Area Forecast Discussion
Issued by NWS State College, PA-- Remove Highlighting --
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FXUS61 KCTP 140331
Area Forecast Discussion
National Weather Service State College PA
1031 PM EST Fri Jan 13 2017
An upper air disturbance will link up with a weak trough of
surface low pressure nosing in from the Ohio River Valley late
tonight and Saturday to bring periods of light snow to central
portions of Pennsylvania and mixed precipitation or freezing rain
across the south. Another area of high pressure will build east
into the region for Sunday with some sunshine, seasonably cold
temperatures and a light northwesterly breeze. Milder conditions
will work back into the area for the middle of next week.
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Regional radar mosaic at 01Z shows a band of light mixed precip
over the Ohio Valley into W Virginia associated with fgen forcing
in entrance region of jet streak over the eastern Grt Lks/NY
state. Latest model guidance suggests the northern edge of this
precip shield may just barely sneak across the Mason Dixon Line
after midnight. Model soundings support the mixed ptype forecast,
with light snow/sleet/fzra equally possible as precip works into
southern Somerset/Bedford/Fulton counties late tonight. For the
rest of central Pa, a dry night is in store under thickening
cloud cover. Min temps expected to range from the mid teens over
the northern tier, to the upper 20s across the Lower Susq Valley.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/...
Light snow and mixed precipitation will slowly advance northward
into the southern half of Pa Saturday, as weak wave of low
pressure approaches from the Ohio Valley. Latest guidance
indicates a changeover to sleet and freezing rain across my
southern tier where advisories are now in effect. Farther north, little
if any snowfall is expected north of I80...thanks to cold dry high
pressure. Light mixed precip will taper off by Saturday evening
across the south.
Blend of latest model guidance indicates any snow accums across
central and southern Pa will be very light, ranging from zero to a
half inch. Likewise, any icing across the southern counties will
be very light as well, but enough to create travel concerns. Highs
will be within a few degrees of freezing across the
south, ranging to the upper 20s north.
.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
Light mixed precip (or very light snow) may linger for a few
hours into the evening hours Saturday across southern portions of
our CWA. Little if any additional snow or ice accum is expected
though as precip will be light. Partial clearing or better will
occur after midnight Sat with just a few flurries possible across
the northern and western mtns of the state.
High pressure will build into the area from the Upper Great Lakes
on Sunday, supplying us with fair, chilly weather and relatively
light nwrly wind. High temps will rebound by some 5-8 deg F on
Sunday with respect to Saturday`s highs.
At the same time, stubborn trough/upper low over the west coast
weakens and lifts across the southern plains into the great lakes
region as pattern. Ridge over the area tries to hold firm as a warm
front lifts through Ohio River Valley early in the upcoming week.
This frontal boundary will be preceded and accompanied by a
light, wintry mix of precip during the morning hours Monday.
A good portion of next week is shaping up to be mild and showery,
as bulk of med range guidance shows a ridge slowly retreating off
the East Coast as remnants of that west coast low get picked up by
the northern stream and track across PA midweek. For Tue into Tue
night, deep southerly flow ahead of that trough will bring a plume
of anomalous PWATS over the region which supports the idea of
showery (rain) and mild weather. As has been the case frequently
lately, the GFS brings the trough through faster than the ECMWF.
Winds turn westerly behind the system as flow turns more zonal,
but with no cold air in sight, temps will remain mild and above
Ridge re-establishes itself over the eastern U.S. for late week,
as mild SW flow persists over the midwest. We`ll be on the eastern
side of this, so subtle shortwaves sliding into the Midwest will
bring varying amounts of cloudiness to the west (less in the east)
with low end chances for light showers.
.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --VFR conditions will prevail tonight as mid-high clouds continue to
increase across the forecast area.
A wintry mix will spread northeast, reaching the southern Laurels
around or shortly after sunrise. The area of mixed
snow/sleet/freezing rain will continue northward Saturday
morning, reaching JST-AOO by mid morning, and to about I-80 by
Latest guidance suggests light snow along the very leading edge of
the precipitation with a changeover to the wintry mix over about
the southern half of the state. Where it snows, visibilities will
quickly become IFR with the area of sleet and freezing rain
favoring low VFR or MVFR conditions. These will develop during the
morning and continue throughout the day. The northern third of the
local flying area will remain VFR throughout as the precipitation
slides just to the south.
Reduced conditions over southern areas will continue into Saturday
night with improving conditions returning for Sunday.
Mon-Tue...Sub-VFR likely with chc of freezing rain/rain.
Wed...MVFR and snow showers west and north, VFR elsewhere.
-- End Changed Discussion --
-- Changed Discussion --Winter Weather Advisory until midnight EST Saturday night for
Winter Weather Advisory from 7 AM Saturday to midnight EST
Saturday night for PAZ024-025-036-064-065.
-- End Changed Discussion --