-- Discussion containing changed information from previous version are highlighted. --
111
FXUS61 KCTP 091042
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
642 AM EDT Thu May 9 2024

.SYNOPSIS...
A front has stalled just to the south of the state. It will try
to move northward slightly today as a wave of low pressure
rolls along it. A pair of upper troughs will dip across PA on
Friday and Saturday. Warmer but still unsettled weather is in
store for next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Low clouds still creeping down from wrn NY, but aren`t too
widespread in coverage at this point. The dewpoints in the
central mtns have risen from their absurdly low values (hello,
Stratosphere) of late Wed and earlier overnight. They should
continue to rise with PWATs rising up to a buck and a quarter
along and S of the Turnpike. SHRA/TSRA, which flared up along
the nearly- stationary front just to our S, will likely enter
Somerset Co before daybreak. The forcing for the SHRA/TSRA this
morning is concentrated over OH at 08Z, and will lift into wrn
PA after sunrise. The shortwave trough will cross PA during the
daylight hours, with additional forcing moving in from the west
by sunset.

The wx problem of the day is how bad the storms will get, and
where (how far east) they will occur. At this point, the SPC DY1
outlook of MRGL risk is well-placed and makes sense with
stability higher over the NE half of the CTP forecast area. The
sfc low riding along the front may nudge the front northward
into srn PA by mid-late morning. Most models keep the lowest
pressure traveling south of the state. So, the entire area may
be pretty stable and the threat of severe wx may be near zero.
However, the approach of an upper trough and the sfc low will
keep the threat of svr wx in play with increasing shear
throughout the day. The main threat today will be damaging
gusts. The presence of the front and low level shear could
bring an isolated tornado into the picture, as well. Will
confine mentions of TS to the south for the time being. There is
some weak elevated instability over the northern half of the
state later this aftn and evening, but not quite enough to make
it enough of a possibility to add it into the forecast/grids.
Maxes today will be 15 to 20F colder than Wed`s lofty values,
and about 5F below normals for early May.

The heavy rain/minor flooding threat is highest across the S,
as well, where repeated/training storms are possible and the
wetter antecedent conditions coexist. As the trough moves
closer, the rain/showers will become more numerous and peak the
PoPs overnight in many places. Mins will only be about 10-12F
lower than daytime temps due to the higher dewpoints and cloud
cover.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
The upper low/trough axis and an inverted sfc trough will be
coincident over the whole CWA in the morning hours on Friday.
This will be making widespread SHRA and perhaps a rumble or two.
The best instability and focus slides to the eastern half of the
state later in the day, and some breaks in the clouds may come
to the western mtns. The is the potential for a dry stretch of
time Friday evening into Saturday morning across wrn PA as
drier air with a minor bump in 5H heights and sfc pres, too.
This break will be short-lived as the unsettled pattern continues
into the weekend. Another upper trough and reinforcement of the
cooler/drier air moves in for Sat. Additional showers are
expected for the entire area, esp in the latter half of the
day. Highs stay in the 50s for everyone Fri, and should be the
coolest day for the next 7, and perhaps for the rest of the
warm season. We should rebound ~5F on the maxes for Sat.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
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 /12Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
Daybreak gives way to high clouds streaming in across western
Pennsylvania this morning. Partly sunny skies with light
variable winds means we will have VFR conditions to start the
day. A surface low approaching the state will cause clouds to
thicken and lower throughout the day today. A surface boundary
has stalled just across the Maryland boarder and depending on
how far north it drifts will determine if we see stronger
convection.

Latest guidance has the surface low tracking to the south of
Pennsylvania, meaning the heaviest rains and greatest
instability for t-storms will also track to the south; however,
we will still see reductions in visibility from scattered
showers and thunderstorms across most sites as we move into
Thursday afternoon. Cigs will also lower through the afternoon
and evening today across the region with MVFR to IFR ceilings
likely into Thursday night.

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...Still a chance of a shower.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...Dangelo
NEAR TERM...Dangelo
SHORT TERM...Dangelo/NPB
LONG TERM...Martin
AVIATION...Bowen