971
AWUS01 KWNH 211628
FFGMPD
TXZ000-OKZ000-KSZ000-COZ000-NMZ000-212230-

Mesoscale Precipitation Discussion 1037
NWS Weather Prediction Center College Park MD
1227 PM EDT Sat Sep 21 2024

Areas affected...High Plains of New Mexico into the Panhandles of
Texas and Oklahoma

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

Valid 211630Z - 212230Z

Summary...Showers and thunderstorms will expand in coverage
through the afternoon while intensifying to feature rainfall rates
nearing 1"/hr. Although storms will generally be fast moving,
repeating rounds could result in 1-3" of rainfall and instances of
flash flooding.

Discussion...The GOES-E WV imagery shows an anomalously deep upper
low moving over northern AZ with impressive downstream lift and
moisture advecting into the southern High Plains of NM. Within
this moisture plume, an area of moderate stratiform rain has
lifted towards the TX Panhandle, while in its wake secondary
convective development is gradually occurring as reflected by
increasing glaciation in deepening cells noted via the day-cloud
phase RGB. Rainfall from the morning precipitation has been as
much as 0.5 inches measured by local mesonets, wetting the soils
ahead of what should be increasing convective activity as PWs
surge to 1.25-1.5 inches, and SBCAPE rises to 1000-2000 J/kg.

As thermodynamics intensify through the aftn, forcing for ascent
is also likely to become more impressive. The potent closed low
and associated trough to the west will gradually push east,
driving intense downstream divergence coincident with increasing
upper diffluence over the southern High Plains. At the same time,
unidirectional low-level southerly flow will begin to
isentropically ascend the southward advancing cold front, and the
overlap of these forcing mechanisms into the elevated
PW/instability will result in widespread convective development as
suggested by high-res simulated reflectivity. The HREF
neighborhood probabilities indicate that rainfall rates have a
20-40% chance of exceeding 1"/hr in the deeper convection, with
some storm organization through 40-50 kts of bulk shear helping to
enhance and lengthen the duration of these rain rates in some
areas. Although 0-6km mean winds will remain around 30 kts,
suggesting progressive cell motions, aligned Corfidi vectors
indicate a strong likelihood for repeating cells which could
produce 1-3" of rainfall in some areas.

7-day rainfall for portions of northeast NM into the Panhandles of
TX and OK has been as much as 400% of normal, leading to locally
saturated 0-40cm soil moisture above the 95th percentile. While
the progressive nature of these heavy rain rates should somewhat
limit the flash flood potential this afternoon, any training or
repeated rounds could cause impacts, especially atop the most
saturated soils or across urban areas, sensitive terrain features,
and burn scars.


Weiss

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

ATTN...WFO...ABQ...AMA...DDC...LUB...MAF...PUB...

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

LAT...LON   37220299 37090182 36810118 36080098 35610122
            34730197 33830305 33340409 33480503 34320544
            35280538 35370537 36400491 36940409