WPC Met Watch

WPC Met Watch


Mesoscale Precipitation Discussion: #0221 (Issued at 240 PM EDT Sat May 04 2024
) MPD Selection


Graphic for MPD #0221

Mesoscale Precipitation Discussion 0221
NWS Weather Prediction Center College Park MD
240 PM EDT Sat May 04 2024

Areas affected...Southern OH...Western & Northern WV...Ext
Southwest PA...

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

Valid 041840Z - 050000Z

SUMMARY...Anomalous moisture and unstable air to produce
1.25-1.75"/hr rates and spots of 2-3" across hilly areas of the
Upper Ohio Valley. Scattered Localized incidents of FF possible. 

DISCUSSION...GOES-E and surface analysis depicted a shallow
cyclone from the surface to the remaining weak inflection at 500mb
along the IND/OH border. A broad area of anomalous deep layer
moisture of 1.25-1.5" exists across much of eastern OH along/head
of a surging warm front that lifting from the surface low near
Cincinnati across NE KY into far W VA.  Clearing skies though the
morning and continued modest moisture advection through the
mid-levels without stabilizing the mid-levels shows low 70s Ts
over upper 60s Tds supporting 1000-1250 J/kg MLCAPEs along the
front to the spine of the Appalachians.

Currently, the stronger flow/convergence in proximity to
increasing orography has resulted in a clustering fo stronger
cooling topped thunderstorms across NE KY moving into SW WV. Given
moisture and strength of updraft, rainfall generation is
supporting 1.5-1.75"/hr.  While cell motions of 15-20kts to the
northeast are likely to limit duration, increasingly complex
terrain and 1-2 hours may result in 2-3" totals which would exceed
both the 1 and 3hr FFG values in the area resulting in localized
flash flooding.  This activity is likely to expand or develop
further upstream through the Upper Ohio Valley through the evening
with similar concerns of localized 2-3" totals.

Further west in SW Ohio...
Cell motions are likely to be much slower given proximity to the
surface to 700mb low. Initial development may linger for a bit due
to said chaotic steering winds, but eastward propagation should
begin with eventual outflow development by late
afternoon....similar slow moving/SHaRS may dot the 700-500mb
confluence axis that extends more or less up I-75 into
West-central Ohio. RAP analysis also suggests an 850-700mb
boundary extending eastward the may harness the cyclonic
convergence along the western side of the WAA in south-central OH
and result in downstream development which may allow for multiple
rounds of less intense thunderstorms but may still allow for
scattered spotty 2-3" totals over a slightly longer duration than
elsewhere but result in low-end flash flooding.  




LAT...LON   40778119 40638070 40258036 39718028 39178044
            38208093 37518179 38078254 38798332 38958459
            39738480 40658385 40338226

Download in GIS format:    Shapefile
 | KML

Last Updated: 240 PM EDT Sat May 04 2024

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