-- Discussion containing changed information from previous version are highlighted. --
086
FXUS61 KCTP 021755
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
155 PM EDT Sun Jun 2 2024

.SYNOPSIS...
A southwesterly flow of increasingly moist air ahead of
weak low pressure over the Great Lakes region will bring
showers today across the Western Mountains of the state with
scattered mid to late afternoon showers possible across the
Central Mountains and Susquehanna Valley.

It will turn warmer with moderate humidity Monday and Tuesday
along with an isolated shower or thunderstorm possible in the
afternoon and evening.

A slow moving cold front will cross the region during the
middle of the week bringing the best chance for rain/storms,
then an upper level trough will build over the region late week
into next weekend with more unsettled weather expected.

&&

.NEAR TERM /THROUGH TONIGHT/...
Clouds will gradually thicken up and lower to under 8 KFT AGL
across the Western Mtns late this morning, across the Central
Mtns early this afternoon, and east of the Susq Valley late in
the afternoon/early this evening. PWATS will rise from 0.5 to
0.7 inches this morning to between 1.25 and 1.5 inches this
afternoon. As such, rain showing up on radar may not necessarily
equate to rain reaching the ground through the morning hours.

Additionally, very little low level convergence is present
within the warm sector spread across our region, nor is there
any significant larger scale deep layer forcing beneath the
favorable quads of a jet. As such, precipitation amounts should
be light. HREF 12 hour amounts ending at 00Z or 06Z Monday are
generally under 0.10" with a few spotty 0.20" + amounts possible
across Central and Western PA. MU CAPE is mainly under 250 J/KG
later today and tonight, however, 925-850 mb based LIs are
about -1C over Southern PA from 22Z today to 05Z Sunday. So a
rumble of thunder can`t be ruled out from isolated/embedded low-
topped TSRA.

High temps this afternoon (before any -SHRA move in from the
west) will vary from the upper 60s to low 70s across the higher
terrain of Northern and Western PA. to around 80 in the
Southeast. Surging dewpoints overnight will be a sign of more
moisture in the air. For locations that get precipitation today
and see some clearing overnight, patchy fog will be possible.
Low confidence in fog coverage based on uncertainty with
overnight cloud cover, but can`t rule out some instances of
valley fog on Monday morning. Lows will range from the mid 50s
in the northwest to low 60s southeast.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
A very weak cold frontal boundary will push south across the
state early in the period before washing out as it nears the
Mason/Dixon line on Monday.

Building upper level ridge to 580dm should favor lower POPs
Mon-Tue. However, the airmass will be trending warmer and more
humid with just a bubble of weak sfc high pressure drifting from
Lake Ontario on Monday to the New England Coast by early
Tuesday. As a result, we can`t rule out spotty diurnally driven
convection. Have gone with isolated wording for shower/storm
potential as pinning down the exact location of storms is
difficult in this type of pattern.

High temps both Monday and Tuesday will range from the mid 70s
across the highest elevations of the North and West to the low-
mid 80s in the Southern Valleys.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
Low pressure passing well to the north of the state in the
latter part of the week will push a cold or occluded front thru
most likely on Thursday. The upper feature driving this sfc
feature is a deepening closed low. The weak moisture plume in
advance of the front will result in mainly light precip. If we
can manage to break into the warm sector, we should have some
thunder Wed night and Thursday. Ensemble plumes suggest most
likely areal average rainfall Wed- Thu is around a half inch
with near zero chances of 1"/24hrs time (20pct). After the front
passes, the rest of the long range period will be dominated by
the big closed low. It is almost cutoff, but does inch eastward
with time. Some guidance (incl Op GFS) has the center of the
upper low cross NY/PA over the weekend. That would make a very
showery time with mainly aftn TS/SHRA and limited heating.
However, 8H temps won`t be too chilly, running just one std dev
to the left (colder) for June.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
-- Changed Discussion --
MVFR cigs starting to occur over the west where precip is almost
to the ground at JST and BFD. Such sparse radar returns, meager
forcing, and low moisture plume riding overhead bends the
forecast to a mainly dry time, but certainly worth at least a
VCSH mention for the next 12 hrs in the west. The forcing slides
to the east by 06Z. Will hold onto the MVFR cigs in the west and
introduce them to UNV/AOO/IPT around 00Z. Fog and IFR CIGS will
be possible late in the west mainly due to the westerly flow
just aloft and the resultant upslope overnight. Since there
won`t be much rainfall and the ground won`t be all that wet,
visbys lower than 1SM are unlikely (40%) for the western
terminals, and less than 20% chc at all other terminals tonight.
Will mention 1-2SM at AOO and UNV just to put forth the idea
that it is not out of the envelope of solutions.

Sunrise should improve any sub-VFR conditions at the central
and eastern terminals. However, the western sites will take a
couple of hours to rise to MVFR. Shortwave ridging overhead
should cap the cu around 8kft in the NW and 12-15kft in the SE
on Monday. The instability and left over moisture could pop a
SHRA or two, but they won`t become too numerous, staying sct or
isold, and mainly in the east/SE where the best of the heat and
leftover mstr will be. There is the possibility (10%) for a TSRA
at MDT or IPT afternoon. Have kept mentions of TS out for this
pkg given that the possibility is so low and generally after
18Z Mon.

Outlook...

Tue...AM fog/IFR possible SE. Otherwise, no sig wx.
Wed...Sct SHRA/TSRA with restrictions possible PM.
Wed night-Thurs...CFROPA with numerous SHRA/TSRA. Flight
restrictions likely (70%). IFR possible (30%).
Friday...AM fog poss, isold-sct PM SHRA/TSRA.
-- End Changed Discussion --

&&

.CLIMATE...
Prelim May and Spring 2024 Temperature & Precipitation Rankings

Harrisburg: T12th warmest; 76th driest May
 T3rd warmest; 33rd wettest Spring

Williamsport: 9th warmest; 22nd wettest May
4th warmest; 11th wettest Spring

Altoona: 9th warmest; 13th wettest May
2nd warmest; 3rd wettest Spring

Bradford: 4th warmest; 36th driest May
Warmest; 21st wettest Spring

&&

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

&&

$$

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