704 
fxus61 kbtv 040234 
afdbtv 


Area forecast discussion 
National Weather Service Burlington Vermont 
1034 PM EDT Thursday Jul 3 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 Friday 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 Friday 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 /03z Friday through Tuesday/... 
through 00z Saturday...main concerns for the first 24 hours will be 
residual low clouds this evening...then fog formation overnight. 
Mainly VFR/MVFR clouds through midnight...though kslk will 
occasionally drop to IFR until 02z or so. After midnight...clear 
skies and light winds with plenty of low-level moisture will lead 
to fog development...especially at kmpv and kslk. Both these 
sites will see MVFR conditions deteriorate to vlifr by late 
tonight...mainly 06z through 10z. Improving conditions 
thereafter....returning to clear skies and p6sm by 14z. Kmss will 
also see some light fog...but conditions are expected to remain 
above IFR. Clear skies and light winds for the fourth. 


00z Saturday through Tuesday...VFR conditions with mostly clear 
skies and light winds through the weekend as high pressure remains 
entrenched across the region. Showers and thunderstorms will return 
Sunday night and Monday morning as an upper level shortwave 
traverses across the north country. A brief break from rain Monday 
afternoon and night...then more widespread showers and thunderstorms 
for Tuesday as surface low pressure tracks north of the Saint 
Lawrence valley. Overall...VFR conditions expected with MVFR in any 
precipitation. Localized IFR possible in any thunderstorms that 
develop. 


&& 


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...mb 
equipment...Hanson