688
AWUS01 KWNH 230707
FFGMPD
TXZ000-NMZ000-231305-

Mesoscale Precipitation Discussion 1362
NWS Weather Prediction Center College Park MD
305 AM EDT Wed Sep 23 2026

Areas affected...Central and Southern NM...Far Western TX

Concerning...Heavy rainfall...Flash flooding likely

Valid 230705Z - 231305Z

SUMMARY...Heavy rainfall from locally repeating rounds of heavy
showers and thunderstorms will drive an increasing threat of
additional flash flooding over the next several hours. Arroyo and
slow/box canyon locations along with sensitive burn scar areas
will be most at risk for seeing flash flooding impacts, some of
which may be significant and life-threatening.

DISCUSSION...The latest GOES-W GeoColor/WV satellite imagery along
with OSPO ALPW data confirms a deep tropical moisture axis lifting
north out of northern Mexico and across sizable areas of the
Southwest with an emphasis on central and southern NM. The
moisture plume is being driven by rather strong deep layer
southerly flow in between an upper level-trough over the Desert
Southwest down through Baja California and the subtropical ridge
farther east across the southern Plains.

Embedded shortwave impulses coupled with larger scale upper-jet
divergence is working in tandem with warm air advection/isentropic
ascent and modest instability (MUCAPE values as high as 500 to
1000 J/kg) to promote regional areas of moderate to heavy rainfall
along with embedded stronger convective elements.

PWs across the region with the long-track deep layer tropical
moisture transport coming from the eastern tropical Pacific and
western/northern Mexico are very anomalous with values well into
the 2 to 3 standard deviation above normal range. OSPO ALPW data
confirms a connection even to Hurricane Polo south of Mexico in
the 700/500 mb and especially 500/300 mb layer.

Over the next few hours, some strengthening of the upper-level jet
dynamics over central and southern NM should favor a corresponding
increase in 850/700 mb moisture flux and general increase in deep
layer ascent for a more organized heavy rainfall footprint.

This moisture flux will be fueling extremely efficient rainfall
and especially where some deeper convective elements materialize
over the next several hours. The latest hires multi-model
consensus led by the 00Z HREF/REFS guidance and recent HRRR
solutions suggest an uptick in convection, with areas of locally
focused orographic enhancement.

Rainfall rates with the stronger pockets of convection may reach 1
to 2 inches/hour, and some additional rainfall totals going
through the early morning hours may reach 2 to 4+ inches. These
additional rains occurring on top of the earlier rainfall will
promote an increasing flash flood threat over the next several
hours. Significant and locally life-threatening flash flooding
impacts will be possible for arroyos, box/slot canyon locations
and burn scar areas.

Orrison

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

ATTN...WFO...ABQ...EPZ...MAF...

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

LAT...LON   36710497 36470434 35760363 34490352 33060408
            31950507 31160576 30930645 30900788 31510864
            32120882 32960876 34220848 35160799 35910735
            36410662 36670594