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fxus61 kbtv 040548 
afdbtv 


Area forecast discussion 
National Weather Service Burlington Vermont 
148 am EDT Friday Jul 4 2008 


Synopsis... 
a weak cold front will continue to push southward into southern New 
England tonight...with any lingering showers ending by middle evening 
across southern Vermont. This front will remain stalled just south 
of the region through the upcoming Holiday weekend as strong high 
pressure builds across northern New York as well as central and 
northern New England. This high will bring generally fair and dry 
conditions to most of the area through Sunday. 


&& 


Near term /until 6 am this morning/... 
as of 1030 PM EDT Thursday...another quick update to the forecast 
to freshen up wording and grids. All precipitation well south of forecast 
area...although left in a slight chance for Rutland/Windsor 
counties through midnight just in case. Updated temperatures with latest 
lav guidance...a little warmer in the St. Lawrence 
Valley...otherwise very similar to earlier forecast. 


Skies to continue to clear and development of patchy fog from 
radiational cooling and plenty of moisture left behind from 
rainfall remains in forecast. 


&& 


Short term /6 am this morning through Saturday night/... 
as of 203 PM EDT Thursday...overall an outstanding stretch of 
weather expected for most areas over the Holiday weekend as 
aforementioned frontal boundary stalls across south coastal New England 
and mean high pressure builds atop our region from the Great 
Lakes/southern Canada. Ensemble mean 850 hpa temperatures would support highs in 
from the middle 70s to lower 80s both on Friday and Saturday under 
mainly clear/partly sunny skies and comfortable humidity levels/light 
winds. Only exception will be across SC Vermont during Sat afternoon 
where a few more clouds and a stray light shower or two may occur as 
weak surface wave rides along old frontal zone south of the area. Will 
continue to downplay precipitation chances across this area due to weak nature 
of wave and dry lower levels...leaning closer to lower metmos pop 
values in these areas. Did opt to lower maximum temperatures slightly 
though...mainly due to possibility of a few more clouds. 


&& 


Long term /Sunday through Thursday/... 
as of 318 PM Thursday...a summertime air mass will be in place across 
the north country at the start of the long term period with 850mb 
temperatures around +15c with weak surface ridging in place. Most of 
the operational models...including the 12z GFS and 00z 
European model (ecmwf)...indicate a middle-level vorticity vicinity of the upper Ohio Valley that 
is nearly cut off from the main band of southwesterly flow displaced 
further north across northwestern Ontario and central/northern Quebec. With 
this vorticity feature...afternoon highs in the middle 80s in the valleys...and 
a moist southerly planetary boundary layer flow...can/T rule out an afternoon thunderstorm 
and some increase in afternoon cloud cover...especially across 
S-central Vermont. Will taper probability of precipitation from 30 percent across southern 
Rutland and Windsor counties down to around 15 percent near the 
international border from 18z sun through 03z Monday. 


500 mb vorticity maximum tracks eastward across New England Sunday night into 
early Monday per 12z GFS. Will generally follow this solution and 
indicate mostly cloudy conditions with a chance of showers Sun night 
through Monday morning...then improving /mostly sunny/ conditions by 
Monday afternoon. No significant change in air mass with little in the 
way of a surface reflection suggests that if the region does clear out 
as expected...high temperatures will reach the low to middle 80s Monday afternoon. 


A stronger westerly zonal flow becomes established over northern New York and northern 
New England for Tue-Wed. A frontal system tracking from southeastern 
Ontario northeastward through the St. Lawrence Valley will bring a chance of afternoon 
showers and thunderstorms on Tuesday. Valley High temperatures should 
still be in the low 80s. As this low tracks to our NE...a surface cold 
front will track southeastward through the north country Tuesday 
night...possibly with an associated band of showers. Low-level cold air advection 
brings a slight cool down on Wednesday with afternoon highs mainly 
in the 70s. No significant weather is currently expected Wednesday night 
into Thursday with highs Thursday generally in the middle to upper 70s 
based on current indications. 


&& 


Aviation /06z Friday through Tuesday/... 
through 06z Saturday...surface observation show vlifr conditions at slk with 
fog creating visible <1/4sm and ceilings of vv001. These conditions are 
expected to develop at mpv between 06-08z and continue through 12z this 
morning...based on light winds and leftover bl moisture. 
Otherwise...aviation challenge will be areal extent of fog/br at 
rut/pbg/btv/mss this morning. Current observation at btv show light easterly 
drainage follow with fog bank just north of the runaway in the 
Winooski River Valley. Expect fog bank to slowly move south and spread 
across the Airport through the early morning hours...therefore will use 
tempo group between 08-11z and indicate visible 1/2sm in fog. Expect some 
br to develop at mss/pbg...but middle/upper level clouds will prevent fog 
development at rut. Expect low clouds/visible to improve by 14z with 
VFR conditions developing for the rest of the day. 


06z Saturday through Tuesday...a stationary boundary with waves of 
surface low pressure located over southern New England into the Middle Atlantic States will be 
focus for showers/storms this weekend. Meanwhile...surface high pressure 
will be overhead with VFR conditions anticipated through 18z Sunday. 
However...some patch valley fog will once again develop at slk/mpv 
between 06-12z on Saturday morning...which will create IFR conditions. 
Some middle/upper level clouds associated with elongated 500 mb vorticity and 
middle level moisture will produce some clouds across rut/mpv taf sites on 
Saturday. Otherwise...the potential for afternoon/evening 
showers/storms will increase Monday into Tuesday...with some IFR 
conditions possible in the stronger storms. 


&& 


Equipment... 
the ASOS at Massena (kmss) is inoperative...only altimeter is 
being reported. Technicians are aware of the problem. In 
addition...the Massena ASOS will be out of service for several 
days beginning Tuesday July 8 as Concrete work begins on the 
sensor foundations. 


&& 


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


&& 


$$ 
Synopsis...jmg 
near term...Hanson 
short term...jmg 
long term...banacos 
aviation...Taber 
equipment... 

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