Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 281058

Area Forecast Discussion
National Weather Service Burlington VT
658 AM EDT Fri Oct 28 2016

Developing coastal low pressure over southern New England will
produce occasional rain and snow across most of Vermont today with
scattered precipitation over northern New York. Additional wet snow
accumulation of an inch or so is possible below 2000 feet. The
precipitation will taper off this afternoon with mostly cloudy skies
and cool temperatures prevailing. Our next weather system arrives on
Saturday with breezy conditions and mainly rain showers as
temperatures climb to near normal levels.


As of 652 AM EDT Friday...Overall forecast on track with only
minor update to capture latest radar trends....which show precip
redeveloping across the champlain valley associated with
developing blocked flow. The combination of easterly mid level
flow and developing northerly winds will continue to produce areas
of light precipitation across vt...including the champlain valley
through this morning. Have mention areas of drizzle this deeper moisture is limited...thinking some patchy
freezing drizzle is possible near the summits associated with
temps near 32f. Otherwise...any snow accumulations will be above
2000 feet as temps have warmed into at least the mid 30s most

Water vapor shows potent 5h energy moving across eastern NY this
morning as closing 5h/7h circulation drops southeast toward
southern New England. This energy aloft is helping to deepen
coastal low pres near the eastern tip of Long Island with 3 hr
pres falls of 4 to 5 mb...along with some lightning activity. This
developing area of low pres will be captured by upper air system
and track north toward the Gulf of Maine mid/upper
level flow advects Atlantic moisture back into most of VT.
NAM/GFS/ECMWF shows a sharp 850 to 500mb west to east moisture
gradient across our region...along with associated qpf fields.
Based on track of surface low pres and developing northwest winds
on backside...thinking additional qpf will range between 0.25 to
0.50 for most of vt...with <0.25 northern NY mountains. The
progged 850mb flow is not all that strong so upslope component for
enhanced precip will be limited as winds are only 15 to 25 knots.

Thermal profiles continue to be challenging this morning with
pockets of near freezing temps continuing associated with the higher
precip rates. For example MPV warmed to 34f earlier this evening with
light precip...but steadier precip has redeveloped and temp has
dropped back to 32 with light snow. Thinking during heavier
precip rates this morning bursts of snow are possible above 1500
feet across eastern/central vt...with an additional slushy inch or
so possible. Given the marginal bl temps not expecting any major
impacts...maybe a few slick spots on untreated secondary roads
across the higher terrain. Also...given the heavy wet nature of
the snow...cannot rule out additional isolated power outage.

As surface low pres deepens our winds will change to the
northwest and progged 850mb temps cool several degrees...while
boundary layer to 925mb continue to warm. Snow levels will
increase above 2000 feet by 15z today. Thinking this supports the
summits staying mostly snow for the entire event with storm total
snow amounts up to 6 inches likely...with localized higher amounts
possible near Killington.

By this afternoon precip will slowly taper off with areas of drizzle
and freezing drizzle possible near the moisture quickly
decreases in the favorable snow growth region and best upper forcing
shifts to our east. Any ice accumulation will be confined to above
3500 feet. High temps with plenty of clouds will range from the mid
30s mountain towns to mid 40s champlain and saint lawrence valleys.

Tonight...depth of moisture continues to slowly decrease with winds
becoming light terrain driven. Some areas of br/fog are possible
given the lighter winds and saturated low levels...especially during
the evening hours...before winds increase again ahead of our next
system. Have mention some chance pops toward morning with thermal
profiles supporting mostly rain showers...except near the summits.
Temps mainly in the 30s to near 40 overnight.


As of 336 AM EDT Friday...Little overall change in the forecast
from previous versions as we head into the weekend with the main
feature being weak low pressure passing north of the Canadian
border on Saturday. Latest models continue to indicate abundant
low/mid level moisture with this system, but synoptic forcing is
rather weak so while we continue to highlight likely PoPs for rain
showers(mainly north), QPF will be light with temps pushing well
above seasonal normals into the mid/upper 40s east to mid 50s
west. By nightfall, the deepest low level moisture begins to shift
east as the low tracks off into the Canadian maritimes and thus
precipitation will gradually taper off by Sunday morning.

Sunday`s forecast has become a little more tricky though as high
pressure begins to build over the Great Lake region, but aloft
weak shortwave energy looks to intensify and dig out a trough over
southern Ontario. Models are showing some light QPF possible along
a washed out boundary draped across our central/southern zones
from Saturdays low, but I`m hesitant to go with more than chance
pops with surface high pressure trying to build in. Temps will be
tricky as well depending on where the boundary sets up, but
thinking across central/northern areas highs will be slightly
below seasonal normals in the mid/upper 40s, with upper 40s to
possibly lower 50s south.


As of 336 AM EDT Friday...Aforementioned high pressure over the
Great Lakes Sunday shifts east across the northeast for Sunday
night and Monday offering a dry and seasonally cool end to the
weekend and start of the work week. Thereafter, this mornings runs
of the GFS/CMC/ECMWF are in a little disagreement with our next
potential system developing out of northern plains Monday
afternoon. ECMWF and CMC stayed consistent to previous run tracks
taking the low north of Lake Superior Monday night to the tip of
James Bay by Tuesday night, while the GFS has trended a little
further south. All push a warm front through the area Tuesday with
the North Country firmly in the warm sector through Wednesday
night, but the more southerly track of the GFS would offer higher
precipitation chances. Have stuck close to consistency from our
previous forecast highlighting some low chance PoPs with highs
Tuesday/Wednesday pushing back into the 50s area- wide as mean
925mb temps jump to +5-10C.


.AVIATION /12Z Friday THROUGH Tuesday/...
Through 12z Saturday...The aviation challenge is lowering
cigs/vis associated with low level moisture and potential ifr
conditions. Current obs show a mix of ifr at rutland to mvfr at
mpv/slk/mss/btv and vfr at pbg. Current radar shows precip
redeveloping across the champlain valley with lowering cigs toward
ifr at btv. Expecting ifr cigs to prevail most of the morning
before lifting between 16-18z today at rut/btv/mpv/
northwest winds develop at 5 to 10 knots. Tonight...soundings
show additional moisture developing...especially slk/mpv with ifr
conditions possible...but these low clouds lift as winds increase
toward morning. Expect higher terrain to be obscured.

Outlook 12z Saturday through Tuesday...Low clouds with ifr
conditions are possible through Saturday morning...before warm
front produces additional showers on Saturday across our northern
taf sites. Periods of mvfr cigs are possible. South to southwest
winds will increase with localized gusts to 30 knots possible at
slk/mss/btv. Surface cold front with a wind shift to the northwest
occurs on Sunday morning with mainly vfr conditions expected for
early next week.




LONG TERM...Lahiff
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