ACUS02 KWNS 210549
SWODY2
SPC AC 210547

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1247 AM CDT Wed Oct 21 2026

Valid 221200Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
CENTRAL ARIZONA INTO FAR WESTERN NEW MEXICO...

...SUMMARY...
Scattered severe thunderstorms are expected across the Southwest and
Four Corners area on Thursday, with the greatest risk across parts
of Arizona. All severe hazards will be possible.

...Synopsis...
A broad longwave mid-level trough will traverse the western CONUS on
Thursday, encouraging continued deep-layer ascent amid the northward
advection of low-level moisture, promoting scattered to widespread
thunderstorm development. At least isolated severe thunderstorms are
possible spanning the Desert Southwest into the Great Basin given
overlapping marginal buoyancy and widespread strong wind fields
aloft. However, across portions of the Desert Southwest, an embedded
mid-level impulse accompanied by a 500 mb speed max atop locally
higher low-level moisture/instability may promote a more focused
risk of severe thunderstorms.

...Desert Southwest into the Great Basin...
Deep-layer ascent, combined with at least some degree of surface
heating ahead of the broader upper trough, will support scattered
thunderstorm development over the Great Basin during the afternoon.
Largely unidirectional (southerly) tropospheric flow will yield
highly elongated, straight hodographs and over 50 kts of effective
bulk (speed) shear. Given 7 C/km mid-level lapse rates and around
500 J/kg MLCAPE, transient supercells and small line segments will
be the main storm modes, accompanied by an isolated severe gust/hail threat.

Farther south into central AZ to far western NM, a 70+ kt 500 mb
southwesterly speed max with 7+ C/km mid-level lapse rates will
overspread southeasterly low-level flow and low to mid 60s F surface
dewpoints. This ambient environment, as shown by forecast soundings,
will yield modestly elongated hodographs, but with appreciable size
and curvature at the low-levels. Given locally higher moisture, up
to 1500 J/kg MLCAPE may be realized in tandem with 50+ kts of
effective bulk shear and over 200 m2/s2 of effective SRH. While CAM
guidance consensus depicts a complex storm mode and several
potential cellular interactions, longer-lived, embedded supercell
structures are possible. Should such storms develop, all severe
hazards will be possible, including a couple of tornadoes.

..Squitieri.. 10/21/2026

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