Mesoscale Precipitation Discussion 0780
NWS Weather Prediction Center College Park MD
925 PM EDT Fri Aug 13 2021

Areas affected...Southeastern to Central Arizona

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

Valid 140124Z - 140700Z

Summary...Widely scattered thunderstorms forming along the higher
terrin in southern Arizona will persist into the late-evening or
early-morning hours.  The atmosphere remains unstable enough for a
few storms to produce some downpours that result in isolated flash
flooding concerns.

Discussion...Widely scattered thunderstorms were persisting across
parts of southern Arizona and extending northwestward into the
central part of the state.  The atmosphere was characterized by
roughly 1500-2000 J per kg instability and precipitable water
values between an inch to 1.5 inch (with greatest values near the
international border).

Given cooling cloud tops on satellite imagery, suspect the
potential for flash flooding will continue into the late-evening
hours.  The daytime run of the HREF continued to paint 40 km
neighborhood probabilities of 1- and 2-inch per hour rates in
parts of southern Arizona through at least 07Z.  The HRRR and NAM
NEST also suggested the potential for 1+ inch per hour rates
continued that long, although other guidance was quicker to weaken
and dissipate the heavy rainfall producing storms.  Based on
short-term radar and satellite trends, tended to follow the
guidace which shows at least some potential for heavy rainfall to
linger beyond 05Z.

Complex terrain, normally dry-washes and orroyos are most
vulernable to flash flooding.

Bann

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

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

LAT...LON   36561277 35831219 33761017 32240939 32050929
            31720902 31540905 31400921 31310945 31310976
            31311027 31331084 31341106 31481151 31691223
            31951280 32061299 32341301 32661283 32851261
            32821203 32701186 32491169 32371136 32501119
            32841128 33051146 33121150 33301177 33781226
            34421323 34951358 35281367 35971339