Area Forecast Discussion
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FXUS61 KCTP 211817
Area Forecast Discussion
National Weather Service State College PA
217 PM EDT Fri Apr 21 2017
A frontal system will move south of the Commonwealth through
this evening and stall south of state during the weekend. An
upper level trof 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 8 PM THIS EVENING/...
Cold front bisecting the state this afternoon extends from
Mansfield southwest to Johnstown is making it ever so slowly
eastward. Warm/stationary front drops from Mansfield south to
Harrisburg, with cold and cloudy conditions persisting to the
east of this boundary. Only isolated showers are occurring with
the front and within the warm sector.
.SHORT TERM /8 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 /18Z FRIDAY THROUGH WEDNESDAY/...
Cold front bisecting the airspace this afternoon extends from
Mansfield southwest to Johnstown/KJST is making it ever so
slowly eastward. Warm/stationary front drops from Mansfield
south to Harrisburg/KMDT, with MVFR/IFR cigs persisting to the
east of this boundary.
Quick improved to VFR occurs behind the cold front with a noticeable
wind shift to nw. Slow improvement is expcted over eastern PA
this evening as cold front passes. Lower cigs will move back
into NW mtns later this eve with colder air moving downwind of
Sat...AM low CIGs possible at BFD.
Sun...No sig wx expected.
Mon...Rain/low CIGs possible southern Pa.
Tue...Rain/low CIGs possible.