Mesoscale Precipitation Discussion 1114
NWS Weather Prediction Center College Park MD
500 PM EDT Sat Nov 02 2024

Areas affected...Far southeast NM into the Permian Basin and
Rolling Plains of Texas

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

Valid 022100Z - 030300Z

Summary...Discrete thunderstorms blossoming across the High Plains
of New Mexico will likely expand in coverage and grow upscale into
clusters through the afternoon. Rainfall rates of 2"/hr or more
are likely, which through several rounds could cause 2-3" of rain
with locally higher amounts. Flash flooding is possible.

Discussion...The regional radar mosaic this afternoon indicates
that discrete thunderstorms, including supercells, have rapidly
developed across southeast NM in the past few hours, and have
expanded into the Permian Basin of Texas. This convection is
blossoming in response to impressive deep layer ascent driven
through PVA downstream of a shortwave lifting across the area
combined with strong upper diffluence within an increasingly
coupled upper jet structure. In the lower levels, 850mb inflow
from the S/SE is lifting isentropically atop a weakening outflow
boundary (which is reflected by a sharp instability gradient),
while concurrently transporting robust thermodynamics northward
characterized by PWs of 0.9-1.2 inches, near the daily record, and
MLCAPE of 1500-2000 J/kg. Rainfall rates within this convection
has been measured by MRMS as high as 1.25-1.5" in the last hour,
leading to modest CREST unit streamflow responses already.

The high-res CAMs appear to generally be under-doing the
convective coverage this aftn, a theme that has been common
through the day. This limits somewhat the confidence in the exact
evolution the next several hours. However, despite coverage and
timing issues with the guidance, they all agree that eventually
thunderstorms will expand and grow upscale into clusters. This
will be supported by a continued increase in deep layer ascent
impinging into persistently elevated thermodynamics as the
low-level flow remains. This should result in thunderstorms that
intensify, supporting rainfall rates which have a 10-20% chance
(HREF) and 30% chance (REFS) of exceeding 2"/hr through the aftn
and into the evening. Mean 850-300mb winds are expected to remain
progressive at 30 kts from the SW, but despite this, as storms
organize through 0-6km bulk shear of 40-50 kts, intense rain rates
through short-term training could result in maximum rainfall of
2-3" with locally higher amounts.

Far southeast NM, the southern Permian Basin, and the southern Cap
Rock have all been very dry the past 7 days, but AHPS rainfall
departures are well above normal north of there. This has lowered
3-hr FFG to just 1-1.5" across the more saturated soils. As
convection expands and organizes, it could move across these more
sensitive soils, leading to potential instances of flash flooding
into the evening.

Weiss

ATTN...WFO...ABQ...AMA...LUB...MAF...OUN...SJT...

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

LAT...LON   35150214 35090174 35030081 34479995 33529946
            32739960 32020063 32010225 32340369 32760419
            33450422 34390390 35010320