-- Discussion containing changed information from previous version are highlighted. --
078
FXUS61 KCTP 190929
AFDCTP

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

.SYNOPSIS...
-- Changed Discussion --
High pressure will begin to build into the region today
accompanied by generally rain-free conditions, light wind and
warmer temperatures that are expected to hold through the
middle of the upcoming week.

A storm system should arrive later Wednesday into Thursday
bringing the next chance of showers and thunderstorms to the
area.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
LLVL moisture taking the circuitous route from the Western
Atlantic, onshore over the Delmarva Region then north along and
to the east of the Allegheny Front has led to widespread
stratus/stratocu across the CWA overnight and early this Sunday.

The cloud cover helped to maintain a 2-3F T/Td spread at most
ob sites and greatly limited any fog formation. Mentioned patchy
light fog in the valleys while painting areas of fog across the
highest ridge tops where the much lower stratus CIGS will likely
intersect the highest terrain across the north and west.

Light northerly flow of drier air just a few KFT AGL will be
sufficient to mix down and poke significant holes in the
shallow low cloud deck as we head through the late morning
hours, and by 18Z there should be 50 percent (or less) sky cover
across practically the entire area.

Morning low temps will once again sport a 5-6 deg F range in the
mid 50s to low 60s with afternoon highs reaching the mid to
upper 70s. HREF MU CAPE increases to between 750-1000 J/KG near
and just to the west of the Allegheny Front late this afternoon
which could support a few highly isolated showers with a brief
TSRA possible in the 20Z-01Z period. Will still leave the
forecast rainfree for now with the POP AOB 10 percent.
-- End Changed Discussion --

&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
-- Changed Discussion --
We are likely to see some areas of fog tonight with the sky
clearing out better, but dewpoints not dipping below 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.
-- End Changed Discussion --

&&

.LONG TERM /TUESDAY NIGHT 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 /09Z SUNDAY THROUGH THURSDAY/...
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.

&&

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

&&

$$

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