Area Forecast Discussion
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FXUS61 KCTP 290045
Area Forecast Discussion
National Weather Service State College PA
745 PM EST Mon Nov 28 2016
A broad storm system centered over the upper plains and midwest
will push a cold front through the commonwealth on Tuesday. A
widespread rain will fall late tonight and Tuesday. A second cold
front will follow for midweek. More rain and mild temperatures
will occur before cooler air and lake effect snow showers return
for the end of the week.
.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
High clouds will lower and thicken through midnight. But, rain
should remain off to the west until close to midnight. Temps will
fall very little in the evening in the west. But, wind may go
calm/light and variable in the east.
.SHORT TERM /MIDNIGHT TONIGHT THROUGH TUESDAY NIGHT/...
Temps may rise late tonight as a strong srly LLJet moves in just
ahead of the cold front. The stability provided by nighttime will
keep the wind from becoming too strong/gusty in the central and
east. However, the hill tops of the west may gust into the l20s
by morning. We typically do not get all that gusty in these south
winds ahead of a front - even in the north. It is usually more of
a problem for the downslope areas of far NWrn PA and wrn NY. The
latest timing is very solid with prev forecasts and guidance. QPF
also solid with 0.25-0.75 inches out of this first FROPA. One
small tweak was to delay the exit of the precip from the SErn half
of the area on Tues aftn. Downstream ridge over the western
Atlantic and New England does not move much and pumps up a little.
Thus, the rain may amount to a little more in the SE. MOS guidance
and llvl mstr plots indicate a low cloud deck forming and sticking
in the nrn mtns and perhaps the Laurels after the front goes by.
Some breaks are expected though, as it will still be daylight and
some mixing is expected. But, it may then be a dismal/damp but
mild night Tues night. A wave develops along the old front over
the Deep South while another front spins off-east of the
midwestern storm center. Will keep chc-low likely pops in for the
very last part of Tues night in the west.
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Another significant wave forming on a trailing cold front will
ride up the west side of the appalachians and spread another slug
of rain up over the area by early Wednesday. Heaviest rain looks
to be over the SW through midday then shift to the SE in the
afternoon (along axis of highest PWAT air) where a period of
moderate rain is likely.
By late week, the upper low that had been hanging out over the
western Great Lakes morphs eastward across southern Canada,
ushering in a prolonged period of cold NW flow aloft and breezy
conditions at the surface - starting with a shortwave rotating
around the base of the low on Thu. The airmass doesn`t look
especially cold (fairly close to seasonal normals), but the cold
air flowing over the still quite warm lakes will be enough to
provide an extended period of widespread cloudiness and frequent
lake effect snow showers over the the NW mountains down into the
Laurel Highlands, possibly lasting all weekend long as the pattern
becomes slowly less amplified.
Much divergence in model solutions for early next week brings a
low confidence forecast during this period. The GFS is suggesting
a cold frontal passage while the ECMWF shows a very amplified
pattern. Went mainly away from the EC, but did include chance for
precip Sun night into Mon.
Temps peak Wed with highs back up into the 50s/lower 60s. Thu
will be a transition day back to colder temps with late
week/weekend just a shade below normal.
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
Expect lowering CIGs overnight, as a warm front approaches from
the Ohio Valley. A core of strong southerly winds aloft will sweep
across the region Tuesday morning, accompanied by a period of rain
and low CIGs. In addition, the combination of the strong winds
aloft and relatively light wind a ground level will yield
widespread LLWS conditions.
Low CIGs and VIS are expected from about 06z-18z in many
locations. LIFR is possible behind the rain in the low CIGs over
the N on Tues aftn/eve. A brief break in pcpn should occur until
the next front moves in on Wed. Much colder air and prolonged NW
flow will follow the second front.
Tue...Low cigs/rain, mainly in the morning W and all day in the SE.
Wed...Rain/low cigs possible.
Thu-Sat...SCT SHSN Ocnl IFR in BFD-JST. ISOLD SHSN AOO-UNV-IPT.