Mesoscale Precipitation Discussion 0799
NWS Weather Prediction Center College Park MD
300 AM EDT Sat Sep 08 2018

Areas affected...Central/Southwest OH...Central/Southeast
IND...Northern KY...

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

Valid 080700Z - 081200Z

SUMMARY...Persistent moderate deformation zone rainfall and few
slow moving cells along N-S outer band within rich moisture
environment pose flash flooding threat.

DISCUSSION...WSR-88D VWP network reflectivity imagery and RAP
analysis fields suggests a weak wave in the 850-7H layer shedding
eastward along deformation zone near IND with a distant
convergence band extending southward with scattered convective
cells along it. 

Strong moisture flux convergence within the a fairly vertically
stacked deformation zone with deep moisture and Total PWATs of
1.75-2" support some convective elements /modest rain rates along
the corridor from the subtle wave eastward into central OH.  Rates
of .5-1"/hr are associated with this zone and subject to
occasionally higher bursts.  As such 2-3" of rain is expected over
the next few hours near/along the I-70 corridor.  Given the
compromised soil conditions, FFG being low (3hr FFG <1.5"), slower
rise inundation flash flooding may be expected over the next few
hours along this corridor.  Even if this rainfall does not induce
flash flooding, it sets the stage for increased threat later in
the evening/overnight hours as the main surface wave (Remnants of
Gordon) track through the same areas.

Further south, the N-S oriented old outer convergence band of
Gordon is acting as an effective cold front slow drifting east. 
Though winds are weak north of the stationary front, they are
veered slightly to for some modest (100-200 m2/s2) effective
helicity for some rotation to the updrafts.  As such this will
periodically  slow eastward progression of these cells allowing
for some compounding totals, as denoted by recent trends in the
Louisville area.  Eventually, the band will reach the Cincinnati
metro area which has seen saturated soil conditions lead to
flooding, and cells capable of 1-1.5"/hr rates may be sufficient
for isolated flash flooding concerns. 

Gallina

ATTN...WFO...CLE...ILN...IND...IWX...LMK...

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

LAT...LON   40658405 40608291 40328244 39808258 39278350
            38768408 38438439 37618507 37588595 38598587
            38908586 39208593 39648650 40218637 40568540