-- Discussion containing changed information from previous version are highlighted. --
292
FXUS61 KCTP 190603
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
203 AM EDT Sun May 19 2024

.SYNOPSIS...
An upper trough overhead will slide east through the late
evening with showers decreasing by late tonight. High pressure
will start to build into the region on Sunday accompanied by
generally rain-free conditions that are expected to hold through
the middle of next week. A storm system should arrive late
Wednesday into Thursday bringing the next chance of showers and
thunderstorms to the area.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Isolated open cellular showers continue to roam areas from the N
Central Mountains to the WC Mountains late this evening as upper
low upper low tracks off the coast and drier air works southward
behind the upper trough axis. Showers will taper by late tonight
with clearing skies and light winds allowing areas of fog to
form overnight. Some fog could become locally dense in the
predawn hours. Lows will range from the mid 50s to around 60.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/...
High pressure rolls in for Sunday. Clouds/fog in the AM clear
out nicely. However, just enough instability develops and enough
moisture lingers to pop a couple of SHRA. Literally just a few
with the highest probability (30pct) over the SErn hill tops.
Maxes in the 70s will be pretty normal. We are likely to see
some areas of fog again Sunday night with the sky clearing out
better, but dewpoints not dipping out of the m50s.

A decent and mostly rain-free stretch of weather is expected
Monday through Wednesday morning, with high pressure dominating
the sensible weather conditions and bringing the driest weather
we`ve seen in a few weeks. We are timing the next weather system
into central PA by Wednesday afternoon. Scattered showers and
thunderstorms may approach western areas by late Wednesday
afternoon, but it looks like most areas stay dry until after 00z
Thurs.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Late evening update holds minor changes to the long-term
forecast, most notably have capped PoPs at Chc Wednesday
evening into Thursday as both GFS/ECMWF models have
showers/thunderstorms along the cold front breaking up as they
enter central PA. Ensemble plumes still outline higher chances
of PoPs in this timeframe so have decided to just cap instead of
trim PoPs at this time.

Prev...
By the middle of next week, upper troughing will move
across Pennsylvania and support a better chance for showers and
thunderstorms. At the surface, there remains plenty of model
uncertainty about the timing of a cold front. The mean timing is
Wednesday afternoon, but individual models bring rain as late
as Thursday morning. If the front moves through Wednesday
afternoon or evening, it could produce the first threat for
severe weather in some time given the aforementioned WAA
bringing greater instability.

After the front moves through, considerable uncertainty exists
in terms of how much and how frequent rain will be. A chance of
showers remains in place through the end of the week despite
zonal flow aloft providing little in the way of synoptic
forcing. The next chance for a widespread soaking rain will come
during the weekend with a center of low pressure developing
across the Ohio Valley by Friday afternoon.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
IFR cigs will prevail across the western airspace/ZOB sector
with lower-end MVFR to borderline IFR cigs over the eastern
airspace/ZNY sector. The visibility should tick lower through
the predawn hours as dewpoint depressions continue to narrow;
however not as confident in <1SM given the expansive low stratus
deck. Conditions will improve after sunrise with a return to
VFR expected by midday. Can`t rule out a spotty shower this
afternoon, however very sparse coverage, low confidence (<20%
POP) and minimal operational impact will preclude mention from
TAF. Focus for later cycles will revolve around fog development
overnight into early Monday morning.

Outlook...

Mon...Patchy AM fog possible, then VFR.

Tue...VFR/no sig wx.

Wed-Thu...Chance of t-storms.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...Lambert/DeVoir
NEAR TERM...DeVoir/Dangelo
SHORT TERM...DeVoir/Dangelo
LONG TERM...NPB/Bowen
AVIATION...Steinbugl/NPB