Severe Thunderstorm Warning 83, NWS State College, PA

Area Forecast Discussion
National Weather Service State College PA
1238 PM EDT Thu Jun 25 2020

.SYNOPSIS...
An upper level trough will pivot across the region today, then
lift out by Friday. Low pressure will track north of Pennsylvania
this weekend, with the trailing cold front likely pushing
through the state Saturday night or Sunday. Pennsylvania is
likely to be on the southwest periphery of an upper low over New
England early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Early morning satellite imagery shows patchy fog has developed in
the deep river/stream valleys of the Alleghenies. Expect the fog
to mix out between 12Z-14Z based on latest HREF.

Upper trough axis is progged to push into the region later today,
accompanied by scattered PM convection, primarily over the
northwest mountains where lapse rates will be steepest. Modest
instability and weak mid level flow/shear indicate a very low
risk of severe weather over most of the forecast area. However,
can't rule out an isolated strong storm toward evening over the
southeast counties, where decent mid level flow and 0-6km shear
could support more organization. GEFS plumes support seasonal
temperatures today with highs from the mid 70s to mid 80s.

Cooling of the boundary layer should cause any showers/storms to
diminish this evening, then expect fair and seasonable
conditions the rest of the night. A calm wind associated with
surface ridge is likely to result in patchy late night fog
again in the deep river/stream valleys of northern Pa, or in
those locations that receive rain late today.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Large scale subsidence, as inferred by model 500-300mb qvec
convergence fields, should result in a mostly sunny Friday.
Given the still chilly mid level temperatures, can't completely
rule out an isolated afternoon shower across northern Pa.
However, will keep POPs below 15pct and leave mention of
showers out of the forecast for now. Mixing down model 800mb
temperatures yields expected highs from the upper 70s over the
Allegheny Plateau, to the mid 80s in the Susq Valley.

An approaching warm front will spread increasing clouds into the
region Friday night, with late night showers/storms possible
across primarily the northern half of Pa. Early showers associated
with warm front appear likely to taper off by late morning, as
nose of low level jet shifts into NY state.

As surface low tracks across southern Ontario, diurnal heating
in warm sector is likely to result in developing PM thunderstorms
across Pa. Cloud cover could potentially suppress convection
across the northwest mountains. Elsewhere, a blend of model
guidance currently indicates moderate cape and mid level winds
of around 40kts, supporting a risk of isolated severe weather in
the form of damaging wind gusts.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Model and ensemble guidance continues to forecast an upper
trough/closed low settling into the Northeast U.S. Sunday into
the middle of next week. The first half of the period shows
good agreement on this set up, though typical timing/intensity
and run to run inconsistencies begin to develop by the end of
the period.

A cold front should get pushed to the south of the PA/MD line on
by Monday as the upper trough/closed low drops southeast from
Quebec. This front should be a focus for scattered showers and
T-storms mainly across the southern tier of CPA on Sunday. A
relative minimum in PWATs downstream of anomalous upper ridge
building over central Canada near Hudson Bay should favor a
mainly dry forecast through early next week before some diurnal
convection begins to creep back into the forecast by the end of
the period. Temperatures should average near to above average
heading into July.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
Conditions will be generally VFR today with WSW winds of 5-10
kts. An upper level trough moving through in the afternoon will
likely trigger a few showers. For now used VCSH this afternoon.

Outlook...

Fri...AM low cigs/fog possible. Mainly VFR PM.

Sat...Afternoon showers/sctd tsra with local reductions in cigs
and vsbys mainly across the NW half of PA.

Sun...Still a chance of showers and storms.

Mon...A chance of showers and storms, mainly south.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

SYNOPSIS...Fitzgerald
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald
LONG TERM...Steinbugl
AVIATION...Martin/Colbert

Hazardous Weather Outlook
National Weather Service State College PA
403 AM EDT Thu Jun 25 2020

PAZ004>006-010>012-017>019-024>028-033>037-041-042-045-046-049>053-
056>059-063>066-260815-
Warren-McKean-Potter-Elk-Cameron-Northern Clinton-Clearfield-
Northern Centre-Southern Centre-Cambria-Blair-Huntingdon-Mifflin-
Juniata-Somerset-Bedford-Fulton-Franklin-Tioga-Northern Lycoming-
Sullivan-Southern Clinton-Southern Lycoming-Union-Snyder-Montour-
Northumberland-Columbia-Perry-Dauphin-Schuylkill-Lebanon-Cumberland-
Adams-York-Lancaster-
403 AM EDT Thu Jun 25 2020

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...Today and tonight.

The probability for widespread hazardous weather is low.

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

Severe thunderstorms with damaging winds 60 mph or greater and
large hail exceeding 1 inch in diameter are possible in a few spots
Saturday, mainly during the afternoon or evening hours.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

Special Weather Statement
National Weather Service State College PA
106 PM EDT Thu Jun 25 2020

PAZ034-035-251730-
Bedford PA-Fulton PA-
106 PM EDT Thu Jun 25 2020

...A STRONG THUNDERSTORM WILL AFFECT PARTS OF BEDFORD AND FULTON
COUNTIES UNTIL 130 PM EDT...

At 106 PM EDT, Doppler radar indicated a strong thunderstorm over
Bedford, moving east at 35 mph.

Wind gusts to 50 mph and pea size hail are possible.

Locations impacted include...
Bedford, Breezewood, Clearville, Everett, Crystal Springs, Wells
Tannery, Valley-Hi, Saluvia, Manns Choice, Defiance, Hopewell and
Rainsburg.

LAT...LON 4002 7865 4020 7820 4017 7814 3994 7805
      3986 7859
TIME...MOT...LOC 1706Z 253DEG 29KT 3999 7853

RXR

Special Weather Statement
National Weather Service State College PA
210 PM EDT Thu Jun 25 2020

PAZ035-036-251845-
Fulton PA-Franklin PA-
210 PM EDT Thu Jun 25 2020

...A STRONG THUNDERSTORM WILL AFFECT PARTS OF FRANKLIN AND FULTON
COUNTIES UNTIL 245 PM EDT...

At 209 PM EDT, Doppler radar indicated a strong thunderstorm over
Harrisonville, moving east at 30 mph.

Wind gusts 40 to 50 mph are possible.

Locations impacted include...
Chambersburg, Guilford, St. Thomas, McConnellsburg, Harrisonville,
Marion, Fort Loudon, Fort Littleton, Saluvia, Roxbury, Upper
Strasburg, Willow Hill, Sideling Hill Rest Area, Fannettsburg and
Orrstown.

LAT...LON 3991 7819 4008 7818 4010 7792 4006 7787
      4011 7783 4013 7761 3986 7760
TIME...MOT...LOC 1809Z 269DEG 29KT 4000 7804

RXR