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361
FXUS61 KCTP 300322
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
1122 PM EDT Mon Apr 29 2024

.SYNOPSIS...
-Well above average temperatures will persist this week with
 highs in the 70s and 80s; near-record highs possible today.

-Cold fronts Tuesday and Friday-Saturday will be accompanied by
 up to a several hour period of showers and isolated
 thunderstorms. There is potential for brief heavy downpours
 with the storms.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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Satellite loop at 03Z shows building cumulus over the
Alleghenies in region of falling heights/moistening boundary
layer ahead of a weak mid level vort max lifting up the
Appalachians. Most near term model guidance continues to
support the chance of an isolated shower across primarily the
north-central mountains as this feature lifts over the area late
tonight. The vort max and any potential showers should have
lifted north of the NY border before dawn.

For most of the area, expect mostly clear skies overnight.
However, a back door cold front pushing into Eastern PA and the
associated upsloping southeast flow could yield late night
stratus over portions of Schuylkill County. After today`s near
record-breaking temps, decent radiational cooling associated
with mostly clear skies and light wind should result in
overnight min temps near 60F.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
The focus on Tuesday will be on a weakening upper level
shortwave over the Midwest, which will push across the region
Tuesday night. Modest height falls, combined with a plume of
+2-3SD PWATs along the attendant low level jet, should support a
round of showers and possible tsra across most of Central PA.
focused during early afternoon over the NW Mtns, late afternoon
over the central counties, and during the evening over the Lower
Susq Valley.

Tall, skinny cape in the 500-1000 J/kg range, combined with
high pwats, support some locally heavy downpours. The 12Z HREF
supports isolated amounts to around 1.5 inches over the
northeast portion of the CWA. Given the low FFG values, can`t
rule out minor flooding in a few spots. Relatively modest
instability/shear profiles indicate the threat of any severe
weather is low.

Increasing cloud cover and showers should result in a cooler
Tuesday for much of the area, especially over the NW Mtns where
thick cloud cover will arrive early. Partly sunny skies, 850mb
temps around 14C and a late day arrival of any showers should
allow readings to reach the mid 80s over the Lower Susq Valley.

Diminishing showers are expected from west to east Tuesday
night, as the shortwave traverses the state. Latest guidance
points to fair weather for most if not all of the forecast area
Wednesday, as surface ridging and much drier air work into the
state behind the exiting shortwave. Mixing down forecast 850mb
temps of around 11C yields expected highs in the 70s Wednesday.
We have leaned toward the lower NBM10pct dewpoints Wed afternoon based
on dry air above a weak inversion in the model soundings.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
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Upper level ridging building over the region should ensure fair
and warm conditions Wed night through at least early Friday.
High pressure tracking north of PA into the Canadian Maritimes
will then result in a developing easterly flow and the onset of
cooler conditions Friday PM into next weekend. All medium range
guidance points to a rainy and cool weekend, especially the
first half, as a southerly low level jet linked to an upper
trough over the Grt Lks and an associated plume of deep moisture
overruns a stationary front over the Ohio Valley. Latest EPS
plumes indicate around a half inch of rain is likely by late
Sunday. Passage of the upper trough and associated occluded
front appears likely to bring drier and warmer conditions by
Monday of next week.
-- End Changed Discussion --

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
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Latest sfc analysis shows a sea-breeze boundary moving across
nrn MD and far srn PA. Wind is going light. A congested patch of
cu is developing VCTY JST and AOO. Many meso models pop isold
SHRA this evening and slide them to the NE into UNV and IPT. The
coverage of these potential SHRA will be <30pct, but it is
still worth a VCSH mention. CAPE should not be sufficient to
allow for deep convection/TS. Wherever a SHRA can pass over an
airfield, they will have a good potential to develop some fog,
but prob of IFR overnight is less than 10pct at any airfield. We
will take IPT and UNV into MVFR vsby, though, as they should
clear out and have the higher chance of getting wet. The lack of
wind will also a plus for fog.

Weak troughing over the central mtns in the morning, and a cold
front will be approaching from the west. However, the front will
take much of the day to cross the Central PA, and may not quite
clear LNS before sunset/00Z. The moisture feed is not great,
and the best instability will be over the NErn third of the
state. Have mentioned TS (PROB30) for almost all terminals for a
few hours, though due to the frontal forcing and PWAT values
around 1.5" as the front passes.

After the front passes, there will be lower clouds hanging out
for many hours post-frontal passage, and these will linger all
night in the western mtns (JST/BFD). These should diminish on
Wed AM. Most of Wed will be VFR.


Outlook...

Wed...Early AM low cigs possible W Mtns.

Thu...No sig wx expected.

Fri...Evening showers/cig reductions possible.

Sat...Widespread SHRA/TSRA. IFR poss.
-- End Changed Discussion --

&&

.CLIMATE...
Record high temperatures were set at the following locations
today (Monday):

SITE        2024 OBS     PRVS RECORD
Altoona          86F     83F (1956)
Bradford         82F     76F (1984)
Williamsport     89F     86F (1942/1974)

&&

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

&&

$$

SYNOPSIS...Lambert
NEAR TERM...Fitzgerald
SHORT TERM...Fitzgerald
LONG TERM...Fitzgerald
AVIATION...Lambert/Dangelo
CLIMATE...Banghoff/Colbert