-- Discussion containing changed information from previous version are highlighted. --
925
FXUS61 KCTP 090530
AFDCTP

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

.SYNOPSIS...
A front has stalled just to the south of the state. It will move
northward just 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 TODAY/...
Low clouds creeping down from wrn NYwill continue moving south
through morning, but probably won`t be 100pct in coverage as
they run into the large patch of dry air. Dewpoints have started
to rise at DUJ-FIG-UNV. As we continue to stratify, they should
continue to rise. SHRA/TSRA flaring up and rolling along the
front which is W-E just 20-30 miles S of the Mason-Dixon Line.
These will likely clip Somerset Co by the end of the night.

Prev...
The main focus of the near-term is a sfc low-pressure with
models converging towards the low tracking across SW PA across
the Mason-Dixon Line and into the DelMarVa region on Thursday.
Surging PWATs ahead of the sfc-low brings rain chances into the
equation during the morning hours on Thursday and continuing
throughout the day. PWATs in the 1.00-1.25" range across
southern PA could lead to localized downpours with isolated
instances of flooding. Farther to the north, a combination of
less instability with less rainfall in the previous evenings
will limit these concerns.

There is some question with regards to instability and the
northward extent on thunderstorm mentions in the forecast,
especially with regards to cloud cover potentially inhibiting
surface heating throughout the day. Deterministic models are
trending towards a southern low-pressure track which will limit
instability in the north, thus have started to trim thunderstorm
mentions back towards the southern tier and mainly over across
SW PA. Further trimming back could be needed in future cycles,
but have kept some thunderstorm mentions in due to some
uncertainty with respect to low track. Meager instability with
sufficient shear across the southern tier could allow for some
isolated thunderstorms that will bring potential to produce
small hail and gusty winds, outlined in the D2 Severe Weather
Outlook from the Storm Prediction Center.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
Late night update brings about little change in the short-term
forecast outside of some increases in PoPs Thursday night, where
models have converged towards solutions of a secondary low
pressure forming south of the area.

Prev...

Period of rain will continue through Thursday night with low
clouds and fog potential in the higher elevations of central PA
increasing where rain chances decrease overnight. The best
chances of rain shifts to eastern PA on Friday with some
potential for dry conditions Friday evening into Saturday
morning across W PA as drier air works into the area. This break
will be short-lived as the unsettled pattern continues into the
first half of the weekend.

Surface low pressure stationed in the Great Lakes will move
southeastward late Friday into Saturday with an associated cold
front approaching the Commonwealth. Surging moisture ahead of
the cold front brings about an increase in rain chances Saturday
morning across W PA and continuing to overspread eastward
throughout the day. Some elevated instability will outline
afternoon/evening thunderstorm chances across western PA with
slightly less confidence across eastern PA as precipitation
moves into the area during the late evening hours.

&&

.LONG TERM /SUNDAY 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 /06Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
VFR conditions and light variable winds will be prevailing
throughout the remaining overnight hours with only high clouds
trickling into the area ahead of the surface low. The northwest
has a low (15%) chance of seeing high end MVFR conditions before
day break with a few lower clouds sneaking in from the north.

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 on Thursday 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/NPB
SHORT TERM...NPB
LONG TERM...Martin
AVIATION...Bowen