Brattleboro, Vermont 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

111
FXUS61 KALY 031430
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
930 AM EST Tue Dec 3 2024

.SYNOPSIS...
Cold conditions will continue today with isolated to scattered
snow showers and flurries around. A clipper system will bring
widespread snowfall later Wednesday into Thursday with windy
conditions and lake effect and upslope snow showers developing
behind the passage of an arctic cold front. Lake effect and
upslope snow showers will continue into Friday before gradually
tapering off.

&&

.NEAR TERM /THROUGH TONIGHT/...
.UPDATE...As of 925 AM EST, primary change to the fcst for this
update was POPs to account for latest radar and model trends.
Still expecting snow showers for locations across the eastern
Catskills into the Mid Hudson Valley, Berkshires and Litchfield
Hills later this morning and afternoon, with coverage more
isolated elsewhere. See previous discussion below...

Previous Discussion:
Longwave troughing will remain overhead through today with an
embedded shortwave passing through the flow during the afternoon
and evening hours. Northwesterly flow will continue to direct a
lake- effect snow band within the vicinity of the western
Mohawk Valley, Schoharie County and into the eastern Catskills.
The passing shortwave should allow the band or fragments of the
band to extend eastward into the mid-Hudson Valley and even into
portions of Berkshire and Litchfield Counties. In addition,
some isolated snow showers or flurries cannot be ruled out
elsewhere, so included slight chance PoPs across the CWA for
this. Most areas will see little or no accumulation from these
snow showers but portions of the eastern Catskills into
Schoharie County and southern Herkimer County could pick up
around one inch where the snow band remains persistent enough.
High temperatures will be similar to Monday with 20s in the
higher elevations and the 30s in the valleys.

The upper trough departs to the east and weak upper level
ridging builds in tonight. Surface flow will also shift
southerly lifting the band northward across the western Mohawk
Valley and Adirondacks then eventually west/northwest of our CWA.
Elsewhere, mainly dry weather is expected through the night
with lows once again dropping back into the teens to around 20.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Key Messages:

- A clipper system will bring widespread snowfall later
  Wednesday into Thursday with windy conditions and lake effect
  and upslope snow showers developing behind the passage of an
  arctic cold front.

- A Winter Storm Watch has been issued for portions of the
  Adirondacks, western Mohawk Valley and southern Vermont from
  Wednesday afternoon/evening into Thursday night.

Discussion:

A potent upper-level trough and clipper system will approach the
area on Wednesday. Mostly dry conditions will start the day with
clouds increasing and thickening from west to east. Warm
advection/isentropic lift will result in snow beginning to
overspread the area Wednesday afternoon with snow initially
favoring the foothills of the southern Adirondacks (central
Herkimer, southern Hamilton and northern Fulton counties) due
to southerly flow resulting in orographic enhancement. Wet bulb
processes will eventually allow snow to begin to fall elsewhere
but could take until the evening hours in some areas.
Downsloping effects could occur within portions of the Capital
District due to the southwesterly flow aloft from the Catskills
reducing amounts there. Marginal temperatures should limit snow
accumulations across the mid- Hudson Valley. Across southern
Vermont, the Froude number less than one will favor blocked flow
and snow favoring the upwind side of the southern Green
mountains (i.e. Bennington County) where the highest amounts are
anticipated.

Snow will continue Wednesday night into Thursday morning before
transitioning to lake effect and upslope snow showers as an
arctic cold front crosses the area. Pending on the time of the
front, some localized snow squalls may occur with steepening low
and mid-level lapse rates from the approaching cold pool aloft
Thursday morning into the early afternoon. Additional light to
moderate snowfall accumulations are expected Thursday into
Thursday night before the trough begins to depart and high
pressure noses in from the west.

The highest snowfall totals (combining the synoptic and lake-
effect/upslope snow) will occur across portions of the
Adirondacks, western Mohawk Valley (especially north of the
Thruway) and in Bennington County, VT where 6 to 12 inches of
snow is possible. Following coordination with surrounding
offices, a Winter Storm Watch has been issued for these areas.
Elsewhere, snowfall amounts of 2 to 5 inches may be common
except from around the City of Albany and points south across
the Hudson Valley where a coating to 2 inches seems likely at
this time. Winter Weather Advisories will likely be needed in
future updates for some areas not included in the Winter Storm
Watch.

Behind the arctic front on Thursday, windy conditions are
expected to develop which will continue into Thursday night.
Wind gusts on the order of 30 to 40 mph are likely which could
lead to some blowing and drifting snow.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
Key Message:

- Confidence remains high (70 - 90%) for temperatures to range
  10 to 15 degrees below normal through next weekend. Friday
  will feature the coldest temperatures which when combined with
  blustery winds will result in feel-like temperatures in the
  single digits.

Strong cold air advection continues into Friday in the wake of
our Alberta Clipper with the incoming air mass 2 to 2.5
standard deviations below normal per the NAEFS. The tight
pressure gradient over the Northeast behind our departing
clipper within the cold air advection regime will support deep
boundary layer mixing and blustery winds into Friday.
Probabilistic guidance shows 20 to 40% chance for wind gusts to
exceed 30mph across the region with chances increasing to 40 to
70% in the eastern Catskills, Taconics, southern Greens,
Berkshires, and Litchfield Hills. Probabilities are highest in
the morning before trending down through the afternoon. Given
daytime temperatures struggling to rise out of the 20s, it will
feel more like single digits. Otherwise, lake effect snow
showers Friday morning exits south of the Mohawk Valley as low
and mid-level flow shifts anticyclonically becoming
northwesterly.

The break in lake effect snow looks short-lived as the incoming
high builds to our south, re-establishing zonal flow and
promoting lake effect and upslope snow showers Friday night into
Saturday for the western Adirondacks and southern Greens.
Elsewhere, mainly dry and chilly on Saturday, albeit not as cold
as Friday, and winds turn lighter. A weak sfc low pressing
through Ontario lifts a warm front through the Northeast on
Sunday but marginal moisture and forcing limits POPs to just 15
to 25% for areas north and west of Albany.

Temperatures trend milder for the new work week as an amplifying
trough in the Central CONUS leads to downstream ridging and
southwest flow over the Northeast. While strengthening
isentropic lift ahead of the approaching warm front will likely
lead to a period of widespread precipitation, exact timing is
still uncertain. Thus, placed 40 - 60% POPs across the region
for Monday. With temperatures trending milder, expecting a
rain/snow mix with snow more likely for higher terrain areas
1000ft+.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
As of 12 UTC/03, BKN-OVC cigs with ceilings 3.5 - 5kft at all
terminals this morning as stratocu clouds off Lake Ontario
spread across the region. MVFR cigs have formed at PSF and will
remain in place through the day. The rest of the terminals
likely remain low-end VFR through the day under BKN-OVC cigs. A
few flurries or brief light snow shower possible at ALB, POU,
and PSF from 18 - 00 UTC but there is low confidence on the
exact placement of any one snow shower impacting a terminal so
only enough confidence to included VCSH. Stratocu cigs give way
to clearing by 00 to 03 UTC/04. Otherwise, light and variable
winds early this morning become west-northwest by 15-17 UTC and
sustained 5-8kts with gusts up to 15kts. Winds turn lighter and
shift to the northwest by 00 - 03 UTC/04.

Outlook...

Wednesday Night: High Operational Impact. Breezy. Definite SN.
Thursday: High Operational Impact. Windy With Gusts To 32 kts. Definite SHSN...SN.
Thursday Night: Moderate Operational Impact. Windy With Gusts To 31 kts. Chance of SHSN.
Friday: Low Operational Impact. Breezy. NO SIG WX.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: Low Operational Impact. Slight Chance of SHSN.
Saturday Night: Low Operational Impact. Slight Chance of SHSN.
Sunday: No Operational Impact. NO SIG WX.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Winter Storm Watch from Wednesday afternoon through late
     Thursday night for NYZ032-033-038-082.
MA...None.
VT...Winter Storm Watch from Wednesday evening through late
     Thursday night for VTZ013.

&&

$$

SYNOPSIS...Rathbun
NEAR TERM...Rathbun/Speck
SHORT TERM...Rathbun
LONG TERM...Speciale
AVIATION...Speciale