Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 190938

Area Forecast Discussion
National Weather Service State College PA
538 AM EDT Thu Oct 19 2017

High pressure will remain over the eastern conus through the
upcoming weekend. Low pressure is likely to track west of the
state early next week with a trailing cold front coming through
Pennsylvania Tuesday or early Wednesday.


High pressure is providing the region with another cool and
tranquil morning. GOES16 nighttime microphysics channel is showing
some patchy valley fog at 09Z, mainly in the deep river valleys
north of I-80.

Any fog should burn off by around 14Z based on latest NAM
guidance. Abundant sunshine should then push readings to near
70F by this afternoon. A shortwave tracking well north of Pa
will push a dying cold front into our region late today. Models
indicate just enough moisture preceding this front to produce
sct late day cu across the northwest mountains. However, lack of
significant forcing or deep moisture support POPs near zero.


A slight increase in low level moisture and an active breeze in
vicinity of dying front should result in milder conditions
tonight in general across central Pa. However, a weaker gradient
and drier air behind front should allow for better radiational
cooling and patchy fog across the northwest mountains Friday
morning. Min temps are expected to range from around 40F over
the northwest mountains, to the upper 40s across the southeast
part of the forecast area.

Anomalous upper ridge will expand northeast from the Ohio Valley
on Friday. Large scale subsidence with this feature should
result in another sunny day. Ensemble mean 925mb temps of around
14C should translate to max temps in the upper 60s and low 70s.


Both the 00Z ECENS and NAEFS maintain an anomalous upper level
ridge over the area through the weekend, which should ensure
fair weather with above average temperatures Sat-Sun. Ensemble
mean 925/850 temps support highs of 70-75F, while light wind and
dry air result in seasonably cool nights.

All medium range guidance indicating there will be a digging
northern stream trough early next week over the upper midwest
and Miss Valley that will eventually phase with closed low
lifting out of the southern states. Considerable model
difference exist with respect to timing/track of this southern
stream shortwave, resulting in arrival of showers as early as
Monday or as late as Tues PM. For now, have slowly ramped up the
chance of rain beginning late Monday. However, will reserve the
best chance of rain for Tuesday/Tues night, when bulk of med
range guidance track shortwave and attendant plume of Gulf of
Mexico moisture across the area. Early QPF estimates from
operational runs and GEFS indicate 1+ inch amounts are possible.

A period of near to below normal temperatures appears likely for
the second half of next week, as upper trough swings east into
the area. However, both GFS and ECMWF ensemble systems indicate
the thrust of the chilly air will be directed west of Pa and
there are indications of rising heights/milder weather across
the entire eastern conus toward the end of the month.


GOES-16 fog channel is starting to show valley fog formation
across portions of the central and eastern airspace. Surface obs
indicate eastern TAF sites have decoupled with temp/dewpt
spreads tightening to within a few degrees. Therefore expect
greatest odds for restrictions at KIPT, KLNS and KMDT in that
order. Fog should dissipate by 14z giving way to VFR. To the
west in ZOB sector, expect VFR to prevail through the period.
Wind gusts will reach the 15-20kt range over the western 1/2 of
the airspace from late this morning through the afternoon. A dry
cold front will push across the airspace this evening and
early tonight accompanied by a light wind shift from 220-250 to
270-330 degrees. High pressure moves back over PA late tonight
into Friday morning.


Fri-Sun...Patchy AM valley fog otherwise VFR.

Mon...VFR to MVFR. Showers possible into Monday night. LLWS
likely Monday night into early Tuesday.


Month-to-date, October 2017 is the warmest October on record at
Harrisburg and Williamsport.




NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald
LONG TERM...Fitzgerald/Ceru
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