Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat Aug 31 2024 08:56:12

AWUS01 KWNH 310856
FFGMPD
MSZ000-LAZ000-311430-

Mesoscale Precipitation Discussion 0955
NWS Weather Prediction Center College Park MD
455 AM EDT Sat Aug 31 2024

Areas affected...Southeast Louisiana...Coastal Mississippi...

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

Valid 310855Z - 311430Z

SUMMARY...Back-building/repeating efficient rain producing banded
tropical showers may produce localized 2-4" totals near coastlines
where convergence is maximized.  Rates of 2-2.5"/hr may quickly
induce possible rapid inundation flooding incident(s) through
early morning.

DISCUSSION...GOES-E WV suite denotes a strong fairly symmetric
TUTT cell over south-central LA slowly sliding eastward.  An
internal vorticity center extends southeastward along the SE LA
coast providing some weak DPVA along the northern edge as it
lifts.  Combined with solid weakly confluent 15-20kt sfc to 850mb
southeasterly flow favorably intersecting coastline favorably for
frictional speed convergence allowing for low level forcing/ascent
to connect to the weak mid-level ascent pattern.  RAP/CIRA LPW
moisture analysis, denotes the confluence band into SE LA and the
MS coast is along the northeastern moisture gradient through depth
with 2.25" over the area quickly diminishing to 2" by Mobile Bay
and 1.5" by the Big Bend of Florida.

Sufficiently unstable Gulf air of 2000 J/kg of MLCAPE in this
narrow skinny profile and deep warm layer should allow for
efficient rainfall production for cells that due develop.  Deep
layer steering would direct cells more northwest to
north-northwest allow for narrow training/repeating convective
elements, though more stable air over the land should weaken cells
not reaching too far into central LA before weakening.  As such,
rates of 2-2.5"/hr are possible with narrow to moderately sized
updrafts.  As such, scattered pockets of 2-4" are possible through
early morning in short-duration for possible rapid inundation
flooding, especially near urban centers.

One caveat to the flooding potential: Given 15-20kts of inflow,
propagation vectors will be back toward the southeast at 5-10kts
and may strengthen with time if initial cells remain fairly
stationary due to cold pool generation.  This would then likely
see convergence axis move upstream, further offshore limiting
totals.=20

Gallina

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!7c0kFp9QTk3B39-GS09d-XzLO2FC01SrilImYINMvYf2qbOr0Sp7er28UazPI8zd4Dex=
JeW_lffO3glz9rbnFojI_5E$  for graphic product...

ATTN...WFO...LIX...MOB...

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

LAT...LON   30989068 30979014 30778921 30648861 30358847=20
            29638880 29088892 28848912 28868937 29059004=20
            28979069 29159113 29569101 29919094 30599109=20
            30919095=20

=3D =3D =3D
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