941 
fxus61 kpbz 231738 
afdpbz 


Area forecast discussion 
National Weather Service Pittsburgh PA 
138 PM EDT Wednesday Jul 23 2008 


Synopsis... 
low pressure will exit the region tonight...with showers and 
thunderstorms ending. High pressure will build into the region 
Thursday...bringing dry and seasonably cool conditions. The next 
frontal system will impact the area over the weekend. 


&& 


Near term /through Thursday/... 
the surface cold front has moved east of The Pit metropolitan 
area...entering the ridges and northern West Virginia. A solid 
line of showers/thunderstorms has developed along the frontal boundary...with 
localized heavy rainfall/flooding this afternoon. The front will 
exit the ridges of western PA in the next 1-3 hours...and across the 
ridges of West Virginia/western Maryland early this evening. 
Further north...the parent upper low will cross the eastern Great 
Lakes tonight...with some potential for showers as a wave rotates 
around the low...clipping northwest PA. Precipitation will end after midnight for 
most areas...with patchy fog developing late overnight. High pressure 
will build across the region Thursday...with residual clouds 
decreasing and temperatures some 3 to 5 degrees below average. 


&& 


Short term /Thursday night through Saturday/... 
a mostly clear and pleasantly cool night in store Thursday night 
under the core of the high. Friday looks mainly dry and seasonable. 
NAM/GFS differ on handling the next frontal system...with the NAM 
depicting a split in the middle level flow...with little precipitation 
through Saturday...and the GFS depicting the frontal boundary 
crossing by Saturday afternoon. Given the better run to run continuity 
of the GFS...will keep chance probability of precipitation for Saturday. 


&& 


Long term /Saturday night through Wednesday/... 
medium range models continue to be in decent agreement bringing 
the next frontal boundary across the region Saturday night...with 
perhaps a secondary cold front for Sunday. Will keep chance probability of precipitation 
for Sat night/sun. Some differences for early next week...with the 
GFS showing yet another wave crossing the area...and the European model (ecmwf) 
showing the feature departing to the south. Drying conds for 
Monday and continuing into Wednesday. Near normal temperatures for 
the long term. 


&& 


Aviation /18z Wednesday through Monday/... 
convection associated with cold front continues to slowly move east 
through our extreme eastern counties. MVFR conds/isolated IFR conds in 
thunderstorms and rain showers with frontal passage. Wind gusts 30-40 kts possible in 
and near thunderstorms. 


Otherwise...Post cold frontal passage...scattered showers through this evening 
as upper short wave approaches and moves through. Therefore...mainly 
VFR conds overnight with isolated MVFR in rain showers through this 
evening. From 08z to 14z scattered MVFR visibilities in br. Surface winds northwest 5-10 kts 
through tonight. 


Generally VFR Thursday and Friday under dominant high pressure. 
Early Saturday morning and on into Sunday lower conds in thunderstorms and rain br as 
next cold front approaches and passes. High pressure builds in for 
Monday. 


&& 


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


&& 


$$