Special Weather Statement, NWS Pittsburgh, PA

Area Forecast Discussion
National Weather Service Pittsburgh PA
352 PM EDT Thu Oct 21 2021

.SYNOPSIS...
Showers and a few thunderstorms will accompany a cold front across
the region this evening.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
No changes were needed for the early eve update as low pressure is on
track to dig across the Great Lakes and drag a cold front acrs the
Upr OH this eve. Showers and a few thunderstorms will accompany that
front with a continued chance for isolated wind damage given the very
strong wind field on the flank of that low. A lack of instability
continues to be the main inhibitor.

As a longwave trough sets up over the Great Lakes tonight into
Friday, an additional embedded shortwave may provide enough vertical
motion to promote localized light showers and/or drizzle early
Friday morning given the saturating boundary layer in a cold
advection regime.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
A series of shortwaves with their jet maxima will cross the region
Friday through Saturday as upper trough remains positioned over the
Great Lakes. Periods of mostly isolated showers are possible while
clouds remain fairly abundant. The lack of warming and insolation
plus remnant cold advection will keep area temperature a few degrees
below normal.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Surface low pressure is expected to deepen and slowly lift from the
Central Plains Sunday in response to a developing trough/jet moving
through the area. The associated warm front will lift northward into
the Ohio River Valley as flow aloft becomes more zonal, with
strengthening jet support and warm/moist advection leading to
increased stratiform rain chances Sunday afternoon into Monday.

The low and upper trough should cross the region Monday into Tuesday,
bringing widespread rain and slightly cooler temperature. Drier and
unseasonably warm should develop thereafter as notable ridging is
expected to build in advance of the next low pressure system.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
A surface cold front is expected to cross the region west to east
this afternoon and evening, with a broken line of showers and
thunderstorms along and just ahead of its leading edge. Isolated gust
up to 40kt may be possible with the stronger storms, otherwise expect
a brief gust and slow veering of sfc wind to the W.

Convection will quickly diminish after FROPA due to cold, dry
advection. Additional shortwave pulses from the overhead trough
should encourage MVFR/IFR cig development and even patchy
sprinkles/drizzle. Timing and duration of these impacts are a little
uncertain as upper flow won't be oriented out of the favorable/more
typical NW.

.Outlook...
Periodic restrictions are expected through the weekend due to upper
troughing, with weak pulses creating localized brief rain chances.
More widespread restrictions and precipitation is likely late Sunday
into early next week with the next low pressure system.

&&

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

&&

Hazardous Weather Outlook
National Weather Service Pittsburgh PA
241 AM EDT Thu Oct 21 2021

OHZ039>041-048>050-057>059-068-069-PAZ007>009-013>016-020>023-029-
031-073>076-WVZ001>004-012-021-509>514-220645-
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-
241 AM EDT Thu Oct 21 2021

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

.DAY ONE...Today and tonight.

Isolated strong to damaging wind gusts will be possible in the
strongest storms this afternoon and evening with a crossing cold
front.

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

Hazardous weather is not expected at this time.

.SPOTTER INFORMATION STATEMENT...

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

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Special Weather Statement
National Weather Service Pittsburgh PA
349 PM EDT Thu Oct 21 2021

PAZ007>009-014>016-022-212030-
Armstrong PA-Jefferson PA-Butler PA-Forest PA-Clarion PA-Venango PA-
Mercer PA-
349 PM EDT Thu Oct 21 2021

...A CLUSTER OF STRONG THUNDERSTORMS WILL IMPACT NORTHEASTERN
MERCER...VENANGO... NORTHEASTERN BUTLER...NORTHERN
JEFFERSON...NORTHWESTERN ARMSTRONG... CLARION AND FOREST COUNTIES
THROUGH 430 PM EDT...

At 348 PM EDT, Doppler radar was tracking a strong thunderstorm 14
miles east of Slippery Rock, or 14 miles southwest of Knox, moving
northeast at 55 mph.

HAZARD...Wind gusts of 50 to 55 mph.

SOURCE...Radar indicated.

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

Locations impacted include...
Oil City, Franklin, Clarion, Brookville, Marienville, Knox,
Rimersburg, Sugarcreek, Brockway, Tionesta, Hasson Heights, and
Stoneboro.

This includes the following highways...
  Interstate 79 in Pennsylvania between mile markers 128 and 137.
  Interstate 80 in Pennsylvania between mile markers 25 and 81.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4144 7896 4144 7897 4145 7898 4145 7906
      4142 7907 4142 7909 4134 7909 4136 7904
      4135 7902 4138 7897 4127 7876 4088 7986
      4148 8025 4149 8000 4156 7991 4160 7983
      4162 7983 4163 7896
TIME...MOT...LOC 1948Z 242DEG 46KT 4114 7979

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...55 MPH

Special Weather Statement
National Weather Service Pittsburgh PA
408 PM EDT Thu Oct 21 2021

OHZ050-059-PAZ029-031-WVZ002>004-212045-
Jefferson OH-Belmont OH-Greene PA-Washington PA-Marshall WV-
Brooke WV-Ohio WV-
408 PM EDT Thu Oct 21 2021

...A CLUSTER OF STRONG THUNDERSTORMS WILL IMPACT SOUTH CENTRAL
JEFFERSON... NORTHEASTERN BELMONT...SOUTHWESTERN
WASHINGTON...NORTHWESTERN GREENE...OHIO...MARSHALL AND BROOKE
COUNTIES THROUGH 445 PM EDT...

At 408 PM EDT, Doppler radar was tracking a strong thunderstorm over
McMechen, or over Bethlehem, moving northeast at 55 mph.

HAZARD...Wind gusts of 50 to 55 mph.

SOURCE...Radar indicated.

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

Locations impacted include...
Wheeling, Washington, Moundsville, Canonsburg, Martins Ferry, St.
Clairsville, Bellaire, Warwood, Bethlehem, West Liberty, Triadelphia,
and Avella.

This includes the following highways...
  Interstate 70 in Ohio between mile markers 217 and 225.
  Interstate 70 in West Virginia between mile markers 0 and 14.
  Interstate 70 in Pennsylvania between mile markers 0 and 26.
  Interstate 79 in Pennsylvania between mile markers 21 and 46.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3983 8076 4007 8090 4032 8043 4025 8008
      3999 8014
TIME...MOT...LOC 2008Z 241DEG 49KT 4001 8069

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...55 MPH