Area Forecast Discussion
Issued by NWS Burlington, VT-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KBTV 210900
Area Forecast Discussion
National Weather Service Burlington VT
400 AM EST Tue Feb 21 2017
High pressure will build eastward across the North Country
tonight bringing mostly clear skies, diminishing winds, and
chilly temperatures. Morning lows early Tuesday will be in the
single digits to mid teens across the region. A weak mid-level
disturbance approaching from the west will bring increasing
cloudiness and developing south winds on Tuesday, with light
precipitation Tuesday night. Precipitation will fall mainly as
light rain. However, pockets of light freezing rain are possible
east of the Green Mountains, and may result in a few icy spots.
Well above average temperatures are expected through the
remainder of the week, with a strong area of low pressure
passing to our west expected to bring widespread rainfall Friday
night through Saturday night.
.NEAR TERM /THROUGH WEDNESDAY/...
As of 1035 PM EST Monday...Only minor noise-level adjustments
to hourly temperature/dewpoint trends into the overnight and
morning hours were needed as of 1030 pm with current forecast in
excellent shape. Clear skies and light winds for the majority
of the night will allow for decent radiative cooling as high
pressure bridges overhead. Current forecast minimum temperatures
from 10 to 18F in the valleys and positive/negative single
digits for the northern mountains still look on track.
Increasing/thickening high cloudiness will begin to advect atop
western counties toward daybreak but will arrive late enough to
have negligible affect on temperatures. Have a great night.
For Tuesday, a shortwave ridge crests across the area with sfc
ridge shifting to our east into the Gulf of Maine by afternoon.
This will induce a southerly gradient flow with surface winds
increasing to 10-20 mph, with gusts to 25mph during the
afternoon hours (especially with channeled flow in the Champlain
Valley). The 12Z NAM RH profiles suggest increasing mid-upper
level clouds by 18Z from west to east ahead of next shortwave
trough across the Great Lakes. Despite increasing clouds, should
see warmer temps with highs in the upr 30s to lwr 40s.
Mid-level height falls and trough axis shift thru quickly
during Tuesday night. Low-levels remain relatively dry, and
overall it appears that approaching precipitation will undergo a
dissipating trend as the trough axis moves thru Tuesday night.
Maintained Likely PoPs during the overnight period, but QPF
values only 0.05-0.10" for most locations, and period of
precipitation will likely only span 2-3 hrs in most spots.
Vertical temperature profiles with continued south winds support
mainly rain with lows in the mid 30s. That said, should see
pockets of temps near freezing as the precipitation moves thru
in spots east of the Green Mtns, and have gone with a light ZR/R
for the ern half of VT. A few hundreths of an inch of freezing
rain is possible, and introduced mention in the Hazardous
Weather Outlook as a few icy spots are possibly for travelers
overnight Tuesday night. We will continue to monitor.
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
-- Changed Discussion --As of 358 AM EST Tuesday...Thursday will see another low pressure
system from the Great Lakes region pass to the north of the
CWA. Light showers, mainly in the northern half of the forecast
area, are expected with the system passes north of the border
and into northern Maine. QPF is minimal with this system with
the Adirondacks seeing a couple tenths of an inch, the Northern
Vermont counties seeing around a tenth and the rest of the state
seeing only a few hundreths of an inch.
Southerly flow will continue to boost temps well above seasonal
norms for Thursday with highs in the 50`s for the majority of the
area and overnight lows in the mid to upper 30`s.
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.LONG TERM /FRIDAY THROUGH MONDAY/...
-- Changed Discussion --As of 358 AM EST Tuesday...Friday sees low pressure tracking north
and west of our region from the Great Lakes Friday through
early Sunday morning. Models are in general agreement of a warm
front lifting through the region Friday afternoon/evening with
precipitation ramping up through the day Saturday with the peak
Saturday afternoon/evening just ahead of the passage of a cold
front. Winds out ahead of the front could lead to gusty
conditions and potential advisory level winds especially across
the Champlain Valley as the 00Z GFS indicates 850mb winds to
reach 65 knots Saturday afternoon. After frontal passage, rain
will switch over to snow showers Saturday night with the strong
cold air advection. Very warm temperatures are expected Saturday
ahead of the cold frontal passage. Temperatures overall look to
be in the 50s with the Champlain Valley pushing a record
breaking 60. A sharp cold front will drop temps quickly back
into the 20s Saturday night. Possible flash freeze issues are
possible with temperatures dropping so sharply after a moderate
rainfall. Moving into next week, more seasonable weather will
return for Sunday through Tuesday.
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.AVIATION /09Z Tuesday THROUGH Saturday/...
Through 06z Wednesday...High pressure across area bringing
mostly clear skies and VFR conditions to the region through
overnight period. Will see increasing clouds above 15kft after
12Z Tuesday as high clouds advance from W-E ahead of the next
trough across the Great Lakes. Precipitation arrives in St.
Lawrence Valley near 00z Wed and eventually sweeps east.
Activity is light with showery rain or freezing rain in eastern
VT with MVFR cigs due to pcpn.
Light and variable winds overnight but as high pressure system
shifts to the east, will see winds developing from the south
toward daybreak Tuesday, increasing to 10-12kts with gusts to
20kts at BTV by 18z Tuesday.
Outlook 06z Wednesday through Saturday... A weak trough will
bring periods of light rain, with pockets of freezing rain east
of the Green Mtns during Tuesday night. Brief MVFR conditions
are possible with this system, mainly during the pre-dawn hours
Wednesday. Generally returning VFR with high pressure Wednesday
afternoon through Friday morning. Warm front approaches from the
southwest Friday afternoon with increasing chances for rain and
periods of MVFR/IFR conditions. Will also see possible sfc wind
gusts locally in excess of 25kts with low-level turbulence and
wind shear late Friday through Saturday as deep low pressure
passes to our west across the Great Lakes and Ontario.