AWUS01 KWNH 060534
FFGMPD
TNZ000-KYZ000-INZ000-ILZ000-MSZ000-LAZ000-MOZ000-ARZ000-061115-

Mesoscale Precipitation Discussion 1130
NWS Weather Prediction Center College Park MD
1234 AM EST Wed Nov 06 2024

Areas affected...AR/MS border into western TN/KY and the lower OH
Valley

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

Valid 060532Z - 061115Z

SUMMARY...Training/repeating rounds of showers and thunderstorms
may produce a couple areas of localized flash flooding through 11Z
from the AR/MS border into western TN/KY and the lower OH Valley.
Rainfall rates up to 3 in/hr will be possible, although 1-2 in/hr
should be more common. Coverage is expected to remain localized.

DISCUSSION...Regional radar imagery showed a broken axis of
showers and thunderstorms stretching from southwestern IN into the
lower MS Valley at 05Z, along and ahead of a slow moving cold
front. 05Z data from the SPC mesoanalysis showed that MLCAPE of
500-1000 J/kg extended from the lower MS Valley into southwestern
TN with weak (<500 J/kg) MLCAPE and MUCAPE to the north into the
lower OH Valley. Slow eastward movement of the boundary and
anomalous moisture (PWATs of 1.5" along the IN/KY border,
increasing to near 2.0" along the AR/MS border) were supporting
locally high rainfall rates within areas of training. Peak
rainfall rates were observed in the 2.5 to 2.7 in/hr range in
Lauderdale County in western TN just prior to 05Z but that axis of
heavy rain has since shifted east.

Forecast movement of the boundary is for slow but steady eastward
progress northward of northern TN, but for nearly stationary
movement south of Memphis. Water vapor imagery showed a subtle
shortwave trough over western LA into the Gulf with slight
buckling of the downstream flow over the lower MS Valley which may
help to support a weak surface wave along the front in LA and
stalling of the front to its immediate north. 25-35 kt of 925-850
mb flow from the S to SSW (despite gradual weakening overnight)
may allow for the repeated regeneration of showers/thunderstorms
over the AR/MS border with areas of training toward the NNE just
ahead of the slow moving front. Rainfall rates of 1-2 in/hr
(locally higher) will be possible within axes of training
resulting in 2 to 3 inches (locally higher) through 11Z.

Farther north, the flash flood threat is expected to be more
limited due to the eastward progression of the cold front, limited
instability and the departing of right-exit region ascent tied to
a 120-140 kt over IL/IN/MI. However, an isolated flash flood
cannot be completely ruled out overnight.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!5Bk5mj0ywGnmHWHTyuAFOz-KVfnWT0oULFfhLEklzQV8SadaiI_X3Phr2Nx0D5CLUonO=
sXd0xVKAs8i8HSXc7fIwlI0$  for graphic product...

ATTN...WFO...JAN...LMK...LZK...MEG...OHX...PAH...

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

LAT...LON   38478748 38208676 37808664 36888701 35518831=20
            34298969 33449075 32979134 33159167 34189099=20
            35698987 36638920 38108796=20

=3D =3D =3D
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