777
FXUS61 KCTP 131114
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
714 AM EDT Mon May 13 2024

.SYNOPSIS...
A warm front will brush northern PA on Monday before a cold
front pushes through on Tuesday. A wave of low pressure
tracking south of the Commonwealth will continue showery
conditions on Wednesday with drier conditions expected
Thursday and Friday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Visible satellite imagery early this morning shows a dendritic
pattern of valley fog across much of Central PA. Further east,
pooling of low level moisture along and east of a weak surface
trough in the Susq Valley has resulted in stratus over the
eastern counties with ridgetop fog noted over the higher
elevations of Schuylkill county. Model guidance and indicates
the fog and low clouds will mix out between 13Z-15Z.

Upper level ridging building over PA should result in a warmer
and drier Monday overall. However, a weak area of low pressure
and its attendant warm front lifting through the Eastern Grt Lks
could produce a few morning showers or afternoon tsra across
the northern half of PA. Partly to mostly sunny skies and a developing
southwest flow should push readings well into the 70s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
High pressure passing off of the east coast and the resulting
southerly breeze should result in a significantly milder Monday
night, with lows in the 50s. Generally fair weather should hold
tonight with upper level ridging over the state. However, a
weakening shortwave lifting out of the Ohio Valley could support
a late night shower over primarily the southwest part of the
forecast area.

Expect an increasing chance of showers and possible tsra Tuesday
associated with an approaching southern stream shortwave lifting
northeast from the Southern Miss Valley. Model RH profiles
support mainly overcast skies, which should act to limit heating
and the chance of tsra. However, surging low level moisture,
combined with modest diurnal heating, should support fairly
widespread showers and isolated tsra by late afternoon based on
the 00Z HREF.

All guidance tracks the surface low linked to the approaching
shortwave south of PA Tuesday night into Wednesday, resulting in
another period of rain. Latest ensemble plumes suggest around a
half inch of rain is likely in most spots by Wednesday evening.
Have tweaked temps downward slightly from NBM guidance Wednesday
due to the expected rain and easterly flow. Raw NAM/GFS surface
temps peak in the 60s over most of the region Wed. Expect rain
to end Wed evening, as the low exits the Mid Atlantic coast.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Late evening update holds no big changes to the long range fcst.
Thursday-ish still has the possibility of being dry for most
locations. The S may have isold diurnal convection - but
shortwave ridging will likely keep it dry. Left the 20-30 PoPs
in for Thurs given by the National Blend respecting the low
predictability of timing and strength of mesoscale features,
like the aforementioned small ridge aloft, at this range.

Prev...
Lingering unsettled weather is possible into Wednesday, as
upper-level low pressure passes overhead.

Medium range models diverge a bit late this week. The ECMWF
continues to show unsettled weather persisting into Thursday,
as the upper- level low pressure very slowly pulls to our east.
The GFS/GEFS is a bit more optimistic, showing an upper- level
ridge bringing a period of dry weather from Wednesday night
through early Friday.

Both medium range models are in agreement in bringing our next
weather maker into the area later Friday into Saturday with
another round of showers and thunderstorms. The result would be
another Saturday with rain, easterly winds, and below average
temperatures - a beloved tradition over the last couple months
in Central PA.

&&

.AVIATION /11Z MONDAY THROUGH FRIDAY/...
A few of the sites in the eastern airfields this morning are
experiencing low clouds from a southerly stream of moisture.
Elsewhere morning valley fog is beginning to lift. Winds should
remain light this morning before ridging continues to build in.

After fog lifts/mixes out, VFR conditions prevail for everyone
today. Winds could become somewhat gusty as high pressure
riding builds and becomes dominant; however, a few light
showers are possible for northern airfields later in the
afternoon (BFD, UNV, and IPT) from a weak upper level trough,
but no restrictions are expected at this time. Most places will
remain dry throughout the day. The next chance for rain and
visibility restrictions will be during the early morning hours
on Tuesday as the next disturbance makes its way to PA.

Outlook...

Tue...Showers/tstms and reductions developing.

Wed...Showery weather and reductions continue.

Thu...Slow improvement, with a few lingering showers possible.

Fri...Deteriorating conditions with showers increasing.

&&

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

&&

$$

SYNOPSIS...Dangelo
NEAR TERM...Fitzgerald
SHORT TERM...DeVoir/Fitzgerald
LONG TERM...Dangelo/Banghoff
AVIATION...Bowen