456
FXUS61 KCTP 140536
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
136 AM EDT Tue May 14 2024

.SYNOPSIS...
A warm front will lift north of the Commonwealth by tonight,
with mainly fair weather expected into Wednesday. A cold front
may touch of a few afternoon showers 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 /THROUGH TODAY/...
Warm front is making the jump northward early this afternoon,
with stratus and light showers lifting north of the PA/NY border
and Endless Mountain region and a good deal of sunshine north of
I-80. Areas south of I-80 have been mostly sunny since morning
fog burned off, and will continue that way through this evening.
An examination of latest guidance indicates quite a bit of mixed
layer Yin in the wake of this morning`s warm frontal showers
over N Central PA. MLCAPEs do recover sufficiently for perhaps
an isolated shower or storm, especially along and north of Rt 6,
but coverage appears less than earlier anticipated and have
shaved POPs for the remainder of the daylight hours after the
current showers over Sullivan County exit shortly.

For the overnight, shortwave ridging along and sfc high
pressure moving off of the east coast and a resulting southerly
breeze will result in much milder conds than last night. Lows
will range through the 50s. A weakening shortwave lifting out
of the Ohio Valley could support a late night shower over
primarily the southwest part of the forecast area.

745 pm update... Earlier isolated showers over the far northern
tier of the Commonwealth have weakened and moved up into NY
State.

Otherwise, a broken mid-level cloud deck from the Ohio
Valley (owing to warm and moist advection aloft) is tracking
into southwestern PA. This cloud mass will gradually thicken
across central PA overnight. There is an outside chance that
some light showers (resulting from weak short-wave ripples
lifting northeast out of the TN and OH Valleys) could sneak into
the Laurels towards daybreak. This scenario seems well handled
by the low chances (20-30%) for showers in the gridded forecast after
about 5 am in this area.

As mentioned in the earlier discussion, tonight will be milder
than recent nights, with lows by daybreak only falling into the
50s area-wide.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
After a much needed but too short reprieve, we`ll see increasing
chances for showers and possible afternoon 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.

Guidance continues to track surface low linked to the
approaching shortwave south of PA Tuesday night into Wednesday,
resulting in another period of rain. 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.

Thursday still has the possibility of being dry for most
locations. Some guidance is depicting somewhat of a ring of fire
feature across western and northern areas with isold diurnal
shra or tsra possible, but for most areas the shortwave ridging
should 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.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
On the large-scale, a fairly zonal upper-level flow pattern is
expected across the CONUS from late this week into the early
portion of next week. Within this zonal flow, an energetic
northern stream will keep frequent short-waves and surface
frontal passages traversing the northern tier of states,
including PA.

Although the above described pattern is not likely to feature
any complete washouts or widespread heavy rainfall, not many
completely dry days are foreseen either, with at least hit and
miss showers likely to prevail.

The most widespread shower activity could occur on Saturday,
with a surface wave anticipated to track south of the
Commonwealth, and a relatively cool E-SE flow pattern in place
in the lower levels. Outside of that, as alluded to above,
showers should be mostly scattered in nature and diurnally
centered on the afternoon and evening hours.

Temperatures should average close to seasonal normals for mid-
May, with mostly upper 60s-70s foreseen by day. The one
exception is Saturday, when upper 50s and 60s are most
probable. Given lots of clouds and shower activity, any
frost/freeze conditions appear highly unlikely, with night-time
lows mostly in the 50s.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
VFR conditions persist overnight and into the day today as high
pressure slowly gives way to increasing moisture and cloudiness
ahead of our next weather system. There is an outside chance
(<10%) at some fog development in the eastern part of the
Commonwealth toward daybreak, but have opted not to mention it
at IPT and MDT given the low probability of occurrence. It is
also worth noting there will be some ~30kt winds at ~2kft this
evening for a few hours, which will remain below LLWS criteria.

By daybreak Tuesday, expect thicker clouds to begin advecting
into the region with gradual lowering throughout the day. MVFR
ceilings will move in from southwest to northeast during the
afternoon as occasional showers and a few thunderstorms drift
across the region. Cloud heights will generally continue to
lower through the afternoon and into the evening with most sites
likely to see IFR cigs after 0Z Wednesday. Not enough
confidence in coverage/timing to include any mention of thunder,
but would not be surprised to see some impacts Tuesday
afternoon and evening.

Outlook...

Tue Night...Showers continue with IFR restrictions likely.

Wed...Restrictions in showers/t-storms and low ceilings.

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

Fri...Deteriorating conditions with showers increasing.

Sat...Showers continuing with reductions.

&&

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

&&

$$

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