Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1251 AM CDT Wed Oct 21 2026

Valid 211200Z - 221200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
CENTRAL AND NORTHWESTERN ARIZONA...

...SUMMARY...
Severe thunderstorms with a potential for large hail, severe wind
gusts and a couple tornadoes are expected today along the Mogollon
Rim across parts of Arizona. Marginally severe wind gusts and an
isolated tornado threat will also be possible along the southern and
central California Coast.

...DISCUSSION...
An upper-level low will approach the California Coast today, as
southwesterly divergent flow aloft remains in place over much of the
Southwest. Ahead of the system, low-level moisture will advect
northward into the Desert Southwest today. An axis with surface
dewpoints in the 60s F will set up to the southwest of the Mogollon
Rim across southern, central and western Arizona. By afternoon,
MLCAPE is forecast to peak in the 1500 to 2000 J/kg range along and
near the moist axis. Over the top of the moist and unstable airmass,
strong mid-level southwesterly flow will be in place. Moderate
instability and strong deep-layer shear will support a substantial
severe threat with storms that develop along the Mogollon Rim from
this afternoon into the evening, near the northern edge of the
stronger instability.

As the upper-level system approaches, a 50 to 70 knot mid-level jet
will overspread the Desert Southwest today. RAP forecast soundings
within the exit region of the jet over north-central Arizona in the
mid to late afternoon have gradually veering winds with height and
50 to 60 knots of 0-6 km shear. In addition, steep mid-level lapse
rates and long hodographs are evident which will result in a
potential for supercells with large hail. The strongest cells could
produce hailstones greater than 2 inches in diameter. Forecast
soundings also have 0-3 km storm-relative helicity in the 175 to 250
m2/s2 range late this afternoon along parts of the Mogollon Rim
suggesting that the stronger supercells will be capable of
tornadoes. The severe threat is expected to persist from mid
afternoon into the evening, with a potential for two rounds of
severe storms impacting parts of north-central Arizona.

...Coast of Southern and Central California...
A large upper-level low pressure system will move toward the
California Coast today. The left exit region of a mid-level jet will
approach the southern and central California Coast. A wave of
precipitation associated with this feature will move to the southern
and central California Coast this afternoon. Instability along the
coast will be sufficient for thunderstorm development. RAP forecast
soundings along the coast this afternoon have strong deep-layer
shear, which will support the development of low-topped supercells.
Some model forecasts have 0-3 km storm-relative helicity around 200
m2/s2 near the coast suggesting that an isolated tornado threat will
be possible. Any cells that rotate and move onshore could also be
associated with isolated severe wind gusts as well.

..Broyles/Leitman.. 10/21/2026

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

Day 1 Fire Weather Outlook  
NWS Storm Prediction Center Norman OK
1159 PM CDT Tue Oct 20 2026

Valid 211200Z - 221200Z

...NO CRITICAL AREAS...

...Synopsis...
A robust mid/upper low and attendant 60-70 knot mid-level jet will
bring in increasing atmospheric moisture from the Pacific into CA,
the Great Basin and portions of the Southwest today through tonight.
The increased cloud cover and related precipitation will mitigate
broader fire weather concerns across the West. Farther east, an
amplifying upper-level ridge over the central U.S. and expansive
surface high pressure over the eastern CONUS will contribute to dry
conditions for much the region. However, diffuse surface pressure
gradients will curtail stronger winds across the lower MS River
Valley and portions of the Deep South where drought and related dry
fuels remain, leading to a reduced fire weather threat today.

..Williams.. 10/21/2026

...Please see www.spc.noaa.gov/fire for graphic product...