Weather Prediction Center issues Mesoscale Precipitation Discussion #215 concerning HEAVY RAINFALL...FLASH FLOODING POSSIBLE564
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Mesoscale Precipitation Discussion 0215
NWS Weather Prediction Center College Park MD
248 PM EDT Sat May 03 2025
Areas affected...Portions of the TN Valley
Concerning...Heavy rainfall...Flash flooding possible
Valid 031848Z - 040048Z
SUMMARY...Bands of heavy showers and thunderstorms will be
impacting portions of the TN Valley going through the afternoon
and evening hours. Some localized potential for flash flooding
will exist where the stronger and more organized storms occur, and
especially with somewhat moist antecedent conditions.
DISCUSSION...The early afternoon GOES-E visible satellite imagery
shows convection developing and expanding in coverage across areas
of eastern MS up through northern AL and into middle TN. Despite
some cloud cover which has tempered the boundary layer
destabilization process, there has been a sufficient level of
diurnal heating to foster MLCAPE values of near 1000 J/kg across
eastern MS and into northern AL, with lesser values noted up
across middle TN.
A cold front meanwhile continues to edge off to the east as a
deeper layer trough and closed low pivots across the middle MS and
lower OH Valley region. The pooling of moisture and instability
ahead of this front this afternoon and evening should continue to
favor a general increase in the coverage of convection, although
the activity should tend to be oriented in linear bands aligned
with the deeper layer southwest flow across the broader TN Valley
region.
Additional boundary layer instability through solar insolation
coupled with fairly strong moisture convergence near the front
should help yield pockets of heavier rainfall rate potential that
may reach as high as 1 to 2 inches/hour. PWs are seasonably moist
with values of 1.2 to 1.4 inches and there is a sufficient level
effective bulk shear (30 to 40 kts) to favor some level of
stronger updrafts/organization for some of these heavier rainfall
rates to materialize.
Hires model solutions generally favor as much as 2 to 4 inches of
rain with the stronger storms and where any brief cell-training
occurs given the linear nature of the convection. Some localized
1-hour and 3-hour FFG exceedance may occur as a result, and some
locations over the broader TN Valley region did see heavy rainfall
yesterday which has led to some moistening of the soils along with
higher streamflows. As a result, some localized potential for
flash flooding will exist going through the afternoon and evening
hours.
Orrison
...Please see www.wpc.ncep.noaa.gov for graphic product...
ATTN...WFO...BMX...FFC...GSP...HUN...JAN...JKL...LMK...MEG...
MOB...MRX...OHX...
ATTN...RFC...LMRFC...OHRFC...SERFC...NWC...
LAT...LON 36798491 36768379 36238345 35048410 33338559
32598673 32248813 32508895 33188908 34398750
36038601
Source:
Weather Prediction Center issues Mesoscale Precipitation Discussion #215 concerning HEAVY RAINFALL...FLASH FLOODING POSSIBLE---------------
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