Frost Advisory 4, NWS State College, PA

731 
WWUS71 KCTP 110921
NPWCTP

URGENT - WEATHER MESSAGE
National Weather Service State College PA
521 AM EDT Thu May 11 2017


PAZ037-041-042-111030-
/O.CAN.KCTP.FR.Y.0004.000000T0000Z-170511T1200Z/
Tioga-Northern Lycoming-Sullivan-
Including the cities of Mansfield, Wellsboro, Trout Run, 
and Laporte
521 AM EDT Thu May 11 2017

...FROST ADVISORY IS CANCELLED...

The National Weather Service in State College has cancelled the
Frost Advisory.

The threat for frost has passed. 

$$

Area Forecast Discussion
National Weather Service State College PA
113 PM EDT Wed May 10 2017

.SYNOPSIS...
Cooler than normal temperatures will continue into the weekend.
Scattered rain showers will move in later Thursday. The weather
will become wetter with more widespread showers for much of the
time from Thursday night into Sunday. Next week promises to be
milder.

&&

.NEAR TERM /THROUGH TONIGHT/...
A very minor short wave drifting southeast over very dry low-
level air here in Central and NW PA was leading to increasing
mid and high clouds, but nothing more than virga (or perhaps at
most a brief sprinkle) is expected across the Allegheny Plateau
this afternoon.

Elsewhere, Enjoy this brief taste of mostly sunny and mild
spring weather this afternoon, because an extended period thick
clouds, rainy and much cooler conditions are on the way for late
this week and coming weekend.

Max temps this afternoon will be several deg F below normal in
most places, ranging from around 60F across the northern tier
counties, to the mid and upper 60s in the valley of central and
southern PA.

The sky does try to clear out in the NE tonight after the
passage of a vort spoke rotating south on the back side of the
departing Upper Low east of the New England Coast. The wind will
also go light. This could allow for some frost and temps in the
m30s in the nrn counties.

The NE few zones are in the growing season. However, with the
uncertainty of how far the thicker cloud cover will spread in
from the SW, we'll continue to mention just the possibility of
frost here, and not yet in the wx grids. Mins elsewhere will be
in the 40s.

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
Front to our SW and NW flow aloft. But, the ridge gets pinched a
bit and MCS may dive into wrn PA around sunrise. So, the day
will start out mainly dry with lots of cirrus overhead, but the
clouds will lower and thicken up through the day from SW-NE.
Temps will probably be a little cooler than today, despite
adding 1-2C to the 8H temps. With an MCS likely on-going but
dying in the morning, the showers may begin anytime in the
Laurels and far western towns. But, it could remain dry all day
in the NE third of the area. Just mentioned thunder in the
Laurels in the aftn, as the weak westerly LLjet in the morning
does not enter into the state. Thus, the thunder will probably
die as it gets into PA. But, heating could pop convection in
the SW later in the day.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
The 500mb flow pattern through the period will feature a slowly
migrating trough/ridge/trough pattern across the northern 1/2
of the CONUS into the western Atlantic. The overall trend in
the sensible weather for Central PA will from unseasonably cool
and wet towards warmer/drier conditions by the middle of next
week.

The models/ensembles have been making adjustments in trying to
resolve the interaction of the northern stream upper low/trough
in southeastern Canada with a southern stream wave lifting out
the southeast U.S. on Saturday. The merger of these two upper
level systems will eventually carry a strengthening coastal
storm northward along/just off the northern Mid Atlantic
(DE/MD/NJ) and New England coast this weekend with risk for
heavy rainfall (1-2 inches possible) across the southern 1/2 of
central PA. GEFS QPF M-climate values show high percentile
values which are a strong indicator of a potential anomalous
rain event for mid-May across portions of the Mid Atlantic, with
greatest risk over southern and southeastern PA. So this will
need to monitored in the coming days. For now, continued to
employ a superblend of NBM/WPC/ECE for temps/pops/QPF which
trended cooler/wetter vs. previous fcst. The Friday-Saturday
period will feature unseasonably cool and wet conditions with
max temps 10-20 degrees below average for this time of year.

Breezy and drier weather should follow behind the storm for
Sunday into Monday with temperatures moderating closer to normal
for mid-May. A more noticeable warm-up appears likely into the
middle of next week as upper level ridge develops downstream of
western high amplitude trough. NBM/WPC/ECE blend yields
widespread 70s by next Wednesday 5/17.

&&

.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
15Z TAFS sent.

VFR conditions will continue today and tonight, with just
varying amounts of mid and high-level clouds streaming
southeast across the region.

clouds will increase, lower and thicken-up during the mid-late
morning hours Thursday, as rather strong warm advection occurs
and an anticipated MCS moves ESE from the Midwest/Ohio Valley
region.

This will likely result in poor conditions for aviation, mainly
later Thursday into early Saturday (though a several hour period
of MVFR Cigs and Vsbys are expected beginning around 10Z
Thursday at KJST.

Expect lower clouds and periods of moderate to heavy rain at
times with this system Thursday night through Friday and right
into Saturday, especially across the Laurel Highlands and Lower
Susq Valley airfields. We had a comparable situation last
Friday with low CIGS and heavy rain.

 Outlook...

Thu...Slight chance of light rain/reduced cigs JST/AOO.

Fri-Sun...Light rain/reduced cigs possible.

&&

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

&&

SYNOPSIS...Dangelo/Lambert
NEAR TERM...Dangelo/Lambert
SHORT TERM...Dangelo/RXR
LONG TERM...Steinbugl
AVIATION...Martin

Hazardous Weather Outlook
National Weather Service State College PA
635 AM EDT Wed May 10 2017

PAZ004>006-010>012-017>019-024>028-033>037-041-042-045-046-049>053-
056>059-063>066-111045-
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-
635 AM EDT Wed May 10 2017

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...Thursday through Tuesday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.