AWUS01 KWNH 022245
FFGMPD
TNZ000-KYZ000-ILZ000-MSZ000-LAZ000-MOZ000-ARZ000-TXZ000-OKZ000-030400-

Mesoscale Precipitation Discussion 0106
NWS Weather Prediction Center College Park MD
644 PM EDT Wed Apr 02 2025

Areas affected...ArkLaTex into mid-MS Valley

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

Valid 022244Z - 030400Z

SUMMARY...There are growing concerns for an axis of heavy
rain/flash flooding to develop from near the ArkLaTex into western
TN/KY through 04Z. Peak rain rates of 2-3 in/hr will be likely
within axes of training, most likely across AR to the MS River.

DISCUSSION...22Z surface radar imagery and surface observations
depicted an elongated axis of thunderstorms stretching from
southwestern IL into southwestern AR. A cold front/outflow
boundary combination was located at the leading edge of the
thunderstorms and visible satellite/radar imagery showed cloud
streets and developing thunderstorms feeding into AR from the
south within 50-60 kt of flow at 850 mb (per area VAD wind plots).
The environment ahead of the cold front was moderately unstable
and very moist with MLCAPE of 2000 to 3000+ J/kg and PWATs of 1.7
to 1.9 inches per a special 20Z SHV sounding and 22Z SPC
mesoanalysis data.

Due to a lack of height falls over the Mid-South, south of an
advancing mid-level shortwave over the upper MS Valley, the
outflow (effective cold front) is forecast to steadily advance
eastward into the lower OH Valley over the next 3-6 hours, while
the southern end of the boundary stalls across the ArkLaTex. The
resultant orientation should align with the mean steering flow
from SW to NE. As robust low level moisture transport and
pre-frontal cells intersect the boundary, coverage of
thunderstorms should increase from near the ArkLaTex into eastern
AR and eventually into western TN/KY over the next several hours.
Areas of training will have the potential to produce 2-3 in/hr
rainfall rates and depending on the persistence of training over
any given location, some higher end rainfall totals (4+ inches)
could materialize.

Flash flooding appears likely within this setup and should overlap
of training occur with any urban centers, locally significant
flash flooding could occur.

Otto

ATTN...WFO...FWD...JAN...LZK...MEG...OHX...PAH...SHV...

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

LAT...LON 37438778 37018735 35378873 34359049 33259241
32659396 32699536 33329565 33769524 34659337
35029237 36189057 36958900

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AWUS01 KWNH 031107
FFGMPD
TNZ000-KYZ000-ALZ000-MSZ000-MOZ000-ARZ000-031705-

Mesoscale Precipitation Discussion 0109
NWS Weather Prediction Center College Park MD
706 AM EDT Thu Apr 03 2025

Areas affected...Mid-South

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

Valid 031105Z - 031705Z

SUMMARY...Additional repeating rounds of heavy showers and
thunderstorms going through midday will continue to favor a
regional threat of flash flooding across the Mid-South.

DISCUSSION...Early morning GOES-E IR satellite imagery shows an
axis of heavy showers and thunderstorms tending to repeat/train
over the same locations across portions of the Mid-South as a
moist and unstable airmass continues to lift north from the Gulf
Coast region.

A moderately buoyant airmass is noted in particular from southeast
AR through northern MS and into a small portion of middle TN with
MLCAPE values of 1000 to 2000 J/kg. Areas off to the northeast
here going up into southeast KY are more stable by comparison with
CAPE values generally under 1000 J/kg. Area VWP data though shows
an impressive southerly low-level jet reaching on the order of 40
to 50+ kts and this is yielding sustainably strong moisture transport.

The combination of this moisture and instability in conjunction
with a well-defined convectively enhanced surface boundary and
divergent flow aloft should favor sustainable clusters of
convection this morning which will tend to be aligned with the
deeper layer mean flow and thus will promote convective cells repeating/training over the same area.

The thermodynamic environment will promote rainfall rates with the
stronger convective cores reaching 1 to 2 inches/hour and
especially considering the level of shear (effective bulk shear of
50+ kts) which will favor pockets of strong and organized
updrafts. The PWs are generally on the order of 1.5 to 1.6 and
this will support these high rainfall rates as well and especially
with the strength of the low-level jet.

Additional rainfall totals going through midday should reach on
the order of 2 to 4 inches with isolated heavier amounts possible.
The heaviest of these rains this morning should tend to be over
central and eastern AR through northwest MS and the western half
of TN where there is better pooling of instability. Flash flooding
is already occurring over many of these areas, and additional
flash flooding is expected through midday.

Orrison

ATTN...WFO...HUN...JKL...LMK...LZK...MEG...MRX...OHX...PAH...

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

LAT...LON 37758373 36908347 35968525 35448668 34688896
34119130 34059300 35039302 36139050 36798830
37608587

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