476
AWUS01 KWNH 030620
FFGMPD
AZZ000-NVZ000-CAZ000-031130-

Mesoscale Precipitation Discussion 0576
NWS Weather Prediction Center College Park MD
218 AM EDT Thu Jul 03 2025

Areas affected...northwestern AZ, southern NV into eastern CA

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

Valid 030617Z - 031130Z

SUMMARY...Isolated to widely scattered instances of flash flooding
will be possible across portions of northwestern AZ, southern NV
into eastern CA through 11Z. High rainfall rates of 0.5 to 1.0
inches in 15 minutes will be possible with storm totals near 2
inches.

DISCUSSION...Area radar and GOES West infrared satellite imagery
showed an increasing trend in convection over northwestern AZ,
centered over central and southern Mohave County through 06Z. Low
level confluence and low level moisture increasing from a
combination of remnant outflow from the east and low level winds
advecting in moisture from the south to southeast have allowed for
an increase in MLCAPE over western/northwestern AZ with 06Z SPC
mesoanalysis data showing 1000 to 2000+ J/kg. The SSE to NNW
oriented instability max was co-located with anomalous moisture
with SPC mesoanalysis estimated PW values of 1.5 inches along the
CA/AZ border to 1.8 inches near PHX.

Continued development of convection is expected over northwestern
AZ, southern NV and eastern CA as low level moisture increases
instability to the west and slightly north over the tri-state
region over the next few hours. Aloft, the region resides to the
east of an upper level trough over south-central CA with a 50-60
kt jet max measured by GOES West DMV over eastern NV, placing
locations over the tri-state region within the favored
right-entrance region for ascent. Mean steering flow from the
south to southwest at 10-20 kt should keep individual cells moving
but upstream development could allow for brief training with high
rainfall rates of 0.5 to 1.0 inches in 15 minutes, with similar
rates observed earlier in the night to the west of the Phoenix
metro. Any instances of flash flooding over southern Nevada,
northwestern AZ and eastern CA should be isolated to widely
scattered in coverage and storm total rainfall is expected to max
out near 2 inches.

Otto

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

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

ATTN...RFC...RSA...STR...NWC...

LAT...LON   37331563 37161428 36151322 34351332 33701460
            34101540 35471630 36721641