Mesoscale Precipitation Discussion 0214
NWS Weather Prediction Center College Park MD
335 AM EDT Sat May 03 2025

Areas affected...Coastal Alabama...Western Panhandle of Florida...

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

Valid 030735Z - 031300Z

SUMMARY...Slow moving/stationary coastal thunderstorms to be swept
up from west to east through early morning with main pre-frontal
convective line.  Highly localized 2-4" totals are possible in
proximity to urban centers posing possible rapid inundation
flooding.

DISCUSSION...Regional RADAR mosaic depicts a mature convective
line with a few bowing segments continuing to march southeastward
across southwest AL into far southeast LA with strong
meso-high/cold pool helping its advancement.  A weak surface wave
appears to have formed in proximity to southern MS, which seems
plausible given strength of onshore southerly to southwesterly
flow.  Strong frictional convergence at the coast at the nose of
an enhanced but narrow moisture plume from the mouth of the MS
river turning more southwest to northeast toward the AL/W FL
coastline continues to feed an expanding (eastward) convective
line at the coast.   Surface to 700mb moisture per CIRA LPW show
values of 1.5 to 1.7" being fed by 15-25kts of flow.  Warm Gulf
air in the upper 70s to low 80s and modest steepening lapse rates
support solid 1500-2000 J/kg of MLCAPE to maintain the stronger
updrafts.   The combination supports cells capable of 1.5-2"/hr
along the warm advective/frictionally forced cells.  While
pre-frontal convective line is advancing sweeping up/merging along
the way, this should result in 2-3 hours of solid rainfall prior
to the main line sweeping through.  As such, localized totals of
3-4" are possible.  

There is a potential factor that may limit flooding impact that
would be related to strength of cold pools from initial convection
pressing outflow boundaries off-shore resulting in best
convergence and downdrafts to be also offshore.  Current trends
suggest this is occurring more upstream and nearer the mixing of
the EML downward with the main-line convection.  So while the
soils are very sandy and likely to support solid infiltration, the
vast urban locations along I-10 from Mobile to Panama City will
have large impermeable surfaces even up to the shoreline; and as
such rapid inundation flooding may be possible over the next
4-6hrs as the main line sweeps through.

Gallina

ATTN...WFO...MOB...TAE...

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

LAT...LON   31008721 30998635 30908573 30268593 30328644
            30298699 30218751 30248828 30878832 30998805