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afdcle 


Area forecast discussion 
National Weather Service Cleveland Ohio 
1143 PM EST Tuesday Dec 2 2008 


Synopsis... 
a ridge of high pressure will move across the Ohio Valley tonight 
then move off the southeast coast Wednesday. A cold front will move 
across the area Wednesday night. 


&& 


Near term /until 6 am Wednesday morning/... 
scattered flurries seem to have ended so will go ahead with evening update 
to remove this from forecast. Also temperatures look to have stalled as 
warm advection counteracts the diurnal temperature drop so will try and 
best pick a range for temperatures to hold steady in for the bulk of the 
night although right near daybreak will probably see a little temperature 
rise as cirrus and some middle clouds move become predominate. 


&& 


Short term /6 am Wednesday morning through Friday night/... 
models a little slower than yesterday...but in general agreement 
moving the cold front now over the plains states across the area 
Wednesday. Of the two models the GFS is just a little faster than 
the NAM. With strong warm air advection ahead of the front precipitation should start as 
rain...then turn to snow behind the front. 


Expect some lingering snow showers over the eastern half of the 
forecast area Thursday morning with the front...with a lull possible 
in the afternoon before the lake effect kicks in. High temperatures 
for the day will be in the morning...with falling temperatures during 
the afternoon. 


Thursday night weak upper level trough swings across the area. 
This combined with 850 temperatures of -14 expect lake effect snow machine 
to start up again. With predominately westerly flow below 5k 
hardest hit will be snowbelt east of Cleveland. 


Models in very good agreement moving next ridge of high pressure 
into the Ohio Valley/lower Great Lakes on Friday. May be late in 
the day/overnight before the lake effect ends over extreme NE Ohio/northwest 
PA. 


&& 


Long term /Saturday through Tuesday/... 
colder than normal temperatures still expected through the long term 
forecast period. Cold front to move through late in the day Saturday 
or Saturday night. Snow showers will return to western areas by 
afternoon...reaching the eastern areas by evening ahead of this cold 
front. Will see a transition then to lake effect snow showers from 
late Saturday night into Sunday night. 800 mb temperatures should be 
around -15c on Sunday so air will be plenty cold for a significant 
lake event. Systems are moving quickly which could be the limiting 
factor to this lake event. But with lake and 800 mb temperatures quite large 
won't take much as seen from Monday night's limited lake event. Both 
12z European model (ecmwf) and GFS showing a high pressure moving across the area on 
Monday. Then another frontal system moving through on Tuesday. 06z 
and 12z GFS...and 12z European model (ecmwf) show this front in the vicinity on 
Tuesday...but significant difference with strength. Precipitation type also 
questionable. For now went close on timing shown on HPC manual 
forecasts...but didn't go nearly as warm as HPC guidance or as cold as 
mosguid...and showed chance of rain or snow. 


&& 


Aviation /06z Wednesday through Sunday/... 
clearing is pushing into northwest PA. South breeze will stay up 
overnight. Patchy middle/high clouds and VFR conditions will continue 
until rain showers develop with the next cold front which should 
reach Northwest Ohio toward dark Wednesday and move east across all taf 
sites early Wednesday night. MVFR ceilings/visibility should develop with the 
onset of showers Wednesday night. 


Outlook...IFR ceilings possible for a short time after frontal 
passage early Thursday morning. Rain will end early Thursday and 
drier air will push in but MVFR stratocumulus will likely linger 
especially across NE Ohio/northwest PA where lake effect snow showers will 
develop. Series of troughs will swing across the area late in the 
week right through the weekend with MVFR ceilings and IFR visibility 
during snow showers. Most of the snow showers should be confined 
to the snowbelt of NE Ohio/northwest PA except on Saturday when the entire 
area will be affected by a clipper system and cold front. 


&& 


Marine... 
windy and unsettled through the entire week...small craft conditions 
will be likely for much of the time. Gales possible for a couple of 
the weather systems. 


Cold front will be moving through the Great Lakes and Midwest 
Wednesday with increasing southwest flow across Lake Erie. Winds 
aloft exceed 40 knots...but warm advection pattern tonight into 
Wednesday will inhibit maximum mixing. Marine layer remains 
relatively stable until right ahead of the front. So will go as 
high as 30 knots Middle-Lake on the lake tonight and Wednesday. After 
the front Thursday winds shift to the west-northwest and remain a 
stiff 20-30knots...still with gales a possibility. Another surge of 
colder air...some of the coldest of the season...will help keep 
winds elevated into Thursday night. West to southwest flow from 
Friday into Saturday as high pressure builds south of the lake. 
Another system comes down from the northern plains across Lake Erie 
for Saturday night into Sunday...again with gales a possibility. 


&& 


Cle watches/warnings/advisories... 
Ohio...none. 
PA...none. 
Marine...Small Craft Advisory until 10 PM EST Thursday for lez142>149. 


&& 


$$ 
Synopsis...djb 
near term...Adams/djb 
short term...djb 
long term...randel 
aviation...kosarik 
marine...oudeman