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WPC Met Watch

Mesoscale Precipitation Discussion: #0547
(Issued at 327 AM EDT Thu Jul 21 2022 )

MPD Selection

Graphic for MPD #0547
Mesoscale Precipitation Discussion 0547
NWS Weather Prediction Center College Park MD
327 AM EDT Thu Jul 21 2022

Areas affected...Southern KY...Eastern TN...Western NC...

Concerning...Heavy rainfall...Flash flooding likely

Valid 210730Z - 211300Z

SUMMARY...Training thunderstorms with additional 2-4" totals
potentially crossing locations of ongoing flooding likely to
continue flash flooding risk through Thursday morning. 

DISCUSSION...Regional RADAR mosaic depicts a mature linear MCS
from south-central KY sagging into eastern TN.  The strength of
the cold pool in combination with progressing height-falls across
central KY into the northern Cumberland Plateau has allowed for
increased southward propagation tilting the orientation of the
line more WNW to ESE, matching with the 500-1000 thickness ridge
across W TN to E KY.  This has oriented the line more orthogonal
to continued sfc to 925mb convergence and upglide to maintain
moisture flux convergence, advecting uncapped unstable upstream
airmass still represented by 3000 J/kg MLCAPE and total PWAT over
2 to max of 2.25".  This should keep rainfall efficiency very high
with rates of 2-2.5"/hr, while instability remains available
(reducing/capping in the 11-13z time frame) slowing into the
1.5-2" range but perhaps maximizing upslope into the western
slopes of the Smokies.

Mean cell motions are not as ideal for training (due to
propagation southward, particularly east) as earlier, but should
remain sufficient for 1-2hrs of duration allowing for additional
2-4" totals.   FFG values across the Cumberland Plateau in E TN,
further reduce 1hr <1.5" and 3hr <2.5" which make flash flooding
likely.  Additionally, areas of significant flash flooding with
totals of 4-7" in proximity to Oak Ridge to Knoxville, TN and
Swain and Clay/Cherokee counties in NC will be particularly
susceptible for reaggravation of flash flooding with even 1"/hr




LAT...LON   36848591 36678442 36648290 36218206 35358237
            35028342 35178455 35668568 36178638 36568641

Last Updated: 327 AM EDT Thu Jul 21 2022

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Page last modified: Thursday, 12-May-2022 19:44:52 GMT