Severe Thunderstorm Warning 170, NWS Pittsburgh, PA

Area Forecast Discussion
National Weather Service Pittsburgh PA
1252 PM EDT Sat Aug 19 2017

.SYNOPSIS...
Thunderstorms are expected with the encroachment of a cold
front this afternoon.

&&

.NEAR TERM /THROUGH TONIGHT/...
The early afternoon update featured further adjustments to near
term POPs as per the latest radar and high res model trends.
Insolation in the wake of morning clouds and weak convection is
destabilizing the Upper Ohio airspace under an encroaching
upper trough. Given the available boundary layer moisture with
that warming, convective redevelopment along the associated weak
surface reflection/reinforcing front emerging off the Great
Lakes is likely. A slight severe risk/SPC -15%, was included in
the HWO with pockets of dry aloft expected to enhance the severe
potentail from marginal mid level flow and overall shear within
the thermal trough.

Showers and storms are projected to exit with the supporting
shortwave early this evening. Precip. probabilities for the
scenario were reconstructed using consensus-short blended
guidance.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
Building high pressure in the wake of the aforementioned system
will result in a dry and seasonable Sunday with slightly lower
dewpoints/humidity.

Warm, moist advection with flat ridging in advance of a midwestern
shortwave as per the latest model solutions indicate increased
humidity with a rapid temperature moderation above the averages
for Monday.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
The aforementioned midwest trough/associated front are likely to
provide the next precip chance by Tuesday. Eastern CONUS troughing
is then forecast to support temperatures a few degrees under
the averages for the remainder of the week.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Thunderstorm chances are expected to increase through the
afternoon with the approach and passage of a shortwave trough.
Will maintain a VCTS/tempo TS mention in the tafs. VFR should
return by evening under building high pressure.

Surface flow will generally remain from the west at 10kts with
occasional gusts to 15kts.

.Outlook...
Widespread restriction potential returns with a late Tue/early
Wed cold front.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...None.
WV...None.

&&

Hazardous Weather Outlook
National Weather Service Pittsburgh PA
1229 PM EDT Sat Aug 19 2017

MDZ001-OHZ039>041-048>050-057>059-068-069-PAZ007>009-013>016-020>023-
029-031-073>076-WVZ001>004-012-021-509>514-201630-
Garrett-Tuscarawas-Carroll-Columbiana-Coshocton-Harrison-Jefferson-
Muskingum-Guernsey-Belmont-Noble-Monroe-Mercer-Venango-Forest-
Lawrence-Butler-Clarion-Beaver-Allegheny-Armstrong-Indiana-
Washington-Greene-Westmoreland-Westmoreland Ridges-Fayette-
Fayette Ridges-Hancock-Brooke-Ohio-Marshall-Wetzel-Marion-Monongalia-
Ridges of Eastern Monongalia and Northwestern Preston-Preston-
Eastern Preston-Western Tucker-Eastern Tucker-
1229 PM EDT Sat Aug 19 2017

This Hazardous Weather Outlook is for western Maryland, east
central Ohio, northwest Pennsylvania, southwest Pennsylvania, west
central Pennsylvania, western Pennsylvania, northern West Virginia
and northern panhandle of West Virginia.

.DAY ONE...This Afternoon and Tonight.

There is a slight chance for severe thunderstorms this afternoon and
early this evening. The primary severe threats are for damaging wind
gusts and hail.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather
 conditions according to Standard Operating Procedures.