Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue Jun 13 2023 07:33:05

AWUS01 KWNH 130732
FFGMPD
LAZ000-ARZ000-TXZ000-OKZ000-131400-

Mesoscale Precipitation Discussion 0475
NWS Weather Prediction Center College Park MD
332 AM EDT Tue Jun 13 2023

Areas affected...Southern OK...Northeast TX...Southwestern
AR...Northwestern LA

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

Valid 130800Z - 131400Z

Summary...Periods of heavy rainfall with rates of 1-2"/hr may lead
to localized totals of 3-4" through early to mid-morning. Isolated
to scattered instances of flash flooding are possible.

Discussion...Elevated convection is expected to initiate and
proliferate along an effective front aloft (between 925-850 mb)
early this morning, as a low-amplitude shortwave subtly digs
east-southeast from near the TX Panhandle. The aforementioned
front aloft is currently located very near (and parallel) to the
Red River of the South (OK/TX border), extending southeastward
into the AR/LA border region (with a stationary surface front
located farther to the south into central TX). The mesoscale
environment in the vicinity of the 925-850 mb front is
characterized by MU CAPE of 1000-2500 J/kg, PWATs of 1.2-1.7
inches (nearing the 90th percentile, per OUN/FWD sounding
climatology), and effective bulk shear of 55-65 kts. This
parameter space should allow for rapid initiation and
proliferation of convection as the low-level jet and associated
moisture transport gradually strengthens (with the CAMs overall in
good agreement with this scenario). While the 850-300 mb mean wind
will favor relatively fast storm motions (being westerly near 40
kts), the parallel orientation to the boundary is expected to
result in training/repeating of heavy rainfall. Rather curved
hodographs may also favor right-moving supercells, which would act
to slow the storm motions a bit (to near 30 kts) with a bit of
veering towards the southeast (which could also allow discrete
convection to take advantage of greater instability to the south).

With rainfall rates expected to easily reach 1-2"/hr with stronger
cells, it is very possible that localized totals through early to
mid-morning could reach 3-4 inches (as corroborated by 00z HREF
40-km neighborhood exceedance probabilities of 10-30% and 5-10%
for 2" and 3" thresholds, respectively). HRRR runs since 23z have
occasionally depicted 3-4" localized totals (through 14z) as well,
but more recent runs (04z and 05z) are more intent on a somewhat
broader swath of 2-3" totals. Either way, 3-hr FFGs generally
range from 2-3" across the region (though are as high as 4" in the
vicinity of the Ark-La-Tex), so isolated to scattered instances of
flash flooding are considered possible.

Churchill

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!7VlxC8NoN5tym5tvbkWcJAMejhVZ-5CVCoRpPIrknKQiEz_N2KQrDmqdrh92O2LOmlRS=
fWyDkSK2-OLGZG9UUfPhn0A$  for graphic product...

ATTN...WFO...FWD...LZK...OUN...SHV...SJT...TSA...

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

LAT...LON   35009746 34679571 34049385 33019239 32199352=20
            32719671 33149941 34289993 34919891=20

=3D =3D =3D
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