AWUS01 KWNH 121124
FFGMPD
MSZ000-LAZ000-ARZ000-TXZ000-121500-

Mesoscale Precipitation Discussion 0705...Corrected
NWS Weather Prediction Center College Park MD
723 AM EDT Wed Jul 12 2023

Corrected for flash flooding tag

Areas affected...Southern Arkansas... Northern Louisiana...Adj Far
NE Texas...Northwest Mississippi...

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

Valid 121122Z - 121500Z

SUMMARY...Extreme rain-rates and totals pressing 8-10" in portions
of Southwest Arkansas will continue to produce significant flash
flooding. Scattered downstream cells into NW MS may have 2-3"+ and
isolated lower end flash flooding thru 15z.

DISCUSSION...GOES-E 1-minute 10.3um EIR shows MCC across southern
AR with two main cooling/overshooting tops (-75C). RADAR depicts
this a a mature arc of convection from Desha/Drew to Bradley and
then back to Miller/Lafayette county. Evolution of the MCC
depicts the combination of MCV and parent mid-level shortwave near
Cleveland county lifting northward. DPVA and low level moisture
convergence from southwesterly overrunning is becoming
increasingly distant from pool of instability across NE TX into N
LA, but given deep 2.25-2.5" total PWats and deep warm layer,
rainfall efficiency has been strong to support 2-2.5"/hr rates.
Forward (northeast) cell motion ahead of the shortwave and weak
propagation should maintain a more scattered appearance lifting
into NW MS over the next few hours, spots of 2-4" are possible in
an hour or two and may result in possible flash flooding, but more
scattered in nature relative to the upwind edge of the complex, so
have extended the MPD into NW MS on this lower-end risk.

RADAR trends show a bit more southward propagation of the upwind
edge of the MCC across SW AR. CIRA LPW denoted a small wedge of
drier air across SW OK that may have mixed into the mid-levels to
allow for increased cold pool generation over the last few hours.
However, 850-700mb moisture channel appears to becoming
increasingly confluent/convergent in the vicinity of Hempstead
county allowing for continued backbuilding and with 2.5" total
PWat values along 20kt southwesterly 850mb flow (64 to 68F Tds)
veering to 25-30kts at 700mb (45-50F Tds) should continue to
support efficient rainfall production of 3-3.5"/hr. Southward
propagation may alleviate the areas of Ouachita/Nevada/Union
counties of receiving more rain, but localized totals of 8-10"
remain probable even with some southward propagation, though more
likely a broader area of 4-6" will occur perhaps into the first
row of NW LA parishes. Flash flooding is likely to continue with
some rural spots experiencing significant flooding still through
the early morning hours (14-15z).

Gallina

ATTN...WFO...JAN...LZK...MEG...SHV...

ATTN...RFC...ABRFC...LMRFC...NWC...

LAT...LON 34669058 34318998 33799002 33269050 32669156
32489247 32659353 33299433 33889441 34439431
34379367 33779293 33769238 33949188 34339152
34589122

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