Severe Thunderstorm Warning 124, NWS Pittsburgh, PA

Area Forecast Discussion
National Weather Service Pittsburgh PA
859 PM EDT Thu Jun 29 2017

.SYNOPSIS...
Temperatures will continue to warm into the weekend, and
humidity levels will also increase. This will return the risk
for showers and storms, mainly Friday and Saturday.

&&

.NEAR TERM /THROUGH FRIDAY/...
BUFKIT soundings continue to advertise a fairly strong lid on
instability as was the case on the 12z sounding this morning.
This has hardly eroded, and it likely responsible for the weak
activity that has been attempting to form to our SW and work
NEward this evening largely falling apart as it has moved toward
and into our area.

However, as a second shortwave trough tries to stream through
the upper-level flow across the northern fringe of the area,
convective activity there may start to have better luck
overcoming the cap. Upstream convection has already developed to
a larger degree than earlier HRRR and hi-res guidance
prognosticated, which yields better confidence in continuing the
PoPs across the northern reaches of the CWA the remainder of the
evening and into the overnight as it streams eastward.
Convection is showing no signs of waning as it is encroaching on
our northern PA zones, and PoPs have been summarily increased
due to increased confidence in a continuation of cap busting as
this convection treks eastward along I-80 beyond sunset.

Dewpoints continue to rise with some locations in the Ohio River
Valley touching 70F as of last hour. This will place a fairly
high floor under our overnight lows. Tonight will be several
degrees warmer than the last few nights. Fries

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
Friday will be a similar forecast to today, save for the
additional warming and higher dewpoints. This warming in the
mid-levels may further strengthen the cap, but the higher
dewpoints will encourage instability numbers. Large scale ascent
will again be dependent on evolution of upstream shortwave
troughs, but we will be closer to the deeper parent trough and
associated surface low. For these reasons, think that we still
stand a better chance at afternoon convection, especially points
north of Pittsburgh.

Temperatures Friday will be above normal with much more
noticeable humidity levels.

Finally, by Saturday the upper-level trough will shift east
crossing sweeping the surface cold front through the area. The
result is Saturday will remain the best chance for widespread
showers and thunderstorms. Exact timing will play a big factor,
but current thinking is enough instability and shear will exist
to develop a few strong thunderstorms. Thus the current Marginal
Risk from the SPC seems prudent.

Temperatures will remain near average values, but with dewpoints
nearing 70, muggy conditions will hold.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Mostly dry weather is expected to return Sun/Mon as surface
ridging builds underneath the upper trough. Another trough is
progged to advance E from the Midwest and Plains regions Tue,
though with uncertainty in timing and location limited POPs to
the chance category for now on the 4th of July.

&&

.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
Continued with prevailing VFR conditions through the next 24
hours, although there are a couple of caveats. FKL/DUJ in
particular will need to be watched over the next several hours
as a band of showers and thunderstorms crosses Ohio into
northern PA later this evening. Expect some weakening as diurnal
heating is lost, but an approaching shortwave should allow some
activity to continue past sunset. Handled with VCSH for now and
will amend if threat increases. Isolated activity at best is
expected south to near PIT, with a dry night further south.
Southwest wind gusts will diminish over the next couple of
hours.

There is a small potential for MVFR ceilings around sunrise
especially north and west of PIT, but will hold off on this for
now pending fate of evening convection.

Better thunderstorm chances will arrive Friday as there should
be less inhibition to convective development. Scattered coverage
is anticipated, and VCTS was used to highlight this.

.OUTLOOK...
Restriction chances will continue into Saturday with the
approach and passage of a cold front.

&&

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

&&

Hazardous Weather Outlook
National Weather Service Pittsburgh PA
423 AM EDT Thu Jun 29 2017

MDZ001-OHZ057>059-068-069-PAZ021-023-029-031-073>076-WVZ002>004-012-
021-509>514-300830-
Garrett-Muskingum-Guernsey-Belmont-Noble-Monroe-Allegheny-Indiana-
Washington-Greene-Westmoreland-Westmoreland Ridges-Fayette-
Fayette Ridges-Brooke-Ohio-Marshall-Wetzel-Marion-Monongalia-
Ridges of Eastern Monongalia and Northwestern Preston-Preston-
Eastern Preston-Western Tucker-Eastern Tucker-
423 AM EDT Thu Jun 29 2017

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

.DAY ONE...Today and Tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

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.

OHZ039>041-048>050-PAZ007>009-013>016-020-022-WVZ001-300830-
Tuscarawas-Carroll-Columbiana-Coshocton-Harrison-Jefferson-Mercer-
Venango-Forest-Lawrence-Butler-Clarion-Beaver-Armstrong-Hancock-
423 AM EDT Thu Jun 29 2017

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

.DAY ONE...Today and Tonight.

Isolated strong to severe thunderstorms are possible late this
afternoon and evening. The main threat would be damaging wind gusts.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Isolated strong to severe thunderstorms are possible Friday
afternoon and evening. The main threat would be damaging wind gusts.

.SPOTTER INFORMATION STATEMENT...

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