752 
fxus61 kpbz 211132 
afdpbz 


Area forecast discussion 
National Weather Service Pittsburgh PA 
632 am EST Sat Nov 21 2009 


Synopsis... 
high pressure will provide a dry weekend. A low pressure system 
moving into the Middle Atlantic States will bring a chance of showers 
Monday night and Tuesday. 


&& 


Near term /through tonight/... 
stratocumulus cloud deck trapped under surface high hanging over 
the upper Ohio Valley looks to persist through much of today 
although some breaks will open at times. Previous forecast highs in 
the 50s look good. Clouds will remain early then then begin to 
break allowing for colder readings and drop min temperatures toward new 
mav guidance. 


&& 


Short term /Sunday through Tuesday/... 
surface high shifts northeast and should allow for some sunshine 
Sunday with mild temperatures. Low pressure system developing 
over the eastern Gulf of Mexico will move to the Virginia coast 
Monday. GFS and new European model (ecmwf) show moisture from system working north 
Sunday night into Monday with a chance for showers as well. 
Temperatures will remain above normal. Tuesday will be in between 
systems with low level moisture slow to clear and skies should 
remain cloudy with above normal temperatures continuing. 


&& 


Long term /Tuesday night through Friday/... 
upper trough begins to dominate this period which will lead to 
much cooler temperatures. 


With model differences in timing...will keep probability of precipitation chance from 
Wednesday into Friday models also coming into line for a bit of a 
colder solution for Thursday and Friday as closed upper low moves 
across the Ohio Valley. Since time range is so far out did not 
lower temperatures dramatically from previous forecast. Snow 
showers mixing now looks to be more definite at night and may 
need to add snow to Thanksgiving day as well. 


&& 


Aviation /12z Saturday through Wednesday/... 
ceiling restrictions will be the primary flight concern today as 
low-level moisture continues to hold across the area. MVFR ceilings 
at kpit...kbvi...and khlg will lift to VFR with IFR-LIFR ceilings at 
kduj and kfkl lifting to MVFR by mid-morning. High pressure will 
continue to build in from the southwest with ceilings breaking at 
kmgw/kzzv this afternoon. Further northward...ceilings will prevail at 
3-4kft across the terminals with MVFR ceilings expected at kduj and 
kfkl this afternoon. 


VFR conditions will prevail Saturday night...except at kduj and 
kfkl where MVFR ceilings will finally erode by Sunday morning. A low 
pressure system moving up the East Coast Sunday night will bring 
the next chance for showers with reduced ceilings 
expected...especially southeast of a kmgw-klbe line. Reduced 
ceilings will be possible across the area on Tuesday as a cold 
front approaches the area from the west and continue into 
Wednesday with rain showers when the front crosses the terminals. 


&& 


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


&& 


$$