223 
fxus61 kpbz 081800 
afdpbz 


Area forecast discussion 
National Weather Service Pittsburgh PA 
200 PM EDT Friday Aug 8 2008 


Synopsis... 
a persistent upper level low pressure system over eastern Canada will 
continue to provide US with cooler than normal weather and 
occasionally the chance of showers or a thunderstorm into next 
week. 


&& 


Near term /through tonight/... 
next in the series of shortwaves crossing the Great Lakes toward 
the axis of eastern Continental U.S. Trough will support more showers and 
storms though early tonight. Better chance for zones north and 
east of pit. Small hail again may be expected under cool middle level 
temperatures. Near term surface temperatures will remain below 
normal. 
&& 


Short term /Saturday through Saturday night/... 
overall pattern expected to persist into the weekend, although 
shortwave ridge in advance of stronger disturbance looks to 
provide a decent Saturday with only slight probability of precipitation for zones north of 
pit. Current timing advances that disturbance southward on 
Saturday night and Sunday with resultant escalation of probability of precipitation. Cool 
temperatures to continue through the short term. 


&& 


Long term /Sunday through Friday/... 
persistent upper level 500 mb low couplet will contiue to pivot around 
each otehr over eastern Canada. This will continue the trend of 
cool weather and possible periodic bouts of showers and 
thunderstorms. Short waves will continue to rotate through. 
However, on Sunday actual secondary cutoff rotating through. 500 mb 
cut0ff system does shows signs of lifting by Friday as next 500 mb low 
pushes east from northern plains and sharpens 500 mb ridge. As a 
result of these upper features, a weak surface system pushes 
through (especially north portions) on Sunday and then another 
Wednesday into Wednesday night. 


&& 


Aviation /18z Friday through Wednesday/... 
expect broken cloud deck as wave of upper level energy swings 
through. Area of showers or storm will weaken and dissipate by 
08z. This activity will provide lower ceilings and visible. 


Break in the activity will allow skies to clear for a time. 
Mostly MVFR visible expected with patchy fog...however river valleys 
will likely see visible dip into the IFR range. 


VFR conditions expected through Sat. 


Next occluded system will slowly move through southern Canada Sat 
night and into upstate New York by Sunday night. Surface front with system 
will push through Sat night and bring another chance for showers. 


Occluded system will keep weather unsettled into early next week. 


&& 


Pbz watches/warnings/advisories... 
Maryland...none. 
Ohio...none. 
PA...none. 
WV...none. 


&& 


$$