413
FXUS61 KBTV 111917
AFDBTV
Area Forecast Discussion
National Weather Service Burlington VT
317 PM EDT Wed Mar 11 2026
.WHAT HAS CHANGED...
As of 317 PM EDT Wednesday...
Confidence has increased in an impactful storm system for early
next week.
&&
.KEY MESSAGES...
As of 317 EDT Wednesday...
1. The potential for localized and minor ice jam related
flooding continues through Thursday, along with minor open water
flooding forecasted for the Ausable River and Otter Creek.
2. Aside from localized cold areas where freezing rain lingers, much
warmer and more humid air has arrived with numerous showers
falling through tonight, with heaviest rainfall expected from
the Adirondacks and points west. A cold front will sweep through
the area tomorrow morning, bringing gusty winds and much colder
air.
3. A clipper system will bring a few inches of snow and
some gusty winds late Friday into Saturday.
4. Active weather is expected from Sunday night through Monday
night, with a range of precip types and gusty winds anticipated.
&&
.DISCUSSION...
As of 317 PM EDT Wednesday...
KEY MESSAGE 1: The latest forecast from the Northeast River Forecast
Center indicates the Ausable River and Otter Creek are expected to
reach minor flood stage on Thursday with Action Stage possible on
the Lamoille, Winooski, and Missisquoi Rivers.
Additional rainfall tonight will be highly variable based on
embedded heavier showers with values ranging from 0.25" to localized
over 1.0" possible. The heaviest rainfall is expected over portions
of northern NY with secondary axis possible across central VT. HEFS
based simulation for Ausable River indicates median value of 6.2
feet, but mostly likely 25% to 75% range in the 5.0` to 8.0` range
with a peak anticipated on Thursday morning. The HEFS shows a
similar type profile for Otter Creek with median just above action
stage of 6.0 feet with slightly less potential for reaching flood
stage.
Meanwhile, these rainfall amounts will cause additional rises on
rivers and streams, this combined with numerous ice jams in place,
could cause renewed localized ice jam flooding. The greatest
potential for additional ice jam flooding based on current ice jam
locations would be the St Regis River at Hogansburg and Brasher
Falls, Saranac and Great Chazy. Still think we have to watch the
Passumpsic River near Lyndonville closely as we head into Thursday
with additional snow melt and rainfall expected.
KEY MESSAGE 2: Through early this evening, very localized freezing rain
continues in the far northern St. Lawrence Valley where temperatures
will stubbornly stay near 31 or 32 degrees for at least a few hours
longer. As of 2 PM, Massena ASOS had measured 0.06" of flat ice with
steadier rain entering the area; potential to approach 0.25" in this
area exists as rainfall rates increase closer to 0.1"/hour.
Overall, showers have become more widespread this afternoon
following more isolated activity this morning, especially over
northern New York but also in a corridor stretching northeastward
across central Vermont. Increasing water vapor transport, with some
input from the Gulf, has been streaming northeastward from western
New York while southerly low level moisture transport has been aimed
at Vermont. While we did have a few rumbles of thunder in the
Adirondacks and south central Vermont this morning, additional
thunderstorms are unexpected. Model guidance MUCAPE is progged to
remain low, under 100 J/kg, through the remainder of the event.
Rainfall rates with the most widespread shower activity in western
New York as been producing 0.1 to 0.4" per hour, with the high end
roughly matching the 90th percentile HREF guidance. This ensemble
guidance and radar trends suggest this heavier rain will into
northern New York, especially the western foothills of the
Adirondacks and points west, this evening. Additional clusters of
heavier rain will then be possible farther east and overnight as
more clusters of showers ride northeastward out of central New York.
As expected, things are looking rather scattered with regards to
footprints of heavier rainfall amounts, but because we are lacking
deep warm clouds, rainfall does not look impactful with regards to
flash flooding. River flooding, as discussed in Key Message 1, will
be somewhat impacted by the footprint of the highest rainfall
amounts as the specific basins may see highly variable amounts
of rain tonight.
With regards to winds, while there will be a powerful jet moving
through the region this evening, saturated and stable air should
limit mixing. Overall, the trend from the 00Z guidance has
continued with lower impacts behind the cold front, although
rapid pressure rises and associated isallobaric wind will
result in gusty winds. Current expectations are for localized
and brief wind gusts mainly 40-45 MPH, especially in northern
New York in typical areas in the lee of the Adirondack High
Peaks. The slightly limited wind potential seems tied to
relatively weak cold air advection, with a trend towards the
surface low looking elongated as it moves near and then just
northeast of the area overnight into the morning hours. Also,
the orientation of the winds out of the west-southwest limits
downslope potential in most of the Vermont terrain.
The potential for any meaningful post-frontal snow is limited,
although higher elevations should pick up at least a coating of
new snow before clouds scatter out during the day on Thursday.
Temperatures will tend to stabilize after falling in the morning
hours in the low to mid 30s in most locations across Vermont and
upper 20s to low 30s in northern New York. Overnight
temperatures will fall back below freezing areawide, putting an
end to an extended thaw and likely producing some slippery
conditions where standing water remains.
KEY MESSAGE 3: A clipper low will move through our forecast area
from west to east late Friday into Friday night. This will
bring a quick round of snow to northern NY and Vermont. The
northern Adirondacks and northern Green Mountains will see the
most snow out of the system and can expect a general 3-6 inches.
Elsewhere, accumulations will range from 1-3 inches. Confidence
in this general range is fairly high, as a look at
probabilistic snowfall suggests reasonable high end amounts for
our forecast area only between 3 and 8 inches, and reasonable
low end amounts between 0 and 3 inches. Our deterministic
forecast falls around the 50th percentile of ensemble solutions.
Given temperatures ranging from the low to mid 30s, some rain may
mix in over lower elevations of the Saint Lawrence Valley and the
Champlain Valley. Breezy south winds will also ramp up during the
day Friday, and become southwest/west overnight. Strongest wind
gusts (25 to 35 mph) can be expected over the northern Adirondacks
and over the Champlain Valley on Saturday. These winds will have an
impact on snow amounts, favoring higher snow totals in upslope
locations and resulting in some shadowing downwind of mountains.
It`s overall not a great setup for the Champlain Valley or much of
eastern Vermont to pickup much snow, but the higher elevations of
northern New York and northern Vermont will get a nice coating of
snow.
KEY MESSAGE 4: The pattern amplifies significantly Sunday,
setting the stage for a rapidly deepening low to lift
northeastward out of the central US and up through southeastern
Ontario and then Quebec. There are multiple potential hazards
associated with the system, and it`s just too early now to pin
them down with details. However, the big picture is taking
shape. A warm front will lift through our forecast area Sunday
or Sunday night. Initially, this could bring some brief snow and
possibly some very brief mixed precipitation to our area. Once
the warm front moves through, strong southerly flow will develop
with a direct Gulf and Atlantic connection. Precipitable water
values will rise to 0.8 to 1.0 inch, which is 2 to 3 standard
deviations and about 300% above normal for this time of year.
Probabilities from NBM ensemble solutions of dewpoints rising
above 45 degrees F are around 50 percent on Monday in our
southern counties. This signals another period of effective
snowmelt is possible (although this one will be brief). The
event will finish off with a period of steady rain as the cold
front moves through, followed perhaps by some brief snow on the
back end.
Expect some rises on rivers with snowmelt and rainfall early next
week, which also should flush out ice from some rivers. We will be
watching the hydro aspects of this system particularly closely. In
addition to hydro concerns, there will be a periods of windy south
winds, particularly within the warm sector of the system.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
Through 18Z Thursday...An active period of aviation weather is
expected with precipitation, gusty winds, and low-level wind
shear. Rain showers will continue this afternoon, which will
become periods of steady rain after 21Z. The exception is KMSS,
where local northeasterly flow is keeping temperatures just
below freezing, supporting freezing rain as the predominant
precipitation type. This -fzra at KMSS is forecast to switch to
predominantly rain after 22Z, though it could last longer if
northeasterly flow holds on longer than expected. Given surface
temperatures hovering just under freezing, it`s a matter of one
degree and thus confidence on ptype timing is lower for this
site. Elsewhere, confidence is high in an all rain ptype for
today into early tonight.
South winds areawide (outside of KMSS) will ramp up this afternoon,
becoming gusty in the 15 to 25 knot range later this afternoon into
this evening. A southwesterly low-level jet will move over this
evening, creating widespread low-level wind shear at all TAF sites
through 03Z, then weaken from west to east between 03Z and 18Z.
Surface winds will shift from south to west between 06Z and 12Z,
increasing in magnitude with gusts in the 20 to 35 knot range
between 12Z and 18Z.
Ceilings are initially mainly VFR, but will eventually lower to MVFR
levels through the night. The exception is again KMSS, where IFR
ceilings will continue through approximately 06Z. Ceilings
areawide will lift from 06Z through 18Z as a front moves
through and winds shift to the west.
As a front moves through Thursday morning, temperatures will drop
rapidly. A few areas could see some brief periods of snow after 12Z
on Thursday, especially over northern NY. No accumulations are
expected, some briefly reduced visibility is possible.
Outlook...
Thursday Night: VFR. NO SIG WX.
Friday: VFR. Chance SN.
Friday Night: Mainly VFR, with local MVFR and IFR possible.
Definite SHSN.
Saturday: Mainly VFR, with areas MVFR possible. Chance SN.
Saturday Night: VFR. NO SIG WX.
Sunday: Mainly VFR, with local MVFR possible. Chance SN.
Sunday Night: Mainly MVFR and IFR, with local VFR possible. Windy
with gusts to 30 kt. Likely RA, Likely SN.
Monday: Mainly MVFR, with local IFR possible. Windy with gusts to
30 kt. Definite RA, Definite SN.
&&
.CLIMATE...
As of 317 PM EDT Wednesday...
More records will be threatened today.
Record High Temperatures:
March 11:
KSLK: 60/1977
Record Precipitation:
March 11:
KPBG: 0.50/1964
&&
.EQUIPMENT...
The Colchester Reef meteorological station is out of service.
This site is not serviced by the NWS and there isn`t an
estimated return to service at present. Please contact us if you
observe winds significantly deviating from the recreational
forecast.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Flood Watch through Thursday afternoon for VTZ001>011-016>021.
NY...Flood Watch through Thursday afternoon for NYZ026>031-034-035-
087.
&&
$$
WHAT HAS CHANGED...Kutikoff
DISCUSSION...Taber/Kutikoff/Duell
AVIATION...Duell
CLIMATE...NWS BTV
EQUIPMENT...NWS BTV
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