842 
fxus61 kctp 070529 
afdctp 


Area forecast discussion 
National Weather Service State College PA 
129 am EDT Tuesday Oct 7 2008 


Synopsis... 
strong Canadian surface high will ridge south into Pennsylvania 
overnight bringing clear skies and widespread cold temperatures in 
the 20s and 30s. Many areas will experience their first frost or 
freeze of the season. The high pressure will hold fair weather 
into Wednesday. Unsettled conditions will return for the second 
half of the week as the high drifts offshore and Gulf moisture is 
pulled northward. 


&& 


Near term /until 10 am this morning/... 
a strong surface high (1034mb or +2-3 Standard deviations from normal) 
will drift southeast from Ontario overnight. The clear skies and 
light wind will combine with below normal precipitable water air of to bring 
perhaps the coldest night of the fall season thus far. Temperatures look 
on track to reach the middle to upper 20s across the northern mountains...and 
lower to middle 30s across much of the remainder of central Penn. 


Large air water temperature will also result in areas of 1/2sm fog in the 
valleys containing lager streams and rivers for a few hours on 
either side of daybreak. 


Frost advisories cover all of the central and south...while freeze 
warnings are in effect for most of the northern mountains...except the 
4 counties (mckean...Potter...Cameron and elk) that had a killing 
freeze early Saturday. 


&& 


Short term /10 am this morning through 6 PM Wednesday/... 
after the early morning frost and areas of valley fog...Tuesday 
looks like a very sunny day that will allow greater than 30f 
rebound from morning lows to the afternoon maxes. Maxes will be 
close to today/S nums...and maybe even a bit milder. 


&& 


Long term /Wednesday night through Monday/... 
high pressure will start the period...but some showers may 
encroach upon the western zones by late Wednesday or Wednesday night as the 
high drifts offshore and Gulf moisture is pulled northward. Both 
GFS and European model (ecmwf) push weak trough through Wednesday night into Thursday with 
chance for showers. 


Then surface high builds in for late week. Upper level features 
differ quite a bit between GFS and European model (ecmwf) in later periods. GFS 
develops upper low over the southeast states and slides it up the coast 
along with increasing moisture through the weekend. European model (ecmwf) also 
shows upper low over the southeast...but it gets thwarted by high 
pressure ridge building over the region this weekend. Tough 
forecast for the weekend...but leaned more toward the drier European model (ecmwf) 
solution and mentioned only low chances for precipitation mainly in the 
southeast this weekend. 


&& 


Aviation /06z Tuesday through Saturday/... 
near cloudless skies and dominant VFR conds through sunrise for most 
airfields. Kipt/kmdt could see IFR/LIFR visibility fog between 
10-13z...then quickly become mixed and return to VFR under high 
pressure. 


Some high clouds could float east from the Ohio River valley this 
afternoon. High pressure slowly slides southeast midweek providing 
decent radiational cooling at night and River Valley fog 
development west/reduced visibilities to MVFR/IFR conds after 06z Wednesday. 
Otherwise VFR conds and mainly clear skies expected through Wednesday. 


Early Thursday/Friday a frontal boundary approaches from the southwest and 
could bring low level moisture and a chance for rain showers and reduced 
cigs/vsbys. 


&& 


Ctp watches/warnings/advisories... 
freeze warning until 8 am EDT this morning for paz004-012-017- 
018-037-041-042. 
Frost advisory until 8 am EDT this morning for paz019-024>028- 
033>036-045-046-049>053-056>059-063>066. 


&& 


$$ 
Synopsis...dangelo/Lambert 
near term...devoir/Lambert 
short term...devoir/Lambert 
long term...rxr 
aviation...beachler