537 
fxus61 kbtv 231453 
afdbtv 


Area forecast discussion 
National Weather Service Burlington Vermont 
952 am EST Monday Nov 23 2009 


Synopsis... 
high pressure will remain over the area through today and this 
evening. A low moving up the coast will affect central and southern 
New England late tonight into Tuesday...followed by another area of 
high pressure Wednesday. A broad area of low pressure will affect 
the region late Thursday on into the weekend. 


&& 


Near term /through tonight/... 
as of 952 am EST Monday...quick update to first two periods of the 
forecast...mainly to reflect latest trends in sky cover...and to keep 
any precipitation later tonight in liquid form. Latest analysis showing light 
south to southeasterly flow has become established in most areas 
this morning as mean surface ridging continues to slide slowly eastward. 
This has allowed moist low level cloudiness of maritime origin to 
creep northward...especially across our eastern Vermont counties. With pronounced 
subsidence inversion remaining in place expect this activity to 
essentially hold in place through middle afternoon...then creep 
steadily northward by this evening as southerly flow strengthens 
slightly aloft. Based off expected cloud cover and marine-modified 
airmass atop the area tonight...believe min temperatures should stay above 
freezing in most areas...especially south. Thus any precipitation that may occur 
with offshore coastal system across our southern counties would be light 
and in the liquid form. Rest of forecast in good shape and other than 
changes noted above...no other adjustments needed at this time. Enjoy the day. 


Previous discussion from 310 am EST Monday... 
surface ridge centered to our north over north Maine/Canadian Maritimes has 
set up easterly flow for gd portion of new eng region. This has 
allowed ll cloud deck to push westward into the County Warning Area as evident by 
latest infrared Sat pic. Expecting this cloud cover to overspread much of east 
Vermont during the day and even filter down into the cvly and portions of 
north New York. Fairly nice day overall on tap...W/ exception being blw normal 
temperatures in areas seeing low cloud shield...especially in east Vermont. Going 
into the evening hours...ridge to our north and east slides further 
offshore...allowing County Warning Area to remain under southerly wind regime. Clouds 
on the increase for central/southern areas going into overngt hours as surface 
low works north along the coast. Models a bit discrepant as to the 
northward push of precipitation/clouds into the area before moving east out to sea. West/ 
effects of blocking ridge still evident over portions of the 
northeast...will continue trend of keeping bulk precipitation over SC 
Vermont...and a sl chance for central areas for precipitation. Some cold air 
initially as a result of clear skies in some areas will allow for 
temperatures to drop some before arrival of precipitation...so will mention a few hours 
where --SW to mix west/rain showers(which will be predominate weather type). 


&& 


Short term /Tuesday through Wednesday/... 
as of 310 am EST Monday...surface low mvs offshore slowly by Tuesday 
morning. East-northeast flow over the region as surface ridge begins to build 
back down over the north country. With easterly fetch still expect 
cloud cover to remain as low exits...so will continue mention of -rw 
through midday and becm clear by the evneing hours. Ridge will remain in 
place going into Wednesday as next system approaches from the 
Great Lakes region. Models have trended slower on approach of this 
next system due to ridge placement. Have kept much of the County Warning Area dry 
with exception being slv and western portions of dacks...although 
gd portion of County Warning Area will see increase in middle/high clouds during the day. 


&& 


Long term /Wednesday night through Sunday/... 
as of 352 am EST Monday...the aforementioned front looks to weaken 
before it moves into the north country Wednesday night Thursday 
morning...with majority of lift and moisture remaining well to 
our south. So i've maintained only a chance of measurable 
precipitation across the forecast area Wednesday night. 


For Thursday....there are still some timing issues with the 
eastward progression of the strong shortwave...and northward 
progression of low developing off Carolina coast. Latest guidance 
slows things down...giving the west and southern portion of our 
area best probabilities of seeing precipitation on Thanksgiving. 
One thing that is consistent is the south to southwest flow over 
New England which keeps temperatures well above seasonal norms 
Thursday...and thus any precipitation should remain all rain for 
the Holiday. 


By Thursday night the coastal low should be somewhere 
near Long Island or The Bench mark...with a front extending back 
into Ontario. At this time we increase potential for precipitation 
across the whole region...especially points west and 
south...spreading east through Friday. The timing of the cold 
air...and consequently change from rain to snow...is very much 
dependent on the position of the surface low. The preferred European model (ecmwf) 
guidance indicates that the low will hug the New England coastline 
with a 
position near downeast Maine Friday afternoon. This will allow 
cold air to move into the region late Friday...with rain changing 
to snow at higher elevations Friday afternoon/early evening...and 
mixing with or changing to snow in the valleys Friday night. 


The system begins to exit the area Saturday...but we remain under 
the broad upper trough and under north to northwest flow through Saturday. 
These favorable upslope conditions mean the potential for snow 
showers continues Saturday....especially in higher elevations and 
points just west of the Green Mountains as the broad trough moves east 
and 
flow becomes more westerly by Sunday...we should see showers 
tapering off. 


&& 


Aviation /15z Monday through Friday/... 
through 12z Tuesday...an inversion once again keeps moisture 
trapped at low levels at most locatoins. Br and or MVFR stratus 
remain at kmpv...krut...kmss...at this hour...with flight 
categories raising to VFR after 16z. Kbtv is sky clear with a bit if 
mist in the air. Kpbg has IFR ceilings due to lake stratus... this 
will lift to MVFR by 14z and VFR by 16z. Kslk is LIFR in fog...and 
will slowly raise to VFR by 16z. Winds are generally south-southeast 5-10 knots 
today...and will diminish to light and variable tonight. In S and east Vermont 
increased moisture from a coastal low means skies will not clear. 
The Greens will be obscured in clouds and clouds will lower to MVFR 
by 00z at kmpv...krut...and even in kslk. Very light rain is 
possible in krut after midnight. This increased moisture...and 
return of nocturnal inversion...will also lower ceilings to MVFR in 
kbtv and kpgb after midnight. 




Outlook 12z Tuesday through Friday... 
Tuesday through Wednesday...MVFR Tuesday morning becoming VFR in the 
afternoon. 
Increasing clouds Wednesday evening. 
Wednesday night through Thursday...VFR/MVFR in rain showers as a 
weak front approaches from the Great Lakes. 
Thursday night through Friday...MVFR/IFR in occasionally heavy 
rain as low pressure moves across the area. 


&& 


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


&& 


$$ 
Synopsis...jn 
near term...jmg/jn 
short term...jn 
long term...amf 
aviation...amf/mb 

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