Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Apr 25 2025 19:59:02

AWUS01 KWNH 251958
FFGMPD
PAZ000-WVZ000-OHZ000-260130-

Mesoscale Precipitation Discussion 0178
NWS Weather Prediction Center College Park MD
358 PM EDT Fri Apr 25 2025

Areas affected...Northern Ohio...Northwest Pennsylvania...

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

Valid 252000Z - 260130Z

SUMMARY...Unseasonable moisture allowing for shallow but efficient
showers and thunderstorms with 1"/hr rates and potential for
repeats and totals over 2", resulting in possible scattered flash
flooding.

DISCUSSION...CIRA LPW and RAP analysis shows strong warm conveyor
belt extending along and ahead of broad large scale trof across
the Mississippi Valley into Lower Ohio/Tennessee Valley.=20
Southwesterly 850mb flow and core of 1.5" TPW noses northward
across east-central IND into northern Ohio with increasing speed
convergence as 30kts of 850mb flow reduce to 10-15kts across the
area of concern.  CIRA LPW percentile on the anomalous moisture
denote a broad area of 95-99th in the surface to 850mb layer (Tds
in the lower 60s) with a bit more focused 95-99th in the 850-700mb
layer across northern OH.  Filtered sunshine through broken cirrus
has brought temperatures in the mid-70s resulting in increasing
unstable environment with MLCAPE axis of 1000 J/kg along a similar
west to east axis at the nose of the LLJ/speed convergence.   As
such, regional RADAR shows increasing convection, while
overshooting tops/CBs below -60C are breaking out across northwest
OH into north-central ahead of DPVA downstream of shortwave trough
energy crossing central IL/IND attm.=20

So, while instability is not extreme for broad updrafts, the
overall coverage of these cores will increase into the afternoon.
Combine this with orientation of the cores along the instability
axis is fairly parallel to the deeper layer WSW to ENE steering
and may support some scattered repeating of cells.  Rates of
1"+/hr are probable so localized totals of 2"+ in 1-3hrs may
result in localized exceedance of FFG values which are generally
1-1.5"/hr and <2"/3hrs across the area of concern.  As such,
scattered incidents of flash flooding is considered possible
through the evening hours.=20

Gallina

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!9R7uAVG39AqR_GgyzNHoocEpXj6N-mLrsgtVJEF9AZUKlLdQ_zutQBTkRo8879qjakSG=
qGXJFCKtMHG7l40ela-YtlA$  for graphic product...

ATTN...WFO...CLE...ILN...IWX...PBZ...

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

LAT...LON   42128004 41587964 40837906 40367935 40258095=20
            40108247 40088414 40398468 41128467 41428446=20
            41598400 41708288 41498233 41938083=20

=3D =3D =3D
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