945
AWUS01 KWNH 050123
FFGMPD
MOZ000-ARZ000-TXZ000-OKZ000-KSZ000-050720-

Mesoscale Precipitation Discussion 0397
NWS Weather Prediction Center College Park MD
922 PM EDT Tue Jun 04 2024

Areas affected...much of OK...southeast KS...far southwest
MO...far western AR...adjacent portions of far northern TX

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

Valid 050120Z - 050720Z

Summary...Clusters of thunderstorms will continue to initiate and
organize into the early overnight hours, with the strongest
updrafts/storms producing rainfall rates of 1-3"/hr. This should
result in localized totals of 2-4" with scattered to numerous
instances of flash flooding likely (particularly given sensitive
soils across the region, but especially over southeast OK and
surroundings).

Discussion...Convection over central KS is gradually gaining
organization this evening, supported by a upper-level shortwave
sinking slowly southeast (providing a source of lift via vorticity
advection). Meanwhile, deep layer moisture flux convergence is
currently maximized just to the south (over central OK), where
convection is beginning to initiate in the vicinity of OK City.
Continued upscale growth of convection is expected to organize
into an MCS through late evening, as the broader mesoscale
environment downstream of the established and initiating storms is
characterized by ML CAPE of 1500-4000 J/kg, PWATs of 1.4-1.8"
(between the 90th percentile and max moving average, per SPC
sounding climatology), and deep layer shear of 25-35 kts. While
thunderstorm clusters are organizing to the north (over southeast
KS) currently, the initiating southern cells (over central OK) are
expected to eventually take over (as this is where instability and
moisture flux convergence are maximzed).

Hi-res CAMs are in reasonably good agreement with the convective
evolution through ~07z, indicating that convection will become
rather progressive (partially due storms becoming cold pool
dominate, but likely more so due to the progression of the
aforementioned shortwave and an accompanying cold front). Given
the favorable environment for organized convection, rainfall rates
will be on the order of 1-3"/hr, which should result in localized
totals of 2-4". These totals may have greater coverage over
portions of OK (should the MCS fully organize as expected, per the
12z HREF EAS, ensemble agreement scale, depiction), but there is
some question to whether convection is able to proliferate as
efficiently as it has over southeast KS thus far (as indicated by
more recent runs of the HRRR). While this initially seems a bit
counterintuitive with the better instability to the south, but the
main reason convection is struggling to initiate is due to the
much stronger mid-level capping to the south. This cap will
eventually erode with the approach of the shortwave, but it is
possible that it is too little too late, allowing the farther
north MCS to become established (which would likely result in the
2-4" localized totals being most likely in the vicinity of
MO/KS/AR/OK border region, rather than over the most saturated
soils across southeast OK into adjacent portions of TX and AR).

While short-term rainfall totals on the order of 2-4" across this
region of the Southern Plains would normally constitute a fairly
modest flash flood threat, the situation is complicated by the
fact that soils are extremely saturated across much of southeast
OK and surroundings. This is indicated by 3-hr FFGs (Flash Flood
Guidance) generally ranging from 1-2" (or less). This makes this
area particularly vulnerable to (yet another) MCS, but soils are
also rather saturated farther north as well (with FFGs generally
ranging from 2-3" across southeast KS into northeast OK). Given
these hydrologic considerations, scattered to numerous instances
of flash flooding are considered likely.

Churchill

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

ATTN...WFO...EAX...FWD...ICT...LZK...OUN...SGF...SHV...TOP...
TSA...

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

LAT...LON   38369505 38279393 37969331 36679391 36079393
            35379361 34769352 34229357 33699368 33119440
            33269643 33799811 35069846 36339812 37639741
            38219620