Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 212335
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
635 PM EST Sun Jan 21 2018

.SYNOPSIS...
Outside spotty light snow or snow showers across northern
counties this evening, mainly cloudy skies and dry weather is
expected tonight. A storm system tracking through the Great
Lakes and St. Lawrence Valley will affect the region Monday into
Tuesday with a variety of mixed precipitation and rainfall.
Behind this system temperatures return to seasonably cold levels
for mid to late week before another round of potentially messy
weather arrives by next weekend.

&&

.NEAR TERM /THROUGH MONDAY NIGHT/...
As of 622 PM EST Sunday...Current forecast in good shape with no
significant changes with this update. Surface analysis shows
weak front draped across our cwa this evening with light north
winds developing across the SLV and CPV. This front will
continue to drop south...before becoming stationary over central
NY into southern VT by early Monday morning. A few light
flurries are possible across northern NY/VT, with Ottawa
reporting some light snow. Current elements look good and no
changes made.

Previous Discussion Below:
Winter Weather Advisories are now in effect for portions of the
area Monday into Monday night.

A fairly quiet night remains on tap for the area as this morning`s
weak cold front remains draped across the area. This boundary
separates seasonably mild air in the 30s to around 40 across our
area from colder readings in the 20s to our immediate north across
southern Quebec and Ontario. For the most part a dry night under
variably cloudy skies and continued seasonably mild temperatures are
expected as lows bottom out in the 20s to locally near 30 in the
Champlain Valley. Very weak overrunning processes streaking
just north of the stationary front may produce some spotty on
and off sprinkles or light snow through midnight or so along the
international border. However, any accumulations should be
minor to negligible and generally less than an inch.

The weather then turns more active for Monday into Monday night as
low pressure tracks from the central plains northeast into the lower
Great Lakes. This will drive a more pronounced warm front through
our area by later Monday into Monday night with a variety of mixed
precipitation. Initially, the cooler airmass off to our north will
bleed southward into northern areas Monday morning before background
flow trends south/southeasterly over time by Monday evening and
especially Monday night pushing temperatures above freezing for many
areas. The exception will be the northern St. Lawrence Valley and
eastern VT where cooler values will hold more stubborn longer. Using
a model-blend for hourly temperature profiles and this morning`s GFS
thermal profiles to govern p-type it suggests a period of mixed
precipitation will arrive with the warm front through the day on
Monday and the first part of Monday night before coverage tapers
somewhat toward Tuesday morning as we enter the warm sector. The
probabilities of mixed precipitation will persist the longest in the
aforementioned cooler areas where some light snow/sleet and icing
are expected. Using a standard empirical-based methodology for icing
it suggests accretions will range from 0.05 to 0.15 inches will
localized higher totals in the immediate St. Lawrence Valley from
Ogdensburg north toward Massena. Winter Weather Advisories have been
issued for these areas accordingly in the Monday afternoon/Monday
night time frame. Temperatures will be quite tricky and heavily
dependent on elevation, topography and timing though the general
idea will be for highs to top out in the 28 to 38 degree range by
late in the day Monday with readings slowly rising Monday night.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
As of 240 PM EST Sunday...As cold front approaches the North
country, rain will spread across the area. Region will be
completely in the warm sector behind cold front which lifted
across the area Monday night, therefore no further threat for
mixed precipitation. Rain will spread west to east across the
area, and highest rainfall totals will be across Southern and
Eastern Vermont. Maximum temperatures on Tue will reach the mid
30s to upper 40s, a few readings in the 50s would not surprise
me. Cold front will push across the area Tuesday night, turning
remaining precipitation to snow showers. Temperatures will dip
into the teens across Northern New York, with teens and lower
20s across Vermont.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 245 PM EST Sunday...Dry weather returns for Wednesday
through Friday night with large ridge of surface high pressure
over the region. The coldest day of the week will be Thursday
with highs only in the teens. Otherwise temperatures will be
closer to seasonal normals with a warming trend headed into next
weekend. We will once again be impacted by a warm rain system
for the Saturday night through Sunday night timeframe, another
system that we will continue to monitor as we get closer to the
weekend.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
Through 00Z Tuesday...VFR conditions will trend toward mvfr at
slk/mss by 03z...before becoming ifr cigs btwn 06-08z. Surface
front draped across our taf sites may help to produce a few very
light snow showers overnight...but any impacts to terminal
sites will be minimal. Clouds will continue to lower overnight
with widespread mvfr conditions expected by Monday
Morning...with areas of ifr cigs possible at pbg/mss and slk. A
wintry mix will develop between 20-22z on Monday with periods of
ifr vis likely at most sites. Light and variable winds
overnight will become south/southeast at 5 to 15 knots...except
northeast at kmss.

Outlook...

Monday Night: Mainly MVFR, with local IFR possible. Likely RA,
Likely FZRA, Likely PL.
Tuesday: Mainly MVFR, with areas IFR possible. Likely RA, Likely
FZRA.
Tuesday Night: Mainly MVFR, with local IFR possible. Chance SHSN,
Chance SHRA.
Wednesday: Mainly VFR, with local MVFR possible. Slight chance
SHSN.
Wednesday Night: Mainly VFR, with areas MVFR possible. NO SIG WX.
Thursday: Mainly VFR, with local MVFR possible. NO SIG WX.
Thursday Night: Mainly VFR, with areas MVFR possible. NO SIG WX.
Friday: Mainly VFR, with local MVFR possible. NO SIG WX.

&&

.HYDROLOGY...
As of 324 PM EST Sunday...Widespread rainfall is expected
across the area by Monday night into Tuesday. Current data
suggests 36-hr rainfall totals ending at 700 pm Wednesday will
range from 0.50 to 1 inch across the area. Given the substantial
loss of snowpack across lower elevations during last week`s
storm, and the fact that the warm-up will be of lesser magnitude
we are not expecting significant ice movement or water rises on
area rivers at this time. This is in close agreement with NERFC
guidance and our latest river forecasts. Conditions will
continue to be monitored closely over the next 48 hours and will
be updated if later information suggests a different scenario
than current thinking.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Winter Weather Advisory from 4 PM Monday to 10 AM EST Tuesday
     for VTZ003-004-006>008-010-012-018-019.
NY...Winter Weather Advisory from 1 PM Monday to 7 AM EST Tuesday
     for NYZ026>028-030-031-034-087.

&&

$$
SYNOPSIS...JMG
NEAR TERM...JMG/Taber
SHORT TERM...Neiles
LONG TERM...Neiles
AVIATION...Taber
HYDROLOGY...JMG


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