Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 210825

Area Forecast Discussion
National Weather Service Burlington VT
425 AM EDT Fri Oct 21 2016

Rain event persists over the North Country as a mid-level
longwave trough continues to dig south and east from Canada. This
trough will become negatively tilted late Friday into early
Saturday, keeping frontal boundary, associated surface low
pressure system and rain over the region through Saturday
night/early Sunday. Colder air will filter in behind this system
along with northwest flow producing upslope rain and snow showers
Sunday through Tuesday. Another surface low pressure system looks
to affect the Northeast Thursday.


As of 425 AM EDT Friday...No big changes. Bulk of precip over Nrn
NY and NW VT this morning. With mid-level trough expected to
become negatively tilted this afternoon, precip shield looks to
pivot NW providing break in rain to VT and portions of Champlain
Valley late morning to early afternoon. At the same time, NAM and
GFS indicate strong low level deformation producing moderate to
heavy rain at times over Nrn NY, before weakening as we head into
the evening hours.

For this afternoon, the most uncertainty lies with exact
positioning of surface low pressure and, therefore, wind direction
as there will be a markedly sharp wind shift over the region.
Models continue to indicate moisture from coastal system will feed
into the NE low pressure system latter half of today into tonight.
This combined with diffluent mid-level flow will result in
possible periods of moderate rain over VT, especially during the

Saturday morning, models find more consensus on surface low
positioning along the southern New England coast, traversing
northward during the day. This means deep NW flow over the North
Country will bring in colder air and terrain enhanced rain


As of 400 AM EDT Friday...Rain will gradually change to snow over
the higher elevations of the Adirondacks and Green Mountains
Saturday night as a closed upper low moves over the region which
will provide dynamical cooling aloft with a change to snow over
the higher elevations. Have leaned toward the warmer GFS MOS
guidance for min temperatures Saturday night, as the NAM MOS
guidance looks too cold. Also, combination of cloud cover and
gusty west winds will help to keep air well mixed and will help to
keep temperatures up. Thus, have lowered snowfall amounts a bit
from the previous forecast given a slower changeover to snow in
the higher elevations.

Models showing precipitation winding down across the region Sunday
morning, with most of the activity done by midday on Sunday.
Models show the region will still be under cyclonic flow Sunday
night from the departing surface low pressure area over Quebec
Sunday night. Have kept in some slight chance pops for rain or
snow showers Sunday night.


As of 400 AM EDT Friday...The north country remains under
cyclonic flow from the departing surface low pressure area over
eastern Quebec Monday and Tuesday. Thus, have kept in slight or
low chance pops for rain or snow showers for Monday and Tuesday.
High pressure will build slowly east from the Great Lakes Tuesday
night, with mainly fair and dry weather from Tuesday night through
early Thursday. On Thursday, a warm front will approach the region
from the Great lakes and the Ohio valley. Have put in a chance of
rain showers into the forecast for mainly Thursday afternoon.


.AVIATION /09Z Friday THROUGH Tuesday/...
Through 06z Saturday...MVFR/IFR conditions persist throughout
this long duration event, coming to an end Sunday night. Rain more
persistent over Nrn NY this morning through early afternoon. Then
increased moisture from subtropical system feeds into the NE low
affecting our area Friday afternoon. This will allow resurgence in
moisture and rain to spread east as the NE low swings from PA to
the srn New England coast Friday night.

Winds gusty where it isn`t raining and LLWS possible over SLK
this morning. Low level jet weakens and exits east early Friday.

Outlook 06z Saturday through Tuesday...

06z Saturday through 00z Monday: A prolonged period of unsettled
conditions is expected with widespread MVFR/IFR in periods of

00z Monday through 00z Wednesday: A mix of VFR/MVFR with upslope
showers in NW flow.


As of 425 AM EDT Friday...Rainfall amounts ranging from 1-1.5
inches have already fallen across the St Lawrence Valley,
northeastward across the northern Champlain Valley this morning.
Rain will continue today through Sunday, being most persistent
over the St Lawrence Valley and Adirondacks. An additional 1 to 3
inches is expected. Given most of the region is in moderate to
severe drought...we are not anticipating any widespread hydro
issues. However...some minor urban and street flooding is possible
associated with the heavier rainfall rates on Friday with leaves
clogging storm drains. Otherwise...some modest rises in local
rivers and streams are likely this weekend...but no widespread
flooding is anticipated.




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