027
AWUS01 KWNH 241739
FFGMPD
NMZ000-AZZ000-UTZ000-NVZ000-242337-

Mesoscale Precipitation Discussion 0494
NWS Weather Prediction Center College Park MD
138 PM EDT Mon Jun 24 2024

Areas affected...Southwest U.S.

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

Valid 241737Z - 242337Z

SUMMARY...Scattered showers and thunderstorms will be capable of
producing high rainfall rates again today, which may result in a
few areas of localized and small scale flash flooding.

DISCUSSION...Recent visible satellite imagery indicates convection
is beginning to develop across the higher terrain of central AZ
into western NM. Compared to yesterday, CAPE and PW values are
equal or even a bit higher in spots today across this region. The
convective QPF signal in the HREF is also slightly higher today,
especially across central AZ into west central NM. HREF EAS
probabilities of exceeding 0.25" in 6 hrs were only 5-10%
yesterday, but are ~15-40% today. These higher EAS probabilities
are indicative of greater convective coverage in the HREF today
compared to yesterday. Observational trends noted above tend to
support this outcome as well.

There were a few flood advisories and flash flood warnings that
resulted from convection yesterday, and given the similar to
slightly better environment today, would expect a similar outcome.
As convective coverage and intensity increases with daytime
heating a localized flash flood risk should evolve. Like the past
couple days, slot canyons, burn scar areas and the normally dry
washes will be most susceptible to isolated flash flooding.

There is more cloud cover over southeast AZ today which may delay
convective initiation there. However the remnant MCV that is
visible on satellite imagery over this area should eventually help
aid in convective development. The threat is more conditional over
south central AZ. The best overlap in instability and PWs are
forecast here, but the trigger for convective development is a
question. However if any cells do form they will be capable of
intense rainfall rates. And while probably after the valid time of
this MPD, there is some signal that convection may eventually
organize along the terrain of central AZ and push south towards
the Phoenix to Tuscon corridor tonight. This could eventually push
an isolated flash flood risk into these areas, and so will
continue to monitor trends.

Chenard

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

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

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

LAT...LON   38681158 38451131 37981135 37171193 36341193
            35261092 34950947 35240874 35260793 34970702
            34600601 34290543 33710514 33040532 32690572
            32940617 33210644 33440675 33330737 33130814
            32750870 32050918 31550926 31200972 31261044
            31241104 31381162 31781233 32241270 32861264
            33711283 34311332 34491363 34851413 35841424
            37001415 37731405 38001341 38121303 38141260
            38491202