Brattleboro, Vermont 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

101
FXUS61 KALY 210907
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
407 AM EST Thu Nov 21 2024

.SYNOPSIS...
Today will feature widespread rain, with a change to
snow expected in the higher terrain tonight. Several inches of snow
accumulation will be possible in the Catskills, with up to a few
inches in higher terrain of the Adirondacks and southern Greens also
possible through tomorrow night. Precipitation tapers to valley rain
and high-elevation snow showers for the weekend, with continued cool
and breezy conditions.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
*Winter Weather Advisory now in effect for Schoharie County, as
 well as for Western Greene and Western Ulster Counties, from 4
 PM Thursday through 1 AM Saturday*

As of 4:05 AM EST...Occluded sfc low is currently located over
the northwestern Great Lakes region, and is nearly vertically
stacked beneath a potent upper low. The system`s occluded front
is currently located across central NY, extending southeastwards
through NY. A wave of low pressure has already developed along
this front beneath the left exit of the upper jet, and should
continue to deepen today is it tracks northwards towards Long
Island. Current radar imagery shows widespread rain along and
ahead of this front, which is now currently advancing
northeastwards into the Capital District, southern ADKs, and
southern Berkshires. Temperatures and dew points are mainly in
the 40s, so precipitation will begin as plain rain even for the
high terrain. Widespread rain is expected today, possibly
changing to wet snow in the high terrain of the Catskills this
afternoon and early evening as the upper low slides over the
Ohio Valley and into PA, allowing cold air to wrap into the
deepening surface low. Rain will be mainly moderate through the
day today, with a few brief bursts of heavier rain.
Nevertheless, with such dry antecedent conditions, flooding does
not look to be a concern. Today will be several degrees cooler
than yesterday, with highs in the 40s for the valleys and
temperatures dropping into the 30s for the high terrain.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
Rain changes to snow tonight in the high terrain, with several
inches of accumulation possible in the Catskills...

Tonight, the upper low tracks from PA into the NYC/Lower Hudson
Valley area. The surface low continues to deepen below 990 mb
as it gets captured by the upper low and abruptly takes a turn
to the west/northwest tonight, moving over the Mid to Lower
Hudson Valley by 12z Friday. Precipitation remains mainly rain
in the valleys, but the high elevations see a switch to snow
with colder air wrapping into the surface low from the
southwest. Once the low becomes vertically stacked late
tonight/tomorrow morning, it will begin to weaken and
precipitation becomes more showery, remaining rain in the
valleys and mostly snow in the high terrain. For valley areas, a
widespread 1 to 1.5" of liquid precip is expected, which should
help with ongoing drought conditions and fire weather over the
past few weeks.

Unfortunately, there remains some forecast uncertainty regarding
how far north and west the surface low will get pulled overnight
tonight. Today`s guidance shifted slightly further to the east
and slightly south with the track of the surface low. This could
reduce potential dry slotting issues cutting down on qpf in the
Mid Hudson Valley, while the shift to the east would also allow
for the colder air to make it further east. Will continue to
monitor trends through the day today regarding the surface low
and adjust accordingly for impacts on qpf and snowfall amounts.

The snow could come down heavily at times tonight in the
Catskills. The setup is not a perfect match to the pivoting snow
band conceptual model developed through collaborative CSTAR
research with SUNY Albany, although many of the necessary
elements are there in the synoptic setup tonight. low to mid-
level FGEN max looks to set up over or just west of the
Catskills as the sfc low backs in tonight, with the 700 mb low
tracking over or just south of the Catskills. This would shift
the best banding potential and highest snowfall rates just
west/southwest of our Catskill zones, which is supported by the
WPC snowband probability tool. Nevertheless, this remain a
dynamic system with plenty of potential for diabatic cooling and
E/SE low-level flow to lead to enhanced snowfall totals across
the higher terrain of western Greene and Ulster Counties. While
we do have warning-level criteria snowfall across portions of
these areas, we did not have enough geographic coverage of these
higher-end amounts to warrant upgrading the advisory to a
warning. The heaviest snows will likely occur near the Big
Indian Wilderness, Slide Mountain Wilderness, and Hunter
Mountain where up to 10" of snow will be possible. The snow will
be of a wet, heavy consistency initially with rations less that
10 to 1, so the weight of the snow could lead to some downed
tree limbs possibly resulting in power outages.

Friday night through Saturday...Upper low slides off the NJ
coast in tandem with the vertically stacked sfc low. With moist
cyclonic flow aloft wrapping around the upper low, we will
continue to see cloudy skies and scattered valley rain/high-
terrain snow showers, but these should diminish in coverage and
become lighter through the period. One potential adjustment to
previous forecasts that will need to be watched is the potential
for an additional period of rain/snow across western New England
Friday night or Saturday as yet another sfc low develops off the
east coast and tracks towards New Brunswick. If this were to
occur, as some sources of guidance now show, then additional
light snow accumulations would be possible in the southern
Greens. Otherwise, we should see a gradual drying trend Saturday
afternoon aside from some light lake effect rain/snow showers in
the western ADKs and western Mohawk Valley. Friday night will
feature lows in the 20s to 30s, with Saturday`s highs in the 30s
(terrain) to 40s (valleys), which will be similar to Friday`s
high temps.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Vertically stacked low pressure will be well off the east coast into
Nova Scotia to start the long term period, though its effects will
still be felt across the region as we close out the weekend.
Lingering moisture and lift wrapping around the low in northwest
flow will continue to work across the Northeast Saturday night into
Sunday, and will keep rain and snow chances in place. The best
chance of precipitation will be mainly in the western Mohawk Valley
and ADKs in the lake effect belts, though low chances (20-40%) are
in place for areas north of the Mid Hudson Valley with CVA moving
into the region. Sunday will be quite breezy as well with gusts
around 25-35 MPH as a tight pressure gradient between the departing
low to the east and building high to the west will be in place.
Temperatures will be quite chilly with highs ranging from the 30s
in higher elevations to mid/upper 40s in valley locations.

We get a brief break in the weather Sunday night into daytime Monday
with high pressure quickly skirting across the area from southwest
to northeast. However, yet another round of low pressure will follow
for the region Monday night and Tuesday with a mix of rain & snow
expected. Chances have increased in this fcst (50-80%), though the
exact amount of precipitation expected remains uncertain.
Temperatures will start out above normal with highs Monday and
Tuesday ranging from around 40 (terrain) to low 50s (valleys) before
falling into low 30s (terrain) to low 40s (valleys) Wednesday.

Deterministic solutions diverge heading into the Thanksgiving
holiday, though some suggest active weather with chances of rain &
snow will persist as another robust system passes near the area.
Look for additional changes to this period in subsequent fcst.

&&

.AVIATION /09Z THURSDAY THROUGH MONDAY/...
Through 06Z Friday...Most sites to see VFR initially, but this will
begin to change over the next several hours as a system brings a
steady rain across the region. Expect conditions to deteriorate with
the rain`s arrival, with MVFR/IFR ceilings and visibilities expected
by daybreak. These conditions will persist through the remainder of
the period at all terminals as the system slowly traverses the area.
Light & variable winds initially will increase out of the east to
northeast around 10 kts after daybreak, and will shift to the
northwest mainly at KPOU/KALB as the surface low nears the terminals
late in the period. KPSF will also see LLWS late in the period with
a 40-50 kt LLJ passing near the terminal.

Outlook...

Friday Night: Moderate Operational Impact. Chance of SHRA.
Saturday: Moderate Operational Impact. Breezy. Chance of SHRA.
Saturday Night: Moderate Operational Impact. Breezy. Chance of SHRA.
Sunday: Low Operational Impact. Breezy. NO SIG WX.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: No Operational Impact. NO SIG WX.
Monday Night: High Operational Impact. Likely SHRA.
Tuesday: Moderate Operational Impact. Breezy. Chance of SHRA.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Winter Weather Advisory from 4 PM this afternoon to 1 AM EST
     Saturday for NYZ047-058-063.
MA...None.
VT...None.

&&

$$

SYNOPSIS...Main
NEAR TERM...Main
SHORT TERM...Main
LONG TERM...Speck
AVIATION...Speck