Area Forecast Discussion
Issued by NWS State College, PA-- Remove Highlighting --
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FXUS61 KCTP 211057
Area Forecast Discussion
National Weather Service State College PA
657 AM EDT Fri Apr 21 2017
A frontal system will move through the Commonwealth this morning
and early this afternoon followed by high pressure. An upper
level cut off low will form over the Tennessee Valley late this
weekend, and could end up bringing a storm up the East Coast in
the first part of next week.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --Nice rope/line echo on the radar mosaic this morning running
from BFD-PIT. Just isold shra along it right now, and no
clearing until well behind it. Have tweaked near term slightly
to move the eastern showers faster to the east, and near term
temps and dewpoints upward slightly.
Widespread showers across the area are devoid of thunder as of
4 am. No specific areas of heavy rain, so flooding not a concern
at this point. These showers are on track to exit the area in
just a few hours, which should create a little break in precip
before the cold front, which appears to almost be to the PA-OH
border, moves across. Not much precip expected with the front as
the WV loop plays out little moisture left in the NW third of
the area. However, residual moisture and mid-day timing of the
front will make sct showers after it gets past UNV/AOO/IPT
where it will pass around or shortly before noon. Have left a
mention of thunder as well with some CAPE generated by the
models. Far SErn towns are in a MRGL risk for severe. Little
convergence will occur at the sfc as the front passes through
there, though. Maxes could near 80F in the far srn tier, and 70s
for a good chunk of the area. But, we need to clear out the
clouds - and this likely won`t happen until after the front
passes. The central mtns and mid-Susq Valley should have enough
sun after FROPA to rise into the 70s. So, the bigger bust
potential lies in the SE.
-- End Changed Discussion --
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
Skies may clear out for a very short time this evening, but
clouds will likely close back in with NW flow and a digging
trough moving across the lower Grrrreat Lakes. 00Z NAM does make
a push for light rain/showers late tonight and in the first half
of Saturday. Will make POPs just CHCs for the south, as GFS is
certain that the precip will stay well to our south with EC also
less-bullish on precip north of the Mason-Dixon. Mins tonight
will be mild again, but highs on Saturday will be about 5 degs
below normals with a decent amount of clouds moving across from
the south and sub-freezing 8H temps in the northlands.
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
With a cut off low progged to form over the Mid-MS and TN
Valleys this weekend, it is very difficult to be certain in many
facets of forecast. The differences in model solutions show up
even before the long term starts - as the NAM is farther to the
north with precip than all other models. While this is usually
cause to discount that one outlier, the close time horizon makes
me think we should give it some creedence. In general, the flat
flow aloft in place before the low gets to our longitude should
keep most of the precip to our south. Then, the changes from the
last forecast cycle get quite substantial. The low creeps
northward as it swings to the east of GA and keeps just off the
coast early in the week and may precip in off the ocean a`la a
Nor`easter. However, this storm does not deepen, nor slow
without a big high to the north. A frontal boundary should
remain to our north/west for much of the week, but may creep
close enough to make showers/storms. Warm air then seems to
establish itself once again pushing temps near/above 80 late in
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
A cold front will push southeast across the region this morning,
accompanied by showers, as well as low CIGs in some locations.
BFD, MDT and LNS already experiencing IFR CIGs at 10Z and
latest model guidance indicates they are likely to remain in the
IFR/LIFR category until after 12Z. Borderline IFR conditions
are possible at JST early this morning, while UNV, IPT and AOO
should see no worse than MVFR conditions.
Improving CIGs expected by late morning, as drier air flows into
western Pa in wake of the cold front and low clouds mix out
ahead of the front in eastern Pa. Model soundings support widespread
VFR conditions by early afternoon. However, an afternoon
shower/thunderstorm could result in a brief reduction at MDT/LNS
as the cold front comes through around 20Z-21Z.
Generally VFR conditions and a diminishing northwest breeze are
expected tonight, as a ridge of high pressure builds in.
However, model soundings do indicate the chance of MVFR CIGs
forming at BFD after about 03Z.
Sat...AM low CIGs possible at BFD.
Sun...No sig wx expected.
Mon...Rain/low CIGs possible southern Pa.
Tue...Rain/low CIGs possible.