Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue May 20 2025 17:00:57

AWUS01 KWNH 201700
FFGMPD
VAZ000-WVZ000-OHZ000-TNZ000-KYZ000-202230-

Mesoscale Precipitation Discussion 0295
NWS Weather Prediction Center College Park MD
100 PM EDT Tue May 20 2025

Areas affected...Eastern KY...Northeast TN...Far Southwest
WV/Western VA...Ext Southern OH...

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

Valid 201700Z - 202230Z

SUMMARY...Strengthening storms with history of quick 1-2" totals
moving towards more hydrologically sensitive grounds and may
result in an isolated to widely scattered incident or two of
localized flash flooding.

DISCUSSION...CIRA LPW depicts a western Gulf connected warm
conveyor belt pressing eastward across the Cumberland and
Tennessee River Valleys; though there is some tilting of the plume
with 700-500mb starting to outpace/outrun the core of the surface
to 850mb layer, but still a solid slug of 1.75" total PWats lay
along/downstream of a corralling mid-level shortwave feature
crossing into northern Middle TN; as such there is moisture flux
trapping along the downshear angle northeast of the low along its
expected path into central KY.  An anchored surface front further
sharpens ascent pattern as it bisects KY from FTK to DVK to JKL
toward a surface inflection in SW WV.  Additionally, last-night's
pre-frontal convective trough has entered an area that has
received solid insolation across Middle TN into central/eastern KY
that an instability axis/bubble has formed with solid 2000 J/kg
CAPE.  Weakly backed mid-level flow ahead of the shortwave is
enhancing weak confluence, deep layer convergence and instability
advection to further enhanced thunderstorm activity.  Cells
near/downshear of the MCV near Allen county have increased
rainfall efficiency to see a few observations at or just below
1"/hr.  This is expected to uptick slightly as updrafts broaden
increasing that duration of the downdraft even just a few minutes
for 1.5-2" totals to occur over the next 1-2 hours as the line
continues a fairly progressive eastward march.

The concern for isolated to widely scattered incidents of
localized flash flooding only further increases due to more rugged
terrain of the Cumberland Plateau and eventually the western
slopes of the Appalachian Range.  Additionally, NASA SPoRT 0-40cm
relative soil moisture values remain elevated at 65-75% and
therefore the lower FFG values of 1.5"/hr and 1.5-2.25"/3hrs are
will within reach for minor exceedance (given duration/totals are
likely to remain less than 3" with this progressive round).  All
considered localized flash flooding is considered possible this
afternoon.

Gallina

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!_X75e2fSTwI0T75wp1o4ayXg-BI0NU8OieXT6DURteTX7y-QuCQGCvbBIdk1emaOJTLo=
OtscYtrjHDT9HG98KUjUdg0$  for graphic product...

ATTN...WFO...ILN...JKL...LMK...MRX...OHX...RLX...

ATTN...RFC...ORN...TIR...NWC...

LAT...LON   38978336 38828228 38448140 37768117 37168192=20
            36568236 35968363 35748472 35738567 36228610=20
            36788595 37698525 38788425=20

=3D =3D =3D
To unsubscribe from WX-STORM and you already have a login, go to
https://lists.illinois.edu and use the "Unsubscribe" link.  Otherwise email
Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM.

--- SBBSecho 3.20-Linux
 * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)

.