493
AWUS01 KWNH 102141
FFGMPD
AZZ000-UTZ000-CAZ000-110300-

Mesoscale Precipitation Discussion 0856
NWS Weather Prediction Center College Park MD
540 PM EDT Sat Aug 10 2024

Areas affected...Western and central AZ

Concerning...Heavy rainfall...Flash flooding possible

Valid 102139Z - 110300Z

SUMMARY...Ample moisture and weak steering flow will continue to
support slow-moving storms, capable of producing heavy rainfall
rates and localized runoff concerns across the region through the
remainder of the afternoon into the early evening.

DISCUSSION...Latest mesoanalysis shows PWs 1.5-2 inches (~2
standard deviations above normal) centered over southwestern
Arizona, with PWs of 1-1.5 inches covering northwestern Arizona.
This moisture along with increasing instability (MLCAPEs ~500-1500
J/kg) has contributed to increasing shower and thunderstorm
coverage over the past few hours, with rainfall rate estimates
reaching ~1.5 in/hr in some of the stronger storms. Storms that
have developed have shown slow south-to-north movement --
supported by weak steering flow along the western periphery of the
subtropical ridge.  The environment is expected to remain
favorable to additional development through the remainder of the
afternoon into the evening, bolstered by a weak shortwave
extending north of an upper low centered over the Baja Peninsula
along with deeper moisture spreading north trough western Arizona.
 Slow-moving storms along with the potential repeating development
may lead to localized flash flooding.

Pereira

...Please see www.wpc.ncep.noaa.gov for graphic product...

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

ATTN...RFC...CBRFC...NWC...

LAT...LON   37011309 36781213 35661140 35041193 34311226
            33511229 32941172 31891041 31381108 31891338
            32421429 33611456 34701427 35421406 36671394