Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 182054
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
354 PM EST Wed Jan 18 2017

.SYNOPSIS...
High is building in and will bring mainly dry conditions for
tonight and early Friday. Low pressure over the midwest will
push a warm front north across the commonwealth Friday. A mild
time is in store for the next several days.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Sun just poked through the clouds over Tussey Mtn and visible
shots show expanding/more-numerous breaks in the downslope off
the central ridge and valley region and into the lower Susq. We
should see a little less cloud cover there until evening. Then,
guidance shows that the inversion lowers, but lots of moisture
will still be trapped underneath it - esp in the west and north.
Will play the role of the pessimist here and call for the holes
in the stratus to fill back in - at least in the central
ridge/valley region. The wind will likely calm again over the ern
valleys and stay 5-6kts over the mtns. Temps should fall off on a
more-normal nocturnal curve tonight...but...mins will be about 15F
above normal.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
Thurs should be a pretty nice day but still rather cloudy in the
morning and early aftn for most of the CWA. SE will again be the
nicest place with the downslope. Light W wind as the center of the
high pressure stays to our S. Deep mixing is not foreseen as the
inversion is still very strong/sharp. However, top of mixed layer
temps in the 0 to +4C range crank out maxes in the u30s to u40s.
Someone in the SE will probably crack 50F, especially if the
stratus breaks up faster than currently expected.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
1020 MB sfc ridge builds NE and over central PA and upstate New
York 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 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.

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
Sunday.

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
period.

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
PA.

&&

.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
Holes finally appearing in the SE. Many locations now MVFR and
should remain there until A) clouds SCT (SE half) or B) upslope
brings them back into IFR later this evening or overnight.
extensive cloud shield stretches all the way back into IL/WI.
Inversion lowers tonight as high pressure moves in. Wind may go
light/vrb overnight in the ern valleys, but most locations will
continue to have a light W wind with the center of the high to our
S. Have mentioned some light fog at most places tonight, but the
biggest threat for IFR due to just fog is KIPT. Looks VFR for Fri
except over the wrn mtns JST/BFD where it may take most of the day
to break through the inversion and finally join up with the dry
air aloft.

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.

Outlook...

Sat...Mainly VFR with MVFR cigs poss W.

Sun...VFR AM then lowering cigs/vis. RA advances fm S-N.

Mon...IFR/MVFR cigs/vis in -RA.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo
LONG TERM...Lambert/Gartner
AVIATION...Dangelo



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