Scientific Forecaster Discussion
fxus61 kbtv 172318
Area forecast discussion
National Weather Service Burlington Vermont
718 PM EDT Thu Oct 17 2019
deep low pressure will slowly depart across Maine overnight,
allowing precipitation to become lighter and more intermittent,
along with a gradual decrease in northwesterly winds. Cloud
cover and seasonably cool temperatures will persist on Friday,
with light to moderate northwest winds. Surface high pressure
building in from the Great Lakes will bring moderating
temperatures and increased potential for sunshine over the
weekend. The next chance for widespread rainfall arrives with a
frontal system on Tuesday into Tuesday night.
Near term /through Friday night/...
as of 340 PM EDT Thursday...weather conditions are gradually
settling down this afternoon as deep surface low (978mb) slowly
fills as it moves from central New Hampshire eastward across southern Maine
this evening and overnight. Have cancelled both the Wind
Advisory and Flood Watch with this package. Per mosaic composite
reflectivity, continue to see steady light rain across nern New York
and the Champlain Valley at 1930z, a function of synoptic-scale
deformation zone and Champlain Valley convergence on northerly
low-level flow. Rainfall rates have decreased below 0.10"/hr,
and additional precipitation through tonight will increasingly
become orographic in nature as deep layer flow becomes nwly
areawide. As this occurs, precipitation will become
increasingly showery and intermittent (with patchy drizzle in
spots), especially in valley locations. Across the highest
elevations, will continue to see snow accumulation, generally
above 3000' elevation this evening, and above 2500' overnight.
Could see 1-3" along the highest summits of the green mtns, and
localized amounts 6-12" across the highest summits of the
Adirondacks, where snow has been progress much of the day. No
wintry impacts expected for populated areas.
Under overcast skies with continued stratus layer in place,
temperatures will be relatively uniform overnight, ranging from
the upper 30s to lower 40s for overnight lows below 2000'
Will see continued northwest flow on Friday, but at lighter speeds
(generally 10-20 mph winds). Appears low stratus deck will be
very slow to clear, and may see a few spotty rain showers (or
higher Summit snow showers) in northwest flow at times, especially
across nern Vermont. High temperatures on Friday mainly mid 40s to
High pressure gradually builds ewd from the Great Lakes Friday
night, and should see partial clearing with increased
subsidence. Lows generally ranging from the 28-32f range across
nrn NY, and generally in the low-mid 30s for lows across
Short term /Saturday through Saturday night/...
as of 404 PM EDT Thursday...on Saturday the northwest flow aloft and
at the surface slackens off as a ridge of high pressure moves in
from the west. Sat starts out with rather chilly with 925 mb temps
around zero but warm 3 or 4 deg c by afternoon. With the northwest flow
still expect some upslope cloudiness, but that should dissipate with
more sun is expected during the afternoon. High temps will get back
into the low to mid 50s, close to normal for this time of year.
Skies should start out mainly clear Saturday night with ridging
aloft and at the surface, but some high clouds are possibly late at
night/early Sunday morning as the ridge aloft breaks down and low
pressure develops along the mid-Atlantic coast. Lows mainly in the
upper 20s to lower 30s.
Long term /Sunday through Thursday/...
as of 404 PM EDT Thursday...the main action in the long term comes
from a negative tilt upper trof and surface frontal system sometime
late Tuesday into early Wednesday with some showers and windy
Right now Sunday looks to be fair with some high clouds but will be
keeping an eye on weak short wave trofs moving through the region
and a a low pressure system forecast to move off the mid-Atlantic
coast eastward and out to sea. At this point we should remain dry
with highs above normal in the 50s and lows in the 30s Sunday night.
On Monday a building upper level and surface ridge moves in behind
sunday's short waves with mostly sunny skies. 925mb temperatures
climbing back to 8-10c with above normal highs into the upper 50s to
Tuesday into Wednesday a negative tilt upper level trof and
associated frontal system will approach and move through the region.
There are some timing differences between the GFS and European model (ecmwf) with the
ec slower keeping the area dry on Tue while the GFS brings showers
in on Tuesday. So Tuesday is looking mostly dry but have some chance
pops for the east and likely to the west for mainly later in the
day. The front moves through Tuesday night into Wed morning with
showers with the ec showing over an inch of rain while GFS is less.
Wed/Thu temps depend on how fast the front moves in/out but have
highs mainly in the 50s and lows in the 40s.
Fair weather returns on Thursday as ridging aloft and at the surface
returns. Highs again a bit on the mild side with readings in the 50s.
Aviation /23z Thursday through Tuesday/...
through 00z Saturday...rainfall is beginning to become lighter
across the north country as a surface low tracks eastward. This
should help visibilities remain between 7 and 10 statute miles
through the overnight period. Ceilings, on the other hand, will
be tricky. MVFR ceilings in the range of 1500 to 2500 ft look
pretty common but there will be some isolated IFR mixed in. The
area with the highest likelihood of this IFR will be kslk so
have included mention just prior to midnight. Winds will remain
elevated through the overnight period with the Champlain Valley
holding onto gusts in the 20 to 25 knot range while elsewhere
should see winds in the 8 to 14 knot range. Winds will increase
again slightly on Friday but will likely cap out at around 25-28
knots. Lingering shower activity is expected through Friday
morning but the impacts on terminals should be negligible as
rain rates will be very low.
Friday night: VFR. No sig weather.
Saturday: VFR. No sig weather.
Saturday night: VFR. No sig weather.
Sunday: VFR. No sig weather.
Sunday night: VFR. No sig weather.
Monday: VFR. No sig weather.
Monday night: VFR. No sig weather.
Tuesday: mainly MVFR, with areas VFR possible. Chance rain showers.
as of 340 PM EDT Thursday...the Flood Watch has been cancelled
as new flooding is no longer expected. Rainfall rates across
western Vermont and the Adirondacks will gradually lessen below
0.10"/hr mid to late this afternoon as deep low pressure over
New Hampshire exits eastward across Maine. Storm total rainfall
amounts thus far have been heaviest from Essex County NY, sewd
across Addison/Rutland/Windsor counties in S-central Vermont. In
these areas, 2-3" rainfall totals over the past 24 hours have
been widespread, with localized totals in excess of 3" (see
recently issued public information statement for specific
amounts). Point Flood Warning continues for cenv1. All other
rivers should crest below bankfull, and rivers will begin to
recede late tonight. Elsewhere, have had reports of a couple
street closures owing to flooding in the towns of
Addison/Lincoln. Have issued a Special Weather Statement to
cover poor drainage and low-land flooding that may linger
through this evening.
as of 330 PM EDT Thursday...a lake Wind Advisory continues into
tonight. Wind gusts around 40 knots earlier today created wave
heights of 5 to 7 feet on Lake Champlain, per reports from Ferry
captains. Weakening pressure gradient on west side of departing
low is allowing winds to slowly decrease. Generally expecting
20 to 30 knots through midnight, and then 10 to 20 knots after
midnight with a few gusts to 25 knots. Wave heights will remain
3 to 5 feet this evening...gradually subsiding to 2 to 4 feet
late tonight. The highest winds/waves will occur across the
southern half of the Broad Lake. Those with recreational plans
on the lake should strongly consider postponing plans until
Friday or the upcoming weekend when wind and wave conditions
will be significantly better.