464
FXUS61 KCTP 050106
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
906 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
throughtout 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/...
Unsettled weather is expected for the long term period with
multiple chances for showers and thunderstorms. The first chance
will come on Tuesday as a warm front lifts north of the area and
moisture advection increases. The best chance for any showers
or storms on Tuesday will be across the southwestern counties.
Wednesday will be the warmest day of the period with highs in
the upper 70s and 80s as the region will be in the warm sector
of an approaching low pressure system. Most model guidance shows
a weak wave of low pressure tracking to our north during the day
on Wednesday along the warm front ahead of the primary low.
This will bring more showers and storms to the area.

The best chance for widespread showers and thunderstorms
appears to be on Thursday as a cold front moves through. Locally
heavy rainfall will be possible with ensembles showing PWATs
approaching 1.3 inches across the southern tier along with
surface CAPE of 500-1000 J/kg. A few stronger thunderstorms
appear possible as well, as deep layer shear begins to increase
as the upper level trough moves in.

Temperatures will be on a downward trend behind the cold front
and into the weekend. Highs on Saturday will range from the
upper 50s across the northern and western mountains to the mid
to upper 60s for the southeast. There is some disagreement in
the models with respect to rain chances through the end of the
period, but scattered showers appear likely as a couple of
shortwaves ride through the southern edge of an upper low
positioned to our north.

&&

.AVIATION /01Z 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 22Z, 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 later tonight 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...Bauco
AVIATION...Fitzgerald