Winter Weather Advisory 10, NWS State College, PA

Area Forecast Discussion
National Weather Service State College PA
119 AM EST Sat Feb 6 2021

.SYNOPSIS...
A breezy start to the weekend will be followed by a quick-
hitting snowfall Sunday morning. Snow may be heavy along and to
the southeast of the I-81 corridor. Seasonably cold and dry
weather expected to start to next week before an active pattern
brings several opportunities for mixed precipitation through
Friday.

&&

.NEAR TERM /THROUGH TODAY/...
1AM/06Z: Minor change to increase POPs near stripe of snow
showers tracking ENEWD from KPIT toward KFIG.

Previous Discussion Issued: 1108 PM EST Fri Feb 5 2021
Upstream clouds and spotty/patchy snow due to the approaching
vort max/short wave trough will pass through early tonight.
Expect only a dusting or an inch at most, and mainly NW of the
Allegheny Front. Wind remains gusty, and might climb again as
the vort max passes overhead. Will continue to mention gusts
25-30KT for the higher elevations all night. Temps won't fall
all that much at first due to the clouds and wind, but some
clearing for the NW is possible closer to sunrise, so mins in
the teens are still looking good there, and 20s elsewhere.

&&

.SHORT TERM /TONIGHT THROUGH 6 PM SUNDAY/...
Moderately gusty winds will persist into Saturday afternoon
before quickly subsiding late in the day as high pressure
brings a short period of fair wx in CPA to start the weekend.

Despite rather abundant sunshine, max temps will be a few to
several degrees lower vs. Friday. Sun should begin to fade with
increasing clouds by Saturday night.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Did not modify the Sat night-Sun forecast with this update.
This evening's update has brought a new wrinkle for the end of
next week, though...warmer temps than the deep freeze prev
advertised. Most medium range models now keep a bit of trough-
digging going on to our west and amplify the flow. This would
put the storm track back overhead, and warmer temps on the whole
due to clouds and poss warm advection. Have made some tweaks to
the National Blend, mainly to increase PoPs slightly mid-week
to allow for the fast flow to bring us an occasional streak of
light precip. Also tried to temper the quite dramatic temp
rise/change from the prev forecast. Still went 5-10F higher
than continuity for Fri temps since I can't argue much with
this (much) warmer solution given the consensus of mass fields
for that time period.

Prev...
A reasonable consensus solution appears to be emerging with the
system for Sunday but there is still plenty of uncertainty with
just how far west the system will reach. The 12z GFS came in a
bit wetter while the NAM and UKMET are much higher in the QPF
department. We raised amounts in line with WPC guidance and now
have a swath of 2-3" across much of the lower Susq with 3-4" in
York and Lancaster Counties. Arrival time would be predawn on
Sunday with precip over Sunday afternoon, this will be a quick
moving system and last less than 12 hours in most places. Held
off on a watch this afternoon as we will likely remain below
warning criteria, but will continue to monitor trends and one
may be needed if latest models trend farther northwest.

NW flow and cold air aloft will support the chance of lake-
effect snow in the NW Snowbelt Sunday night and Monday morning.
Winds shift Monday morning sending the higher chances of LES
north of the CWA.

Latest model runs are still disagreeing about the system on
Tuesday. The likelihood of seeing precip Tuesday is increasing,
but the timing and intensity of the storm is uncertain. Have
chance pops on Tuesday for now, and temps will be warm enough
for rain in the south and snow in the north.

After Tuesday, the overall trend in temperatures will be below
average. Any precip that falls within this period will be snow
no doubt. Models hint at another potential storm next weekend,
but due to the drastic disagreement between models I only have
slight chance pops for the end of next week.

Prev Disc...
Both the 12Z ECENS and 18Z GEFS support fair and chilly
conditions Monday, as surface high drifts across the state.
Beyond that, medium range guidance all shows an anomalous
longwave trough centered over the northern plains through the
end of next week. A shortwave rotating through the base of this
trough appears likely to affect Pa Tuesday. The strength and
track of the associated clipper low remains uncertain, but
current guidance indicates a period of light snow is possible
with some rain possible in the south. Veering flow behind this
system is likely to tap some of the anomalous cold air over the
Grt Lks, so below normal temperatures are likely the second half
of next week. There is some indication that another shortwave
will affect the area by Thursday with some light snow. However,
there's plenty of uncertainty given it's 7 days out.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
Weak upper level disturbance moving through the state at TAF
issuance time. A check of current observations shows minimal
decrease in visibility and only a drop to MVFR at the lowest.
Mainly added a VCSH for a few hours.

As the disturbance moves east by sunrise, conditions will
improve to VFR in all locations with winds increasing from the
west. Added WS wording for the daylight hours as winds just
above the surface will approach 45-50kt.

As a storm system moves toward southeast PA Saturday night,
expect an mid level overcast layer to develop after sunset.

Outlook...

Sun...A several to 8-hour period of light snow possible early
Sunday across the SE third of the state, otherwise a slight
chance of light snow elsewhere.

Mon...Mainly dry.

Tue...A chance of light snow with possible reductions to MVFR
and brief IFR conditions. Rain could mix in times.

Wed...Improving conditions.

&&

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

&&

SYNOPSIS...Steinbugl
NEAR TERM...Dangelo/Steinbugl
SHORT TERM...Lambert
LONG TERM...Dangelo/Travis/Wagner
AVIATION...Martin/Tyburski

Hazardous Weather Outlook
National Weather Service State College PA
111 PM EST Fri Feb 5 2021

PAZ036-056>059-063>066-061815-
Franklin-Perry-Dauphin-Schuylkill-Lebanon-Cumberland-Adams-York-
Lancaster-
111 PM EST Fri Feb 5 2021

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...This afternoon and tonight.

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

There is increasing confidence in period of accumulating snow Sunday
morning. The most likely area for a plowable accumulation is along
and east of the I-81 corridor.

Additional bouts of wintry weather are possible on Tuesday and
Thursday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

PAZ004>006-010>012-017>019-024>028-033>035-037-041-042-045-046-
049>053-061815-
Warren-McKean-Potter-Elk-Cameron-Northern Clinton-Clearfield-
Northern Centre-Southern Centre-Cambria-Blair-Huntingdon-Mifflin-
Juniata-Somerset-Bedford-Fulton-Tioga-Northern Lycoming-Sullivan-
Southern Clinton-Southern Lycoming-Union-Snyder-Montour-
Northumberland-Columbia-
111 PM EST Fri Feb 5 2021

This Hazardous Weather Outlook is for central Pennsylvania.

.DAY ONE...This afternoon and tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.