|Mesoscale Discussion 1211|
< Previous MD Next MD >
Mesoscale Discussion 1211
NWS Storm Prediction Center Norman OK
1154 AM CDT Sat Jul 01 2017
Areas affected...portions of central/eastern
Pennslyvania...central/western Maryland...West Virginia
Panhandle...and northern Virginia
Concerning...Severe potential...Severe Thunderstorm Watch likely
Valid 011654Z - 011800Z
Probability of Watch Issuance...80 percent
SUMMARY...Thunderstorms are expected to increase in
coverage/intensity this afternoon with a risk for damaging winds and
perhaps large hail. Trends will be monitored and a Severe
Thunderstorm Watch is likely prior to 19Z.
DISCUSSION...Thunderstorms have been slowly intensifying across
portions of southern New York and western/central Pennsylvania in
the vicinity of a surface trough of low pressure as of 1645Z.
Downstream, diurnal heating of a moist air mass with dew points in
the lower 70s continues, and surface-based instability by early/mid
afternoon should range between 1000-locally 2000 J/kg. Increasing
large-scale ascent will develop over the area this afternoon as a
mid-level impulse moves northeast from the lower Great Lakes/Ohio
Valley, contributing to a continued increase in thunderstorm
coverage/intensity. Deep-layer southwesterly shear of 30-40 kts
will promote multicell clusters/line segments with a threat for
damaging winds this afternoon. Some potential exists for a
supercell with mid-level rotation, especially with more discrete
cells across the discussion area, resulting in the potential for
isolated large hail.
A Severe Thunderstorm Watch will likely be needed prior to 19Z for
much of the area.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 38627687 38517786 39027841 40007843 40897808 41297785
41777767 42107751 42447692 42617647 42637624 42607598
42347552 41527477 40867474 40117526 38627687
Top/All Mesoscale Discussions/Forecast Products/Home