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221
FXUS61 KCTP 090008
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
808 PM EDT Wed May 8 2024

.SYNOPSIS...
- Dry conditions expected to continue through Thursday morning
  as a dry cold front stalls over southern Pennsylvania.
- A wave of low pressure will move across southern PA Thursday
  evening.
- This system will bring periods of rain and potentially gusty
  thunderstorms over the southwest third of the state.

&&

.NEAR TERM /THROUGH THURSDAY/...
Relatively gusty W/WNW winds will continue into the early
evening before steadily decreasing throughout later this evening
and into the overnight hours. Dry conditions are expected to
continue with model soundings outlining mid-level dry air
inhibiting precipitation. Increasing clouds are expected late in
the overnight period.

After winds decrease this evening, focus turns towards 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. Further to the
north, a combination of less instability with less rainfall
Tuesday night into Wednesday morning 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. The European suite of
deterministic models has taken a more southerly track, which
could limit the northward extent and intensity of thunderstorms
Thursday afternoon/evening. The GFS does outline a track across
SW PA and across the PA-MD border, which would allow for some
warming and some potential for destabilization with some
isolated thunderstorms potentially producing small hail and
gusty winds across SW PA and along the southern tier, outlined
in the D2 Severe Weather Outlook from the Storm Prediction
Center.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
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/...
The aforementioned low moves off the coast on Friday and will
allow for relatively cool temperatures across central PA with
lingering showers as the unsettled pattern continues into the
weekend with an upper low crossing the region. The best chances
of precipitation tapering off will be in the overnight Saturday
morning period with chances increasing into the latter half of
the weekend.

Drier period will continue into the first part of next week, the
rest of the long term period, as upper level ridging
builds/moves across the eastern U.S. thanks to long wave
troffing being reconstituted across the Plains/eastern Rockies.
This will likely mean more rounds of strong to severe
thunderstorms for the Plains, but a more settled pattern and
milder temps in the East, at least for few days.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
For the 00Z TAF package, backed off on the mention of lower
conditions at BFD late tonight. Dewpoints are quite low, and
gusty winds all day had a chance to dry things out.

Speaking of gusty winds, winds holding on a bit longer than
one would expect for this time of day. However, winds should
weaken over the next few hours.

Main change for Thursday was to slow down on how fast the
lower conditions come in. Models trending further south with
the low track lately, and thus the northern edge of the rain
ends up further south, than what was noted several days ago.
Also the low dewpoint air will limit lower visibilities early
on.

Still would expect poor conditions at times from late Thurday
into the upcoming weekend, as multiple systems move across the
region.

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...NPB
NEAR TERM...NPB
SHORT TERM...Lambert/NPB
LONG TERM...Gartner/NPB
AVIATION...Martin