184
FXUS61 KCTP 100822
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
422 AM EDT Fri May 10 2024

.SYNOPSIS...
- A stationary front will continue to be present across
  southwestern PA to northern VA for the next 24 hours as a few
  waves of low pressure move east along it.
- The front will push southeast to the Delmarva Coast late
  Friday.
- Several upper level troughs will move across PA through
  Saturday, bringing periods of light to moderate rain.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Regional radar loop at 08Z shows the bulk of the heaviest rain
shifting east of the forecast area associated with the passage
of mid level shortwave evident in water vapor imagery. However,
a lingering easterly flow off of the Atlantic Ocean, combined
with large scale forcing ahead of an upstream trough, should
result in a steady rain across most of the forecast area today.
The deepest moisture and highest pwats have shifted east of PA,
so rain rates should be light. Ensemble plumes indicate
additional rainfall during the daylight hours will likely range
between 0.3 and 0.6 inches, with the highest amounts over the
north-central part of the state.

Due to the NBM`s warm bias in easterly flow/CAD scenarios, we
have undercut its max temp forecast slightly by blending with
the much cooler NAM surface temps. Expect highs to range from
the upper 40s on the ridgetops, to the low 50s in the valleys. Upsloping
flow over the Laurel Highlands is currently resulting in fog on
the higher ridgetops of Somerset/Cambria counties, which should
persist through around 12Z today.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
Rain should taper off this evening from west to east, as the
upper trough passes over the state and surface ridging builds in
from the Grt Lks. Light wind, partial clearing and wet ground is
likely to result in patchy late night fog.

After a break from the rain tonight into early Saturday, expect
a return of showers Saturday PM associated with height falls
ahead of a potent upper level shortwave diving across the Grt
Lks. Strong large scale forcing, in combination with some
minimal model cape, supports high POPs with a tsra possible in
spots, especially over the western half of the forecast area.
Unimpressive pwats signal that rainfall Sat PM should not be
significant, generally between 0.1 and 0.2 inches based on
ensemble mean qpf.

The upper trough is progged to cut off and track along the
PA/NY border Sat night into Sunday morning. Low level
instability associated with this feature should result in
plenty of cloud cover and at least scattered showers lasting
into early Sunday. Brightening skies and diminishing showers
look likely by Sunday afternoon, as the upper trough exits the
state and surface surface ridging builds in from the west.
Mixing down progged 850mb temps of around 4C translates to
expected highs in the low to mid 60s over much of the forecast
area, with upper 50s over the higher terrain of Eastern PA.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Tendency to have a large scale upper level ridge over the west
this weekend, will result in much below normal 500 mb heights
over the east into next week.

While some milder and drier conditions will be possible Monday
into Tuesday, much of the time it will be cooler than normal
and wet from time to time for much of the upcoming week. Sunday
will be one day that will feature gusty winds and cold temperatures.

&&

.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
Rain showers will continue to impact cigs and visby throughout
central PA for the remainder of the overnight hours. Most
airfields will experience IFR to LIFR conditions as some rain
could be moderate at times. The threat for thunder has ended
with instability having weakened and rain will be mostly
stratiform through the morning.

Fog development is likely across the south western airfields
near the Laurel Highlands in the early morning hours today
before day break. These sites, mainly JST and AOO, could
experience visby less than 1 mile.

Very little improvement is expected during the day on Friday as
stratiform rain will continue to be present through the afternoon
hours and cigs are likely to remain MVFR to IFR. We`ll likely
get a small break from the rain after 00Z Saturday before the
next trough is progged to swing through Saturday afternoon.

Outlook...

Fri...Low cigs/drizzle possible, especially in the morning.

Sat...PM showers/low cigs possible, mainly W Mtns.

Sun...AM low cigs possible W Mtns. Sct afternoon showers/brief
vis reductions possible.

Mon...AM dry and mainly VFR. Showers return PM.

Tue...Showers and tstms.

&&

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

&&

$$

SYNOPSIS...NPB
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald
LONG TERM...Martin/Gartner
AVIATION...Bowen