Area Forecast Discussion
Issued by NWS Burlington, VT-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KBTV 210732
Area Forecast Discussion
National Weather Service Burlington VT
332 AM EDT Sun Aug 21 2016
A cold front across southeastern Ontario and western New York this
morning will shift eastward, crossing the North Country this
afternoon and evening. Gusty south winds will occur in advance of
the front through early afternoon, followed by widespread showers
and a few thunderstorms as the frontal rainband moves through mid
afternoon through the evening. Some showers will produce locally
heavy downpours. On Monday, high pressure returns bringing cooler
temperatures and drier weather. Weather will remain dry through
Thursday with high pressure in control, along with a gradual
moderation in temperatures.
.NEAR TERM /THROUGH TONIGHT/...
As of 239 AM EDT Sunday...Forecast generally on track. Active period
of weather expected as vigorous shortwave trough across WI/upper
MI at 07Z begins to make its way ewd with increasing large-scale
forcing across the North Country by this afternoon. Generally dry
and breezy this A.M., but a period of moderate to briefly heavy
rain is expected later this afternoon into the first half of
tonight. Attendant cold front across sern Ontario early this
morning will shift into nrn NY by 00z Monday, and then sweep
eastward across the North Country and east of the CT River Valley
by 06Z Monday. Strong sea- level pressure gradient in place this
morning across the North Country ahead of frontal system, along
with 2-3kft winds of 40-45kts based on KTYX VAD. Should translate
into widespread southerly surface winds of 15-25mph, with gusts to
30 mph, and locally 35 mph in the Champlain Valley morning through
mid- afternoon with channeled flow. A lake wind advisory has been
posted for Lake Champlain.
Southerly flow in advance of approaching frontal system will rapidly
increase PW values, reaching 1.6-1.7" by early afternoon, and around
2" along the cold front late in the afternoon/evening hours. SBCAPE
is limited due to lapse rates near moist adiabatic, but values
around 500 J/kg should be sufficient for some embedded thunderstorms,
producing brief heavy downpours.
In terms of timing, appears pre-frontal trough and associated
showers begins affecting the St. Lawrence Valley 16-18Z, and
slowly shifts across the Adirondacks into the Champlain Valley by
21Z. Bulk of rainfall for the Champlain Valley and points east
will be between 21-03Z, and then ending from west to east by 06z
Mon with strengthening mid- level wswly flow accelerating frontal
motion overnight. Will generally see 0.5 to 1.0" rainfall amts,
but locally higher with any embedded tstms. That said, motion of
cold front appears progressive enough that we should avoid any
hydro related problems.
High temperatures this afternoon upr 70s to lower 80s with
abundant mid- upr clouds followed by rain showers later in the
day. Lower clouds have developed east of the Green mountains with
moisture return, and will keep temps generally in the mid-upr 70s.
Temps cooler quickly during the pre-dawn hours Monday with
westerly wind shift and increasing low-level cold air advection.
Lows generally in the 55-60F range across VT, but lower 50s across
.SHORT TERM /MONDAY THROUGH TUESDAY/...
-- Changed Discussion --As of 332 AM EDT Sunday...Upper trough is exiting the area to the
east Monday morning...but there may still be some lingering
showers east of the Green Mountains in the morning. Northwest flow
in the low and mid levels will promote cold air advection and
below normal temperatures are expected with highs in the mid 60s
to lower 70s. High pressure builds in Monday night and with clear
skies and light winds...looking at below normal temperatures to
continue with lows in the lower 40s to lower 50s. This shot of
below normal temperatures will be short lived as temperatures
quickly rebound to seasonal normals on Tuesday with plenty of
sunshine and no precipitation expected.
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.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
-- Changed Discussion --As of 332 AM EDT Sunday...The warming trend that began on Tuesday
will continue into Wednesday and Thursday as southwest flow aloft
becomes established over the region. Highs will be in the low to
mid 80s both days. Dry weather will continue Wednesday into the
first half of Thursday before a trough of low pressure moves in
Thursday night and Friday. This will allow for increasing clouds
and the chance of showers and thunderstorms Thursday night into
Friday. High pressure follows in behind the trough of low pressure
on Saturday for drier weather and slightly below normal
-- End Changed Discussion --
.AVIATION /07Z Sunday THROUGH Thursday/...
Through 12Z Monday...Cold front approaching from SE Ontario and
wrn NY will bring an active period of weather, especially 18Z
Sunday through 06Z Monday. Early this morning, increasing S-SE
winds occurring as pressure gradient intensifies. South winds
10-15kts expected areawide, and should see gusts to 25kt at BTV
through 18Z Sunday associated with channeled flow in the Champlain
Valley. Increasing low-level moisture is bringing MVFR ceilings
along/east of the Green mtns, and expect this to be the case
through the day, with HIR TRRN OBSCD. Elsewhere, VFR with
lowering ceilings from west-to-east as front approaches from the
west this afternoon. Should see scattered showers affecting
MSS/SLK toward 18Z, and into the Champlain Valley by 21Z, and
RUT/MPV toward 00Z Monday. Generally MVFR conditions late
afternoon through evening within frontal rainband. Intervals of
IFR possible with embedded heavy downpours, and with isold
thunderstorms. Winds shift into the west and Northwest with FROPA
overnight, and showers tapering off from west to east after 06Z
Monday. Strong frontal inversion and trapped low-level moisture
suggests areas of MVFR ceilings will persist through 12Z Monday
with HIR TRRN OBSCD.
NOTE: Rutland AWOS (RUT) is not operating. Because of the lack of
disseminated observations, we continue our suspension of
amendments for the RUT TAF. Once the communication problem has
been resolved, and we again get routine observations automatically
transmitted, we will lift that restriction.
Outlook 12Z Monday through Thursday...High pres in place with
mainly VFR conditions. Only exception will be LIFR fog possible
MPV/SLK 06-13Z each morning.
As of 200 AM EDT Sunday...Southerly winds continue to increase
this morning with strengthening pressure gradient in advance of
surface cold front across sern Ontario/wrn NY. Will generally see
sustained south winds 20-30kts across Lake Champlain through
early to mid-aftn, before subsiding with onset of rain showers as
frontal rainband moves into the region from the west. Showers will
contain heavy downpours this afternoon, and a few thunderstorms
are also possible late afternoon into early evening. Those
planning on boating today should be aware of the strong south
winds and potential for heavy rain showers later in the day.