121
AWUS01 KWNH 231826
FFGMPD
NMZ000-AZZ000-UTZ000-NVZ000-CAZ000-240025-

Mesoscale Precipitation Discussion 0493
NWS Weather Prediction Center College Park MD
225 PM EDT Sun Jun 23 2024

Areas affected...Southwest U.S.

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

Valid 231825Z - 240025Z

SUMMARY...Scattered showers and thunderstorms this afternoon will
be capable of producing high rainfall rates once again that will
be capable of causing localized/small-scale areas of flash
flooding. Any localized slot canyons, burn scars, and the normally
dry washes will be the most vulnerable to enhanced runoff concerns.

DISCUSSION...A substantial amount of moisture with tropical
origins remains in place across a large area of the Southwest
U.S., and this moisture coupled with the diurnal heating cycle
will favor the development and expansion of at least scattered
showers and thunderstorms going through the afternoon hours that
will be capable of producing locally very heavy rainfall rates.

Already the midday GOES visible satellite imagery shows areas of
orographically focused shower and thunderstorm activity beginning
to initiate across the higher terrain of southern UT, the Mogollon
Rim of AZ, and also farther east across areas of central NM
including the Sacramento Mountains and portions of the Sangre De
Cristo range farther to the north.

SBCAPE values are on the order of 1000 to 1500+ J/kg locally, but
these magnitudes are expected to increase over the next few hours
as additional solar insolation takes place. Meanwhile, the PWs are
anomalously very high for this time of the year and as high as 3
to 5+ standard deviations above normal across central/southern AZ
and above the 95th percentile of climatology here. Elsewhere
across central NM and for areas of northern AZ and southern UT,
they are as high as 2 to 3 standard deviations above normal.

Expect additional expansion of orographically enhanced showers and
thunderstorms over the next few hours with rainfall rates that
will be capable of reaching 1 to 2 inches/hour, and especially
with the stronger and locally terrain-anchored storms.

Proximity of a weak MCV across west-central AZ also may act as a
focus for locally more concentrated areas of convection and the
12Z HREF guidance overall suggests the Mogollon Rim area and
portions of south-central AZ should have the heaviest rainfall
potential given a combination of deeper moisture, instability and
overall forcing. Some rainfall totals of 2 to 3 inches, with
isolated heavier amounts will be possible.

Isolated to widely scattered instances of flash flooding will once
again be possible given the thermodynamic and orographic set-up
for convection. The area slot canyons, burn scar areas, and the
normally dry washes/arroyos will be particularly sensitive to the
runoff concerns and flash flooding.

Orrison

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

ATTN...WFO...ABQ...EPZ...FGZ...GJT...PSR...SLC...TWC...VEF...

ATTN...RFC...ABRFC...CBRFC...WGRFC...NWC...

LAT...LON   39061115 38210964 36640894 36090802 36120691
            36630472 36270360 35050371 33850447 32770499
            32450577 32640668 32740876 31730981 31341061
            31631221 32391278 33371349 34121430 35331476
            36841398 38691265