- Day Three
acus03 kwns 250732
Storm Prediction Center ac 250731
Day 3 convective outlook
National Weather Service Storm Prediction Center Norman OK
0231 am CDT Mon Jun 25 2018
Valid 271200z - 281200z
..there is a marginal risk of severe thunderstorms from the Ohio
Valley eastward into western Virginia and Pennsylvania...
Scattered strong to severe storms are possible from the Ohio Valley
eastward into western Pennsylvania and Virginia on Wednesday.
A shortwave trough will move eastward across the Ohio Valley during
they day, and will lose amplitude as it continues across the
northeast. At the surface, low pressure will move from lower Michigan
across the lower Great Lakes, with a cold front trailing
southwestward across Ohio and into the middle MS valley. Ahead of
the low, substantial southwesterly flow will spread warm and moist
air northward, with widespread upper 60s f dewpoints supporting
areas of moderate instability.
To the west, fast zonal flow aloft will exist across the northern
rockies into the northern plains, with rising heights overnight as
an upper trough develops over the northwestern states. A nocturnal
southerly low-level jet will transport a moist and unstable air mass
northwest across the northern plains, possibly supporting isolated
..OH/WV/PA and surrounding states...
A large area of strong instability will exist across much of the Ohio
and Tennessee valleys, with MLCAPE in excess of 2000 j/kg common. Flow
aloft with the upper wave will result in marginally favorable wind
profiles supportive of clusters of severe storms, and a zone of
veering winds with height across PA into WV may enhance srh and
support an isolated supercell. However, scattered storms are
possible throughout the day producing rain and outflow, which lends
uncertainty to placing a slight risk due to air mass contamination.