Heavy Rain/Flooding MS/AL
From
Mike Powell@618:250/1 to
All on Mon Jun 9 07:34:00 2025
AWUS01 KWNH 090920
FFGMPD
ALZ000-MSZ000-LAZ000-ARZ000-091500-
Mesoscale Precipitation Discussion 0409
NWS Weather Prediction Center College Park MD
519 AM EDT Mon Jun 09 2025
Areas affected...Central MS...Southwest AL...
Concerning...Heavy rainfall...Flash flooding possible
Valid 090920Z - 091500Z
SUMMARY...Training WAA convective cells with capability of 2"/hr
rates and spots of 2-3"+ may result in possible localized
incident(s) of flash flooding through early morning.
DISCUSSION...Regional RADAR and surface observations show rapidly
decaying MCS continuing to press eastward along the LA/AR border
with outflow boundary starting to reach northeast LA where it
intersects with slowly lifting frontal boundary that has had some
active convection along it earlier this mornign across S MS.
Surface to boundary layer winds are increasing with approach of
the MCS and slightly increased WAA over the boundary breaking out
more numerous updrafts across central MS connecting up to the
lifting older cluster out of south-central MS. From 850-500mb,
winds are fairly flat from west to east to allow for solid
potential for training of these cells. CIRA LPW also denotes the
weak amplifcation of the surface to 850mb moisture up the MS River
Valley but also still pooled along the deeper layer boundary
toward SW AL and active cluster in south-central AL as well. TDs
in the mid-70s with 850-500mb moisture axis continue to support
2-2.25" total PWats and with upstream faster flow associated with
the MCS, propagation vectors have reduced to about 5kts and are
supportive of backbuilding into the approaching outflow boundary.
As such a few hours of efficient rainfall/training should allow
for 2-3"+ totals across central MS.
Slowly the cells will move into more senstive soil conditions from
east-central MS into south-west AL from last evening's heavy
rainfall, this may increase the potential for higher than normal
run-off and incidents of flash flooding, but the air is drier
aloft and more stable, and without very strong WAA to advect
northward it may be more difficult to maintain stronger convection
across this region, but at the same time, will not require as much
rainfall totals (2-2.5" in 3-6hrs) than over the drier conditions
of central MS. Either way, hourly rates and 3hour totals will be
close enough to suggest localized incidents of flash flooding will
be possible through early morning hours.
Gallina
ATTN...WFO...BMX...JAN...MOB...
ATTN...RFC...ALR...ORN...NWC...
LAT...LON 33649014 33468862 32828762 32548709 32258628
31638628 31168664 31268799 31788932 32029021
32289124 32859149 33449128
$$
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