Severe Thunderstorm Warning 287, NWS Pittsburgh, PA

Area Forecast Discussion
National Weather Service Pittsburgh PA
140 PM EDT Sat Aug 28 2021

.SYNOPSIS...
Thunderstorm chances continue today and tomorrow under a warm, humid
air mass and shortwave activity. The track of Hurricane Ida will
need to be monitored closely, heavy rainfall may occur Tuesday into
Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Warm, humid conditions will continue throughout the day as a ridge
resides over the East Coast. Showers and thunderstorms will continue
into the evening as an embedded shortwave tracks east into western
PA. With moderate mid-level lapse rates and a moderate amount of
DCAPE, downburst potential will be lacking. However, high rain
rates are expected with a deepening warm cloud layer and above
average PWATs. Weak flow aloft will also support isolated areas of
heavy rainfall; flooding may occur if storms training over a region
for a long period of time.

Showers and storms may continue into portions of the overnight time
period with elevated instability available.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
An incoming trough over the northern Great Lakes will flatten the
ridge over the East Coast tomorrow afternoon; zonal flow will likely
prevail. With no change to our warm, moist air mass over the Ohio
River Valley, thunderstorms should once again develop early afternoon
into the late evening.

Shear should remain generally weak until the late evening but DCAPE
values are expected to grow with incoming dry air in the mid to
upper-levels; a few isolated strong storms can't be ruled out.
Localized flooding in training clusters of heavy downpours can't be
ruled out as well.

By Monday, the aforementioned trough and its associated frontal
boundary will advance south into the Pittsburgh area. The front
should lose forward motion a bit as the trough lifts back towards
Quebec, placing the Upper Ohio Valley in quasi-zonal flow aloft... or
nearly parallel to the frontal boundary / baroclinic zone.
Thunderstorms and showers are likely to develop along this area of
convergence. A narrow band of localized flooding, orientated west to
east, could develop if the boundary remains stationary for a long
period of time.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
By Tuesday, remnants of Ida will progress up through the TN Valley
and into central Appalachia. The system will begin to phase with the
northern stream as it approaches our area late Tuesday and into
Wednesday.

The worst case scenario if the track continues to hold, a swath of
rainfall between 2 to 4 inches south of Pittsburgh Tuesday into
Wednesday; 1 to 2 inches elsewhere. However, the passage of a cold
front to the northwest could change the outcome of Ida's track
considerably and the worst case scenario should not hold a lot of
weight of confidence.

Slightly cooler and drier conditions are anticipated late week and
into the Labor Day Weekend with building high pressure.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Isolated to scattered convection could result in brief restrictions
but otherwise, general VFR is expected. Given uncertainty in any
particular location, have opted to use VCTS in latest TAFs.

.Outlook...
Little pattern change through Monday will result in continue isolated
to scattered afternoon thunderstorms and potential patchy morning fog
and low stratus.

&&

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

&&

Hazardous Weather Outlook
National Weather Service Pittsburgh PA
540 AM EDT Sat Aug 28 2021

OHZ039>041-048>050-057>059-068-069-PAZ007>009-013>016-020>023-029-
031-073>076-WVZ001>004-012-021-509>514-290945-
Tuscarawas-Carroll-Columbiana-Coshocton-Harrison-Jefferson OH-
Muskingum-Guernsey-Belmont-Noble-Monroe-Mercer-Venango-Forest-
Lawrence-Butler-Clarion-Jefferson PA-Beaver-Allegheny-Armstrong-
Indiana-Washington-Greene-Westmoreland-
Higher Elevations of Westmoreland-Fayette-
Higher Elevations of Fayette-Hancock-Brooke-Ohio-Marshall-Wetzel-
Marion-Monongalia-
Ridges of Eastern Monongalia and Northwestern Preston-Preston-
Eastern Preston-Western Tucker-Eastern Tucker-
540 AM EDT Sat Aug 28 2021

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

.DAY ONE...Today and tonight.

Hazardous weather is not expected at this time.

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

The potential for heavy rainfall and flooding will increase Tuesday
and Wednesday as the remnants of tropical system Ida move into the
Ohio Valley.

.SPOTTER INFORMATION STATEMENT...

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

Special Weather Statement
National Weather Service Pittsburgh PA
234 PM EDT Sat Aug 28 2021

PAZ023-281900-
Indiana PA-
234 PM EDT Sat Aug 28 2021

...A STRONG THUNDERSTORM WILL IMPACT EASTERN INDIANA COUNTY THROUGH
300 PM EDT...

At 233 PM EDT, Doppler radar was tracking a strong thunderstorm 8
miles northeast of Indiana, moving southeast at 10 mph.

HAZARD...Wind gusts up to 50 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Indiana, Clymer, Chevy Chase Heights, Ernest, Marion Center,
Creekside, Dixonville, Commodore, Brush Vly, and Yellow Creek State
Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4057 7888 4047 7908 4075 7923 4084 7903
      4067 7883
TIME...MOT...LOC 1833Z 328DEG 10KT 4073 7908

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH