499
AWUS01 KWNH 171917
FFGMPD
GAZ000-ALZ000-MSZ000-180030-

Mesoscale Precipitation Discussion 0471
NWS Weather Prediction Center College Park MD
317 PM EDT Tue Jun 17 2025

Areas affected...Southeast MS...Alabama...Northwest GA...

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

Valid 171915Z - 180030Z

SUMMARY...Weakly organized convective cells congealing with
potential for some localized repeating/mergers capable of 2"+/hr
rates and localized totals 2-3" in about 3hrs may result in focus
rapid inundation, particularly near urban centers.

DISCUSSION...GOES-E WV suite shows the very slow moving and narrow
positively tilted mid-level trough across the MS into TN/Lower
Ohio Valleys.  Embedded within are two meso-scale shortwave
features that are directing/corralling convective activity into
weakly organized linear features.   The lead wave in southern
Middle TN extends some wrap around southwesterly flow to bow out
the deeper layer confluence zone eastward across N AL before it
angles back southwest across west-central AL and southern MS
toward the weaker trailing/tail-end wave near SW MS/NE LA.  Deep
layer moisture is well above average with values of 2-2.25"
along/ahead of the deeper layer axis.  Traditionally summer like
temperatures in the mid 80s over lower to middle 70s Tds support
ample CAPE over 2000 J/kg for stronger updrafts.  Aloft, there is
modest divergence along the eastern right entrance to the jet,
especially given that it is also moderately anticyclonically
arched for broad scale divergence to allow for modest outflow for
a few up/downdraft cycles to help feed moisture flux into the
increasingly confluent band of convection.  Effective bulk shear
values are 20-25kts to show some weak organization for linear
features or propagation through outflow boundary/low level
convergence/collisions with other outflows.

Still, the overall 10.3um EIR loop and RADAR mosaic shows an
overall broad coverage of these cells capable of short-term bursts
of up to 2"/hr.  This is particularly evident from Clarke, MS to
Hale county, AL with a bit of deep layer steering for increased
duration as cells have a few extra minutes of repeating/training
given the north-northeast cell motion along the same oriented
confluence axis.  Additional incidents are probable to occur with
time further north and east as the overall trof slowly slips
eastward overall.  Hydrologically, the rates up to 2"/hr are
problematic across central AL into NW GA where 1hr FFG are at or
below those rates.  These cells are likely to cross larger urban
centers with hydrophobic ground conditions that could be quickly
overwhelmed by the short-term magnitude of heavy rainfall, but
otherwise incidents of flash flooding are likely to be widely
scattered an narrow in areal coverage/focus through the evening
across the area of concern.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BMX...FFC...HUN...JAN...MOB...

ATTN...RFC...ALR...ORN...NWC...

LAT...LON   34958456 34758385 33548471 32548630 31618760
            31268835 31048917 31268998 31988999 33168892
            33658826 34288791 34408670 34868581