274
FXUS61 KCTP 310536
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
136 AM EDT Fri May 31 2024

.SYNOPSIS...
Canadian high pressure will build southeast into Pennsylvania
Friday and Saturday. The high will pass off the East Coast by
late this weekend into early next week, then a cold front will
likely traverse the state next Thursday.

&&

.NEAR TERM /UNTIL 7 AM THIS MORNING/...
Some sites are running a little cooler than the fcst curve and
dewpoints in JST and Somerset are 31F and 32F respectively. So,
just by subtracting one deg F from the going MinT, our next
tier of zones to the SE of the going advy went into frost advy
range. While the hill tops should still have a little wind
through sunrise, most of the valleys will go calm. Expanded the
frost advy to cover almost all the NWrn half of the CWA. Left
wind and PoPS (zeroes) alone, and tweaked the sky to go to
zeroes a little faster.

Prev...
Cu are dying, but it did sprinkle (trace) for 10 minutes at
AOO. So, a couple of people could have had a drop or two, but
not worth a mention of measurable precip (PoP).

Nearly ideal conditions for radiational cooling are setting up
tonight across the western half of PA, as the upper trough lifts
out and Canadian High Pressure builds in, accompanied by clear
skies, dry air and a calm wind. We continue to lean towards the
cooler guidance (MAV) and close to the 10th percentile NBM mins
which reach the upper reaches of the favorable ranges for frost.
Dry boundary layer, warmer stream temps and fairly warm ground
may preclude frost potential, but collaborated a Frost Advy
headline for my northern tier and NW Mountain counties with BUF
and BGM from ~midnight through 7AM Fri. A large water/air temp
difference of >25 degrees also favors patchy late night fog in
the deep river/stream valleys of the NW Mtns.

&&

.SHORT TERM /7 AM THIS MORNING THROUGH 6 PM SATURDAY/...
Little changes to the going forecast for Friday and Saturday
with this cycle. Large scale subsidence and low- pwat air
points to abundant sunshine Friday, as high pressure pushes into
the state. Mixing down 850mb temps of around 8C translates to
highs from the upper 60s to mid 70s. Friday night should be
another cool one, as the surface high builds directly over PA,
resulting in clear skies, a calm wind and min temps below NBM
guidance. The airmass in general should be moderating, so expect
readings not quite as cool as tonight.

Upper level ridging is progged over PA by Saturday, as the
surface high slips off of the East Coast, resulting in a mostly
sunny and warmer start to the weekend. GEFS 2m temp anomalies
Sat afternoon are few degrees above climo, translating to highs
of 75-80 over most of Central PA.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Late evening update holds very few changes. Not enough to
mention here, at least. Thursday still looks like the best day
to get wet.

Prev...
A shortwave trough moving through the region late Saturday
night into Sunday. This feature will bring the next chance of
showers and thunderstorms to central PA.

Longer range guidance shows multiple shortwaves moving through
the region into the middle of next week bringing renewed chances
for showers and storms. PoPs have decreased for Monday, which
now looks like it will be a generally dry day. Chance or greater
PoPs return for Tue-Thu.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
Looking at mainly clear skies and VFR conditions prior to late
Saturday night, as high pressure builds over the area.

Some lower conditions into the far west Sunday morning, as
higher dewpoints are advected eastward.

Outlook...

Sat...Mainly clear skies with VFR conditions.

Sun-Tue...Showers and thunderstorms possible.

&&

.CLIMATE...
Will be sending out 2 AM climate data here shortly, low for
IPT was around 50 degrees for Thursday, not the 36 as noted
earlier.

Earlier information below.

WILLIAMSPORT: A RECORD LOW TEMPERATURE OF 36 DEGREES WAS SET AT
WILLIAMSPORT PA EARLY THIS MORNING. THIS BREAKS THE OLD RECORD
OF 37 DEGREES SET IN 1949.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
Frost Advisory until 8 AM EDT this morning for PAZ004>006-
010>012-017-018-024-033-037-041.

&&

$$

SYNOPSIS...DeVoir/Fitzgerald
NEAR TERM...DeVoir/Fitzgerald/Dangelo
SHORT TERM...DeVoir/Fitzgerald
LONG TERM...Dangelo/Colbert
AVIATION...Colbert/Bowen
CLIMATE...Martin