SPC AC 211626

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1126 AM CDT Sun Jul 21 2024

   Valid 211630Z - 221200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   CENTRAL AND SOUTHERN ARIZONA...AND FROM SOUTHERN COLORADO TO EASTERN
   NEW MEXICO...

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

   ...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 (becoming 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 accompany the
   stronger downdrafts.  The overall severe risk appears too limited in
   time/space to include a 5-percent severe wind highlight.

   ..Smith/Jirak.. 07/21/2024

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