948
FXUS61 KCTP 050314
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1114 PM EDT Sat May 4 2024

.SYNOPSIS...
Cloudy skies with areas of light rain, drizzle and fog will
persist throughout the weekend. High pressure slowly building
eastward from the central Great Lakes will bring some drying and
brightening to northern and central Pennsylvania by Monday and
Tuesday, but the south will remain on the cloudy side with some
showers. The pattern remains unsettled mid to late week with
weather systems bringing rain chances Tuesday night into
Wednesday, and Wednesday night into Thursday.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Boundary layer convergence continues to ramp up this evening
over central PA as 850 mb jet amplifies in rich deep layer
moisture environment combined with easterly llvl maritime flow.
This will continue to support widespread light rain and drizzle
throughout central PA through the overnight and keep
temperatures within a few degrees of current readings through
12z Sunday morning.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
Sunday will be unseasonably cool with slowly decreasing easterly
flow from off of the western Atlantic, as we start to see an
increasing southerly component in time. This will lead to a
slight rebound in warmth over especially western/southwestern
periphery of the CWA as steadier precip tapers off. Fcst highs
should range from 55F in the Endless mtns and southern Poconos
to ~70F in the far southwest corner of the CWA (near Confluence
in Somerset County).

Even with the advancing warm sector, scattered diurnal
convection appears likely to the west of the Alleghenies Sunday
afternoon which could spill into central PA late in the day as
CAPE values increase. The SPC MRGL risk SWO clips a portion of
Warren County. Everywhere else remains under general thunder.

The CAD pattern loses its grip Sunday night into Monday as a
weak cold front presses southeast from Lake Erie. This will
allow for the possibility of night time convection along the
cold front. Guidance has been bullish on fog development and the
mention of it has increased in coverage in the wx grids. Fcst
lows Sunday night are +10-20F above climo for early May in the
low 50s to near 60F.

Temperatures are forecast to bounce on Monday with fcst maxes
getting back into the 70-80F range. High pressure and low pwat
air should dry out the northern tier, but nearly stationary
frontal zone will maintain a chance of showers/t-storms over
south central PA through Monday night.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Upper level ridging over PA indicates warm and generally dry
conditions are likely Tuesday. However, a warm front lifting out
of the Ohio Valley could result in increasing clouds with a PM
shower/tsra, primarily across the western counties. The bulk of
medium range guidance supports a very warm Wednesday with
scattered convection, as the area briefly breaks into the warm
sector south of a weak low tracking across upstate NY. A round
of convection may accompany the trailing cold front. Ensemble
mean pre-frontal 850mb temps around 16C suggests max temps as
high as the mid to upper 80s are possible over the Lower Susq
Valley.

The best chance for widespread showers and thunderstorms
appears to be on Thursday associated with a deepening upstream
trough and wave of low pressure riding along the stalled cold
front just south of PA. The surface low and deepest moisture is
progged to shift east of the area by Thursday night. However,
falling heights ahead of the upper trough will likely support
scattered, diurnally-driven convection Friday and Saturday,
along with a downward trend in temperatures. EPS mean 850mb
temps by Saturday are only around 3C, which is supportive of
highs ranging from just the mid 50s to mid 60s.

&&

.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
A moist southeast flow preceding a slow-moving warm front in the
Ohio Valley will produce low cigs and rain across the forecast
area through at least Sunday morning. At 02Z, some MVFR cigs
are noted across the eastern half of the state. However, all
guidance points to deteriorating conditions overnight with
widespread IFR/LIFR cigs by early Sunday morning. LIFR cigs are
most likely where the southeast flow is forced to ascend the
higher terrain of Central PA. Strengthening south-southwest
winds aloft will result in marginal LLWS overnight into Sunday
morning. Bufkit soundings indicate the best chance of LLWS
criteria being met will across the northern tier of the state.

Little improvement in flying conditions are expected over most
of Central PA Sunday, as a moist southeast flow off of the
Atlantic persists. However, model soundings indicate some
modest improvement is possible late in the day along and west of
the spine of the Alleghenies.

Outlook...

Mon...AM low cigs/fog likely.

Tue...Patchy AM valley fog possible, mainly Southern PA. Isold
PM tsra impacts possible Western PA.

Wed...AM low cigs possible NW Mtns.

Thu...Rain/low cigs possible. PM tsra impacts possible
southwest PA.

&&

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

&&

$$

SYNOPSIS...DeVoir/Bowen
NEAR TERM...DeVoir/Steinbugl/Bowen
SHORT TERM...DeVoir/Steinbugl/Bowen
LONG TERM...Fitzgerald/Bauco
AVIATION...Fitzgerald