NWS Burlington, VT wrote its last area forecast discussion before the first event at Dec 23, 12:47 AM EST, 3 hours 13 minutes earlier.
Area forecast discussion, Dec 23, 12:47 AM EST, 3 hours 13 minutes before
Area Forecast Discussion
National Weather Service Burlington VT
1247 AM EST Fri Dec 23 2022
.SYNOPSIS...
A powerful storm system is expected to bring a significant high wind
event to the region tonight into Friday morning with widespread
gusts of 50 to 75 mph, along with scattered to widespread power
outages. As much colder air races into the region Friday afternoon
and evening, a flash freeze is likely with temperatures rapidly
below freezing and lingering rain briefly changing to snow before
ending Friday evening. The combination of snow melt and rainfall
will produce sharp rises on waterways with several rivers
potentially reaching minor flood by late Friday into Saturday.
Additionally, continued strong winds will result in below zero wind
chills across the region while parts of northern St. Lawrence County
will also see lake effect snow develop Saturday into Sunday.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 928 PM EST Thursday...Winds are starting to increase along
the western slopes this evening, with a few locations having
reported gusts of 35-45 mph. The core of the jet still lies
across central PA/NY, but it should continue to strengthen and
lift north and east overnight as low pressure deepens over
MI/Ontario. Precipitation will also continue to spread northward
overnight. Currently mainly seeing reports of snow, but portions
of the St Lawrence Valley have been receiving light freezing
rain as warm air starts to spread over colder air wedged in on
northeast winds. Temperatures should start to warm in earnest
(and not just here in the Champlain Valley, where we've warmed
to 39F at BTV) after midnight through the early morning hours,
turning any wintry precipitation over to plain rain. The going
forecast has this all covered, so no changes were needed with
this update.
Previous forecast...No major changes have been made to the
forecast in regard to the expected weather and impacts from a
powerful storm system affecting almost all of of the lower 48. As
we've been highlighting for several days, this will be a multi-
faceted event with a wide range of hazards, the most we've seen from
a single storm in some time across the North Country and Vermont.
Details follow in chronological order:
Winter Weather Advisory (Tonight into early Friday morning)...
The first hazard expected is of the wintry kind as warm air
advection lifting into the region atop a cold airmass will
present an environment favorable for mixed precipitation.
Overall forecast soundings continue to favor mainly a mix of
rain and snow, with snow at the onset rapidly changing to rain
in the valleys below 1500 feet. Varying degrees of a warm nose
aloft though presents the chance for pockets of freezing rain
and sleet, mainly across the higher elevations above 1500 feet
with the best chance for accumulating snow over the eastern
Adirondacks and southern Greens. Below 1500 feet a dusting to an
inch of accumulation is possible, while higher up the potential
exists for 3-6" mid-slope and 6-9" near the summits. This will
be wet snow as well with ratios generally 5-8:1 which alone
supports some slippery travel for the morning commute, but
combined with increasing wind gusts of 30-40 mph the likelihood
of power outages will certainly be exacerbated in these regions.
The High Wind Warning and Wind Advisory (Tonight through Friday):
Unfortunately NWP remains unchanged in the 12Z suite, and if
anything leads to increased confidence that much of region will
experience a significant high wind event rivaling a small handful of
historical events with peak wind gusts comparable to a category 1
hurricane. The focus for the highest gusts continues to be across
the southeast downslope regions on the western facing slopes of the
Adirondacks and Green Mountains, but the impressive strength of a
low level jet of 100kts 850mb and even more impressive 60-80kts at
925mb continues to support 50-75 mph wind gusts bleeding downwind
into western portions of the Champlain Valley where population
centers aren't as accustomed to seeing winds of this magnitude.
Elsewhere, winds generally won't be quite as strong though still
quite gusty in the 35-45 mph range, but some higher elevations in
counties such as Orange and Windsor could still see some gusts
approach 60 mph. This jet is already taking shape over southern
Vermont where KRUT is currently gusting up to 25kts, and will be
peaking between midnight and 7 AM Friday before gradually abating
thereafter. As a result, scattered to widespread power outages are
anticipated due to downed trees and/or tree limbs on power lines.
&&
.SHORT TERM /SATURDAY NIGHT/...
As of 338 PM EST Thursday...
The Flash Freeze (Friday afternoon into Friday night):
Heading into Friday afternoon and evening, a sharp cold front
is expected to bring rapidly falling temperatures on order of 5
degrees or more per hour, dropping from afternoon highs in the
mid-40s to around 50, to below freezing and into the teens and
20s by 5-7 PM. Lingering rain will briefly change to snow while
the temperatures are rapidly dropping and depending on how much
falls, this could make the situation worse if that snow gets to
melt on roadways. A flash freeze still looks like a real problem
given this scenario, so know the roads before you go as you
travel this holiday weekend.
The Flood Watch (Friday night into Saturday):
Details below in the hydro section, but in short a flood watch
remains in effect for the combination of warm temperatures, wind
and snowmelt to contribute runoff into area waterways. A few
mainstem rivers are expected to reach into minor flood stage,
and small creeks and streams will definitely see significant
rises.
Lake Effect Snow Warning (Friday night through Saturday Night):
Finally, as if all the above mentioned wasn't enough, a long
duration lake effect snow event looks to take shape Friday night and
continue likely through Sunday. The bulk of the event will occur
Friday night through Saturday night where large delta T's between
the warm waters of Lake Ontario combined with persistent
southwesterly flow (actually reaching advisory criteria) will create
a favorable environment for lake effect snow stretching northeast
from Lake Ontario into southern St. Lawrence County. Highest
accumulations are expected in the usual locales south and west of
Route 68 and 56, where 8-16" is forecast. Combine this snowfall with
winds gusting 40-50 mph and it's easy to say that travel will be
hazardous across the area.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 338 PM EST Thursday...Will see a gradual quieting down of the
active weather conditions during the extended portion of the fcst
across VT and northern NY. Main focus Christmas day will be the
evolution of ongoing lake effect snow bands off Lake Ontario. On the
synoptic-scale, mid-level trough axis will be crossing sern Ontario
Christmas morning. This will allow lake effect snow bands extending
into St. Lawrence county Christmas morning to gradually shift
southward as low-level winds veer westerly with time. Looking for an
additional 1-3" of snowfall along and south of the Rte-11 corridor
from Gouverneur to Canton, and an addition 1-3" in the Star
Lake and Cranberry Lake vicinity during the afternoon before
bands shift south of St. Lawrence county during Sunday
afternoon. Elsewhere, some light flurries or snow showers are
possible, but minimal accumulation or road impacts expected
Christmas Day. It will remain brisk with Christmas Day highs in
the low-mid 20s, and SW winds generally 10-20 mph, with a few
higher gusts.
Sunday night into Monday, will see a gradual lessening of gradient
winds across our region as high pressure builds eastward from the
Ohio Valley. Other than some flurries across southern St. Lawrence
County and the Adirondacks, generally dry conditions expected with
reduced cloud cover. Lows Sunday night generally in the single
digits to teens, with highs in the low-mid 20s again for Monday.
Surface high pressure will be the controlling weather feature across
NY and New England for Tuesday and early Wednesday. May see a mid-
level trough with limited moisture bring a chance of snow shower
activity later Wednesday into Wednesday night with possible light
snow accumulations. However, overall trend will be for air mass to
moderate during the mid-week period. Should see temperatures
trending gradually upward, with highs on Tuesday in the low-mid 20s,
followed by upper 20s to lower 30s for Wednesday, and low-mid 30s
for Thursday.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
Through 06Z Saturday...Widespread, severe aviation wx impacts
are expected late tonight through Friday morning with extreme
low-level wind gusts and low-level wind shear.
Precipitation will continue, with intervals of more intense and
little precipitation. Some FZRA is being reported at KMSS, and
SN at KPBG, KEFK, and KMPV, and then the rest is RA. This should
transition over all terminals about 09z to 10z. Depending on the
rates, visibility could range between 1 and 6SM. Ceilings
expected to be variable as well, ranging between 700 to 4000 ft
agl.
Main aviation wx story will be the very strong E-SE winds early
Friday. A vigorous low-level jet (70-85kt winds at 2kft agl) will
result in extreme low-level wind shear and turbulence at all
TAF locations. Strong winds will mix to the surface in frequent
gusts, including gusts of 50+kt expected at KRUT 08-13z and at
KBTV 10-15z. Generally 35-45kt surface gusts at times
elsewhere. Strongest winds should begin to subside Friday
afternoon, with a southwesterly wind shift accompanying a
frontal passage early to mid afternoon hrs on Friday.
Rain showers will switch to a few hours of snow showers,
especially northern NY/VT before largely ending about 00z
Saturday. It will remain breezy with wind gusts still 25-35 kts
through that timeframe. Lake effect snow will begin to reach
KMSS about 02z Saturday.
Outlook...
Saturday: VFR. Strong winds with gusts to 40 kt. Chance SHSN.
Saturday Night: VFR. Windy with gusts to 35 kt. Likely SN, Slight
chance SHSN.
Christmas Day: VFR. Chance SHSN.
Sunday Night: VFR. NO SIG WX.
Monday: Mainly VFR, with local MVFR possible. NO SIG WX.
Monday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Tuesday: Mainly VFR, with local MVFR possible. Slight chance
SHSN.
&&
.HYDROLOGY...
As of 338 PM EST Thursday...A FLOOD WATCH remains in effect
from Friday afternoon through Saturday evening due to a
combination of snowmelt and rain.
Basin average rainfall of 1.5" to 2" and 1-2" of liquid equivalent
from snowmelt is likely. The highest rainfall totals are expected in
eastern facing slopes of the Adirondacks in Essex County, New York
and across the southern Greens in Windsor County, Vermont, which
could have locally higher totals to 2.5". Minor flood stage is
forecast to be reached on the Otter Creek at Center Rutland, the Mad
River at Moretown, and the East Branch of the Ausable River which
are of the highest concern at this time. Minor flooding is also a
possibility on the Winooski River at Essex Junction, though
confidence of occurrence is lower. Elsewhere, significant river
rises are expected, and minor poor drainage and urban street
flooding is possible.
For details on specific area rivers and lakes, including observed
and forecast river stages and lake elevations, please visit the
Advanced Hydrologic Prediction Service /AHPS/ graphs on our
website.
&&
.EQUIPMENT...
NOAA Weather Radio WXM-44 atop Mount Ascutney is currently off
the air due to a suspected problem with the RF transmission
cable/jumper at the antenna. A site visit will be necessary to
isolate the issue and, unfortunately, a return to service is
unknown at this time.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...High Wind Warning until 7 PM EST this evening for VTZ002>009-
011-016>019.
Winter Weather Advisory until 7 AM EST this morning for
VTZ018>020.
Flood Watch from this afternoon through Saturday evening for
VTZ005-008>011-017>021.
Wind Advisory until 7 PM EST this evening for VTZ010-020-021.
NY...Wind Advisory until 1 PM EST Saturday for NYZ026-027-087.
High Wind Warning until 7 PM EST this evening for NYZ029>031-
034.
Lake Effect Snow Warning from 1 PM this afternoon to 7 PM EST
Sunday for NYZ029-087.
Winter Weather Advisory until 7 AM EST this morning for NYZ031-
034.
Flood Watch from this afternoon through Saturday evening for
NYZ031-034.
&&
SYNOPSIS...Lahiff
NEAR TERM...Hastings/Lahiff
SHORT TERM...Lahiff
LONG TERM...Banacos
AVIATION...Banacos/Haynes/SLW
HYDROLOGY...BTV
EQUIPMENT...BTV