-- Discussion containing changed information from previous version are highlighted. --
174
FXUS61 KCTP 190919
AFDCTP

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

.SYNOPSIS...
*Mostly cloudy through the midday hours today with patchy
 valley fog early this morning.

*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 PM THIS EVENING/...
An elongated, north/south upper level trough stretching from the
Carolina Coast to Southern new England will support weak sfc low
pressure just southeast of Cape Cod. A BKN-OVC layer of
stratocu and altocu clouds covered most locations in Central PA,
and the bulk of the area will stay dry today.

Temps will start the day from the low 50s over the mountains
north of KIPT, to the low 60s across the Lower Susq Valley.

Anomalous -u component/easterly sfc-850 mb flow will back to the
northeast today and will advect drier air into the region from
upstate NY, gradually breaking up the dual layer of cloud cover
this afternoon. Aside from a small area containing some brief
showers moving West-Southwestward, expect rain-free conditions
over the CWA today.

The earliest/greatest amount of clearing should be over the
western half of the state this afternoon, 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.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
Surface ridging building over the region should result in
variable amounts of clouds tonight with patchy morning valley
fog a good bet across the Northern Half of PA both today and
Friday.

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 /09Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
515 AM update.

Wide range of conditions here just before sunrise. Dense fog
just outside the office. TAFS updated here.

Earlier discussion below.

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 improve 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.
-- End Changed Discussion --

&&

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

&&

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

&&

$$

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