Mesoscale Precipitation Discussion 0207
NWS Weather Prediction Center College Park MD
1017 PM EDT Thu May 01 2025

Areas affected...Rio Grande Valley of Southwest TX....

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

Valid 020215Z - 020700Z

SUMMARY...A few more hours of intense rainfall with cell
collisions and localized 2"/hr and totals to 4" continuing
possible flash flooding concerns through early overnight period.

DISCUSSION...RADAR mosaic and lightning mapping loop shows
maturing cold pool across Uvalde/Kinney county with an arching
bowing segment from a developing MCV near Medina county back
toward a strong super-cell feature near Zavala county before
angling back toward maturing complex of cells along the Serranias
del Burro west of Maverick county.  Surface analysis shows the dry
line rapidly retreating up the Rio Grande toward the lower Pecos
therefore shifting all forcing to maintain convection along/ahead
of the convective outflow.  CIRA LPW shows the nose of a very deep
anomalous moisture surge through the Rio Grande with Sfc-850mb
values over .75" with supportive 850-500mb helping to support
1.5"+ totals advected on increasing backed southwesterly flow up
the river valley.

A pool of remaining conditionally unstable but slowly capping
instability with 2500-3000 J/kg of CAPE is also being ingested to
the line to help support vigorous thunderstorms for a few more
hours at least.  As such, saturating lower profiles should
maintain some rainfall efficiency with reduction lost to hail
production with each hour.  Given the flux, rates of 2-2.5"/hr are
probable and likely for the next few hours slowly diminishing with
stabilization and slowing intensity of the cold pool/forward flank
isentropic ascent.  Given this though, storm scale
interactions/collisions become more probable resulting in
localized intense bursts and spots of 3-4" in 1-2hrs given slowed
forward progress.  

While Hi-Res CAMs show quick devolution of the complex, they are
also reduced in assimilation of coverage/intensity of ongoing
convective environment, particularly the HRRR which as a tendency
to rapidly diminish ongoing cells in a stabilizing
environment...much faster than reality.  As such, the threat of
cells propagating southeast to east-southeast with intense rates
capable of inducing scattered flash flooding remains possible
through the early overnight period. across Southwest TX and the
Rio Grande Valley.

Gallina

ATTN...WFO...CRP...EWX...

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

LAT...LON   29569861 29429829 28839804 28299806 27939841
            27729899 27679962 27890002 28320045 28630069
            28840071 28970050 28900023 29019989 29439959
            29549926