Weather Prediction Center issues Mesoscale Precipitation Discussion #1112 concerning HEAVY RAINFALL...FLASH FLOODING POSSIBLE910
AWUS01 KWNH 221801
FFGMPD
NYZ000-PAZ000-WVZ000-OHZ000-222300-
Mesoscale Precipitation Discussion 1112
NWS Weather Prediction Center College Park MD
200 PM EDT Sat Aug 22 2026
Areas affected...North & Eastern OH...Western PA...Far Western
NY...Far Northern WV...
Concerning...Heavy rainfall...Flash flooding possible
Valid 221800Z - 222300Z
SUMMARY...Multiple rounds of scattered thunderstorms capable of
1-1.5", suggest random intersections resulting in widely scattered
spots of 1.5-2.5". Low FFG (<2"/3hrs) and larger urban areas
suggest incidents of flash flooding are possible this afternoon
into evening.
DISCUSSION...GOES-E WV shows broad long-wave trough across the
Great Lakes with an upstream strengthening/digging shortwave
crossing Lake Michigan which is starting to result a developing
triple-point in central LP of MI as the main surface low in NW
Lake Huron continues to strengthen. A southern stream
wave/vorticity center is well defined across south-central OH
helping to direct the effective warm front from near CLE to ZZV
and UNI eastward with enhanced low level moisture and higher
Theta-E air pooled along it, with MLCAPEs reaching 2000 J/kg,
where warm conveyor belt moisture is also peaked around 1.3-1.5"
for TPW. Surface to boundary layer convergence from SW to SE
across the boundary has resulted in broad convective development
though cells updrafts are broadening, they remain widely spaced
with some hints of multiple north-south oriented bands.
Increased convergence near lake-breeze off Erie, further enhances
shower activity. Given the moisture and solid instability rates
of 1-1.5" are more likely, but totals will probably be in the 1"
range given forward propagation/cell motions eastward are
expected.
Upstream, initial cluster of thunderstorms over SE MI is sliding
into the slightly increased unstable air over north-central OH,
while further convergence along the cold front across
south-central MI into NE IND is starting to build overall as well.
Compared to the warm front, mid-level moisture is a bit less and
overall TPWs are closer to 1-1.25" but directional and speed
convergence may allow for cells to be comparable to the eastern
warm front band, but still similarly progressive and likely to
result in peak of 1" totals; so no one cell is likely to exceed
even the lower FFG values of 1.5-2"/hr. However, given the
increasing coverage and broadening updrafts intersecting
footprints from each round may allow for widely scattered spots of
1.5-2.5" by 00z and with 3hr FFG in the 1.5-2" range especially
along I-70 in central OH to W PA (~2/3hrs across N Ohio) incidents
of exceedance are considered possible this afternoon into evening.
Gallina
...Please see www.wpc.ncep.noaa.gov for graphic product...
ATTN...WFO...BUF...CLE...CTP...ILN...PBZ...RLX...
ATTN...RFC...RHA...TAR...TIR...NWC...
LAT...LON 42607899 42237837 41297833 40787882 39067998
38988142 39398255 39898334 40788374 41398370
41718319 41558246 41838140 42168054 42278010
Source:
Weather Prediction Center issues Mesoscale Precipitation Discussion #1112 concerning HEAVY RAINFALL...FLASH FLOODING POSSIBLE---------------
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