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afdpbz 


Area forecast discussion...updated 
National Weather Service Pittsburgh PA 
847 PM EST Tuesday Dec 2 2008 


Synopsis... 
high pressure will bring dry and mild conditions Wednesday. A 
cold front will bring rain Wednesday night and colder air and snow 
showers Thursday. Much colder air for the weekend. 


&& 


Near term /through Wednesday/... 
minor adjustments to overnight cloud cover. Current Sat pics show 
back edge of the cloud cover lining up nicely with the -6 or -7 
850 mb isotherm. Have used this to time cloud cover. Models 
indicating warm air advection begins to kick in around 06z. With cloud cover 
decaying a bit faster than expected have lowered overnight lows. 
For Wednesday...with southerly flow increasing...limited cloud 
cover...and a milder atmospheric column...temperatures will warm 
nicely on Thursday...with lower 50s possible across far southwest 
PA/northern WV. Further north and along the ridges...snow cover 
will limit the warming...with some of the higher ridges across 
Garrett County remaining around 40 Wednesday afternoon. 


&& 


Short term /Wednesday night through Friday/... 
a cold front will approach from the west Wednesday evening...entering 
eastern Ohio after midnight...and across western PA/points east 
Thursday morning. Precipitation will begin as rain for most areas by late 
Wednesday night...changing over to snow across eastern Ohio after 
sunrise Thursday...and by afternoon for PA/WV/MD. Precipitation amounts 
will be generally light...with one quarter inch or so of water 
equivalent for most areas. Temperatures Thursday will rise little 
in PA/points east...and will have a slow fall across eastern Ohio. 
By Thursday night...flow will become W/NW...with lake enhanced 
snows developing. Will keep accumulations under advisory levels 
Thursday night/Friday for now...but ridges and areas north of 
I-80 could see some significant accumulation. 


&& 


Long term /Friday night through Tuesday/... 
a low pressure system will push eastward across the Great Lakes 
Saturday and off the New England coast by late Sunday. This system 
will bring a chance of snow showers Saturday and Sunday. Temperatures 
will be below normal over the weekend. 


Surface high pressure is expected to bring dry weather Monday with 
the next system bringing rain showers Monday night and Tuesday. 
Temperatures should recover to near normal Tuesday. 


&& 


Aviation /02z Wednesday through Sunday/... 
broken stratocu near MVFR but mainly VFR will erode west to east 
this evening as surface ridge builds in and lower levels dry out. 
Expect VFR conditions through Wednesday afternoon as ridge slides 
east to the Atlantic coast. 


Next system will approach the upper Ohio Valley Wednesday night 
with a cold front pushing across the forecast area Thursday morning. 
MVFR/IFR restrictions are likely with rain and snow showers late 
Wednesday night and Thursday. 


Cold westerly flow behind system will support scattered snow showers 
mainly across the northern terminals and along the ridges late 
Thursday and Friday. Flight restrictions can be expected in snow 
showers. 


The next low pressure system will bring a chance for more snow 
showers and possible restrictions Saturday afternoon into Sunday. 


&& 


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


&& 


$$