650
AWUS01 KWNH 041458
FFGMPD
WVZ000-OHZ000-KYZ000-INZ000-ILZ000-042000-

Mesoscale Precipitation Discussion 0555
NWS Weather Prediction Center College Park MD
1057 AM EDT Thu Jul 04 2024

Areas affected...Portions of the Ohio River Valley

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

Valid 041456Z - 042000Z

Summary...MCS continues this morning across portions of the Ohio
River Valley. Periods of training storms with 2"/hr rainfall rates
will maintain a threat of some flash flooding this morning as the
complex moves east.

Discussion...IR and regional radar this morning depicts a
northeast-southwest oriented arc of thunderstorms exhibiting some
training characteristics as the complex lifts east-northeast.
Recent radar and MRMS hourly rainfall estimates suggest 2"/hr
rainfall rates have materialized within the most intense cores of
this activity over portions of southeast IL and IN.

This maintenance of this complex remains tied to a focused
low-level jet providing plenty of convergence and theta-e
advection atop a well defined (but balanced) cold-pool, with 40-50
kts of 850 mb inflow evident on KLSX and KVWX VWPs ahead of an
emerging MCV. An anticyclonically curved jet streak is also noted
to the north over the Upper Midwest, which will likely contribute
additional forcing for ascent. Within the inflow region of this
complex, recent mesoanalysis and GPS estimates denote 1000-2000
J/kg MUCAPE and PWATS upwards of 2.2-2.4" -- which is well above
the 90th percentile and near the daily record max for some
sounding sites in the region. When combined with warm cloud layers
around 13000 feet, the environment will remain highly conducive
for efficient warm rain production this morning as the environment
spreads east.

Over the next several hours, the concern remains for periods of
this efficient training to persist across the Ohio Valley.
Overnight CAMS in the HREF suite have struggled with the placement
and orientation of QPF through the morning hours, likely in part
due to issues initializing the MCV. However, recent runs of the
HRRR seem to have a somewhat better handle on the mesoscale
environment surrounding the MCS--including both the MCV location
and subsequent uptick in low-level inflow. Where echo training can
occur, rainfall amounts of 2-4" in a fairly short amount of time
will be possible through 19-20Z. This could lead to scattered
instances of flash flooding as FFGs in the region are quite low,
around 1-2"/hour.

Asherman

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ILN...ILX...IND...JKL...LMK...PAH...RLX...

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

LAT...LON   39978491 39868423 39298301 37978254 37468336
            37838570 37148796 37778853 38948765 39768642