454
FXUS61 KCTP 281128
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
728 AM EDT Sun Apr 28 2024

.SYNOPSIS...
-Occasional showers possible overnight with patchy fog;
 scattered thunderstorms Sunday, especially across northern PA
-Temperatures rise above average Sunday and warmth persists all
 week with highs in the 70s and 80s; near-record warmth Monday
-Cold fronts Tuesday and Friday-Saturday bring rain & storms.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Plenty of clouds and some drizzle continue over the ridge and
valleys of central Pennsylvania while areas west of the
mountains enjoy temperatures near 70 all night.

A warm front associated with these mild temperatures to our
west will drift eastward across PA today. Winds will shift to
the southwest, paving the way for plentiful warm advection and a
very mild afternoon.

A high pressure ridge axis will cross Pennsylvania Sunday
afternoon, helping focus a ring of fire pattern of showers and
thunderstorms in New York and perhaps the northern tier of our
forecast area. Currently, scattered showers and thunderstorms
are found in the Finger Lakes region of NY. Although a majority
of hi-res guidance keeps showers along and north of I-80,
efficient moisture and temperature advection farther south will
support showers and thunderstorms all the way to the Mason-Dixon
Line. Have added a slight chance of storms there centered on
peak heating between 4 and 6PM, with higher probabilities
farther north.

With Pennsylvania fully in the warm sector southwest of the warm
front today, temperatures will soar into the 70s and 80s.
Clouds and showers/storms will be more plentiful in the north,
where highs in the low 70s could be a little too high if
anything. Farther south, highs in the mid 80s are well within
reason barring any significant showers/storms making it toward
the I-76 corridor. Unlike the previous mild days we`ve had so
far this spring, this warm stretch will be accompanied by a
noticeable uptick in humidity. Dewpoints will approach 60F in
the Lower Susquehanna Valley.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
A very mild night is in store for Sunday night thanks to the
higher dewpoints that will be in place. Mostly clear skies will
allow for efficient radiational cooling such that temperatures
fall to near or just above the dewpoint temperatures. In
locations that receive rainfall Sunday afternoon, patchy fog is
likely Sunday night into Monday morning. Based on the current
forecast, locations north of I-80 are most likely to have fog.
Lows on Monday morning will be in the 55 to 60F range, which is
+10 to +15 compared to average.

Monday will be the warmest day of the week as the ridge of high
pressure reaches its maximum northward extent Monday afternoon.
Surface high pressure to the south of PA will result in ample
sunshine and west-southwest flow and a true summer day. Recent
model guidance continues to suggest MaxTs in the 80s nearly
everywhere and an outside chance at 90 near the Mason-Dixon
line. Some afternoon convection across mainly northern PA does
appear plausible given embedded shortwaves within the ridge axis
and have upped PoPs compared to previous forecast cycles mainly
for areas north of I-80. If convection manages to occur, MaxTs
across northern PA could be limited to the upper 70s but will
still be well above seasonable averages.

Monday night will be similar to Sunday night with temperatures
falling near the dewpoint temperature (upper 50s to low 60s).
Some increasing high clouds will begin streaming in overnight
ahead of an approaching cold front. Light rain showers could
begin affecting far northwest PA by daybreak, but dry conditions
are likely for the rest of the area.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
An unsettled pattern is expected to continue into Tuesday as
low pressure from the Central Plains moves northwest of the area
and brings a weak sfc cold front across the area during the
morning and early afternoon hours. Guidance has started to
indicate a secondary area of sfc low pressure forming along the
DelMarVa later in the afternoon/evening hours before quickly
racing off to the northeast. This feature, noted in both
GFS/ECMWF guidance has lead to a slight bump up in PoPs Tuesday
evening into the early morning hours of Wednesday. The rest of
Wednesday trends drier as upper-level ridging takes hold;
however, some convective thunderstorms/showers could occur if
enough sfc heating takes place. There is low confidence at this
time, so have capped PoPs at a SChc (15-25%) in the late
afternoon/early evening timeframe.

Diverging solutions emerge in deterministic model guidance
Thursday and into Friday after the upper-level ridge moves
eastward. The European suite of model guidance suggests a
stronger ridge axis will provide another stretch of dry and
above-average temperatures Thursday and into Friday while the
North American suite suggests a weaker ridge axis allowing for
shortwaves to bring showers and thunderstorms throughout the end
of the week. By the weekend, there is a bit more agreement in
upper troughing and an accompanying surface low pressure system
affecting the northeastern US. This would favor rainy conditions
and a shift back to seasonable temperatures in its wake.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
Low clouds and fog are leading to IFR/LIFR conditions across
much of Central Pennsylvania, with the exception being the far
western part of the area where cigs/vsby have been VFR for most
of the night. Conditions will gradually improve over the next
few hours and VFR conditions are expected areawide by 15Z. There
is still some threat of LLWS at BFD for the next few hours, but
this will decrease as surface winds pick up through the
morning.

Scattered thunderstorms will develop during the afternoon across
the northern tier and may lead to brief visibility restrictions.
The airfields most likely to be impacted by any storms will be
BFD and IPT, though its possible that a few showers or storms
could reach UNV as well. Any places that see rain in the
afternoon will likely see fog develop Sunday night and into
Monday morning as low level moisture becomes trapped below an
inversion.

Outlook...

Mon...No sig wx expected.

Tue...Isold PM tsra impacts possible.

Wed...Early AM low cigs possible N Mtns.

Thu...No sig wx expected.

&&

.CLIMATE...
With an early August sun angle in place, this will help
temperatures soar into the mid and upper 80s on Monday over the
Susquehanna Valley. Record high temperatures are in the mid 80s
and these could be challenged.

&&

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

&&

$$

SYNOPSIS...Banghoff
NEAR TERM...Banghoff/Tyburski
SHORT TERM...Banghoff/Tyburski
LONG TERM...Banghoff/NPB
AVIATION...Bauco
CLIMATE...Tyburski