Severe Thunderstorm Warning 59, NWS Pittsburgh, PA

Area Forecast Discussion
National Weather Service Pittsburgh PA
739 PM EDT Thu Jul 13 2023

.SYNOPSIS...
A series of crossing cold fronts will maintain occasional shower
and thunderstorm chances through early next week. Some
thunderstorms could be severe this afternoon and evening with
one of the crossing fronts.

&&

.NEAR TERM /THROUGH FRIDAY/...
Mesoscale Update... A surface cold front continues its slow
track southward across Ohio and West Central PA. A special 18Z
PIT RAOB sounding indicates a cap and dry air aloft, which is
supported by a low K index seen on recent mesoanalysis as well.
CAPE is available if the cap is broken, with 0-6km shear around
40 kt. Isolated/scattered thunderstorms are still expected to
develop in the vicinity of the front, though dry air entrainment
and capping aloft may preclude convective if forcing along the
front is not sufficient. If storms develop, dry air aloft could
enhance a downburst potential as evaporative cooling would
accelerate downdrafts in thunderstorms through early evening.
SPC has maintained the marginal risk for severe thunderstorms
due to this, and will maintain this mention in the Hazardous
Weather Outlook.

More favorable conditions for thunderstorms exists south of I
70, where little if any capping is seen, and better instability
(ML CAPE 1500-2500 j/kg) is observed. The left exit region of an
encroaching upper jet should also provide additional lift in
this same area. Numerous showers and thunderstorms are expected
to develop through late afternoon in this area. Dry air aloft
should also result in a downburst potential in any organized
thunderstorms. 0-6km shear was also ranging from 35-40kt. A
severe thunderstorm watch has been issued through 9 pm for
portions of the area in coordination with SPC and surrounding
NWS offices. It appears large hail and damaging wind gusts are
the main hazards in this area, though with favorable
directional shear/curved hodographs, there is also a low tornado
potential. In addition, any training of tstms could result in
localized flooding. The severe potential should decrease later
this evening as instability wanes.

Restructured the POPs through early this evening to reflect the
above reasoning. Expect an overall gradual decreasing trend to
the POPs overnight, though scattered showers and thunderstorms
are still expected, especially S-SE of PIT, as a shortwave
trough interacts with some moisture streaming northeastward
ahead of it.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
Isolated to scattered showers and thunderstorms are possible
Friday, especially east of I 79, as the shortwave completes its
passage through early afternoon. Isolated convection will be
possible in the afternoon as convective temperatures are
reached, though a lack of a significant trigger should limit
this potential.

Generally dry weather is expected Friday night as shortwave
riding builds ahead of a Midwestern shortwave trough. This
trough should move east on Saturday, tracking across the Upper
Ohio Valley region late in the day through the evening. Shower
and thunderstorms should again increase in coverage with its
approach and passage.

Scattered showers and thunderstorms are expected under broad
upper troughing and low convective thresholds on Sunday, though
coverage is in question with no strong forcing progged.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Model ensembles indicate the closed low across Central Canada
will drift eastward through the period, opening into a trough by
mid to late week. Upper troughing extending south of the low across
much of the Eastern CONUS should maintain occasional scattered
showers and thunderstorms at times as individual shortwaves
rotate through the longwave trough. The trough should begin to
flatten somewhat by late week, as the low opens and shifts
northeastward. Temperatures should average near seasonable
levels through the period.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Scattered +TSRA ongoing across portions of southeast OH,
northern WV, and southwestern PA to begin the TAF period. Expect
temporary/local restrictions at impacted terminals. Stronger
storms are capable of producing gusty, erratic winds and large
hail. Outside of convection, light winds and VFR conditions
prevail.

Storms should wane late this evening, though a few showers may
linger overnight. Expecting patchy fog with MVFR (locally IFR)
vsbys to settle in overnight, especially in areas that received
rain this evening.

.OUTLOOK...
Shortwave movement within transient westerly flow will promote
periodic restrictions in showers and thunderstorms through early
next week.

&&

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

&&

SYNOPSIS...WM
NEAR TERM...WM
SHORT TERM...WM
LONG TERM...WM
AVIATION...Cermak

Hazardous Weather Outlook...UPDATED
National Weather Service Pittsburgh PA
403 PM EDT Thu Jul 13 2023

OHZ068-069-PAZ031-075-076-WVZ004-012-021-509>514-142015-
Noble-Monroe-Greene-Fayette-Higher Elevations of Fayette-Marshall-
Wetzel-Marion-Monongalia-
Ridges of Eastern Monongalia and Northwestern Preston-Preston-
Eastern Preston-Western Tucker-Eastern Tucker-
403 PM EDT Thu Jul 13 2023

...SEVERE THUNDERSTORM WATCH 482 IN EFFECT UNTIL 9 PM EDT THIS
EVENING...

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

.DAY ONE...This afternoon and tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Severe Thunderstorm Watch.

Showers and thunderstorms are likey through the evening. Some storms
could be severe, with large hail and damaging wind. In addition,
isolated tornadoes are possible in the strongest storms. Locally
heavy rain is also possible, especially for areas that see multiple
thunderstorms.

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

There is a low probability for widespread hazardous weather.

.SPOTTER INFORMATION STATEMENT...

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

OHZ039>041-048>050-057>059-PAZ007>009-013>016-020>022-029-073-074-
077-078-WVZ001>003-142015-
Tuscarawas-Carroll-Columbiana-Coshocton-Harrison-Jefferson OH-
Muskingum-Guernsey-Belmont-Mercer-Venango-Forest-Lawrence-Butler-
Clarion-Jefferson PA-Beaver-Allegheny-Armstrong-Washington-
Westmoreland-Higher Elevations of Westmoreland-Indiana-
Higher Elevations of Indiana-Hancock-Brooke-Ohio-
403 PM EDT Thu Jul 13 2023

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

.DAY ONE...This afternoon and tonight.

There is a low potential for isolated severe thunderstorms through
early evening, with the main hazards expected to be damaging wind and
large hail.

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

There is a low probability for widespread hazardous weather.

.SPOTTER INFORMATION STATEMENT...

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

WM