Weather Prediction Center issues Mesoscale Precipitation Discussion #784 concerning HEAVY RAINFALL...FLASH FLOODING POSSIBLE162
AWUS01 KWNH 022206
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Mesoscale Precipitation Discussion 0784
NWS Weather Prediction Center College Park MD
605 PM EDT Fri Aug 02 2024
Areas affected...Portions of the Lower Great Lakes and Upper OH
Valley
Concerning...Heavy rainfall...Flash flooding possible
Valid 022205Z - 030405Z
SUMMARY...Scattered to broken areas of heavy showers and
thunderstorms will promote a threat for isolated to widely
scattered instances of flash flooding going through the evening
hours.
DISCUSSION...The late-day GOES-E GeoColor satellite imagery in
conjunction with dual-pol radar shows scattered to broken areas of
showers and thunderstorms impacting areas of southeast MI down
through eastern IN and western OH. The activity continues to be
influenced by a deep layer low pressure system that is gradually
settling east-southeast into the OH Valley. DPVA ahead of the low
center and interaction with a moist/unstable airmass across the
upper OH Valley region should favor a regional threat of locally
heavy showers and thunderstorms going well into the evening hours.
MLCAPE values remain on the order of 1500 to 2000 J/kg across much
of central and western OH, with somewhat lesser values seen
farther off to the east into northern WV and western PA.
Meanwhile, PWs across the region are locally around 1.75 inches,
and these magnitudes are somewhat anomalous (1.5+ SD above normal)
for this time of the year.
Rainfall rates with the areas of convection this evening are
expected to be as high as 1 to 2 inches/hour. Gradually by later
this evening as boundary layer instability becomes increasingly
exhausted, the rainfall rates and general coverage of convection
should begin to subside. However, going through at least the
mid-evening hours, the storms will be sustainable and will also be
rather slow-moving. The slow cell-motions and heavier rates will
foster a threat for some localized 2 to 4 inch rainfall totals.
The 12Z/18Z HREF guidance generally supports this potential and
does reflect some low-end probabilities of seeing the 1-hour and
3-hour FFG values exceeded as this evening's convection advances
east across the upper OH Valley. This will include much of central
and eastern OH, northern WV and far western PA in time. Thus, the
expectation is that some isolated to widely scattered instances of
flash flooding will be possible.
Orrison
...Please see www.wpc.ncep.noaa.gov for graphic product...
ATTN...WFO...CLE...ILN...IND...IWX...JKL...PBZ...RLX...
ATTN...RFC...NCRFC...OHRFC...NWC...
LAT...LON 41778496 41538338 41438204 41498091 41597995
41007940 40137941 39048014 38368179 38428361
38978488 39868554 40838581 41508566
Source:
Weather Prediction Center issues Mesoscale Precipitation Discussion #784 concerning HEAVY RAINFALL...FLASH FLOODING POSSIBLE---------------
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