278
AWUS01 KWNH 140345
FFGMPD
TXZ000-NMZ000-AZZ000-140843-

Mesoscale Precipitation Discussion 1277
NWS Weather Prediction Center College Park MD
1144 PM EDT Sun Sep 13 2026

Areas affected...portions of Southeast AZ & Southwest NM

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

Valid 140343Z - 140843Z

Summary...Showers and thunderstorms persist across Southeast AZ
and are increasing in coverage in southwest NM while additional
activity exists near El Paso TX.  Hourly rain amounts to 2" could
lead to flash flooding.

Discussion...Scattered showers and thunderstorms continue across
far southeast AZ and are growing in coverage across southwest NM.
Other thunderstorms lurk near El Paso TX.  The region is
sandwiched between a Western Trough aloft and an incoming upper
level low retrograding across northern MX and lies within a region
of 700 hPa confluence.  Precipitable water values are 1.75"+ in
the Lower AZ Deserts and 1-1.25" at elevation.  CIN has set in; MU
CAPE is 500-3000 J/kg.  Effective bulk shear is ~20 kts.

Both the 00z HREF and 00z REFS guidance keep convection going for
several more hours before some fading occurs at 08z or so.  There
appears to be some westward shift in the 700 hPa confluence axis
with time, so there should be a general westward drift/shift in
group thunderstorm motion, which could be hastened by instability
exhaustion.  While the guidance flares convection back up at some
point after 10z, with the nearby upper trough and upper low
impinging on the region from the southeast, it`s unclear if a
convective break will actually occur.  Hourly rain amounts are
possible where cells are stationary, manage to train, or merge.
This could lead to flash flooding in burn scars, arroyos/dry
washes, slot/box canyons, and urban areas.

Roth

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

ATTN...WFO...ABQ...EPZ...PSR...TWC...

ATTN...RFC...FWR...STR...NWC...

LAT...LON   33450833 32910634 31300579 31160861 31131092
            32181167 33411149