813
AWUS01 KWNH 240422
FFGMPD
LAZ000-ARZ000-TXZ000-OKZ000-241030-

Mesoscale Precipitation Discussion 0312
NWS Weather Prediction Center College Park MD
1221 AM EDT Fri May 24 2024

Areas affected...southeast OK and southwest AR into the Ark-La-Tex

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

Valid 240430Z - 241030Z

Summary...Localized flash flooding is possible overnight with
1-3"/hr rainfall rates, storm totals of 3-5".

Discussion...Convection is loosely organizing late this evening
along the Red River of the South, composed of a right-moving
(eastward) supercell that originated from the dry line and a
multi-cell cluster of storms (moving northeast with the mean flow)
downstream of the supercell. In addition, the mesoscale
environment is supportive of continued growth and organization
with PWATs of 1.4-1.8 inches (near the 90th percentile, per SHV
sounding climatology), MUCAPE of 2000-3000 J/kg (increasing by as
much as 500-1500 J/kg over the past several hours), effective bulk
shear of 35-55 kts, and moderate to strong low-level moisture
transport (via a strengthening southerly LLJ).

The 00z HREF suite has done a good job anticipating convective
initiation this evening (especially compared to last night in the
same region), but there is still a considerable amount of spread
between the individual ensemble members. Most hi-res models
indicate at least localized totals 3-5", though a couple
(including the HRRR and ARW) limit totals to 2-3". While the
observational trends are already more supportive of the more
aggressive solutions (considering MRMS is estimating localized
hourly totals of 2-3" already with the multi-cell clusters along
the Red River), the experimental WoFS also seems to be picking up
on this (with the latest 0300z and 0330z runs now indicating 90th
percentile accumulated rainfall of 4-5"). Most of the guidance
agrees that these totals will most likely occur along and near the
Red River heading into the Ark-La-Tex, which follows the upwind
propagation vectors towards the ESE @ ~30 kts. This is notably a
good bit farther south than the current E-NE storm motion, so cold
pool development must be sufficient enough to organize and achieve
this ESE motion (which seems likely with an MCS maintenance
composite parameter of 90-100). If convection remains more loosely
organized without a dominate cold pool, then totals may remain
more limited (with localized flooding possibly more focused from
southeast OK into southwest AR, which the ARW2 and FV3 are closer
to depicting).

Churchill

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

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

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

LAT...LON   35729502 34809238 32359330 33179706 34469866
            35299820