderstorms are not expected through tonight.

....Synopsis/Discussion...
In mid/upper levels, mean troughing will be maintained over the
east-central CONUS as one strong shortwave trough effectively is
replaced by the next upstream.  The leading perturbation -- located
over the STL vicinity -- is supporting an area of large-scale ascent
in the form of both DCVA and a warm-advection conveyor.  In turn, an
arc of precip with embedded showers and isolated/episodic
thunderstorms is apparent just ahead of the trough.  Meager yet
sufficient moisture above the boundary layer, and cooling aloft,
will continue to support elevated MUCAPE up to about 200 J/kg,
sporadically extending into icing layers suitable for lightning
generation.  The most probable corridor for related, isolated
thunder potential will be into midday from parts of the lower Ohio
Valley toward the southern Appalachians.

After that, the causative perturbation will weaken and move out to
the Atlantic.  Another, similarly evolving shortwave trough --
evident in moisture-channel imagery over portions of southern SK and
eastern MT -- should dig southeastward and strengthen through the
period.  This feature should reach the Mid-South and southern parts
of the Mid Mississippi Valley by 12Z tomorrow, on a similar but
slightly more southerly track relative to the leading shortwave.
However, forecast soundings suggest even weaker moisture, coupled
with more stable lapse rates in typical lightning-generation layers,
rendering thunder potential (if any) too isolated and uncertain for
an outlook area.

Isolated lightning has been noted in a baroclinic-leaf pattern
preceding a cyclone over the northeast Pacific (well west of the
Pacific Northwest).  Weakly favorable low/middle-level moistening
and destabilization in the related warm-advection plume may reach
portions of the Olympic Peninsula late afternoon into evening, as
the ridge aloft moves away.  Elsewhere, boundary-layer drying/
stabilization from prior frontal passages (from the Plains eastward)
and progressive, strong, synoptic-scale ridging aloft (across the
West) will preclude thunderstorms.

...Edwards/Kerr.. 12/04/2023

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