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fxus61 kpbz 221653 aaa 
afdpbz 


Area forecast discussion...updated 
National Weather Service Pittsburgh PA 
1153 am EST Sat Nov 22 2008 


Synopsis... 
snow showers mainly north of Pittsburgh will continue to diminish 
through the afternoon as high pressure builds for a dry Sunday. 
Low pressure and precipitation will again affect the area for the 
first half of the work week. 


&& 


Near term /through tonight/... 


Have continued the lake effect advisory for the afternoon but 
event is clearly on the wane as high pressure is building from the 
west and pushing the baroclinic zone eastward. 


That high will keep the rest of the area dry tonight...although 
crossing shortwave will Mar opportunity for a clear sky over the 
upper Ohio Valley. Still a cold night though...especially over the 
snow covered areas...forecast of which will remain below guidance numbers. 


&& 


Short term /Sunday through Sunday night/... 


Dry weather may be expected with high pressure crossing the 
region. Wind will become S/SW with the eastward progress of the 
system. Tightening gradient with the advance of Midwest low 
pressure will result in warm advection and general improvement 
although more significant snow cover will be a limiting factor. 




Long term /Monday through Friday/... 


Models coming into general agreement for a rather stormy week. 
A frontal system will approach the area Monday...crossing the 
area Monday night. Precipitation will begin across eastern Ohio 
Monday morning...spreading east Monday afternoon. Given decent model 
agreement and run to run continuity...will increase probability of precipitation Monday 
afternoon/night to likely/categorical for all areas. Thermal profiles 
suggest initial precipitation across eastern Ohio Monday morning will 
likely be snow but then quickly change over to rain...with all 
liquid for SW PA/points south and east Monday. North of I-80...precipitation 
could mix at times with snow. Colder air will work back in behind 
the front Monday night...changing precipitation back to snow. For Tue/Wed... 
both GFS/European model (ecmwf) show the upper low stalling just to the NE...with 
significant moisture in northwest flow remaining over the area. Position 
of the low will be critical for snow potential...but for now will 
increase the north and ridges to likely Tue/Wed...with chance probability of precipitation 
further southwest. Precipitation will begin to diminish Thanksgiving day 
as the low is prognosticated to move into New England...with dry conditions 
for Friday. 


&& 


Aviation /18z Saturday through Thursday/... 
high pressure will build in from the southwest and end lake 
effect snow showers near the northern terminals by this evening. 
Otherwise, the high will provide for VFR conditions through 
Sunday night. A low pressure system will develop and move east 
toward the region on Monday. This system has the potential to 
develop into a winter storm over the East Coast by middle week. 
Therefore precipitation...and reduced conditions will be possible 
anytime Monday afternoon through Wednesday. 


&& 


Pbz watches/warnings/advisories... 
Maryland...none. 
Ohio...none. 
PA...lake effect Snow Advisory until 6 PM EST this afternoon for 
paz007>009. 
WV...none. 


&& 


$$ 


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