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109
FXUS61 KCTP 090322
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1122 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/...
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Winds have largely died down to a light, northwesterly wind
this evening with highest winds along the highest elevations of
NE PA. Dry conditions are expected to continue with model
soundings outlining mid-level dry air inhibiting precipitation
and some dry air mixing down to the surface across central
Pennsylvania. This could inhibit cloud cover forming overnight,
but generally mixing will become less relevant and allow for
cloud formation during the early morning hours.

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. Further 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 further to the north, thus have started to trim
thunderstorm mentions back towards the southern tier and 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.
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&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
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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.
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&&

.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 /03Z THURSDAY THROUGH MONDAY/...
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Late evening update.

Updated TAFS now that winds have died down.

Earlier discussion below.

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 Thursday
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.
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&&

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

&&

$$

SYNOPSIS...NPB
NEAR TERM...NPB
SHORT TERM...NPB
LONG TERM...Martin
AVIATION...Martin