Mesoscale Precipitation Discussion 0810
NWS Weather Prediction Center College Park MD
105 AM EDT Sun Sep 09 2018

Areas affected...Northern/Northeast KY...Southern OH...Western
WV...

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

Valid 090505Z - 091005Z

SUMMARY...Reduced rapid onset flash flooding shifting to longer
duration flooding.  Potential upstream redevelopment/training.

DISCUSSION...GOES-16 10.3um loop remains dominated by large but
warming cirrus canopy across Northern KY attm, though breaks in
the upper level clouds denote the stretched low to mid-level swirl
back over SW IND.  The forward progress of the remaining
convective cores of the convective line continues to race quickly
into Menifee county, producing less than 1.5" as it passes not
leading to flash flooding.   As such the overall threat will shift
to the stronger isentropic ascent along the 850mb front with the
strengthening LLJ.  While upstream environement across central KY
within the LLJ has some remaining instability, the LLJ is fairly
unidirectional and has limited speed shear for only occasional
embedded redeveloping cells.  The LLJ is expected (and denoted in
VWP) to increase over 30-40kts supporting a backbuilding/training
environment if cells can develop across the saturated areas of
Northern KY into SW Ohio, but this is appearing less likely, but
still possible as connecting moisture axis/plume is stretching
thin.  Still many of the Hi-res CAMS are persistent in breaking
out additional convection around the 7-8z time period, enough to
warrant some possible flash flooding concern given the saturated
grounds/low FFG wouldn't need much to lead to flash flooding.

Of greater flooding concern, is the remaining prolonged moisture
convergence at the nose of the LLJ along the deformation zone from
southern OH into N WV.  Here flux is strong and moisture is ample
(Total PWATs of 1.7-1.9"), but the lack of instability should
limit rates to below 1"/hr and 2-3" totals over the next 6hrs
lending to longer term inundation flooding concerns.  All in all,
a downward turn, but still modest potential for possible flooding
through the early morning hours.  

Gallina

ATTN...WFO...ILN...JKL...LMK...PBZ...RLX...

ATTN...RFC...OHRFC...

LAT...LON   39968091 39258065 38788118 38068233 37908328
            37928422 38608477 39308475 39508426 39678340
            39948222