NWS Burlington, VT wrote its last area forecast discussion before the first event at Mar 13, 7:41 PM EST, 1 hour 19 minutes earlier.
Area forecast discussion, Mar 13, 7:41 PM EST, 1 hour 19 minutes before
Area Forecast Discussion
National Weather Service Burlington VT
841 PM EDT Mon Mar 13 2023
.SYNOPSIS...
A long duration winter storm will impact portions of the region
tonight through Wednesday. The potential for wet, heavy snow
accumulations exists with this system, along with difficult
travel and chances for power outages, mainly in southern central
Vermont and in Essex County, New York. Dry weather is expected
again for Thursday,along with warming conditions. Another storm
system is likely on Friday, which appears to be a mainly rain
event at this time.
&&
.NEAR TERM /THROUGH TUESDAY NIGHT/...
As of 751 PM EDT Monday...A few small changes were made, but
overall things look on track for now with regards the winter
storm just getting underway. Noticed RT 100 near Ludlow at
around 2200 feet had suddenly become slick as wet snow began to
accumulate, and would expect this trend to continue as snow
rates pick up in the higher terrain this evening. Snow levels
generally near 1500 feet should gradually lower so overall the
going precipitation-type forecast looks good. A slight delay in
the changeover to snow was made primarily in the Champlain
Valley overnight.
Previous Discussion...
Our latest headlines are:
* Winter Storm Warning in effect for western Essex County of New
York and much of southern and central Vermont, adding
Washington and Orange Counties.
* Winter Weather Advisory in effect for much of the Adirondacks
and eastern Essex County in New York, and much of northern
Vermont. It has been expanded to include the rest of the
Northeast Kingdom.
An area of low pressure off the Carolina Coast will begin to
quickly deepen and retrograde as it interacts with a weak low
near Long Island while it wraps into an upper level low. This
event will sort of feature two different events, though in quick
succession. The first event will be from the Long Island low,
which will develop as vorticity advection of the negatively
tilted upper low and excellent upper diffluence allow for height
falls. This precipitation will overtake the warm front that is
presently washing out across the area, and it will arrive late
this evening. Initially falling as a rain-snow mix, a transition
to snow is expected overnight. Forecast QPF and hourly snowfall
rates have increased, though the probability of 1 inch per hour
rates seem mostly confined to higher terrain. There will
initially be some terrain shadowing from a 35 knot low-level jet
at 850 hPa, but being at the nose, it should not be overly
strong this time around compared to the last low-level jet. In
association with this, there could be some downsloping for
western slopes, but mainly 20 to 30 mph.
Next, the low off the Carolina Coast will begin to take over, as
better jet dynamics and baroclinicity, as well as being near the
warm waters of the Gulf Stream, allow the low to quickly deepen.
It will initially reside outside the benchmark, and we may see
the northward progression of precipitation briefly reverse
before it pivots northwest while it matures. The further west it
moves, the closer strong 700hPa FGEN will be to the area. So,
for the most part, this seems to yield additional moderate snow
across eastern Vermont. We will be on the fringe, and due to
temperatures at 32 to 36, we will rely greatly on the snowfall
rates for accumulations. West of the Greens and below 1000 ft
elevation, amounts should remain between 2 to 4 inches for the
most part. Around 1000 to 2000 foot elevation, amounts range
between 3 to 7 inches, with higher totals of 6 to 10 inches in
eastern Vermont due to closer proximity to the FGEN band. Higher
elevations remain cooler, and will have less of these problems,
banking 10 to 16 inches 2000 feet above sea level. So, for the
most part, this seems to yield additional moderate snow across
eastern Vermont.
This will result in a sharpening pressure gradient over the
region as well. North winds will increase Tuesday afternoon,
with the stronger gusts in the Champlain Valley and portions of
eastern Vermont. North gusts around 30 to 40 mph, locally to 45
mph near the southern end of Lake Champlain, is expected Tuesday
evening. In combination with the wet snow, which could be heavy
at times, there should be areas of drifting snow and some power
outages wherever snow loading can take place. Based on the
increased amounts, it could be scattered, but mainly isolated
impacts are likely. This will help entrain dry air on the north
side of the tightly wound circulation, though. By Tuesday
night, despite the strong winds, we become blocked as winds turn
more northwesterly. Additional 1 to 3 inches of snow should
take place on the backside.
Forecast guidance has shifted west and north. However, the last
several events have seen these jaunts in the near term that
have not come to fruition. The present forecast is light
compared to some of the available guidance. If better snowfall
rates can become established and dry air entrainment ends up
being less of an issue, then it is a possibility that snowfall
amounts could be 2 to 4 inches higher in spots. Regardless,
expect the difficult travel Tuesday morning, and perhaps Tuesday
evening as gusts increase to produce areas of blowing or
drifting snow.
&&
.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
As of 318 PM EDT Monday...A powerful vertically stacked 980mb surface
low meanders and slowly moves east of Nantucket, bringing possible
blizzard conditions to coastal MA and to Cape and the Islands. For
us, the winds turn northerly and with the Froude numbers suggesting
blocked flow, expect gusty conditions to persist along with snow
showers during the day on Wednesday. But given how dynamic the low
pressure system is, expect plenty of dry air to be wrapped around
into the mid levels of the atmosphere. As the day goes on, expect
the snow showers to be increasingly scattered and confined to the
Green Mountain spine. Sunshine could even make a return across our
western zones, as the low pressure system gradually pulls away.
Expect generally up to 2 inches across the valleys with higher
amounts in the higher elevation. Temperatures will be fairly
seasonable with highs in the mid 30s across the valleys, although
the gusty conditions will make it feel more like the teens and 20s.
Overnight lows wise, if we get more clearing and/or winds to abate,
could see more widespread temperatures in the mid and upper teens.
If not, 20s will be more prevalent.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 318 PM EDT Monday...We remain in a fairly active pattern with
ingredients for a potential late week system just showing up in the
West Coast. Obviously, there is still plenty of uncertainty given we
are still 4 days out. What we are confident in is the temperatures
continuing to run near or just below normal this week. This means
that even as we approach astronomical spring, we will continue to
have the potential for accumulating snowfall including across the
valleys. After all, BTV has 13.2 inches of snow seasonally from this
point onwards. From a teleconnections standpoint, the PNA is
forecast to be slightly positive through end of the week, i.e.
northern Rockies ridging. And with the NAO staying slightly
negative, there just might be enough wiggle room for late season
winter storm late week.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Through 00Z Wednesday...MPV, RUT and MSS are currently MVFR with
precipitation lifting north into our region. Other sites remain
VFR at this time. Expect all sites to experience a variety of
flight categories over the next 24 hrs. At this time we are
seeing light rain, light snow or a mix of the two.
Winds are beginning to shift from southeast to east, with a
broader swath of precipitation edging northwards. This should
result in more widespread reductions to ceilings and
visibilities. There may be some areas of rain initially, but
towards 05z-07z, it should become all snow. The heaviest
precipitation is most likely at RUT and MPV, and have locally
down to 1/2SM or 3/4SM visibilities. Will assess trends for
remaining sites, but generally have 1-2SM visibilities and
ceilings 1500-2500 ft agl through about 15z. Some variability in
SLK, RUT, EFK, and BTV is likely as winds become easterly
around 5 knots. Towards 15z, winds should become northerly and
increase again to 6 to 11 knots. Anticipate some improvements to
ceilings and visibilities for all as somewhat drier air moves
in for a short while. RUT is likely to remain more restricted
closer to the incoming system, and then after 18z, we should see
additional snow move in from the east and north winds continue
to increase, becoming gusty at all sites.
Outlook...
Tuesday Night: Mainly MVFR and IFR, with local VFR possible.
Windy with gusts to 30 kt. Definite SN, Likely SHSN.
Wednesday: Mainly MVFR and IFR, with areas VFR possible. Windy
with gusts to 35 kt. Likely SHSN.
Wednesday Night: Mainly VFR, with areas MVFR possible. Chance
SHSN.
Thursday: VFR. Slight chance SHSN.
Thursday Night: Mainly VFR, with areas MVFR possible. Slight
chance SHSN.
Friday: Mainly VFR, with local MVFR possible. Chance SHRA, Slight
chance SHSN.
Friday Night: Mainly IFR, with areas MVFR possible. Likely SHRA.
Saturday: Mainly MVFR, with local VFR possible. Chance SHRA,
Chance SHSN.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Winter Weather Advisory until 8 AM EDT Wednesday for VTZ003-
004-006-007-009-017.
Winter Storm Warning until 8 AM EDT Wednesday for VTZ008-010-
011-018>021.
NY...Winter Weather Advisory until 8 AM EDT Wednesday for
NYZ029>031-035.
Winter Storm Warning until 8 AM EDT Wednesday for NYZ034.
&&
SYNOPSIS...Haynes
NEAR TERM...Haynes/Kutikoff
SHORT TERM...Chai
LONG TERM...Chai
AVIATION...Haynes/Neiles