Subj : DAY1SVR: Day 1 Convective Outlook
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Jan 01 2023 12:56:51

ACUS01 KWNS 011256
SWODY1
SPC AC 011255

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0655 AM CST Sun Jan 01 2023

Valid 011300Z - 021200Z

....THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PARTS OF
CENTRAL/SOUTHERN ARIZONA...

....SUMMARY...
Isolated strong-severe thunderstorm gusts are possible today over
parts of central/southern Arizona.

....Synopsis/Discussion...
In mid/upper levels, a pronounced synoptic-scale trough is evident
in moisture-channel imagery from the interior Northwest south-
southwestward across the central CA Coast to the Pacific west of
Baja.  An embedded vorticity max and developing 500-mb low appears
over the Sierra west of BIH.  This low will intensify by 00Z and
reach the LAS area, with trough northward over ID and southward down
the lower Colorado River Valley and past central Baja.  By 12Z, the
low should reach southeastern UT, with trough northward to a col
over northwestern WY, and southward from the low across eastern AZ
and northwestern mainland MX.

An associated area of surface low pressure -- complicated by the
highly varied terrain over which it will cross -- should move
erratically from its initial position over the southern Sierra to
south-central/east-central UT by 00Z.  Meanwhile, a trailing Pacific
cold front crosses the lower CO River Valley and western/central AZ,
reaching southeastern UT and eastern AZ.  By 12Z, the front should
reach the lower Pecos Valley, the TX South Plains, TX/OK Panhandles,
and southeastern CO, to a low over northwestern CO.  Warm
frontogenesis -- already underway across parts of the Panhandle and
OK -- will continue and shift or relocate northward to the central
Plains and mid Mississippi Valley by 12Z tomorrow.

....Central/southern AZ...
Isolated severe gusts may accompany a strongly forced band of
convection (with embedded thunderstorms) this afternoon over the
outlook area.

Surface temperatures will remain cool, with diurnal heating strongly
muted by extensive cloud cover.  Still, destabilizing prefrontal
moisture/theta-e advection is expected, with dewpoints in the 40s to
50s F.  Very near the front and convective band, such moisture will
underlie steepening midlevel lapse rates along the leading rim of
the mid/upper trough's DCVA field.  This should promote development
of surface-based effective-inflow parcels, with 100-500 J/kg of
lower-elevation MLCAPE in a narrow preconvective corridor.  With
strong frontal/QLCS forcing and intense deep-layer wind fields, a
low-CAPE/high-shear convective band may bring strong-severe gusts to
the surface, in addition to the strong ambient gradient winds likely
in some locales.

...Edwards/Broyles.. 01/01/2023

$$

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