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fxus61 kpbz 230734 
afdpbz 


Area forecast discussion 
National Weather Service Pittsburgh PA 
234 am EST Monday Nov 23 2009 


Synopsis... 
low pressure moving along the middle Atlantic coast will bring 
scattered light rain today and tonight. A stronger low pressure 
system moving across the Great Lakes Wednesday and Thanksgiving 
day will bring colder temperatures and rain and snow showers into 
the weekend. 


&& 


Near term /through tonight/... 
area of scattered light rain edging north across West Virginia 
will move north and spread across region later today and continue 
into tonight. Higher probability of precipitation will be along the southeast ridges as 
upper level system and surface low pressure moves off the Atlantic 
coast. Temperatures to average above normal. 


&& 


Short term /Tuesday through Thursday/... 
residual low level moisture will keep slight chance probability of precipitation in the 
ridges early Tuesday otherwise a dry period until later Tuesday 
night when moisture ahead of digging upper low in the western 
lakes heads into region. Chance probability of precipitation Wednesday and Thursday ahead 
of closed low. Still above normal Wednesday for temperatures then 
colder Thursday. 




&& 


Long term /Thursday night through Sunday/... 
little change in the extended forecast compared to yesterday. Upper 
level low will slowly move from the central Great Lakes New 
England Sunday. Expected showers to persist through much of this 
time period. Temperatures will drop to near or slightly below 
freezing Thursday and Friday nights...but with these being the 
first two nights in some time with below freezing 
temperatures...at this point do not think there would be any 
accumulating snow. 


Models have surface low pressure developing off the New England 
coast Friday night...but this system should be too far to the east 
to affect local weather. As the upper low moves to the east Friday 
night...northwest flow should allow for the development of some 
lake effect showers into Saturday. Conditions should dry out 
Saturday night as high pressure moves in from the southwest. 
Temperatures will be below normal through this time period. 


&& 


Aviation /07z Monday through Friday/... 
surface low pressure will move along the East Coast and maintain low 
level east flow cross the region. Expect stratocumulus to persist 
from the ridges into central PA with MVFR ceilings at kduj and klbe 
at least through the morning. 


West of the ridges...broken cirrus will lower to middle deck by late 
morning and then to MVFR ceilings beginning late afternoon. 


Scattered showers and fog may also cause some MVFR restrictions this 
afternoon into tonight. 


A low pressure system will develop over the Missouri Valley on 
Tuesday...strengthening as it moves into the Great Lakes by 
Wednesday. This system and its associated cold front will return the 
chance for reduced ceilings across the area for the rest of the week. 


&& 


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


&& 


$$