-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCTP 192009
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
409 PM EDT Thu Oct 19 2017

.SYNOPSIS...
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.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
A warm afternoon in progress throughout as shearing upper trof
and moisture challenged cold front push out of the eastern Great
Lakes.

Based GOES 16 and sfc observations, front is now crossing Lake
Erie. Temps are well into the 60s north and into the lower 70s
south in moderate southwest boundary layer flow. The front will
cross central and north central PA through this evening with
little more than a wind shift to the west and sct high clouds.
1026 mb sfc ridge over eastern TN will build northward towards
the Ohio Valley overnight, providing mostly clear skies
overnight. Mins will range from near 40F northwest to the upper
40s southeast. Decent radiational cooling will allow for valley
fog to form again on Friday morning.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
Strong upper ridge expands northward from the Ohio Valley on
Friday...with large scale subsidence leading to another sunny
day across central PA. 925mb temps of around 14C should
translate to max temps in the upper 60s and low 70s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
-- Changed Discussion --
Both the 12Z ECENS and NAEFS maintain an anomalous upper level
ridge over the area through the weekend. This should ensure
fair weather with above average temperatures Saturday to Sunday.
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.
-- End Changed Discussion --

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
VFR conds with surface wind gusts in the 15-20kt range over the
western 1/2 of the airspace through the afternoon. A dry cold
front will push across the airspace this evening and early
tonight accompanied by a directional wind shift from 220-260 to
270-330 degrees. High pressure moves back over PA late tonight
into Friday morning.

Outlook...

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

Mon-Tue...VFR to MVFR. Showers likely. LLWS. Strong FROPA.

Wed...MVFR with shwrs likely.

&&

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

&&

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

&&

$$
SYNOPSIS...DeVoir
NEAR TERM...DeVoir
SHORT TERM...DeVoir
LONG TERM...Fitzgerald/Ceru
AVIATION...DeVoir/Steinbugl
CLIMATE...