AWUS01 KWNH 012126
FFGMPD
OHZ000-KYZ000-INZ000-020325-

Mesoscale Precipitation Discussion 0778
NWS Weather Prediction Center College Park MD
526 PM EDT Thu Aug 01 2024

Areas affected...Portions of Indiana and Ohio

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

Valid 012125Z - 020325Z

Summary...Increasing convective coverage and intensity will result
in isolated to scattered flash flood concerns over portions of
Indiana and Ohio into this evening.

Discussion...Convection is beginning to increase in coverage and
intensity across portions of central IN, and this trend is
expected to continue into this evening. Over the past 3 hours
MLCAPE has increased by around 500 j/kg over this corridor, with
values currently within the 2000-3000 j/kg range. PWs are on the
increase as well, with values around 2" expected to generally
cover the area. This environment will be conducive for heavy
rainfall rates. The improving thermodynamic environment combined
with an approaching mid level shortwave suggests convective
coverage will continue to increase over the next few hours.
Individual cell motions will likely stay rather quick, generally a
limiting factor for flash flooding. However note a broad southwest
to northeast oriented convergence axis across IN and OH...which
should act as a focus for convective development. Given storm
motions will generally be parallel to this convergence axis, some
convective training can be expected. In addition, effective bulk
shear of ~30 kts supports some multi cell organization to
convection, another factor in locally extending rainfall duration.

Given these factors, expect an isolated to scattered flash flood
threat to evolve into the evening hours across portions of central
IN into OH. The 18z HREF probabilities of exceeding 3 hr FFG get
as high as 40-70% over portions of the area. HREF 3" neighborhood
exceedance probabilities are over 40%, but 5" exceedance drops to
near zero. Recent runs of the HRRR support similar QPF
amounts...with pockets of 2-4" appearing likely. This portion of
IN and OH have not been as wet of late, and thus soil saturation
is actually below average, and streamflows are near to below
average as well. Thus initially this area should be able to take
some of the heavy rainfall without impacts. However as convective
coverage increases and local training occurs, do expect we will
see an isolated to scattered flash flood risk materialize across
the region.

Chenard

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

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

LAT...LON 41208296 41178240 40938199 40368230 39688298
39378359 39158432 39118482 39108592 39538659
39808671 40068636 40628508 41088349
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