Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Thu Oct 22 2026
Valid 221200Z - 231200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL AND
EASTERN ARIZONA INTO WESTERN NEW MEXICO...
...SUMMARY...
Scattered severe thunderstorms are expected across the Southwest and
Four Corners area today into tonight with the most intense storms
likely across parts of Arizona and New Mexico. All severe hazards
will be possible.
...Southwest and Four Corners...
The deep upper low initially over the CA coast will move inland and
continue eastward through the day, slowly weakening into an open
wave. A belt of enhanced southerly mid-level flow (70+ kt) along the
eastern periphery of the cyclone will remain in place over the
Southwest and Four Corners. Several embedded shortwave perturbations
will rotate around the cyclone, aiding in continued low-level
southerly flow across eastern AZ and southwest NM. Here, surface
dewpoints in the upper 50s to low 60s F and diurnal heating should
contribute to moderate buoyancy amid deep and strongly veering wind
profiles favorable for severe storms.
One or more bands of convection are likely to be ongoing across
central/eastern AZ early this morning along a weak surface trough.
Cooling mid-level temperatures ahead of the approaching low and
persistent upslope flow along the central and southern portions of
the Mogollon Rim will maintain buoyancy through the diurnal minimum
with reintensification of these storms likely as heating develops
over the lower deserts. Storms will likely be supercellular
initially. Large hail (perhaps to around 2 inches) and a couple of
tornadoes will be the main concern, focused where the largest
buoyancy and strongest low-level shear will overlap in southeastern
AZ. With time, increasingly meridional flow and numerous storm
interactions will favor more linear modes and perhaps a transition
to a greater damaging wind threat by later in the afternoon.
Farther north into the Great Basin, sufficient destabilization for
more than sporadic severe storms is much less certain owing to lower
surface dewpoints and significant cloud cover. Still, model guidance
shows a few hundred J/kg of MLCAPE may develop with pockets of
better heating from eastern NV, UT and into southwestern CO. Flow
aloft will remain fairly strong (50-60 kt) helping to elongate mid
and upper-level hodographs. DPVA and upslope trajectories should
support numerous showers/thunderstorms with some potential for
organization into clusters or supercell structures. Damaging wind
gusts are the most likely hazard, though marginally severe hail is
also possible with any of the stronger rotating storms into the
evening.
...Southern California...
As the upper-level low moves overhead during the afternoon, cold
mid-level temperatures (around -20C at 500 mb) and modest surface
heating will support weak destabilization with MLCAPE of 500-750
J/kg. Low-topped convection near the coast may be ongoing early and
continue into the early afternoon before mid-level ascent begins to
decrease. Given the ambient vorticity with the upper-low and local
terrain effects, a brief tornado is possible with the strongest
storms along with isolated wind damage potential. Severe potential
should rapidly diminish as the upper trough moves eastward late
through the afternoon and into the evening.
..Lyons/Jirak.. 10/22/2026
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