813
FXUS61 KCTP 191735
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
135 PM EDT Sun May 19 2024

.SYNOPSIS...
High pressure is building into the region. Generally rain-free
conditions, light wind and warmer temperatures 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.

&&

.NEAR TERM /THROUGH TONIGHT/...
We`re just a month from the solstice, and the sun is still
having trouble breaking up the morning stratus in places where
it was thickest. However, many areas have broken out and have
seen some sunshine before the sun self-destructed and mixed the
moisture up into higher-based cu. Overall, max temps still seem
on track. There could still be an isold SHRA this aftn in the
SE/Poconos or Laurels, popping off the high ground. But,
chances/coverage are slim (20pct).

Prev...
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.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
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.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Confidence is increasing in the timing of the frontal passage to
be Wednesday afternoon and evening. The surface low is currently
progged to be positioned north of the great lakes and track well
north of PA into central Ontario and eventually into Quebec. The
resulting cold front will track across the Ohio Valley and into
the Mid-Atlantic region. This will bring showers and
thunderstorms across PA late Wednesday into early Thursday,
however uncertainty remains as to the extent of these storms.
Southerly flow ahead of the front will bring warm air advection
and instability, but medium range guidance suggests these
storms could breakup as the front crosses into central PA.
Therefore PoPs have been capped at 60% for now.

After the front moves through, considerable uncertainty still
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, and even the latest
guidance is suggesting these weekend showers could be scattered
to isolated given a lack of significant forcing and some ridging
building in Friday to Saturday.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
Mainly VFR conditions prevail across the airspace for the early
afternoon; however a few sites are still stubbornly holding onto
MVFR low clouds. All sites should improve to VFR later this
afternoon. 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 tonight will shift back to fog (west/central) and low
stratus restrictions (east) into early Monday morning. Areas
that have mostly cleared will dry out making confidence in
widespread fog low, but a mention of IFR fog conditions have
been made in the TAFs for the eastern sites.

Outlook...

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

Tue...VFR/no sig wx.

Wed-Thu...Chance of t-storms.

Fri...Mainly VFR, slight chance of showers.

&&

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

&&

$$

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