Area Forecast Discussion
Issued by NWS Burlington, VT-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KBTV 191144
Area Forecast Discussion
National Weather Service Burlington VT
744 AM EDT Wed Apr 19 2017
A series of low pressure systems will move from west to east
across northern New England today through Friday. Expect showers
to increase over the area this afternoon and tonight before
ending early Thursday morning. Drier weather briefly returns
Thursday afternoon but a second low pressure system moves in
Thursday night and Friday morning for widespread rainfall across
the region. Drier weather returns once again for Friday
afternoon through the first part of the weekend.
.NEAR TERM /THROUGH THURSDAY/...
-- Changed Discussion --As of 744 AM EDT Wednesday...Going forecast in good shape with
no real changes needed at this time as clouds will continue to
increase this morning as well as the winds. Best precipitation
chances come this afternoon and tonight. Flood warning issued
earlier for Lake Champlain continues as the lake just went above
flood stage at Rouses Point.
Updating the forecast discussion to indicate a flood warning
was issued for Lake Champlain versus the initial thinking that
only a special weather statement would be needed. Already seeing
a northward push of water toward the Canadian border early this
morning and we have not even developed the strongest south
winds yet. Speeds will increase into the 25 to 35 knot range and
push even more water northward plus develop 3 to 6 foot waves.
The lake level is already high and with these expected
conditions...flooding is likely to occur from the Burlington
area northward. Already seeing the lake level near 100 feet at
the Rouses Point gage so it should not take much to go just
above that and enhance the potential for flooding. The flooding
threat will exist today into tonight and start to diminish as
winds taper off later tonight.
Otherwise...water vapor imagery shows shortwave trough moving across
the area early this morning and this feature is helping to moisten
up the atmosphere...but not enough to produce any precipitation. It
will be the second shortwave trough...currently over the Upper
Midwest that should help moisten the atmosphere sufficiently to
produce precipitation. Expecting rain showers to start moving into
northern New York this afternoon and across Vermont during the late
afternoon and evening hours. Looking at a general tenth to a third
of an inch of rain with the second shortwave...highest amounts over
northern New York and the northern half of Vermont and lesser
amounts over central and southern Vermont. Highs today will
generally be in the 50s with 40s in the mountains.
The showers will come to an end after midnight as the shortwave
trough moves east of the region. It now looks like a good part of
the day on Thursday will be dry before another shortwave trough
approaches the region Thursday night. We should be able to see some
sunshine Thursday with highs in the 50s and some lower 60s down
across south central Vermont.
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.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 333 AM EDT Wednesday...Really not a whole lot of change
from the previous forecast thinking, or my own from yesterday
with the main changes being to slow precip arrival Thursday
night just a tad, and lower storm total QPF values slightly.
Vertically stacked low pressure entering into the western Great
Lakes Thursday night will track east/northeast over the
Ontario/Quebec border by Friday morning, and further northeast
into central/southern Quebec Friday night. A deep moisture feed
on southwesterly flow between the low and high pressure anchored
off the Southeast coast will spread steady rainfall across the
North Country from west to east late Thursday evening through
Friday morning with PWATS 2-3 standard deviations above normal
producing 36 hour rainfall totals by Friday evening averaging
around 0.75" with some isolated amounts up to and inch possible.
Overall not looking for any widespread hydro issues with area
waterways running high, but a few concerns remain. See hydro
section below for the details.
Relatively progressive nature of the system has the bulk of
precipitation exiting to our east Friday afternoon as a mid-level
dry slot builds in and the trailing surface cold front approaches.
As the front swings through the region Friday night we could see a
resurgence of precipitation across portions of central/northern
Vermont as the flow turns west/northwest and is marginally
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 333 AM EDT Wednesday...Overall trend for the long term
period will be towards quieter weather once we get through
Saturday morning where the aforementioned surface low continues
to exit east off the Maine coast Friday night, and the parent
upper trough swing through. A few isolated to scattered showers
will be around early Saturday morning, but by the afternoon
surface high pressure begins to build southeastward from
southern Ontario/Quebec and will dominate the North Country`s
weather through Saturday night with dry conditions expected.
For the Sunday/Monday timeframe overall we continue to highlight
mainly dry conditions but the forecast area will be in a squeeze
play between a northern stream trough and southern stream energy
pulling through the central/south East Coast. The latest CMC and
ECMWF support the northern stream system dominating and remaining
unphased with only a thin ribbon of enhanced moisture swinging
through the region Sunday night into Monday morning, while the GFS
is slightly stronger with the southern stream. With either solution,
we`ll offer low chance for showers across our southern zones during
this period, but could see PoPs increasing with time is trends
change. High pressure does look to return for Monday/Tuesday.
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --Through 12Z Thursday...VFR conditions are expected through at
least 18z with only mid and high level clouds moving into the
region. Eventually showers and lower clouds will move in
between 18z and 06z with MVFR/VFR ceilings and visibilities
expected. Gusty south to southwest winds will also develop after
14z with gusts in the 20 to 30 knot range through 00z before
tapering off. Showers will also taper off after 06z.
Thursday: VFR. NO SIG WX.
Thursday Night: VFR/MVFR. Breezy. Definite SHRA.
Friday: VFR/MVFR. Breezy. Chance SHRA.
Friday Night: VFR. Chance SHRA.
Saturday: VFR/MVFR. Chance SHRA.
Saturday Night: VFR. Slight Chance SHRA.
Sunday: VFR. Slight Chance SHRA.
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With two systems bringing rainfall to the North Country this week
there are a few concerns on area rivers/streams/lakes which continue
to run high with continued higher elevation snowmelt, albeit a bit
slower lately due to seasonal temperature. Basin average QPF through
Friday from the 2 storms will be in the 0.75-1.25" range across the
region with latest ensemble and local model forecasts showing the
potential for a few northern gages to reach action and minor flood
stage by Friday afternoon. Lake Champlain continues to creep ever so
slowly closer to flood stage (100 feet) every day, and expect minor
flooding to occur by this weekend, while rivers of greatest concern
to reach minor flood stage are the Ausable, Barton, Winooski, Mad,
and Missisquoi at this time.