Mesoscale Precipitation Discussion 0600
NWS Weather Prediction Center College Park MD
555 PM EDT Tue Jul 09 2024

Areas affected...portions of the Ohio Valley

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

Valid 092155Z - 100300Z

Summary...Training/repeating rainfall rates of 1-2"/hr may lead to
localized totals of 3-5". Isolated to scattered instances of flash
flooding are possible.

Discussion...Post-tropical cyclone Beryl is tracking northeast at
24 mph across the MS/OH Valleys this afternoon, and convection has
become focused primarily east of the center (both along the warm
front and across the warm sector (post-frontal). Discrete
supercells have become the most efficient rainfall producers, with
rainfall rates of 1-2"/hr. Otherwise, convection is generally
producing rates of 1"/hr or less (with stratiform rainfall north
of the center generally producing 0.5"/hr or less). Along and
ahead of the warm front, the mesoscale environment is
characterized by ML CAPE of 1000-2000 J/kg, precipitable water
values of 2.0-2.3 inches (near record values, per SPC sounding
climatology from surrounding sites), and ample effective bulk
shear of 45-55 kts.

With convection is remaining rather progressive due to the strong
dynamics of this post-tropical system, there is a distinct risk of
localized training/repeating of heavy rainfall rates (1-2"/hr) in
and around the aforementioned warm front (stretching from southern
IL across the IN/KY border region). The 18z HREF probability
matched mean QPF depicts localized totals of 3-5" (with
corresponding 40-km neighborhood probabilities for 3" exceedance
of 20-30%). A much broader region to the north and east of the
cyclone has relatively high odds of localized 2" exceedance (per
40-km neighborhood probabilities of 40-70%), and corresponding
Flash Flood Guidance (3-6 hr) generally ranges from 2-3". As a
result, isolated to scattered instances of flash flooding are
possible (with the greatest risk over southeast IN and adjacent
portions of IL/KY).

Churchill

ATTN...WFO...ILN...ILX...IND...LMK...LOT...LSX...OHX...PAH...

ATTN...RFC...LMRFC...NCRFC...OHRFC...NWC...

LAT...LON   40708771 40468699 40008630 39578588 38888511
            37718531 36608585 36338744 36668815 37898853
            39648992 40328948 40648867