Area Forecast Discussion
Issued by NWS Burlington, VT-- Highlight Changed Discussion --
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FXUS61 KBTV 281814
Area Forecast Discussion
National Weather Service Burlington VT
214 PM EDT Fri Apr 28 2017
-- Changed Discussion --Clearing skies tonight will give way to more clouds before
sunrise as a cold front approaches the region. The front will
produce another chance for showers Saturday, followed by
noticeably cooler temperatuers Sunday. More chances for rain
enter the forecast early next week as a low pressure system
moves through the Great Lakes region.
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.NEAR TERM /THROUGH SATURDAY/...
-- Changed Discussion --As of 155 PM EDT Friday...Clouds decreasing this afternoon
behind the weak front. Surface dewpoints have dropped from the
50s into the 40s, while temperatures have rebounded into the
70s. Clear skies to persist for the first half of the night,
then moisture advances into the region at the mid levels in
advance of the next surface front. The forecast area is under
the influence of 500mb westerly flow between high pressure
centered off the mid atlantic coast and a trough over northern
Quebec. Shortwave trough will sweep through southern Quebec to
help move the surface front through.
Dry forecast tonight, with southerly winds much of the night
recovering from today`s cold front. Lows generally in the 50s
in the Champlain valley and 40s elsewhere. The shortwave trough
passes Saturday morning, with low level winds turning westerly
and chance pops mainly central/southern portion of forecast
area. Saturday the front pushes south from the Canadian border
about mid day, and westerly winds turn northerly with cold air
advection beginning. There will be time for mid day high temps
to warm into the 60s before the cooldown begins.
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.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 330 AM EDT Friday...some differences have cropped up
amongst the 00z suite of models with regard to the
strength/depth of cold air that comes in from the north Saturday
night behind the cold front, and then the resulting speed of
warming later on Sunday as that front lifts back north as a warm
front. In addition, differences exist with how much precip will
fall (and exactly where) associated with overrunning with the
warm front. In a nutshell, the NAM is 10-15 degrees colder than
the GFS for Sunday`s temperatures. The NAM also has a batch of
rain come across late Saturday night/early Sunday morning
associated with the initial warm air advection push. Up to now,
we`ve been advertising dry weather for that period. The GFS
indicates increasing clouds, but is dry. Don`t think the NAM is
right about the precip, but I think it`s on to something with
colder temperatures on Sunday given it`s slightly better near
surface vertical resolution and support from the ECMWF for
cooler temperatures. With plenty of clouds and shallow low level
northerly winds continuing to advect cool temperatures for at
least half the day, it makes sense to go cooler. I dropped
temperatures from the previous forecast about 6 to 8 degrees,
but that might not be enough. Needless to say, not very high
More consensus for areas of showers or just a steady rain to
develop across northern areas Sunday night in association with
the warm front setting up just north of the border along with
strong isentropic lift thanks to strengthening low/mid level
southwest winds. NAM and ECMWF are fairly robust on rainfall
amounts along the border Sunday night, on the order of 1" by
early Monday morning. GFS is much much less. At this point,
thinking 0.30-0.45" along the Int`l border by 12z Monday.
.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 330 AM EDT Friday...00z suite of models is still in
pretty good overall agreement with the scenario for early to mid
week. Thus stuck with the model blend, which isn`t much
different than what we had in the forecast. Going day by day...
Monday: we should be in the warm sector, with the warm front
just to our north. However close enough that we`ll have plenty
of clouds and showers around. Some instability sneaks in across
northern NY by the afternoon, so isolated t-storm is not out of
the question. Pretty strong pressure gradient sets up, so breezy
southerly winds (especially in the Champlain Valley) are
expected. Monday night a surface trough will move through the
region, accompanied by a band of showers. Decent moisture tap,
so some briefly heavy downpours are possible. A bit of
instability as well, so a rumble or two of thunder is not out of
the question. Does move through quickly, so I don`t think we
are looking at any significant hydro concerns, but still enough
to monitor as we go through the weekend.
Tuesday/Wednesday: Longwave trough settles across the region,
with deep west/northwest flow and low level moisture about.
Means plenty of clouds, scattered showers and a bit breezy at
times. Cooler air filters in slowly later Tuesday and Wednesday,
so Tuesday should be above normal for highs, but closer to or
slightly below for Tuesday.
Thursday: Weak ridging tries to develop, so lesser threat of
any showers, but still expect a good amount of clouds.
Unfortunately another developing storm system will be moving
toward the region from the south later in the day. So even if we
have any sunshine, clouds will win out by later in the day.
Though beyond the period for the forecast, Friday could feature
a good amount of rain and perhaps some wind. GFS and ECMWF begin
to significantly diverge at that point, so way more questions
than actual answers. It`s still a week away, so nothing to worry
about right now.
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
Through 12Z Saturday...VFR conditions will persist outside
isolated and brief period of MVFR cigs at KMPV and KMSS through
late this morning. Strong gusty winds channeling up the St
Lawrence Valley will see SW gusts up to 30kts today. Other
terminals could also see gusts of 15-25kts.
Winds subside overnight to less than 10kts with increasing and
lowering clouds, but remaining VFR. Showers expected to approach
late in the period, ahead of a cold front.
Saturday: VFR. Breezy. Slight Chance SHRA.
Saturday Night: VFR. NO SIG WX.
Sunday: VFR. Slight Chance SHRA.
Sunday Night: MVFR. Chance SHRA.
Monday: VFR/MVFR. Breezy. Likely SHRA.
Monday Night: VFR/MVFR. Likely SHRA...TSRA.
Tuesday: VFR. Breezy. Chance SHRA.