081 
fxus61 kctp 131148 
afdctp 


Area forecast discussion 
National Weather Service State College PA 
748 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 on Wednesday...bringing drier and cooler 
weather for later in the week. 


&& 


Near term /until noon today/... 
areas of valley fog will dissipate between 1330 and 1430z this 
morning. 


&& 


Short term /noon today through 6 PM Tuesday/... 
the center of high pressure (1030-1040 hpa) at the surface...currently 
centered over wern PA...will drift south-southwest. This will bring even 
warmer temperatures than yesterday. 


850 hpa temperatures will warm by another 2 degree c today...to around 
+16-17c (nearly +2 St deviations from normal). This will translate 
to maximum temperatures in the middle 70s across the mountains...to lower 80s in our 
southeast zones (which will be a whopping 15f above normal). 


Winds will be light southwest to west during the late morning and 
afternoon hours. 


For tonight...clear to partly cloudy skies and light wind will be 
bring fairly similar conditions to what we had Sunday night 
(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 /12z Monday through Friday/... 
generally clear skies and VFR conditions prevail this morning. 
Some areas of valley fog in the Susquehanna valley around 
seg/thv/ipt/MDT and also over Western Mountain counties at duj and 
figure. Fog will burn off in a few hours...by 14z...and VFR 
conditions will prevail. 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...lacorte/Lambert 
near term...lacorte/gartner 
short term...Lambert 
long term...beachler 
aviation...jung 
fire weather...