Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 230935
AFDCTP

Area Forecast Discussion
National Weather Service State College PA
535 AM EDT Tue May 23 2017

.SYNOPSIS...
Rain should pass to the southeast of the area later today and
tonight. The most likely period for rain in Central PA will be
Wednesday night into Thursday. The weather pattern will be
unsettled into the holiday weekend with a few opportunities for
rain through Memorial Day. Seasonal temperatures will trend
a bit cooler with rain expected late-week, with a modest
rebound likely into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Despite a steady stream of high clouds, the visibility has
continued to trend lower across parts of the mid-lower
Susquehanna Valley with some sites 1/4sm. Will continue to
monitor vis trends for possible SPS with impact to the AM
commute. Fog should dissipate shortly after daybreak.

HIRES model blend keeps the area rain-free through 00z with a
consensus "best" chance (15-30%) occurring later this evening
across the far southern and southeastern parts of the CWA or
mainly to the south of the PA Turnpike. Odds favor the near
term period staying dry under thickening high to mid level
clouds in advance of deep trough/closed low dropping south from
MN to MO by 24/12z.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
The deep closed low evolves slowly east from the Mid MS Valley
across the Central Appalachians Wed-Thu with complex surface
low occlusion over the OH Valley and secondary development from
the Mid Atlantic Piedmont to the New England coast by 26/12z.
Despite differences in QPF, the models generally agree with
the most likely period of rain from Wed ngt-Thu. Total rain
amounts for the 24hr period ending 00z Fri are 0.50-1" and
derived from a multi-model/WPC blend. Rain should turn more
showery Thu ngt into Friday under cyclonic flow aloft. Temps
trend cooler with expected clouds and rain.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
By Friday, the low lifts to our NE as trough axis lifts
through. Though the day should bring gradual improvement in the
weather, highs Fri could end up several degrees below current
guidance in CAA NW flow, a thicker low-level cloud deck and
potential for light showers/drizzle - esp NW half of CWA.

Sat should bring a return of brighter skies, albeit briefly,
and may end up being the nicest day of the long weekend as weak
ridge propagates through. Clouds will already be on the
increase Sat afternoon and persist into Sun and Mon as a warm
front develops over the Ohio Valley (with low pressure gradually
organizing over the Midwest). Proximity of this frontal
boundary along with deepening trough over the western Great
Lakes will bring potential for showers Sun and Mon. Plenty of
uncertainty in strength/placement of main weather features
across model guidance during this time however, so forecast
details remain somewhat elusive for late weekend.

&&

.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
Fog starting to thin out.

09Z TAFS adjusted for this and sent.

Any fog across eastern PA will burn off just after sunrise.
Most of the day will feature just some high clouds. Perhaps some
light rain late, but mainly south of the TAF sites, based on
the airmass in place and guidance keeping most of the area dry.

Wed morning may feature more fog and low clouds, given that
fcst lows are at or below fcst dewpoints, cross over
temperatures. Still time to look this over, as it would be
mainly after 06Z. Another factor will be that the high clouds
could cut down on the cooling late Tuesday and early Wed.

.OUTLOOK...

Wed...Evening rain/low cigs possible, esp JST/AOO.

Thu...Rain/low cigs likely.

Fri...Showers/MVFR cigs NW. VFR SE.

Sat...No sig wx expected.

&&

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

&&

$$
SYNOPSIS...Steinbugl
NEAR TERM...Steinbugl
SHORT TERM...Steinbugl
LONG TERM...Lambert/RXR
AVIATION...Fitzgerald/Martin



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