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Area Forecast Discussion (AFD)

Issued by State College, PA (CTP)

FXUS61 KCTP 172327

Area Forecast Discussion
National Weather Service State College PA
727 PM EDT Tue Sep 17 2019

An extended period of dry, pleasant, and mostly sunny weather is 
expected to last through the rest of the week. The prolonged dry
spell will feature patchy valley fog in the morning, followed by
comfortable afternoons and cool nights with light winds and low 
humidity. Temperatures are forecast to rise above average this 
weekend with an increasing chance for rain by early next week.


Today will begin a multi-day stretch of mostly sunny, dry and 
pleasant weather in central PA. Started with NBM guidance and
continued to lower dewpoints in the afternoon based on pattern 
recognition and forecast soundings. Cool and comfortable tonight
with lows in the mid 40s to low 50s and fog developing in the 


Patchy fog should again greet central PA tomorrow morning. Once
this lifts it will be a fair weather day. The dry weather 
pattern continues through midweek with high pressure remaining 
firmly in control to the west of Humberto. High temperatures 
should fade a few degrees Wed-Thu as low level flow turns more 
to the east. Min temps should also tick lower and may touch the 
upper 30s in the usually colder spots across the northern tier.
 The lower dewpoint trend will continue with Thursday being the
driest. The mid levels are very low and given the potential that
they mix down RH/s could be well below 30 percent. So expect for
dry air Wednesday and Thursday. The areas that will be worst
will be through the southern half of PA on Thursday.


A building upper level ridge with above normal heights will be
located across the Mississippi Valley and Eastern U.S. right 
through much of the upcoming weekend. Precipitable water values
will dip to below normal at only 10-15mm Thursday into Friday
(from PA south through the Carolinas), before slowly rebounding
back to right around normal in the range of 20 to 25 mm. 

Max temps Thursday will be similar, if not a deg F or two cooler
than Wednesday's, before gradually increasing on Friday and
peaking between 10-15 deg F above normal Sunday into Monday.
Although the temps will be well above normal, record values
don't appear to be threatened at this point. 

POPs increase Sunday night and Monday as a cold frontal boundary
slides SE across the state. For now will keep pops in the high
chc category. PWAT anomalies will be dissolving with this fropa,
so only light rainfall amounts are expected.


Building high pressure will provide VFR conditions through the
remainder of this evening into the early overnight hours. 
Patchy fog and low clouds are expected to develop after 
midnight, especially in the valleys, which could cause vsby/cig
reductions at several central PA TAF sites.

Fog and low cloudiness will burn off Wednesday morning, leaving
VFR conds with a light east-northeasterly breeze of 5-10 knots 

Expect more of the same through the remainder of the week, with
VFR conditions dominating. Brief reductions are possible during
the late-night/morning hours in patchy fog or low clouds.


Wed-Sun...AM valley fog/low clouds possible, otherwise 
generally VFR.




NEAR TERM...Ceru/Steinbugl
SHORT TERM...Ceru/Steinbugl
LONG TERM...Lambert/Steinbugl