AWUS01 KWNH 082212
FFGMPD
AZZ000-NVZ000-CAZ000-090310-

Mesoscale Precipitation Discussion 0985
NWS Weather Prediction Center College Park MD
610 PM EDT Sun Sep 08 2024

Areas affected...Southern CA into Far Southern NV and Northwest AZ

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

Valid 082210Z - 090310Z

SUMMARY...A threat for isolated to widely scattered instances of
flash flooding will continue into the early evening hours from
areas of locally heavy showers and thunderstorms.

DISCUSSION...The mid-afternoon GOES-W visible satellite imagery
shows scattered areas of showers and thunderstorms across portions
of the higher terrain of southern CA and locally across some of
the open desert areas of eastern CA and far southern NV. Some
areas of showers and thunderstorms have also been seen developing
over northwest AZ.

The convection is generally associated with the strong diurnal
heating cycle coupled with terrain-driven differential heating
boundaries/circulations and the presence of at least a modest
amount of moisture through the vertical column. SBCAPE values of
1000 to 1500 J/kg are noted locally across areas of southern CA
through southern NV. The better moisture is generally in the
mid-levels of the column (500 to 700 mb layer) based off the
latest CIRA-ALPW data, but this is still facilitating
cold-convective tops and locally heavy rainfall rates based on the
latest satellite trends.

Ongoing areas of locally heavy showers and thunderstorms may tend
to further expand in coverage over the next 2 to 3 hours before
the activity then begins to wane as surface-based instability
gradually becomes exhausted. The PWs are seasonably moist across
the region, and coupled with the instability, this should favor
convection over the next few hours that will still be capable of
producing rainfall rates of 1 to 1.5 inches/hour.

Some spotty storm total amounts of 2 to 3 inches will be possible
where any cells become locally anchored over the high terrain, and
some of these slow-moving cells have already occurred over the
higher terrain of southern CA. These rainfall amounts may result
in additional concerns for isolated to widely scattered instances
of flash flooding going into the early evening hours.

Orrison

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!70WNzAzxHUt_pCRJIj9YSaKX45qOdTze0KcbEPBhWr7f9Tbeg08KcQZ4t3jkRjxQ-qGh=
EWvoI2Fon1jGBkqG25bFz5g$  for graphic product...

ATTN...WFO...FGZ...HNX...LOX...PSR...SGX...VEF...

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

LAT...LON   36891476 36871327 36311233 35111156 34311185=20
            34331279 34741412 34631558 34311610 33941654=20
            33641657 33261652 32641639 32481684 32971706=20
            33501734 34001771 34291819 34691839 35141827=20
            35601775 35771712 36051649 36541575=20

=3D =3D =3D
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