461 
fxus61 kbuf 022355 
afdbuf 


Area forecast discussion 
National Weather Service Buffalo New York 
655 PM EST Tuesday Dec 2 2008 


Synopsis... 
lake snows will weaken this evening as a ridge of high pressure 
brings moderating temperatures...then some sunshine on Wednesday. A 
sharp cold front will bring rain late Wednesday night...followed by 
midwinter cold and lake snows from Thursday afternoon into the 
upcoming weekend. Low pressure may bring a more general snowfall on 
Sunday 


&& 


Near term /through Wednesday/... 
update as of 540 PM... 
not a big change in the forecast at this time but we were able to 
cancel the lake effect snow warning for the Eastern Lake Ontario 
counties as the lake effect bands became weaker and more diffuse. 
Additional accumulations only another inch or two. 


Earlier discussion below in its entirety... 


Lake effect snows off Lake Erie have been moving north and 
weakening through the afternoon as the lake effect band off Lake 
Ontario is anchored on the Tug Hill plateau and should remain 
rather strong into the evening. Mesoscale models are depicting the 
weakening trend on the Lake Erie lake effect quite well and also 
show a good handle on the Lake Ontario snow bands. Will drop the 
les warning east of Lake Erie but maintain the warning east of 
Lake Ontario as there may be another 4 to 6 inches in the steady 
snow band before it weakens further and lift northward later this 
evening. 


Middle level warm advection will bring all lake effect snow to an end 
overnight and also bring some middle level cloudiness which may help to 
hold overnight lows to the lower or middle 20s for much of the area. 
There should be colder teens in the southern tier where fresh snow 
and some breaks in the clouds will allow cold air to pool in the 
valleys. 


Southwesterly flow become more southerly as the next trough enters 
the western edge of the Great Lakes on Wednesday. There will be 
limited sunshine on Wednesday as the dirty upper ridge crosses the 
area and brings a broken deck of middle clouds to the forecast area. 
The saving Grace is that there should be a downsloping wind and 
850mb temperatures in the +2c to +3c range which will bring the daytime 
temperatures up into the 40s over much of the forecast area. 


&& 


Short term /Wednesday night through Friday night/... 
rain will develop after midnight Wednesday night ahead of a strong 
cold front. After the front passes Thursday morning to midday, the 
rain will change to snow with 850 mb temperatures falling from -4c at 12z 
to -11c by 00z at buf. Temperatures should be steady in the morning, 
then fall in the afternoon. Post frontal subsidence and a strong northwest 
flow will limit the lake effect at first, but it should increase 
Thursday night across the southern tier and east of Lake Ontario in 
the usual snow belt in the Oswego, Jefferson, Lewis County Triangle, 
with the 850 mb flow at 280 off Lake Erie and 270 off Lake Ontario. 
The NAM and GFS agree that the lake snows should drift south a bit 
on Friday then back north in the northern edge of the favored belts 
Friday night. Well over a foot is likely east of Lake Ontario, and 
hefty amounts are also likely off Lake Erie. Lake effect flags will 
be needed again starting late Thursday and continuing into the long 
term period. 


&& 


Long term /Saturday through Tuesday/... 
low pressure over the upper lakes Saturday morning will back the 
winds to southwest and move the lake snows to near the St Lawrence 
River off Lake Ontario and the Niagara peninsula with enough shear 
developing to weaken them. The low then pushes a general light 
snowfall across the area Saturday night and Sunday. -14 c air at 850 
mb follows the low, and lake snows will redevelop southeast of the 
lakes in a northwest flow Sunday night, with scattered snow showers 
possible most areas. 


The GFS and 00z European model (ecmwf) differ in timing for next week, so it is too 
soon to be definitive, but at this time it looks like ridging on 
Monday will bring wind shear and fair cold weather, with perhaps 
lingering lake effect southeast of Lake Ontario. Finally, the next 
low will bring moderating temperatures and a chance of snow changing 
to rain Tuesday. 


&& 


Aviation /00z Wednesday through Sunday/... 
in response to the steering flow becoming more sout southwesterly 
and warming aloft is still causing Minor Lake effect bands to 
drift northward and weaken. The activity will likely end all 
together by midnight well north of Watertown. There will be 
trapped moisture however as a subsidence inversion lowers. This 
will likely cause MVFR ceilings at times through 06z mainly over 
kbuf...kiag and kart. Kjhw will also likely have MVFR ceilings through 
this evening with moisture trapped below the inversion. Drier air 
will advect in overnight with lower clouds scattering out and middle 
and high decls moving across the area in response to warm 
advection. These VFR conditions will persist through the end of 
the current taf period. 


Outlook... 


Wednesday night...MVFR/IFR overnight in rain. 
Thursday MVFR in snow showers...IFR east of the lakes in lake 
effect snow. 
Friday...IFR in lake snows east of the lakes..VFR 
elsewhere. 
Saturday...deteriorating to IFR/MVFR in widespread snow 
showers. 
Sunday...MVFR with IFR southeast of Lake Ontario in lake snows. 


&& 


Marine... 
brisk southwest winds will subside slowly tonight. Look for fresh 
south to southwest winds on Wednesday...becoming brisk southerly 
Wednesday night ahead of the next cold front. Winds will then 
shift abruptly to west and northwest in the wake of the front 
Thursday with brisk westerlies continuing into Friday. 


Wind speeds will be sufficient for small craft advisories off Lake 
Erie and the east end of Lake Ontario through at least Friday. 
As the winds become more southerly waves will subside below 4 feet 
along the South Shore of lakes Erie and Ontario overnight. 


&& 


Buf watches/warnings/advisories... 
New York...none. 
Marine...Small Craft Advisory until midnight EST tonight for lez020. 
Small Craft Advisory until 4 am EST Wednesday for lez040- 
041. 
Small Craft Advisory until midnight EST tonight for 
loz042>044. 
Small Craft Advisory until 7 am EST Thursday for loz045. 


&& 


$$ 


Synopsis...apb 
near term...Sage/wch 
short term...apb 
long term...apb 
aviation...jjp/Sage 
marine...apb