496
FXUS61 KCTP 090311
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1111 PM EDT Tue Oct 8 2024

.SYNOPSIS...
* A weak surface trough moving southeast from the Great Lakes
  region will bring the potential for isolated to scattered lake
  effect rain showers this evening before dry conditions
  overspread the region through the end of the work week.
* The influence of high pressure will bring about cooler
  temperatures and light winds, increasing frost and freeze
  concerns Wednesday night and Thursday night.
* Milder temperatures for the weekend will precede the return of
  rain late this weekend into next week.

&&

.NEAR TERM /UNTIL 10 AM WEDNESDAY MORNING/...
Clouds and even a few showers are sneaking across the nrn
border. There have even been 3-4 CGs over wrn NY with the lake
induced instability available. These showers will be sliding
S/SE thru the next few hrs, peaking around 05-06Z over the nrn
mtns, and likely not getting many places wet any far S of I-80.
The chc for meas precip (0.01" or more) is still rather low as
the cloud bases are high and dewpoints in the U30s and L40s
there.

The wind has died off and the cooling has been a little sharper
over the last 2 hrs. Going fcst mins looked OK everywhere but
the NW where there could be more clouds than earlier
expectations, and we`ll raise the mins just a deg or two.

&&

.SHORT TERM /10 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
As we progress into Wednesday and Thursday nights, potential
for frost (and even a freeze) will be possible across the
northern tier and the Laurel Highlands. Skies will continue to
clear out under the influence of surface high pressure that will
slowly move towards the forecast area. This will bring clear
skies that support radiational cooling and light winds that will
bring a greater concern of frost formation.

The 12Z HREF probabilities outlines Thursday night as the best
chance for widespread frost. There still remains roughly 30%
probability of frost across our western counties tonight. Thu
night the probabilities increase to ~60-80% for areas of frost
over the Northern Mountains and Laurel Highlands. Surface
temperatures could also reach freezing for a few counties in the
north west, and guidance will continued to be monitored for
trends in temps. Recent deterministic guidance has trended
cooler in recent runs and given the signal for radiational
cooling, and MinTs have been trimmed down again from NBM
guidance in both timeframe (Wed/Thu morning).

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
This extended period begins on a cold but tranquil note, with
areas of frost likely to be widespread in many areas on Friday
morning; Patchy frost is possible over the Lower Susquehanna
River Valley as well. Local freezes are even possible over the
northern valleys on Friday morning.

Closed low exiting eastern Canada late this week briefly
transitions to zonal flow over Central PA by Saturday and
Sunday, before another closed low replaces it over eastern
Ontario and Quebec by Monday. Below normal heights and upper
level troughing will extend all the way down the eastern
seaboard through this timeframe. Highly amplified upper ridge
builds into the Upper Midwest by mid to late week, continuing on
dry conditions across much of central Pennsylvania through the
first half of the weekend.

At the surface, a moisture-deprived cold front will cross the
region on Saturday associated with a fairly deep low pressure
center located in Nova Scotia. Main impact locally will be gusty
winds Friday night into Saturday morning as the pressure
gradient moves overhead. By Saturday afternoon, the front will
lift back north as warm front with surface low pressure moving
over the Great Lakes. This will help foster moderating
temperatures Saturday night and Sunday.

Late this weekend, ensembles show surging PW along with a
shortwave and associated low-pressure across southern NY
tracking a cold front through central Pennsylvania, bringing the
next chance of precipitation across the area in the Sunday
afternoon/evening timeframe and continuing into Monday morning.
Light shower activity could reach western/northwestern areas as
early as Sunday morning. Instability remains weak, so no
mention of thunder at this time.

By early next week, high pressure at the surface and upper
troughing aloft will support an influx of some of the coldest
temperatures so far this season. Northwest flow over the
relatively warm lakes will support lake effect showers and
frequent chances for frost and/or freezing temperatures.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Widespread VFR conditions will persist for most of the upcoming
TAF period with high pressure just to the south of Pennsylvania
helping maintain tranquil conditions. A weak disturbance will
bring increased cloud cover across Central PA overnight, with
cloud bases likely to be 5-7kft. A few rain showers are
possible at BFD, but no visibility restrictions are expected
from -RA. At this time, cloud cover over the northern tier is
likely to limit the formation of valley fog, but any clearing
would enhance the potential for visibility restrictions at BFD
from BR/FG.

During the day on Wednesday, fair weather cumulus will develop
as VFR conditions prevail. West-northwest winds will gust 15 to
20kt during the afternoon. A weak west to east oriented cold
front will drift south and bring low VFR, high MVFR ceilings to
the northern tier late in the day (likely reaching BFD around
00Z).

Outlook...

Wed-Fri...Patchy AM valley fog possible N Mtns.

Sat...Gusty winds with cold front passage (SW -> NW winds)

Sun...Restrictions possible north & west in showers and reduced
cigs.

&&

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

&&

$$

SYNOPSIS...Lambert/Bowen
NEAR TERM...Lambert/Dangelo/Bowen
SHORT TERM...NPB/Bowen
LONG TERM...DeVoir/Banghoff
AVIATION...Banghoff