AWUS01 KWNH 021637
FFGMPD
TXZ000-OKZ000-KSZ000-NMZ000-022200-

Mesoscale Precipitation Discussion 1113
NWS Weather Prediction Center College Park MD
1236 PM EDT Sat Nov 02 2024

Areas affected...Far eastern New Mexico, Texas Panhandle, western
Oklahoma

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

Valid 021635Z - 022200Z

Summary...Convective cells are expected to regenerate along an
outflow boundary and track E/NE through the afternoon. Rainfall
rates in excess of 1"/hr are likely, resulting in axes of 2-3" of
rain with locally higher amounts. This could result in instances
of flash flooding.

Discussion...A longwave trough centered over the Great Basin is
amplifying this morning as evidenced by RAP height falls across
that region. This is resulting in sharpening downstream SW flow
tapping moisture from the Pacific, and PWs of 1.1 to 1.3 inches
have surged into the TX Panhandle, near daily records for early
November. Into this moisture, deep layer lift is increasing as
height falls and divergence downstream of the primary trough axis
increase, and overlap with an impressively coupled jet structure
to produce diffluence aloft. This ascent is being enhanced by
mesoscale lift as low-level southerly flow from south Texas surges
northward on 850mb winds of 20-30 kts, lifting isentropically atop
an outflow boundary evident on the regional radar mosaic. Although
this outflow boundary is progged via hig-res guidance to continue
to shift progressively E/SE, this isentropic ascent should result
in regeneration and training of cells through the aftn.

Rainfall rates in current convection are generally modest, but
MRMS 1-hr rainfall accumulations suggest isolated instances of
1-1.5" of rain in the past hour. These rain rates are somewhat
minimized by a lack of pronounced instability, as the SPC RAP
indicates a sharp MLCAPE gradient from 250-1000 J/kg across the
southern TX Panhandle. As the 850mb LLJ continues from the south
however, there is good agreement that these more robust
thermodynamics will surge northward, reaching 1000-2000 J/kg this
aftn. This should result in increased coverage of rainfall rates
exceeding 1"/hr as progged by both HREF and REFS hourly rain rate
probabilities. At the same time, mean 0-6km flow will remain
around 30 kts from the S/SW, suggesting cells that regenerate
along the SW portion of this outflow as it stalls will shift N/NE
and train. This indicates potentially two axes of heavy rainfall:
one along this SW flank where cells repeatedly develop, and a
second maxima into western OK where mean flow is more parallel to
the boundary to enhance training. In both these areas, HREF
neighborhood probabilities for 3"/6hrs reach 40-50%.

Somewhat limiting to the flash flood potential today is
exceptionally dry antecedent conditions reflected by AHPS 30-day
rainfall that is generally less than 25% of normal, leading to
NASA SPoRT 0-40cm soil moisture that is around the 10th
percentile. This suggests that flash flooding should primarily be
isolated the next several hours, but where any of these 1-2"/hr
rates train/regenerate, instances of flash flooding will be
possible.

Weiss

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!_sivuCLqYWpUQiub-d02x7hSO9eQHxahb4Oq6eMz4jPq8QnsL-Ao_dEApWdSLfLdFcmJ=
C2zuhuEeXPDLEwAeJ1F0xP8$  for graphic product...

ATTN...WFO...ABQ...AMA...DDC...ICT...LUB...MAF...OUN...

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

LAT...LON   37109866 36999825 36129816 35579814 34769848=20
            34139894 33380018 33070197 33050336 33220390=20
            33780416 34500396 35100278 35530133 35930028=20
            36599923=20

=3D =3D =3D
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