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Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0259 PM CDT Sun Jul 21 2024

Valid 212000Z - 221200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
CENTRAL AND SOUTHERN ARIZONA...

...SUMMARY...
Scattered severe thunderstorms are forecast this afternoon into the
evening across parts of central and southern Arizona. Isolated
severe storms are also possible from southern Colorado to eastern
New Mexico.

...20Z Update...
The primary change to the outlook was the introduction of a
wind-driven (15 percent) Slight Risk over portions of central and
southern Arizona. Thunderstorms are increasing in coverage along the
Mogollon Rim early this afternoon, and with the approach of a subtle
midlevel wave, this trend should continue. These recent convective
trends have increased confidence in a sufficient amount of storms
(and related congealing outflow) spreading southward off the Rim --
with a risk of scattered severe gusts into this evening. For
additional details, reference MCD #1690.

..Weinman/Smith.. 07/21/2024

.PREV DISCUSSION... /ISSUED 1126 AM CDT Sun Jul 21 2024/

...Synopsis...
Water-vapor imagery late this morning shows a mid-level disturbance
moving south-southeast across WY/CO to the east of a mid-level ridge
located over the Interior West.  A mid-level shortwave trough will
move northward along the Pacific Northwest coast into British
Columbia by tonight.  Farther east, a mid-level trough/low centered
over the lower MO/mid MS Valleys will meander slowly eastward.  

...Sangre de Cristos and adjacent escarpment/plains...
Scattered orographically favored thunderstorm development is
forecast by early to mid afternoon across the mountains ahead of the
aforementioned weak upper disturbance.  A seasonably moist airmass
(reference 12 UTC Albuquerque raob data) is in place across the
region with considerable cloud breaks and partly sunny skies noted
in visible-satellite imagery.  Strong heating will foster upwards of
500-1250 J/kg MLCAPE by peak heating.  Modest deep-layer shear will
limit overall convective organization potential, but the stronger
multicells (beco*ing numerous in coverage) will likely be capable of
an isolated hail/wind risk through the early evening before this
activity dissipates. 

...AZ...
A weak PV anomaly was noted in upper-layer water-vapor imagery this
morning over northern AZ.  This upper feature may aid in storm
development near the Mogollon Rim later this afternoon with
scattered thunderstorms forecast.  A hot and a deeply mixed
sub-cloud layer in the lower desert will likely support some risk
for severe gusts via evaporatively cooled downbursts as this
activity slowly pushes southward late this afternoon through the
evening.  Isolated to widely scattered severe gusts (60-75 mph) are
possible with the stronger cores and outflow surges.  

...Central/eastern Oregon into northwest NV...
Model guidance indicates scattered thunderstorms are forecast to
develop later this afternoon on the southeast periphery of the
mid-level shortwave trough glancing the region.  Inverted-V profiles
per forecast soundings suggest gusty winds may acco*pany the
stronger downdrafts.  The overall severe risk appears too limited in
time/space to include a 5-percent severe wind highlight.