687
FXUS61 KBTV 231744
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
144 PM EDT Mon Sep 23 2024

.SYNOPSIS...
Stationary high pressure across New England will remain in place
through Tuesday. An approaching frontal system from the Great Lakes
region will spread mid and upper level clouds across the North
Country today, along with a chance for light rain showers across the
St. Lawrence Valley. A stronger upper level low will finally bring a
wetting rain to the region Wednesday into Thursday. Temperatures
will slowly trend downward over the next several days, but generally
remain above average for late September.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 127 PM EDT Monday...Radar continues to show an area of
light showers moving eastward through our forecast area. Given
some shallow dry air at the surface (dewpoint depressions
around 15 degrees), most areas will just see some light
sprinkles, but some accumulating light rain of a few hundredths
is possible especially over the Adirondacks. Otherwise,
forecast is on track with temperatures in eastern Vermont
already having moderated as expected.

Previous discussion...High pressure will continue to dominate
across the region today while a weakening shortwave trough
approaches from the Great Lakes. Fairly widespread shower activity
associated with the trough can be seen marching eastward into
eastern Ontario/western NY early this morning. The question remains
how long this precipitation can hold together as it encounters the
persistent ridge and drier airmass over our region. While hi-res
guidance is somewhat mixed on how extensive shower coverage will be,
expect at least a few showers will make it into the St Lawrence
Valley a bit later this morning. Have increased PoPs just a bit
through early afternoon across St Lawrence County with isolated to
widely scattered activity seems most likely. Regardless, any showers
will be light with just a few hundredths of rainfall expected. From
the Adirondacks eastward, main impact from the trough will be ample
cloud cover with perhaps just a few sprinkles west of the Champlain
Valley. This increased cloud cover will serve to keep temperatures a
bit cooler than previous days; highs will generally6 be in the mid
60s to around 70F. A tightening pressure gradient between the
weakening trough and resident ridge will keep south to southeast
winds a little on the breezy side, generally 5 to 10 mph with gusts
around 15 mph.

Any showers that do make it into the St Lawrence Valley will
dissipate late this afternoon and evening, with dry weather expected
through the remainder of the near term period thereafter. Clouds
will lessen overnight, and anticipate partly to mostly clear skies
by daybreak Tuesday. Clouds will begin to increase again late
Tuesday ahead of our next system, especially across northern NY.
After lows mid 40s to mid 50s tonight, the increased sunshine on
Tuesday will allow temperatures to warm into the upper 60s to low
70s.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/...
As of 310 AM EDT Monday...Tuesday night into Wednesday will start
with a warm front trying its best to push against our persistent
dry, high pressure. There will be a shortwave riding over an upper
ridge axis along coastal England that will slowly give way. With a
pocket of deep moisture associated with the shortwave, we will
observe a surge of precipitation lift northwards and exit north
along the international border midday. There should be a brief break
in precipitation heading into Wednesday night. Breezy southeast to
southerly flow is expected as well with gusts 15 to 25 mph. With
rain showers and the developing warm front, it`ll be a fairly cool
day. Some locations east of the Greens may struggle to climb above
60, while the rest of the region should at least lower to mid 60s.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
As of 310 AM EDT Monday...Models are in great agreement, despite a
relatively complicated set up. An upper low across the Mississippi
River Valley will fail to phase with the northern stream trough and
rather begin to interact with a developing tropical cyclone. So a
strong northern stream upper low will dive southeast across the
North Country Wednesday night into Thursday bringing additional
rounds of showers until the attendant surface low and potent cold
front dive southeast Thursday night. Higher moisture fluxes will
remain south as the future tropical systems gets entangled with the
upper low across the lower Mississippi River Valley. In the wake of
the cold front, strong mid- level ridging will build over the weekend
and shunt any tropical moisture away from our region. Despite the
strength of the cold front, the brunt of cold advection will be to
our east, and so we will likely end warmer behind the system simply
from the lack of cloud cover and increasing thicknesses with mid-
level ridging. So the weekend is shaping up to be a gorgeous one
across the region, with near to slightly above normal temperatures
in the mid 60s to lower 70s during the day and 40s to lower 50s at
night.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Through 18Z Tuesday...Widespread VFR conditions are expected
throughout the TAF period with just some BKN-OVC mid/high
clouds. Overnight fog tonight is not expected to be widespread,
and have elected to keep it out of the TAFs at this time.
Thinking is that with the pressure gradient remaining overhead,
we`ll see enough wind just off the surface to prevent dense fog
development at any of our TAF sites. However, some BR with
occasionally reduced visibilities is possible. Winds will remain
from the south through this afternoon at 5-10 knots, becoming
light and variable tonight, and then resuming from the
south/southeast 5-10 knots Tuesday morning.

Outlook...

Tuesday Night: VFR. Slight chance SHRA.
Wednesday: Mainly MVFR, with areas VFR possible. Chance SHRA.
Wednesday Night: Mainly MVFR, with local IFR possible. Likely
SHRA.
Thursday: MVFR/IFR conditions possible. Chance SHRA.
Thursday Night: Mainly VFR, with local MVFR possible. Slight
chance SHRA.
Friday: MVFR/IFR conditions possible. NO SIG WX.
Friday Night: Mainly VFR, with areas MVFR possible. NO SIG WX.
Saturday: Mainly VFR, with local MVFR possible. NO SIG WX.

&&

.MARINE...
As of 315 AM EDT Monday...A Lake Wind Advisory is in effect
through this afternoon. South winds of 15 to 25 kt will persist
through midday, with the strongest winds occurring over the
broad lake. Wave heights of 3 to 5 ft can be expected on the
broad lake, with 1 to 3 ft elsewhere.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.

&&

$$
SYNOPSIS...Hastings
NEAR TERM...Duell/Hastings
SHORT TERM...Haynes
LONG TERM...Haynes
AVIATION...Duell
MARINE...Hastings