Area Forecast Discussion
Issued by NWS State College, PA-- Highlight Changed Discussion --
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FXUS61 KCTP 190946
Area Forecast Discussion
National Weather Service State College PA
446 AM EST Thu Jan 19 2017
High pressure will build northeast across Pennsylvania today,
providing dry conditions through early Friday. Low pressure over
the midwest will push a warm front north across the commonwealth
during the day Friday bringing a several hour period of steady
rain. Relatively mild conditions will persist for the next
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Another night/early morning spent under an extensive blanket of
low clouds and patchy light fog, as lowering inversion will keep
llvl moisture trapped beneath it for much of central PA.
Most places will see a 5-8 kt west to west-northwest breeze
through the mid morning with some gusts into the mid and upper
teens across the NW mtns and Laurel Highlands.
Min temps will be fairly homogeneous...ranging from the lower to
middle 30s throughout Northern and western PA to near 40F in the
larger metro areas across the lower Susq Valley.
Subsidence inversion base lowers by about 1000 feet throughout
today which should yield some breaks in the increasingly shallow
strato cu deck. High temps today will be in the lower-mid 40s
across the Northern and Western Mtns, and 45 to 50F from the
Central mtns to the Lower Susq Valley.
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
1020 MB sfc ridge builds NE and over central PA and upstate New
York into Thursday night as a sharp upper ridge builds over the
NE states (sliding from the spine of the Appalachians to the
Eastern Seaboard by midday Friday).
The first half of tonight will start off partly to mostly cloudy,
then turn overcast in many places by 12Z Friday.
The main weather maker for early in this period will come in the
form of a warm front that will lift north over the state during
the day Friday. Operational model and EFS consensus us for a few
periods of rain to occur Friday - primarily during the daylight
hours as the nose of a 40-45 kt swrly LLJ helps to transport a few
bands of relatively strong 925-850 mb Theta-E convergence over the
state. Rainfall amounts should be between 2 and 4 tenths across
much of the forecast area during the Friday period.
Consensus Model QPF ranging from 1-2 tenths of an inch across the
Mtns north and east of KIPT, to between 3 and 4 tenths of an inch
in the SW agrees well with the concept categorical - 100 percent
pops in our gridded forecast (and depicted by the latest several
runs of the NBM).
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
The upper ridge is forecast to re-establish itself over the
eastern U.S. over the upcoming weekend, bringing mild and mainly
dry conditions Saturday, through at least the mid morning hours on
Daytime temperatures across most of Central Pennsylvania will be
well above normal, but the departures for overnight lows should be
greater by several degrees more throughout the entire extended
Another wave approaches/lifts into the OH valley late in the
weekend into next Monday. Again, temps could be marginal at the
start of pcpn overnight Sunday for some ice or snow, but the bulk
of pcpn looks to be rain at this point. However, some guidance,
especially the ECMWF, is suggesting enough cold air may arrive at
the end of the pcpn for wintry p-types across northern/northwester
.AVIATION /10Z THURSDAY THROUGH MONDAY/...
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Strong inversion will keep low clouds around the area this
Some minor changes made.
Earlier discussion below.
High confidence that blanket of low clouds will
continue through the overnight with IFR restrictions persisting
over the west and MVFR for much of the central and the east
(though KUNV/KAOO may dip to IFR for a couple of hours bracketed
by sunrise as inversion continues to lower. Other concern with
plenty of low level moisture trapped will be potential for fog.
Winds becoming light will promote formation of fog, with most
areas settling between 2-4sm.
High pressure building in for Thursday will finally mix enough
drier air down from aloft to erode clouds - initially breaking in
the SE starting mid morning and spreading to the NW by early/mid
Next trouble will be on Fri as the surface ridge gets squeezed
and upper ridging is poked to the east by a strong short wave
trough rotating poleward from a central CONUS upper cut-off. Warm
advection will bring in clouds and deteriorating flying conditions
into MVFR/IFR in the early morning SW and around noon in the NE.
Fri...Restrictions developing early. Rain/Snow north and rain
south early. Rain areawide in the afternoon.
Fri night...Widespread restrictions in areas of drizzle.
Sun...Widespread IFR/MVFR restrictions. RA advances fm S-N.
Mon...Widespread IFR restrictions in -RA. LLWS poss.
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