FXUS61 KBTV 232318
Area Forecast Discussion
National Weather Service Burlington VT
718 PM EDT Sat Oct 23 2021
Quiet and seasonably chilly weather will continue through Sunday.
Then a very active period of weather begins early Monday morning
with widespread rainfall expected through Tuesday. This will be
followed by additional periods of rain for the latter half of
the week and then again next weekend. Temperatures will be
mainly near to above normal from Tuesday through the rest of the
.NEAR TERM /THROUGH SUNDAY NIGHT/...
As of 642 PM EDT Saturday...Expecting another chilly night tonight as
we remain under weak surface ridging overnight. Meanwhile, a weak
mid-upper level shortwave trough rotating eastward across the
Adirondacks and Champlain Valley, is associated with scattered
to broken mid-level clouds. Appears that as this feature shifts
east of VT, that there will be potential for better radiational
cooling after midnight under mostly clear skies. As such,
temperatures could fall more rapidly after midnight. Most
locations should see temperatures similar to last night, and
perhaps even a little colder for areas that see the fewest
clouds. Patchy/widespread frost will be possible with lows
dipping into the upper 20s to mid 30s. Should be within a degree
or two of freezing at BTV around daybreak, and slightly above
freezing along the shores of Lake Champlain with the moderating
influence of the warmer lake waters (water temperature still 59F
at Diamond Island and 60F at the USGS gage at Burlington).
The cooler and dry weather will continue on Sunday. A few showers
are possible over the St Lawrence Valley into the western
Adirondacks as flow turns more westerly/southwesterly ahead of the
approaching upper low, but any rain will be light given dry air in
place. Highs will be similar to today, mainly in the upper 40s to
lower 50s. Clouds will increase late in the day and then overnight
as a warm front begins to lift northward toward the region. Warm air
advection precipitation will spread from south to north after
midnight Sunday night. The increasing cloud cover will help keep
temperatures warm enough for the precipitation to fall as rain,
though the highest elevations will see mostly snow with perhaps an
inch of accumulation or so above 3000 ft by daybreak Monday. Can`t
rule out a bit of rain/snow mix in the higher terrain of the
Northeast Kingdom either, but no accumulation is expected. Overnight
temperatures will range from the lower 30s in the Northeast Kingdom
to the lower 40s in the wider valleys.
.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 321 PM EDT Saturday...A warm front will be lifting north
through the region Monday morning with light rainfall overspreading
the North Country from south to north. The 850 mb theta-e packing
seems marginal with the frontal boundary which should limit
convergence and lead to a light steady rainfall vs any type of
convective enhancement. Much of the North Country will be underneath
a "junky" warm sector during the afternoon hours on Monday with
several rounds of light rainfall falling from a low stratus deck. It
won`t be until late Monday night into Tuesday morning that we see
another solid round of rainfall begin to develop across the region.
This round of rainfall looks to be more prolific as southeast to
easterly flow in the low to mid- levels should advect some Atlantic
moisture into the region and a developing upper level low pressure
system tracks across the region.
During the overnight hours on Monday, a negatively tilted upper
level trough will approach the North Country from the west. A weak
surface low is expected to develop near Long Island Tuesday morning
with a triple point low developing east of Benchmark. The biggest
question is how long the surface low will survive near Long Island
as all indication points to the triple point low becoming the main
low pressure feature by late Tuesday. This will have a sizable
impact to rainfall and winds across the region. Rainfall will
overspread the region Tuesday morning but we will have to wait and
see if we can be in the sweet spot to see some frontogenetic
enhanced rainfall on the northwest side of the low pressure system.
It is interesting to see how the evolution of this system resembles
that of a Nor`easter but still shows subtle differences within the
vertical column. Rainfall amounts will range from about 0.75 to 1.25
inches with the rainfall from Monday and Tuesday with higher amounts
possible should we enter the sweet spot for a brief period on
Tuesday. We will see rainfall taper off after midnight on Tuesday as
the upper level trough amplifies further south and we see significant
dry air stream into the region from a Canadian continental airmass.
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 321 PM EDT Saturday...All signs currently point to PoPs
dwindling throughout the day on Wednesday with dry weather in store
for Thursday. We aren`t expecting any significant rainfall like we
may see on Tuesday but could see some showers produce up to a
quarter of an inch of rain across eastern Vermont throughout the
day. A brief extension of surface high pressure centered near James
Bay should bring us a dry day on Thursday and Friday but this will
be short lived as another amplified upper level trough will bring
increasing rain chances increase Saturday.
The potential for a strong storm system will exist on Saturday and
Sunday with a strong upper level trough and upper level low tracking
across the Ohio Valley. There is a lot of uncertainty to how this
system will evolve with some models hinting at rapid cyclogenesis
off the east coast (looking at you 00Z ECMWF) while others depict a
weaker feature tracking across Pennsylvania and New York. There will
be a high likelihood of rainfall late Friday into Sunday given the
low tracks on all deterministic guidance at this time with the
potential for moderate to heavy rainfall on Saturday. There is just
too much model disagreement to even try to mention rainfall totals
or the potential for strong downslope winds (it`s possible) at this
time. Regardless, next weekend is shaping up to be less than ideal
for outdoor activities and we will be watching this system closely
over the next several days to see what impacts may be seen across
the North Country.
.AVIATION /23Z SATURDAY THROUGH THURSDAY/...
Through 00Z Monday...Mainly VFR to prevail through the TAF
period, with local MVFR fog possible at SLK, MPV, and RUT from
about 09Z to 12Z. Otherwise, few to broken cloud deck 3500-5000
ft or above 10000 ft will be the rule through the forecast
period. Winds 3 to 6 knots, generally out of the northwest, but
variable at times before 12Z, then at SLK and MSS, switching to
more west to southwesterly beyond 14z.
Sunday Night: Mainly VFR, with local MVFR possible. Chance RA.
Monday: Mainly MVFR, with local IFR possible. Likely RA.
Monday Night: Mainly MVFR, with local IFR possible. Likely RA.
Tuesday: Mainly MVFR, with local IFR possible. Definite RA.
Tuesday Night: Mainly VFR, with areas MVFR possible. Likely RA.
Wednesday: VFR. Chance SHRA.
Wednesday Night: VFR. Slight chance SHRA.
Thursday: VFR. NO SIG WX.