-- Discussion containing changed information from previous version are highlighted. --
146
FXUS61 KCTP 042300
AFDCTP

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

.SYNOPSIS...
Cloudy skies with areas of light rain and drizzle, along with areas
of fog, will persist throughout the weekend. High pressure
slowly building eastward from the central Great Lakes will bring
some drying 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/...
Light rain continues to move across central Pennsylvania from
SW to NE. Current MRMS shows precipitation bands across the mid-
atlantic region from central Ohio to the coast of Maryland.
Additional rain will likely develop across southern tier of the
commonwealth near the Mason-Dixon line in the early afternoon
hours.

The latest hires model guidance supports periods of rain
throughout today and into tonight ahead of an upper level
shortwave lifting out of the Tennessee Valley. The associated
southerly low level jet and plume of higher pwats will
overrun a dome of cool/stable air (entrenched within a CAD
pattern configuration) to bring 0.25-0.75" of rain to the area.
This pattern will also ensure a significant cool down from
recent days with fcst max temps in the 50-60F range or 10 to 25
degrees cooler vs. yesterday depending on location. Not much
change in sensible wx overnight with periods of rain continuing
with lows in the 45-50F range or +5-10F above early May climo.
Patchy fog will be possible overnight in the higher elevations
with low dewpoint departures and relatively stable air near the
surface.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
Sunday looks to be another relatively cool day for early May
due to a persistent southeast flow off of the Atlantic. However,
a slight rebound in warmth is expected over the western and
southwestern periphery of the CWA as steadier rain tapers off.
Fcst highs 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).

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 /22Z SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
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.
-- End Changed Discussion --

&&

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

&&

$$

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