AWUS01 KWNH 310956
FFGMPD
NCZ000-GAZ000-TNZ000-ALZ000-311500-

Mesoscale Precipitation Discussion 0101
NWS Weather Prediction Center College Park MD
556 AM EDT Mon Mar 31 2025

Areas affected...Northern AL...Northwest
GA...South-central/Southeast TN...

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

Valid 311000Z - 311500Z

SUMMARY...Multiple rounds of repeating thunderstorms capable of
2-3" totals may result in isolated incidents of flash flooding
into early morning hours.

DISCUSSION...GOES-E WV suite shows convective line across
Middle-TN is starting to reduce southeastward progression between
the exiting of the main shortwave across the Great Lakes and the
approaching wave across the Ozarks.  Upstream convective complex
is starting to feedback with developing outflow jet with
transverse banding features noted across the Mississippi River
Valley.  VWP suite shows 700-500 steering flow is becoming
increasingly parallel to the orientation of the old convective
line across southern TN, while GWX 925-850mb flow shows some
backed inflow obliquely intersecting the old outflow
boundary/convective line across NW to north-central AL; with weak
southerly surface to boundary layer flow proving some flux of
remaining unstable, moist air across northern AL. 

As such, GOES-E 10.3um and Regional RADAR shows an uptick in
convective vigor along and downstream of the approaching shortwave
energy in N MS into NW AL.  Narrow MLCAPE axis of 1000-1750 J/kg
remains across the area of concern to feed the development as well
as maintain approaching stronger cells across N MS.  Given the
aforementioned steering flow supporting parallel flow to the
boundary, there is an increasing chance of a few hours of
training/repeating convective cores ahead of the main line and
approaching cold front.  While deep layer moisture is more limited
than further upstream, solid low level Tds in the mid to upper 60s
and solid 80-100% RH values through 850-700mb along the axis
should allow for efficient rainfall production with limited loss
to evaporation.  So with overall Total PWats around 1.5-1.6";
rates of 1.75"/hr occasionally reaching 2"/hr are possible.  With
one to two hours of repeating with very slow southeastward
propagation of the line, spots of 2-3" totals are becoming more likely.

Soils are not as dry as locations to the south and east, with
average soil saturation around 55-60% through 40cm,  FFG values
across the area are near/at the limits of these hourly rates and
totals.  However, given the average nature of the soils, perhaps
infiltration will be fairly solid to keep flash flooding risk
limited to typically prone areas and urban locations or isolated
spots over the FFG.  All in all, a spot or two of flash flooding
is considered possible, if training conditions are ideal
downstream of MPD 99 in AL/S TN/NW GA.

Gallina

ATTN...WFO...BMX...FFC...HUN...MRX...OHX...

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

LAT...LON   35808471 35668418 35308406 34848426 34478470 
            34088539 33708637 33238811 33738822 34468812 
            34938800 35158752 35408644 35658534 

$$
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