800
FXUS61 KCTP 281834
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
234 PM EDT Tue May 28 2024

.SYNOPSIS...
A mid and upper level trough and associated cold air aloft will
bring us scattered to numerous afternoon and early evening
showers today and Wednesday, with a few isolated thunderstorms
possible.

Late this week it will turn mainly dry to close out the month of
May with above average temperatures returning into the first
week of June.

&&

.NEAR TERM /THROUGH TONIGHT/...
Lead shortwave aloft and sfc trough embedded within broad
cyclonic flow over the Northeast U.S. will combine with strong
diurnal heating to expand the current area of numerous showers
drifting SE from the Northern Mtns this midday hour.

Max POPs through the mid-late afternoon hours are over the NW
half of the CWA and trend lower (to virtually nothing) over the
the Lower Susquehanna Valley through 21-22Z.

However, by 22-23Z, the primary belt of showers will sink south
of Interstate 80 and focused about 30NM north and south of a
like from KAOO to KSEG and KAVP.

Otherwise, look for a mix of clouds and sun today with a
westerly breeze gusting between 25-30 mph. Highs will range
from 65-80F from northwest to southeast.

Showers will gradually diminish through the evening with mainly
dry conditions expected tonight. Focus will shift to more
potent upstream disturbance rotating into the Upper Ohio Valley
by 12Z Wed. Min temps will be in the low to mid 50s or near to
slightly above (+5F) late May climo.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
Short-range model consensus continues to signal the greatest
coverage of showers and t-storms will be Wednesday afternoon
into the the evening in association with a stronger shortwave
and possibly a meso-b scale weak sfc low rotating along the
PA/MD line.

These features will combine with steeper lapse rates/more
instability (thanks to abnormally cool 700mb temps with MU CAPE
values in the 600-900 J/KG range) to promote numerous
showers/t-storms especially over Central and Southern PA in the
afternoon and early evening.

The diurnally enhanced convection will fade/shift to the east
Wednesday night. Final shortwave digs southeastward from the
lower Great Lakes with 500mb heights bottoming out on Thursday.

Should skies clear out sufficiently and the wind become light
and variable late Wed night/early Thu morning, there`s a chance
for patchy light frost in the coldest high valleys near and to
the east of KBFD.

A couple of showers are possible Thursday afternoon beneath the
upper trough axis, but lower pwat air being directed into the
region via NNW low level flow should keep most places dry.
Seasonably strong high pressure dome migrates eastward Thursday
night into early Friday morning which will support the drying
trend through late week or the end of May. Temperatures will be
seasonably cool for this time of year with the largest
departures from climo (-5 to 10F) Thursday-Thursday night. Min
temps could dip into the upper 30s in the NW mtns.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Medium range models remain in good agreement for an extended
stretch of dry weather extending from Thursday through Sunday
morning. Temperatures under a large dome of Canadian high
pressure will start out below normal, with quite pleasant
conditions and low humidity on Thursday and Friday, before
temperatures moderate and humidity creeps up on Saturday and
Sunday. By Sunday afternoon, high pressure will slide off to the
east and an approaching upper disturbance and frontal system at
the sfc should combine with increasing moisture to increase
POPs on Sunday and Sunday evening, and then points east from
Monday through the middle of next week as additional
disturbances propagate through the WNW upper flow.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Outside of NW PA, widespread VFR conds are expected to prevail
for most of the time and across much of the region (Central Mtns and
the Susq Region) through the late afternoon hours.

Across NW PA, CIGS will reside mainly in the MVFR range but will
likely dip into the IFR range after 03Z Wed and even approach
IFR/LIFR thresholds after 07Z Wednesday.

Breezy Westerly to West-Northwest winds (10-15KT with gusts
upwards 25KT) are expected throughout the daylight hours
areawide and are expected to become lighter after sunset.

Scattered-numerous showers are expected to expand to the south
across PA this afternoon with highest confidence in SHRA at
airfields across NW PA through 20Z, then across the Central PA
airfields later this afternoon and early this evening.

Isolated low-topped TSRA are possible this afternoon and
evening, but confidence remains too low (< 20%) to include
mentions at any of the terminals as of 12Z Tuesday. There is
also less confidence at MDT/LNS on how close rainfall makes it
to the terminals, so have opted to keep mentions out of the 12Z
TAF package.

Restrictions look increasingly likely tomorrow night with
higher confidence where rain falls today and wind become light
overnight. At this time, have trended cigs downwards at BFD/JST
with recent guidance suggesting LIFR conds. Have opted to keep
IFR mentions out of AOO/IPT/UNV due to lower confidence at this
time, but trended down towards MVFR where lower cigs are
possible.

Outlook...

Wed...Brief restrictions are possible in scattered-numerous
showers/isolated TSRA, but much of the time should be VFR.

Thu-Sat...Predominantly VFR.

&&

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

&&

$$

SYNOPSIS...Lambert
NEAR TERM...Lambert
SHORT TERM...Lambert
LONG TERM...DeVoir/Steinbugl/Martin
AVIATION...Lambert/NPB