SPC MD 435

SPC MD 435


Mesoscale Discussion 0435
NWS Storm Prediction Center Norman OK
0229 PM CDT Sun Apr 14 2024

Areas affected…portions of central/eastern Ohio into Pennsylvania

Concerning…Severe potential…Watch likely

Valid 141929Z – 142130Z

Probability of Watch Issuance…80 percent

SUMMARY…Thunderstorms are expected to develop by 4-5 pm EDT.
Damaging gusts and isolated large hail will the the main hazards
with this activity as storms track south-southeast through the
evening. A severe thunderstorm watch will likely by needed in the
next 1-2 hours.

DISCUSSION…Boundary-layer moisture has gradually increased through
the day across the Upper Ohio Valley into northeast PA, with surface
dewpoints now in the mid 40s to low 50s F. Strong heating beneath
steep lapse rates is supporting weak destabilization. Deepening
cumulus has been noted over Lake Erie into western NY the past hour
or so, indicating increasing ascent is overspreading the region. The
expectation is that this activity will continue to deepen and
potentially become more surface-based with time as it shifts
southward into OH/PA over the next few hours.

Initial cells will likely quickly develop into linear segments given
unidirectional flow, which is also parallel to a
south/southeastward-advancing surface cold front. Given steep
low-level lapse rates and modest boundary-layer moisture, damaging
gusts are expected. Furthermore, steep midlevel lapse rates and cold
temperatures aloft will support isolated large hail, especially with
any convection that remains cellular/semi-discrete. Some improvement
of low-level shear is expected with time, resulting in somewhat
enlarged low-level hodographs. This may support a tornado or two,
but marginal low-level moisture will limit the overall tornado risk.

..Leitman/Smith.. 04/14/2024

…Please see www.spc.noaa.gov for graphic product…


LAT…LON 40768277 41258110 41947686 42107557 41887519 41547500
41027539 40697604 40377712 39857919 39768057 39748213
39978271 40358292 40638290 40768277

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