ACUS02 KWNS 200600
SWODY2
SPC AC 200558

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1258 AM CDT Tue Oct 20 2026

Valid 211200Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
CENTRAL INTO EASTERN ARIZONA...

...SUMMARY...
Severe hail/wind and perhaps a tornado may occur over portions of
Arizona, southern Utah and western New Mexico on Wednesday.

...Synopsis...
A mid-level trough will move ashore through the day Wednesday,
promoting large-scale ascent of a moistening airmass across the
Desert Southwest to the Four Corners region. Scattered thunderstorms
are expected over these regions, and given the anticipated overlap
of marginal to moderate buoyancy with a highly sheared airmass, a
few severe thunderstorms are possible.

...Desert Southwest to the Four Corners...
Marginal instability should develop through the day, primarily
driven by increasing low-level warm-air and moisture advection
(given ample cloud cover expected). Surface dewpoints should
increase into the 60s F, especially over central AZ, yielding over
1500 J/kg MLCAPE given 7+ C/km mid-level lapse rates. A 50-70 kt
southwesterly 500 mb jet will overspread the warm sector and
accompanying southeasterly antecedent flow, yielding elongated
hodographs with sizeable low-level curvature. Supercell
thunderstorms are expected by late afternoon, accompanied by a
severe wind and hail threat. Given the size of the low-level
hodographs, a tornado or two may also occur.

...Central to southern CA Shoreline...
The core of an 80 kt 500 mb jet will overspread central and southern
CA during the later half of the period (00-12Z Thursday), resulting
in relatively straight but highly elongated hodographs. During this
time frame, a moist marine airmass will advect to the CA shoreline
while being overspread by 6.5-7 C/km mid-level lapse rates, yielding
250-500 J/kg of short and thin MLCAPE. Given the scant buoyancy,
convection should be low-topped, with short line segments and
supercell modes possible. A damaging gust or two is the main threat
with any stronger storm that can reach the shore, as well as a
landfalling waterspout.

..Squitieri.. 10/20/2026

$$
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