Area Forecast Discussion
Issued by NWS Burlington, VT-- Highlight Changed Discussion --
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FXUS61 KBTV 210335
Area Forecast Discussion
National Weather Service Burlington VT
1035 PM EST Mon Feb 20 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 TUESDAY NIGHT/...
-- Changed Discussion --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.
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.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
As of 348 PM EST Monday...Low pressure system passes well North
of the region Wednesday. Mild temperatures are expected with
region mainly in the warm sector through the day. Maximum
temperatures will be in the 40s. Will have clouds through most
of the day due to weak surface trough crossing the area.
Wednesday night will remain mild with temperatures only dropping
into the mid to upper 30s across the area with clouds remaining
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 348 PM EST Monday...On Thursday another low pressure
system will pass from the Great Lakes region north of our
forecast area. Light showers are expected with this feature as a
weak surface trough crosses the area. Another larger and deeper
low pressure system will impact the area Fri through Sunday.
Some warm air advection light showers is expected on Friday as
low pressure system lifts into Great Lakes area and warm front
stretches out ahead of it lifting across our area. Highest
probabilities of precipitation with this feature will be
Saturday afternoon and overnight as cold front and best
vorticity advection lifts across the area. Have mentioned likely
pops at this time. Generally an inch to an inch and a half of
qpf is expected, mainly rain. Saturday night will see remaining
precipitation change over to snow showers with strong cold air
advection. We will have very warm temperatures on Saturday ahead
of the cold frontal passage. Temperatures will max out in the
upper 40s to mid 50s, then sharp cold front will drop temps back
into the 20s Saturday night. Will have to watch for possible
flash freeze issues with temperatures dropping so sharply after
a moderate rainfall. Quieter and mores seasonable weather will
return for Sunday and Monday.
.AVIATION /04Z Tuesday THROUGH Saturday/...
Through 00z Wednesday...High pressure building ewd from sern
Ontario will bring 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 the end of this forecast
period but still VFR but trending downward.
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 00z 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.