825
FXUS61 KCTP 190446
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1246 AM EDT Thu Sep 19 2024

.SYNOPSIS...
*Mostly cloudy tonight with patchy valley fog
*Little to no rainfall expected Friday into early next week
 perpetuating one of the driest September`s so far on record
*Daytime temperatures peak +5-10 degrees above average Friday
 and Saturday before trending seasonably cooler next week

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A weak surface low off of the Delmarva Peninsula and the
associated plume of Atlantic moisture has exited the area
late this evening, while backing low level flow to the
northeast advects drier air into the region. Therefore, expect
a rain-free remainder of the night for the vast majority of
Central PA.

Low dewpoint depressions going into the evening, combined with
light winds and some partial clearing, should result in patchy
late night valley fog. See no reason to deviate from NBM min
temps, which range from the low 50s over the mountains north of
KIPT, to the low 60s across the Lower Susq Valley.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY/...
Patchy valley fog, and possibly some lingering stratus over
the southwest part of the forecast area, should give way to
mostly sunny skies by Thursday afternoon, as surface ridging
builds in and the associated northerly flow advects drier air
into Central PA. The brightest skies should be over the western
half of the state, while southerly flow/waa aloft linked to a
cut-off low over VA could result in a lingering veil of cirrus
over the eastern half of PA. The return of sunshine should
result in a marked jump in max temps compared to today. GEFS 2m
temp anomalies support highs in the upper 70s to low 80s for
most of the area.

Surface ridging building over the region should result in fair
and warm weather Friday into Saturday, with patchy morning
valley fog a good bet. Latest global guidance tracks a weak
shortwave just north of PA late Saturday. This feature should
have little moisture to work with and the best forcing is
progged to pass north of the state. Therefore, keeping POPs just
below 15pct for now over most of the region. Max temps may be
slightly lower Saturday, due to low level flow veering to the
east off of the Atlantic.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
A trend toward cooler and cloudier weather appears likely Sunday
into the middle of next week associated a developing cold air
damming scenario ahead of a slow moving warm front in the Ohio
Valley and high pressure over the Canadian Maritimes. An
increasingly moist southeast flow off of the Atlantic may result
in patchy stratus Sunday. However, model RH profiles indicate a
much better chance of cloudy, cool conditions Mon-Wed.

As for rainfall, a weak shortwave and associated plume of
enhanced pwats overrunning the warm front could produce
scattered showers Sunday night into early next week. Upsloping
flow could also yield patchy drizzle over the Central Mtns early
next week. However, a better chance of a more widespread/significant
rainfall is slated for the middle of next week associated with
a deepening upstream trough over the Miss Valley. Cloud cover
and a southeast flow should result in cool days but above normal
nighttime lows Mon-Wed.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
For the 06Z TAF package, main change was to back off on fog
and low clouds a bit.

Fog will be mainly limited to areas where the mid level clouds
clear out. Low clouds could form in these areas as well.

Expect conditions to imrpove by 14Z if not sooner, as slightly
drier works in from the north.

For early Friday morning, more fog and low clouds will be
possible, as skies will be clear and winds light. This will
allow temperatures to fall to near the dewpoint temperature.

Outlook...

Fri-Mon...Valley fog in the morning; otherwise VFR/no sig wx.

&&

.CLIMATE...
The first day of Autumn 2024 (Fall Equinox) begins at 8:44 am
EDT on September 22nd.

&&

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

&&

$$

SYNOPSIS...Steinbugl
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald/Steinbugl
LONG TERM...Fitzgerald/Steinbugl
AVIATION...Martin/Bowen
CLIMATE...NPB