ZCZC SPCSWOMCD ALL
ACUS11 KWNS 212220 
SPC MCD 212220 
AZZ000-212345-

Mesoscale Discussion 1692
NWS Storm Prediction Center Norman OK
0520 PM CDT Sun Jul 21 2024

Areas affected...portions of south-central Arizona

Concerning...Severe Thunderstorm Watch 558...

Valid 212220Z - 212345Z

The severe weather threat for Severe Thunderstorm Watch 558
continues.

SUMMARY...Scattered thunderstorms over higher terrain could move
south and will remain capable of damaging gusts this afternoon and
into the evening.

DISCUSSION...Radar imagery shows scattered thunderstorms have
developed across the higher terrain of central AZ this afternoon.
Despite only modest deep-layer shear profiles, large inverted-v
thermodynamic profiles have allowed strong downdrafts to develop.
These high-based storms have already produced several measured
severe gusts within the higher terrain. While the initial cores have
moved little and begun to weaken, outflow has moved south/southwest
ahead of the initial convection evident in regional surface obs.
Damaging gusts will remain possible as the outflow moves into the
north/east sides of the Phoenix Metro in the next 1-2 hours.
Additional storm development will remain possible along/ahead of the
outflow as it encounters upper 50s to low 60s F dewpoints and
moderate buoyancy in the lower elevations. Confidence in the exact
convective evolution is somewhat low owing to modest flow aloft and
chaotic storm interactions, but any storms able to move off the
terrain with surging outflow will remain capable of damaging gusts
into this evening.

..Lyons.. 07/21/2024

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

ATTN...WFO...TWC...FGZ...PSR...VEF...

LAT...LON   33020998 32760987 32710993 32521017 32491052 32541209
            32551218 32681324 33451332 34311348 35131332 34211171
            33581066 33211015 33020998 

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