519
AWUS01 KWNH 291449
FFGMPD
NYZ000-PAZ000-MDZ000-WVZ000-OHZ000-292045-

Mesoscale Precipitation Discussion 0340
NWS Weather Prediction Center College Park MD
1048 AM EDT Wed May 29 2024

Areas affected...Upper OH Valley

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

Valid 291448Z - 292045Z

Summary...Slow moving thunderstorms are expected to increase in
coverage from eastern OH into northern WV and western PA into the
afternoon. Rainfall rates of 1-2 in/hr with localized totals of
2-3 inches may result in some localized to scattered areas of
flash flooding.

Discussion...GOES East water vapor imagery showed a mid-level
closed low/vorticity max located over northern OH at 1430Z,
associated with an area of slow moving showers and embedded
thunderstorms stretching from north-central OH into western PA.
Recent reports to the south of Sandusky Bay showed observed
rainfall rates of 1 to 1.5 in/hr since 11Z along with isolated
totals over 2 inches with slow movement of heavy rain cores.
Current instability values are low, represented by the 12Z PIT
sounding with 191 J/kg, and moisture is rather modest with
precipitable water values of 0.7 to 1.0 inches across the Upper OH
Valley, which will limit heavy rainfall potential.

However, as the mid-level vorticity max over north-central OH
translates toward the ESE through mid-afternoon, weak 0-6 km mean
wind of ~5 kt or less will spread across northeastern OH into
western and northern PA, supporting slow movement of heavy
rainfall cores. Farther south, across far northern WV into
southwestern PA, cell motions are expected to be more progressive
but brief west to east training may still allow for isolated areas
of 1+ in/hr rainfall rates. While cloud cover will limit
instability across portions of the region, sufficient moisture and
instability (MLCAPE forecast up to 750 J/kg) will be present to
support rainfall rates of 1-2 in/hr in a few locations with
possible totals between 2-3 inches through 21Z. Flash flood
guidance of 1-2 in/hr suggests some localized to scattered areas
of flash flooding will be possible.

Otto

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

ATTN...WFO...BUF...CLE...CTP...ILN...PBZ...RLX...

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

LAT...LON   42067998 41957878 41677819 40957808 40357827
            39957864 39587954 39538065 39738178 40188301
            40588355 41158349 41568313 41488250 41618208
            41768124