Mesoscale Discussion 1418
NWS Storm Prediction Center Norman OK
0509 PM CDT Mon Jul 24 2017
Areas affected...Northern VA...MD...DE...southeast PA...southern NJ
Concerning...Severe potential...Watch unlikely
Valid 242209Z - 250045Z
Probability of Watch Issuance...20 percent
SUMMARY...Isolated strong to severe storms are expected to persist
across eastern Pennsylvania into New Jersey, with some increase in
coverage possible over the next several hours farther south into
Maryland and northern Virginia.
DISCUSSION...Storms are currently ongoing along a cold front, from
central NY across eastern PA and into western VA. An outflow
boundary currently exists near the PA/NJ border, with cooler and
more stable air to the east. Ahead of the front and south of this
outflow, a moderately unstable air mass remains with precipitable
water values still in excess of 1.50" across the Delmarva.
With areas of continued heating (although decelerating), and the
approaching front, some increase in storm coverage and intensity is
possible, and this scenario is supported by several models. Weakly
veering winds with height (as seen on LWX VWP) appear sufficient for
a supercell or two, especially with southeastward storm motions.
Hail, wind, or a brief tornado would all be possible.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 37907691 38017792 38607836 39397741 40417629 40737591
40767558 40557513 39957482 39427439 38737497 38387500