AWUS01 KWNH 291002
FFGMPD
SCZ000-GAZ000-291600-

Mesoscale Precipitation Discussion 0809
NWS Weather Prediction Center College Park MD
602 AM EDT Sat Jul 29 2023

Areas affected...southeastern Georgia, southern South Carolina

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

Valid 291000Z - 291600Z

Summary...Deep convection has exhibited a modest increase in
coverage over the past 1-2 hours around a weak tropical wave
centered over southeastern Georgia. A few hours of heavier
rainfall could result in localized, but isolated flash flood
potential over the next few hours.

Discussion...Over the past 1-2 hours, deep, yet slow-moving
convection has developed around the center of a weak tropical low
over southeastern Georgia. Areas of hourly rain rates approaching
2 inches was already noted west of Savannah. The convection was
located in an abundantly moist airmass, with PW values exceeding
2.25 inches. Additionally, MLCAPE values across the discussion
area range from 500 J/kg in inland areas to 2000 J/kg nearer to
the coast. These values - along with low-level convergence
associated with the tropical low - should promote additional,
persistent heavier downpours at times today.

The convection should occur across areas of FFG thresholds in the
2.5-3 inch/hr and 3-4 inch/3-hr range. Flash flooding will become
possible as longer-lived convection manages to persist for longer
than an hour. Low-lying and/or urbanized areas could also
experience excessive runoff more readily and with lower rain rates
compared to surrounding areas.

Over time, models/CAMs focus heavier rainfall potential across
areas from just west of Savannah eastward along coastal areas of
South Carolina through 15Z. These areas will experience the
greatest chance of localized flash flood impacts through that time.

Cook


ATTN...WFO...CAE...CHS...FFC...ILM...

ATTN...RFC...SERFC...NWC...

LAT...LON 34118001 33977896 33627866 32517960 32118106
31988216 33038268 33658156

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AWUS01 KWNH 100949
FFGMPD
GAZ000-TNZ000-ALZ000-MSZ000-ARZ000-101547-

Mesoscale Precipitation Discussion 0900
NWS Weather Prediction Center College Park MD
549 AM EDT Thu Aug 10 2023

Areas affected...Mid-South through Northern Mississippi/Alabama

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

Valid 100947Z - 101547Z

Summary...Rounds of organized convection continue to shift
east-southeast from northern Arkansas through northern Alabama
through mid-morning. High moisture content and sufficient
instability continue to allow keep heavy rates. Flash flooding is
possible.

Discussion...An impulse over northern AR has lead to backing of
mean layer flow to just north of west which is aligned with
redeveloping activity northeast AR into the Memphis metro.
Additionally two lines of organized convection are moving
orthogonal to the mean flow over northern MS and AL. High moisture
with PWs of 2.1" to 2.3" will be maintained in 30kt WSWly low
level flow and instability will hold around a sufficient 1000-2000
J/kg MUCAPE.

Recent hourly rainfall estimates have been generally 1-2" in
northeast AR though they have weakened as they reach Memphis,
probably due to less instability there. The progressive lines have
generally produced 1 to 1.5" hourly rainfall. Given the strong low
level flow maintaining moisture/instability, there is a risk for
2-4" over the discussion area through 15Z.

FFG thresholds are lower, around 1.5"/hr around Memphis and in
northern AL where wetter soils are present. Flash flooding should
remain localized and is considered possible.


Jackson

ATTN...WFO...BMX...FFC...HUN...JAN...LZK...MEG...OHX...

ATTN...RFC...LMRFC...SERFC...NWC...

LAT...LON 35719157 35719056 35418958 35028801 35058610
34278542 33608528 33258555 33028635 33318790
34008959 34749027

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