Flash Flood Warning 1, NWS Pittsburgh, PA

Area Forecast Discussion
National Weather Service Pittsburgh PA
338 PM EDT Tue May 28 2019

.SYNOPSIS...
Rounds of showers and thunderstorms can be expected through Thursday.
Some of the storms may be severe, particularly this afternoon and
evening, as well as on Wednesday. A brief period of dry weather may
arrive with high pressure on Friday.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Severe thunderstorms have blossomed across the northern CWA, with
all severe hazards possible. As low pressure tracks to our north
along the Lake Erie shore along a quasi-stationary boundary, this
will help to back low-level winds and create more directional shear,
in addition to the already present speed shear in the 0-6km layer.
Special 17Z PBZ sounding already shows CAPE of over 3000 J/kg, with a
deep profile. Supercell structures will continue to be observed into
the evening hours. The shear and robust CAPE in the -10C to -30C
layer point to the large hail potential, with several reports of golf
ball sized hail or larger already received. Strong winds are also
likely, with potential downbursts given high DCAPE/surface delta
theta-E values noted on the observed as well as model soundings. With
the expected backing of low-level flow, a few tornadoes will also be
possible, especially with right-moving supercells.

The sounding showed PWAT of about 1.2 inches. This, along with the
generally cellular nature of the convection so far, should keep
flooding concerns isolated at best. Cannot rule out one or two
instances of cell training producing heavy rain however.

Activity will start to decrease later this evening with the loss of
instability, although a few showers or storms may continue overnight
in the vicinity of the boundary across mainly the central CWA.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY/...
Another round of severe thunderstorms is possible Wednesday afternoon
and evening. With the stationary boundary expected to lie somewhere
north of Pittsburgh during the day, the highest threat of severe
weather appears to across southern sections of the CWA, where SPC has
an enhanced risk in place. Conditions fairly similar to today will be
experienced, with another buildup of CAPE above 2000 J/kg south of
the boundary. Strong speed shear and fairly unidirectional flow will
once again support bowing line segments/supercells with damaging
winds and large hail. A tornado or two will remain possible once
again, although flow will once again need to back a bit more in the
low levels for a higher threat. Depending on rainfall totals from the
activity today, the flood threat may be a bit higher in some areas.

Storm coverage and intensity will drop off once again Wednesday
night. Surface low pressure will move across northern Ohio and far NW
Pennsylvania Thursday afternoon and evening, which will bring another
round of showers and thunderstorms. Temperatures will cool slightly
as the front starts to advance southward.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
The stubborn southeast U.S. ridge will finally be flattened somewhat
by the shortwave accompanying the Thursday low pressure system. A
brief break from the rain will be seen Friday afternoon and night
under high pressure. The next front will return rain chances over the
weekend, with cooler temperatures by Sunday. The first portion of
next week appears dry, with near or below normal temperatures.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
Showers and thunderstorms will develop this afternoon due to a
combination of lift along a weak cold frontal boundary just south of
Erie and daytime destabilization. Storm will move east southeast with
the 700mb flow through the evening hours, and likely will impact
most sites north of I-70 with the strongest storms along the I-80
corridor. Less certainty on the southern and western extent of these
storms, and will largely be dictated by these storms creating their
own cold pool and driving the frontal boundary farther south than
projected.

Widespread restrictions are likely to develop Wednesday morning in
the wake of today's convection, as increased moisture in the boundary
layer will remain stuck under a low level inversion. Though not
likely considering expected cloud cover, valley fog will be possible
if some clearing occurs.

.Outlook...
Periodic restriction potential will continue through Fri as rounds of
storms and associated disturbances cross the region.

&&

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

&&

Hazardous Weather Outlook
National Weather Service Pittsburgh PA
205 PM EDT Tue May 28 2019

OHZ039>041-049-050-PAZ007>009-013>016-020>023-029-073>076-WVZ001-002-
291815-
Tuscarawas-Carroll-Columbiana-Harrison-Jefferson OH-Mercer-Venango-
Forest-Lawrence-Butler-Clarion-Jefferson PA-Beaver-Allegheny-
Armstrong-Indiana-Washington-Westmoreland-Westmoreland Ridges-
Fayette-Fayette Ridges-Hancock-Brooke-
205 PM EDT Tue May 28 2019

...TORNADO WATCH 274 IN EFFECT UNTIL 10 PM EDT THIS EVENING...

This Hazardous Weather Outlook is for 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.

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

   Tornado Watch.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Scattered to numerous severe thunderstorms are expected once again
Wednesday afternoon and evening. The main threat will be damaging
wind gusts and large hail. An isolated tornado is possible as well.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

MDZ001-OHZ048-057>059-068-069-PAZ031-WVZ003-004-012-021-509>514-
291815-
Garrett-Coshocton-Muskingum-Guernsey-Belmont-Noble-Monroe-Greene-
Ohio-Marshall-Wetzel-Marion-Monongalia-
Ridges of Eastern Monongalia and Northwestern Preston-Preston-
Eastern Preston-Western Tucker-Eastern Tucker-
205 PM EDT Tue May 28 2019

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

.DAY ONE...This afternoon and tonight.

Isolated to scattered severe thunderstorms are expected late this
afternoon and this evening. The main threat will be damaging wind
gusts and large hail. An isolated tornado is possible as well.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Scattered to numerous severe thunderstorms are expected once again
Wednesday afternoon and evening. The main threat will be damaging
wind gusts and large hail. An isolated tornado is possible as well.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PITTSBURGH PA
544 PM EDT TUE MAY 28 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0543 PM     HAIL             MARS                    40.70N  80.01W
05/28/2019  M1.00 INCH       BUTLER             PA   NWS EMPLOYEE

&&

EVENT NUMBER PBZ1902162

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE PITTSBURGH PA
548 PM EDT TUE MAY 28 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0500 PM     HAIL             ZELIENOPLE              40.79N  80.14W
05/28/2019  E1.00 INCH       BUTLER             PA   SOCIAL MEDIA

            CORRECTED TIME FROM PREVIOUS REPORT OF 534 PM

&&

CORRECTED EVENT TIME...REMARKS

EVENT NUMBER PBZ1902156

CL

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE PITTSBURGH PA
557 PM EDT TUE MAY 28 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0540 PM     HAIL             GIBSONIA                40.63N  79.97W
05/28/2019  M1.75 INCH       ALLEGHENY          PA   NWS EMPLOYEE

&&

EVENT NUMBER PBZ1902163