973 
fxus61 kctp 131543 
afdctp 


Area forecast discussion 
National Weather Service State College PA 
1143 am EDT Monday Oct 13 2008 


Synopsis... 
a large area of high pressure will cover the middle Atlantic region 
through much of Tuesday before drifting southeast and allowing a 
cold front to pass through the state Wednesday and Thursday. This 
front will be accompanied by a few showers...followed by 
cooler and somewhat drier weather for late in the week. 


&& 


Near term /until 7 PM this evening/... 
periods of thicker Alto cumulus and cirrus streaming southeast will briefly 
dim the sun this afternoon...but otherwise will have minimal 
effect on previous forecast (very warm) high temperatures. Maximums in the 75 to 
80f range in many locations will be some 13-16f above normal. 


The only "slight" change to temperatures was throughout the middle susq 
valley...where the late morning/early afternoon break of the 
stronger surface based inversion will keep temperatures up to several degree f 
cooler in the deeper valleys. 


&& 


Short term /7 PM this evening through 6 PM Tuesday/... 
for tonight...partly cloudy skies and light wind will be bring 
fairly similar conditions to what we had early this morning (though 
a few degree f milder with slightly less valley fog). Lows at 
daybreak Tuesday will be mainly 45-50f. 


&& 


Long term /Tuesday night through Sunday/... 
high level of confidence with upper level ridge center relaxing 
south across coastal Gulf of Mexico mid-week...this should allow a 
semi-zonal flow ahead of a developing wave inflection Wednesday/Thursday 
across Central Plains. As we transition from broad ridge middle-week a 
high latitude vorticity maximum slides across Ontario/Quebec. Upper level 
ridge will influence how quasi-stationary boundary lays out from vorticity 
maximum. At this time thinking is dry weather holds through Wednesday. Operational GFS 
paints a secondary vorticity developing upstream of quasi-stationary 
boundary...however placement and timing remains a challenge. 
Confidence is higher that precipitation will arrive across alleghenies 
early Thursday and linger as trough axis swings into middle-Atlantic 
region. 


Confidence has grown with respect to intensity/placement of trough 
late week into next weekend...850mb temperatures cool to -2 to -4 degree c 
Sat/sun. Placement of surface ridge from operational GFS would suggest 
a cool NE flow sliding SW across New England into the Middle-Atlantic 
States. 


Overall temperatures appear to start out near seasonal and cool to a few 
degrees below seasonal next weekend. 


&& 


Aviation /16z Monday through Friday/... 
VFR conditions will prevail this afternoon. High clouds spilling 
down from the north will be the most notable change from the last 
24 hours. 


Another round of valley fog and poor visibilities will form in the same 
locations for early Tuesday morning. Wednesday may hold some rain showers...but 
generally VFR cigs/vsbys. 


VFR returns for Thursday and Friday as a large area of high 
pressure builds in from the Midwest. 


&& 


Fire weather... 
dry...warm weather may support increased wildfire activity today. 
The persistent dry weather and above normal temperatures will cause 
relative humidities to fall into the 30 percent range this afternoon 
and 10 hour fuel moisture values are in the 7-8% range statewide. 


However...winds will be light under high pressure. That said...no 
fw watches nor rfw warnings are anticipated as weather criteria 
will not meet critical values. Low level moisture will be on the 
increase Tuesday into Wednesday as a cold front approaches the region and 
help keep afternoon relative humidities higher than today. 


&& 


Ctp watches/warnings/advisories... 
none. 


&& 


$$ 
Synopsis...Lambert 
near term...Lambert 
short term...Lambert 
long term...beachler 
aviation...jung 
fire weather...gartner