Mesoscale Precipitation Discussion 0121
NWS Weather Prediction Center College Park MD
251 PM EDT Fri Apr 04 2025

Areas affected...Arklatex...Ozark Plateau...Lower MS
Valley...Lower OH Valley

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

Valid 041850Z - 050050Z

SUMMARY...Numerous areas of heavy showers and thunderstorms will
continue to evolve going into the evening hours, with concerns for cell-training, and locally very heavy rainfall totals. Numerous to
widespread areas of flash flooding, including significant and
life-threatening impacts, are expected to gradually occur going
into the evening hours.

DISCUSSION...The early-afternoon GOES-E IR/WV suite shows a
vigorous mid-level trough continuing to gradually eject east out
across the southern High Plains which is interacting with a very
moist and strongly unstable airmass surging northward ahead of it
involving the Arklatex/Lower MS Valley and portions of the Lower OH Valley.

The latest surface analysis shows an area of low pressure becoming
a bit better defined across far northeast TX with a warm front
extending northeast from there up across central AR, northwest TN,
and into southern KY. Strong warm air advection is surging
poleward of this front with the aid of a south-southwest low-level
jet of 40 to 50+ kts. GOES-E visible satellite imagery shows a
substantial amount of solar insolation helping to destabilize the
warm sector over the Lower MS Valley and Mid-South, and the latest
RAP analysis a broad area of MLCAPE values into the 2000 to 3000
J/kg range. Farther to the north, a lot of this CAPE coupled with
strong isentropic ascent is yielding a corridor of locally
enhanced elevated convection currently across northwest AR,
southwest to central MO, and in a more broken fashion farther off
to the east into parts of the Lower OH Valley.

Flash flooding is already ongoing over sizable portions of the
Ozark Plateau from elevated training convection with rainfall
rates into the 1 to 2 inch/hour range. However, over the next few
hours, a much more substantial outbreak of strong to severe
convection including supercell clusters should evolve over parts
of the Lower MS Valley and especially the Arklatex region.
Enhanced instability and strong shear low-level shear parameters
will be key to this.

Rainfall rates will be increasing to as much as 2 to 3 inches/hour
with the stronger and more organized supercell structures, and the
concern by this evening with be a setup conducive for convection
training over the same area in close proximity to the
aforementioned wave of low pressure and related orientation of the
front. A trailing part of this front will extend down into areas
of northeast TX, with the northeast extension lifting up into the
Lower OH Valley.

Very heavy rainfall totals are likely by this evening, with parts
of northeast TX through west-central and northern AR likely seeing
as much as 3 to 5 inches of rain with isolated heavier totals
possible. The heavy rains with somewhat lesser totals will also
likely impact areas of southern MO. Given the rainfall totals and
wet antecedent conditions, numerous to widespread areas of flash
flooding, including significant and life-threatening impacts, are
expected to gradually occur heading into the evening hours.

Orrison

ATTN...WFO...FWD...LSX...LZK...MEG...OUN...PAH...SGF...SHV...TSA...

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

LAT...LON 38848910 37778816 36738896 35739043 34379228
32599413 32059512 32049620 32729687 33909669
35719526 38249194

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