Area Forecast Discussion Issued by NWS State College, PA
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000
FXUS61 KCTP 171922
AFDCTP
Area Forecast Discussion
National Weather Service State College PA
322 PM EDT Sun Mar 17 2024
.SYNOPSIS...
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A trend toward much below normal temperatures for mid to late
March started today and the cold air will stick around for much
of the workweek ahead.
This colder air will be accompanied by gusty West-Northwest
winds and several bouts of snow showers, especially over the
Alleghenies and Laurel Highlands where a few to several inches
of total snow accumulation is expected by Wednesday morning.
Temperatures will moderate to near normal by next weekend.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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Colder air, in the wake of the cold front that pushed through
the state last night and early today, will gradually deepen as
we head through the remainder of today and tonight.
There`s quite a strong north to south temp gradient across the
CWA with 700 mb temps ranging from about -8C across the
Southern Tier of PA to between -15C and -17C over the north.
The push of the notably colder air up north will lead to the
upper part of the stratocu falling within the DGZ. This
favorable thermal profile for snow showers will combine with a
few spokes of mid-upper level DPVA (approaching from Northern
Ohio and Southern Lower Michigan), to maintain fairly numerous,
albeit brief snow showers through dusk across the northern Mtns
of the state, with a mix of rain/snow showers throughout the
deeper valleys where surface temps were in the mid to upper 40s.
There should be a several hour break in the snow showers
across the Northern Mtns late tonight/early Monday.
Temps the rest of this afternoon should be steady (north and
west), and may climb another degree F or two over the
southeast, but will be battling the strong CAA.
The CAA will drop the 8H temps into negative territory for all
the CWA by the end of the day. 8H temp at BFD may be -7C by
sunset.
Low temps tonight will be AOB freezing across almost all the
CWA. That hasn`t occurred for quite a while (beginning of the
month).-- End Changed Discussion --
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
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The axis of an amplifying upstream mid/upper level trough and
associated deepening cold air will drift over the region late
Monday/Monday night. This feature will generate lake effect
SHSN and some brief late morning/afternoon squalls for the next
36+ hrs. The predominantly westerly surface wind direction
will also generate some upslope snow in the Laurels, but not
much, with the bulk of the moisture off the Glakes being focused
near and to the North of Rte 6.
Some light snow accums locally 1-3 inches during this 24-30 hour
period are expected for Warren/McKean Cos. However, over the
course of the 60 hours through Wed Morning, those same NWrn Mtn
locations may get up to 4-6" of snow, with localized totals of
2-3 inches possible on the ridges to the west of RT 219 over the
Laurel Highlands.
At this point, it`s just too slow of an accumulation to hit the
threshold needed for a Winter Weather Advisory. The ground
temps and daytime temps will just warm enough that the accums
will be more trouble overnights than during the daylight.
A positively-tilted longwave trough will swing overhead on
Monday, and yield some instability. But, moisture will be
lacking and little sfc frontogenesis/organization is seen on
Monday. Better instability looks like it will occur on Tuesday
as a Clipper low moves across the CWA. If the sfc low goes
across NY or our nrn tier, that could set up a nice cold-frontal
line. There could still be a squall on Monday, mainly NW, but
the SHSQ parameter is poor/low. The wind will be gusting close
to 20KT anyway.
High temps Monday afternoon should hold in the L30s on the
higher elevs, and only get into the M40s in the far SE.-- End Changed Discussion --
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
-Winter feel through the first full day of Spring
-Risk of locally heavy snow showers and squalls Sun night-Tue
-Longest stretch of below average temps since mid-January
Despite plenty of signs of early Spring thanks to one of the
warmest winter seasons and first 15 days of March on record, the
first official week of Spring 2024 will begin on the cold side
with frequent snow showers downwind of Lake Erie and over the
Allegheny Plateau. There will also be the potential for
localized snow squalls through midweek along with late season
lake enhanced and orographic snow accumulation in the favored
snowbelts and higher terrain.
Several reinforcing shots of cold air will maintain one of the
longest stretches (3-5 days) of below climo temperatures since
mid-January. That speaks to how mild it has been over the last
few months. Each cold shot will bring a renewed/enhanced shot of
heavier snow showers. Hires guidance currently shows the most
widespread potential for convective snow showers Sun night - Mon
morning, again Mon night-Tuesday.
Latest guidance suggests one last cold shot Thursday,
potentially setting the stage for synoptic wintry mix Thursday
night into Fri morning ahead of the next weather maker. Still
several days out, so there is high uncertainty with the
potential system at the end of the week, and whether warmer air
will make a return for next weekend.
&&
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
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Low-end VFR to ocnl high end MVFR cigs are expected for the
Northern and Western Mountains for the rest of this afternoon
and evening with ocnl -SHRA (mixed with or falling as -SHRA in
the valleys), while VFR category sct- bkn clouds will be found
across the Central and SE part of the PA.
Borderline VFR/MVFR cigs could spill into the Central Mtns
(AOO, UNV, IPT) during the late afternoon/evening hours as
cooling aloft occurs with the approach of a few upper level
disturbances. The Lower Susq Valley (MDT, LNS) should remain
VFR right through tonight and Monday.
West-Northwesterly wind will frequently gust between 20 and 25
MPH late this afternoon/early this evening, before subsiding by
5-10 mph overnight then picking back up to similar speeds and
gusts that we experienced today.
Outlook...
Monday-Thurs...Periodic snow showers and reductions, primarily
across the higher terrain of Northern and Western PA. This will
be enhanced by reinforcing shots of unseasonably cold air and
gusty W/NW winds. West to Northwest wind gusts could peak in
the 35 to 40 mph range on Wednesday.-- End Changed Discussion --
&&
.CLIMATE...
Astronomical Spring (vernal equinox) begins on Tuesday March 19
at 11:06 PM EDT.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Lambert
NEAR TERM...Lambert
SHORT TERM...Lambert/Dangelo
LONG TERM...Steinbugl
AVIATION...Lambert/DeVoir/Bowen
CLIMATE...Steinbugl