Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 191143
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
643 AM EST Thu Jan 19 2017

.SYNOPSIS...
As surface high pressure and an a ridge aloft build into the region
today, areas of morning drizzle should dissipate through the day,
but a developing low level inversion will keep skies cloudy right
through Friday and into the weekend along with above normal
temperatures. A storm system shifting out of the southeastern states
Monday will bring the potential for a wintry mix Monday night,
changing to all rain for Tuesday.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 643 AM EST Thursday...Mid/upper level shortwave trough
shifting through the Northeast this morning continues to provide
areas of low clouds and drizzle to the North Country through
mid-day before surface high pressure and an upper ridge building
east from the Ohio Valley brings an end to precipitation this
afternoon. Moving forward into tonight and Friday, despite
strong subsidence building in aloft, a developing low level
inversion will trap abundant moisture below 925mb with very
light winds in the boundary layer. This combination isn`t good
for any clearing, except at the mountain top level, so will
continue to highlight cloudy skies through Friday morning before
the inversion possibly breaks Friday afternoon with some peaks
of sun possible towards sunset. Should be interesting to see
what the summits look like Friday morning as I suspect they`ll
be above the clouds. With so much cloud cover through the
period, temps will have a hard time warming much today and
falling off tonight so think highs will mainly run in the
mid/upper 30s and lows only in the mid 20s to low 30s. Light
wind fields and warm air moving over fresh snowpack will also
enhance the potential for fog to develop tonight, and feel it
will be fairly widespread after sunset reducing visibility below
a mile at times. Not much airmass change for Friday either so
temps should be similar to Thursday, but with the hope of a
little afternoon sun could see some low 40s out there, mainly in
the Champlain Valley.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/...
As of 311 AM EST Thursday...Relatively quiet weather continues
into the Friday night/Saturday time frame. A quick perusal of
this morning`s data suggests a fairly consistent theme showing
blocking upper ridging across New England will act to dampen an
approaching shortwave trough advancing northeast from the Ohio
Valley/Mid-Atlantic during this period. With light warm thermal
advection rippling in aloft expect a return to mainly cloudy
skies with perhaps some spotty very light rain and/or snow
arriving from the southwest over time and weakening in coverage
as we progress into Saturday. Any snow accumulations will be
negligible and generally less than an inch - mainly across
elevated terrain. Temperatures will continue very mild with lows
Friday night from the mid 20s to lower 30s and Saturday maxes
from the upper 30s to lower 40s.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
As of 311 AM EST Thursday...As we progress into the extended
portion of the forecast the one certainty is a continuation of
unseasonably mild weather with daily mean departures averaging
from +10 to +20 degrees. This has been a very consistent signal
among varying ensemble output over the past 10 days or so. Our
most notable weather will occur during the Monday/Tuesday time
frame as a rather potent southern stream system phases with
northern stream energy across the northeast before exiting into
the maritimes by mid-week. Examination of model thermal profiles
suggests at least a threat of some light sleet or freezing rain
in customary areas of northern New York and eastern VT into
Monday evening before boundary layer warming transitions p-type
to rain in all areas by Tuesday. For the Champlain Valley this
will primarily be a light rain event. Any icing threat appears
rather marginal at this time given such mild boundary layer
temperatures but a light glaze can`t be ruled out, at least at
this point. Other minor concern will be the potential for gusty
southeasterly downsloping winds, especially along the western
slopes of the Green Mountains later Monday afternoon into Monday
night as mean 925-850 mb flow may exceed 40 knots. This will
eventually predicate some adjustment of model qpf fields as
valley/terrain shadowing/enhancement effects will be magnified.
Higher-res guidance will certainly provide more detail as we
draw closer in time.

Behind this system mean lower to mid level flow remains
southwesterly, so little cooldown/airmass change is expected
through Thursday at this point. With several additional
shortwave impulses crossing the area the idea of a daily threat
of scattered rain/snow shower activity also appears reasonable
as progress into Wed/Thu. Afternoon highs should from the mid
30s to lower 40s with overnight lows averaging in the upper 20s
to lower 30s - more typical of March than January.

&&

.AVIATION /12Z Thursday THROUGH Monday/...
Through 12Z Friday...Mainly offering a persistence forecast in
regards to ceilings as a developing low level inversion will
trap current moisture/clouds beneath it with little overall
airmass change expected through the next 24 hours. This
highlights mainly IFR cigs at KMSS/KSLK and MVFR elsewhere,
exception being VFR at KPBG through the daylight hours. VFR
vsby through the day trends to a mix of MVFR/VFR in fog after
00z with some spotty IFR. Winds light and variable through the
period.

Outlook 12Z Friday through Monday...

12z Friday - 00Z Sunday - Inversion layer looks to possibly
break Friday but could continue to see prolonged stretches of
MVFR ceilings, and perhaps IFR at times for SLK/MPV. In addition
to low clouds, patchy BR/FG also possible.

00Z Sunday through 00Z Tuesday - Generally VFR Sunday. Moisture
laden low pressure approaching from the south brings potential
for widespread precipitation (mostly rain) for Monday with MVFR
and intervals of IFR conditions. SE gusts in excess of 25kts
possible at KRUT late Monday.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.

&&

$$
SYNOPSIS...Lahiff
NEAR TERM...Lahiff
SHORT TERM...JMG
LONG TERM...JMG
AVIATION...Lahiff


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