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015
FXUS61 KCTP 150544
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
144 AM EDT Wed May 15 2024

.SYNOPSIS...
-An upper low traversing the region will support scattered rain
 and a stray thunderstorm or two through Wednesday.
-High pressure builds on Thursday bringing drier and mild
 conditions along with the only sunshine of the week.
-Clouds and showers return later on Friday, preceding yet
 another wet and cool Saturday as the unsettled pattern persists.

&&

.NEAR TERM /THROUGH TODAY/...
Quick update to note the enhanced area of low to mid level FGEN
forcing and enhanced upper level divergence/diffluent flow
associated with the left exit region of a compact 60 kt jetlet
drifting north over the Susq Valley. KCCX indicated numerous
small areas of instantaneous rainfall rates of 0.3-0.4 in/hour
across the Lower/Mid Susq Mainstem with a few 0.5-0.6 in/hr
pixels.

This has led to a large deviation in placement and amounts of
QPF on the Meso-B scale across Central PA and the Susq Valley
with the HRW FV3 member of the HREF doing the best job, while
most other members were significantly out of position or
underestimating amounts (i.e. the HREF) by over 0.50"/6 hours
(00Z-06Z Wed).

Increase QPF amounts to between 0.75 and 1.0 in a fairly narrow
strip over the Susq River and points about 20-30 km either side
of a line from KSEG to KIPT. Conversely, trimmed amounts across
portions of the Central Mtns overnight.

Previous...

A surface low developing over N Carolina/Southern VA ahead of an
approaching shortwave/upper low will produce deepening easterly
flow overnight. The influx of moisture will help keep skies
mostly cloudy as cool but stable air generates periods of
light rain across the region. Lows tonight between 55 and 60
will be +5 to +15 compared to normal. Low clouds and rain along
with light winds will promote reduced visibility and some patchy
fog overnight, especially on ridgetops.

Little change to the pattern expected through Wednesday as
easterly flow, overcast skies, and scattered light rain
persist. An 850 mb low will drift over the Delmarva region as
the nose of an approx -2 sigma Southeasterly 925-850 mb jet
drifts N over the Mid Atlantic Piedmont region. A classic cold
air damming scenario support trending below guidance and keeping
high temperatures in the low to mid 60s. Have scaled back on
the likelihood and extent of thunder chances as well. Rain will
not produce any significant rainfall rates, but multiple rounds
of precipitation should produce an average of a half inch of
rain across the region through Wednesday evening.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY/...
Conditions will improve Wednesday night through Thursday as a
wedge of high pressure drifts south from Canada, though
improvement could be relatively slow. Areas of low clouds and
ridgetop fog are likely to persist through Thursday morning
before clearing skies build in later Thursday afternoon. With
upper troughing slowing moving east of the region and cold temps
aloft, can`t rule out some scattered showers in the afternoon.

Thursday afternoon could be the only time we see blue skies this
week. Sunshine will help temperatures get closer to
climatological averages ranging from the low to mid 70s.
By Thursday night, upper level ridging will shut off any
lingering shower activity while high clouds begin to stream in
ahead of the next weather maker. Another mild night with lows in
the 50s on Thursday precedes a dry start to Friday. By Friday
afternoon, southeasterly flow ahead of an approaching low
pressure system will bring a return of overcast skies and
showers to the region.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
The synoptic pattern Friday into Saturday looks fairly similar
to the pattern in place right now (Tuesday into Wednesday) with
a surface low passing to our south and an upper low drifting
overhead. Shower activity will increase Friday night and
continue into Saturday with persistent overcast conditions and
southeasterly flow. As a result, yet another cool, cloudy, and
rainy Saturday is expected. Highs will remain in the low 60s and
may even need to be trimmed further in a classic cold air
damming scenario. The only consolation for these dreary
stretches is that they have kept the threat for severe weather
at bay.

By the second half of the weekend, conditions may start to
improve with a trend toward drier and milder conditions. That
being said, these cold air damming set ups are consistently
stubborn and Sunday may end up being just about as cloudy, cool,
and damp as Saturday.

Heading into next week, zonal upper-level flow pattern is
expected across the CONUS. 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 this 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. 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. Given lots of
clouds and shower activity, any frost/freeze conditions appear
highly unlikely, with night-time lows mostly in the 50s.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
Low pressure will lift up the East Coast overnight, spreading
rain and low cigs across Central PA. At 06Z, IFR/low-end MVFR
cigs are noted across the region. A moistening southeasterly
flow should yield widespread IFR/LIFR cigs by daybreak.

Expect modest improvement in flying conds by Wed afternoon, as
low pressure pulls off of the Mid-Atlantic coast. A moist
easterly flow should help maintain the low clouds. However,
rain should taper off and a bit of diurnal heating/mixing should
result in a slight increase in cigs. Ensemble prob charts
continue to suggest that by Wed afternoon will be confined
mainly to the Laurel Highlands (KJST), with predominantly MVFR
conds elsewhere.

Outlook...

Thu...AM low cigs possible, mainly N/W.

Fri...AM low cigs/fog possible, especially Central Mtns. Evening
showers/storms possible west.

Sat...Rain/low cigs possible, esp Central Mtns.

Sun...Lingering low cigs possible.
-- End Changed Discussion --

&&

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

&&

$$

SYNOPSIS...Banghoff
NEAR TERM...Lambert/Banghoff
SHORT TERM...Banghoff
LONG TERM...Banghoff
AVIATION...Evanego