743
FXUS61 KCTP 101551
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1151 AM EDT Fri May 10 2024

.SYNOPSIS...
Upper level troughing will remain over Pennsylvania through
this weekend with shortwaves tracking over the state and
focusing rainfall today and Saturday night into early Sunday.

The upper trough will lift out early next week, then a cold
front will likely push through Tuesday. A wave of low pressure
is likely to track south of Pennsylvania next Wednesday.

&&

.NEAR TERM /UNTIL 11 PM THIS EVENING/...
Regional radar loop at 1530Z shows a large area of light to
moderate rain covering much of the CWA with the exception of
potions of the Laurel and Lower Susq Valley. There was even
some brief heavy rain associated with small areas of 40+ DBZ
echoes seen across Central and NE PA where the best mid level
FGEN forcing was located along with the nose of a -2 to -3 sigma
easterly LLJ (deviation from the normal u-component of the
wind at this time of year).

This moisture laden llvl easterly flow will persist for the
next 4-6 hours before the sfc-850 mb low slides off the Mid
Atlantic Coast and cause winds to back around to the north then
northwest, which will lead to a diminished rain intensity and
periods of light rain/drizzle this afternoon and evening. A
sooner transition will occur across the Western Mtns.

Temps were chilly for mid may and in a tight range on only 5-6
deg F, ranging from the mid and upper 40s across the higher
terrain of the North and West, to the low 50s in the Central
and Southern Valleys of the state. Little change other than a
few deg F rise in temps (mainly across the Western Mtns) will
occur this afternoon.

Additional rainfall amounts this afternoon will likely rain from
2-4 tenths of an inch, with the highest amounts over the north-
central part of the state and Western Poconos where the
aforementioned nose of the LLJ will linger the longest.

&&

.SHORT TERM /11 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 /16Z FRIDAY THROUGH TUESDAY/...
Widespread rain across central Pennsylvania will continue to
impact cigs and vsbys, keeping them mainly in the IFR to low
MVFR range through early tonight.

As the llvl wind backs from the east through the north and to
the northwest, cigs will ocnly dip into the LIFR range with
ocnl IFR vsbys at KJST and KBFD.

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...continued low cigs in rain of varying intensity.

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...Lambert/Fitzgerald
NEAR TERM...Lambert/Fitzgerald
SHORT TERM...Lambert/Fitzgerald
LONG TERM...Martin/Gartner
AVIATION...Lambert/Bowen