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fxus61 kbtv 210738 
afdbtv 


Area forecast discussion 
National Weather Service Burlington Vermont 
238 am EST Friday Nov 21 2008 


Synopsis... 
a continued cold stretch of weather will prevail across the north 
country through the next several days. Skies will remain cloudy 
overnight resulting weakened clipper system passing to our south. 
A reinforcing cold front arrives during the day Friday bringing 
the Prospect for scattered snow showers Friday and into early 
Saturday...especially in mountain locations. The next chance for 
light to moderate precipitation arrives with an upper level 
disturbance Monday afternoon into Monday night. 


&& 


Near term /until 6 am this morning/... 
as of 909 PM EST Thursday...quick update to this evenings 
forecast...mainly to reflect somewhat greater coverage of light shsn 
activity across central and northern areas overnight. Latest 
analysis showing persistent moist cyclonic flow across our area 
this evening. This combined with weak enhancement from orographic 
lift and Great Lakes moisture has allowed scattered light shsn to 
Blossom across many areas this evening. Due to shallow nature of 
moisture field and dry lower levels...only trace amounts of a 
dusting to perhaps a few tenths of an inch expected overnight. 
Nonetheless...due to increased coverage of this activity have 
opted to raise probability of precipitation to chance for most of central/northern areas 
overnight. Otw...inherited forecast in excellent shape...and other 
than tweaking sky/temperature data to current conds...no other 
adjustments needed. Enjoy the evening. 


Previous discussion...as of 330 PM EST Thursday...clipper type surface 
low that dropped southeast of our area today is now nearly 
indiscernible. Vorticity maximum has weakened...although plenty of middle 
level moisture across the area continues and area remains covered 
in overcast skies. Scattered flurries across the area today will 
continue overnight. Ample low level instability and some upslope 
influence will continue. Warm bias in MOS temperatures continues...and 
seemed like bias corrected nam12 had the best idea for temperatures. Min 
temperatures overnight across the Champlain Valley and Saint Lawrence 
valley will be in the lower 20s...elsewhere the overnight lows 
will be in the middle teens...with lower teens in the more sheltered 
and notoriously colder locales. 


&& 


Short term /6 am this morning through Sunday/... 
as of 345 PM EST Thursday...an upper level trough will dig south 
and east from the northern Great Lakes Friday...with axis making 
it to northern New York by 00z Sat. Some upslope snow showers are 
expected. Cold air advection will continue through the day Friday and overnight 
into early Saturday morning. Upper level trough axis will cross the 
area and upper low drops south and east of our area on Saturday 
morning. The coldest core of cold air still looks to be over the 
area early Saturday morning. 850 temperatures will dip to about -16 
degrees c. Cold air advection in the lowest levels of the atmosphere and steep 
lapse rates will kick off snow showers in the higher elevations 
of Vermont and northern New York...especially in west and 
northwest facing mountain locations. This will start in northern New 
York on Friday...then across Vermont Friday night and into 
Saturday. Have continues to indicate maximum temperatures well below 
guidance numbers for Friday through Saturday night. Middle to upper 
20s in the Saint Lawrence and Champlain valleys...with teens to 
lower 20s in the higher elevations. Overnight lows will be around 
20 in the Champlain Valley...single digits in the dacks...and middle 
teens in the Saint Lawrence valley and across the rest of 
Vermont. Northwest winds will continue across the area...with winds 
gusting at times on Saturday as pgf increases with low pressure 
system passing well to our east off the coast of New England. By 
Saturday night high pressure begins to build into the region and 
upper level low pivots well north of the region. 


&& 


Long term /Sunday night through Thursday/... 
as of 238 am EST Friday...unsettled weather expected for much of the 
extended period. Broad area of high pressure over the Atlantic 
will provide blocking pattern for the NE. On Monday...surface ridge 
still close enough to the East Coast to allow warm front associated 
west/ approaching slow to lift north of area during the day. During 
frontal passage...cold air from overngt will alow precipitation initally to be as light 
snow...then transition into rain shower/SW mix in valley locales as 
southerly winds kick in allowing some warm air advection into the area. Initial 
model probability of precipitation a bit high with bringing surface cold front through the area late 
Monday into Tuesday. Will transition back some...with best chances 
in nny until overngt Monday. Coastl low will form as front mvs 
offshore...then pivot north as it gains strentgh. This is going to 
allow strong easterly flow(bufkit suggests at least 30-45 miles per hour 
potential above 1000-1500ft) to set up over the region through Tuesday. 
West/ temperatures floating near the freezing mark over hir elev of c and east 
Vermont...potential exists for wintry mix(sleet/pockets of Fr 
rain/snow)...before going to mostly rain during the day Tuesday. North New York 
should stay cold enough to keep precipitation all snow and with high quantitative precipitation forecast 
potential...several inches of snow possible. Warm air does not 
reach into all of New York during the day Tuesday. Low will then shift 
ashore and remain over the north country into the end of the 
week...again due to blocking ridge offshore. Will transition rest 
of forecast period over to all -SW for County Warning Area due to cold air wrapping 
in to region as low mvs ashore. 


&& 


Aviation /08z Friday through Tuesday/... 
through 06z Saturday...all forecast sites will see varying cloud 
cover during period...from vfr(bkn-ovc035-045) down to mvfr(bkn020-030) 
at times. Precipitation during period will consist of mainly scattered flurries 
due to low cloud cover...but some bands through 10z this morning and 
again after 00z Sat may lower visibility to MVFR at times (4-5sm). Winds 
through entire forecast period will be west-northwest 5-10kts west/ some gusts 
around 15-20kt from 12z Friday-00z Sat. Hir terrain will be obscured. 


After 06z Saturday...through Monday...MVFR ceilings over the higher 
terrain with tempo MVFR in the Champlain Valley due to lower ceilings 
and scattered snow showers will be the norm through Saturday. 
Summits should stay obscured during most of this period with 
moist low levels and persistent northwest upslope flow. Sunday could be 
the clearest day with a short wave ridge moving into the area. By 
Monday clouds will increase with some very light snow...but 
visible/ceilings should stay VFR. 


&& 


Equipment... 
due to a local server failure...certain products from National Weather Service 
Burlington will be unavailable...including point and click 
forecasts on the web...and all phone recorded forecasts. 
Technicians are aware of the problem and will work to restore this 
data tomorrow. We apologize for any inconvenience. 


&& 


Btv watches/warnings/advisories... 
Vermont...none. 
New York...none. 


&& 


$$ 
Synopsis...neiles 
near term...jmg 
short term...neiles 
long term...jn 
aviation...jn/lahiff 
equipment...btv 

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