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816
FXUS61 KCTP 200937
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
537 AM EDT Mon May 20 2024

.SYNOPSIS...
A ridge of high pressure at the surface and aloft over
Pennsylvania will bring dry conditions, light wind and warmer
temperatures through Wednesday. A storm system moving north of
the Great Lakes will push its southward trailing cold front
through the region on Thursday bringing the next chance of
showers and thunderstorms.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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A light east to southeasterly low level flow was advecting an
area of low stratus across the Lower Susq Valley and Western
Poconos early this morning, while mainly clear skies elsewhere
allowed the temp and dewpoints to dip into the mid 50s with the
spread narrowing to a deg F or less. This has led to locally
dense fog to form throughout the valleys of Scent PA, the
Laurels and NW Mtns where the heaviest rain occurred over the
past several days. Issued an earlier Special Weather Statement
to cover the fog over our SW zones where the fog is currently
most widespread. *Update - Issued a Dense Fog Advisory through
13z today in collaboration with LWX for expanded coverage of
dense fog in the valleys of Central and Western PA.

A bit different from Sunday AM, any low clouds and fog should
burn away by 15Z and should help temps this afternoon rise a
few to several degrees warmer than Sunday`s maxes.

As noted by previous shifts and highlighted on multiple model
guidance that show and axis of CAPE likely exceeding 1000 J/KG,
there could be just enough instability across the nrn tier of
and Western Mtns in the aftn to pop a few stray showers and
and TSRA. Left PoPs in the 20-30pct range during the 20Z Monday
to 00Z Tuesday.
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&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
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Tonight will be similar to the last few nights, with perhaps
less of a recurrence of the nighttime stratus. Valley fog is
probable again tonight and will maintain the mention of patchy
fog. Min temps early Tuesday in the upper 50s to around 60 will
likely be a bit milder than Mon AM as well .
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&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Tuesday and Wednesday will be very warm days with south to
southwesterly flow and plentiful sunshine. Expect highs to reach
the 80s both days, and some valley spots could even touch 90
degrees on Wed aftn.

Surface low pressure is progged to track north of the Great
Lakes and well north of PA during the mid to late week period.
The associated cold front will cross Pennsylvania Wed night or
early Thurs, accompanied by scattered showers and thunderstorms.

After the front moves through, uncertainty remains as to how
far to our south it will settle before stalling. This could keep
a chc of showers across at least southern PA through the end of
the week.

There is considerable uncertainty heading into next weekend,
but it appears that there is a chc that our weather could
remain unsettled.

&&

.AVIATION /10Z MONDAY THROUGH FRIDAY/...
Valley fog has developed across the northwest 2/3 of the
airspace resulting in localized visibility at or below airfield
minimums (1/2-1/4SM). Max IFR fog confidence is focused over
the south central terminals AOO/JST/UNV based on obs trends and
IR satellite imagery. Expect VFR/IFR fluctuations at BFD. MVFR
to IFR stratus layer expanding over southeast PA and will impact
LNS/MDT and perhaps IPT-which may also experience restrictions
in fog through the predawn hours.

Valley fog will dissipate quickly in the morning, but the low
clouds in the southeast airspace will be slower to break. MVFR
ceilings could remain in place across the Lower Susquehanna
Valley through 18Z. Widespread VFR conditions are expected
once fog/low cloud erode with light winds. Some guidance shows
the potential for a isolated thunderstorm across the northern
tier later this afternoon, but confidence/coverage remains too
low to include mention in the TAFs.

Outlook...

Tue...VFR/no sig wx.

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

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

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
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Dense Fog Advisory until 9 AM EDT this morning for PAZ005-006-
010>012-017>019-024>028-033>037-041-042-045-046-049-050-056.
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&&

$$

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