Scientific Forecaster Discussion
fxus61 kbtv 190745
Area forecast discussion
National Weather Service Burlington Vermont
345 am EDT Fri Apr 19 2019
a strong warm front will continue to lift across the north
country tonight with scattered showers and breezy south winds.
These winds and precipitation will result in mild overnight
lows. This same boundary will become stationary across the
region on Friday into Saturday with several rounds of showers
developing, which combined with melting snow pack will cause
sharp rises on local waterways. The heaviest rainfall with
the greatest threat for flooding will be across northern New
York into northern Vermont, including the Northeast Kingdom late
Friday into Saturday. Additional scattered showers are likely
Saturday night into Sunday.
Near term /through Saturday/...
as of 956 PM EDT Thursday...showers have re-blossomed over
portions of the forecast area this evening. Especially across
northern New York and the Northeast Kingdom of Vermont. High
resolution guidance continues to indicate that showers will be
around for much of the night therefore have continued the
mention for chance showers across entire area. Otherwise, going
forecast remains in good shape.
Previous discussion...gusty winds have developed across
portions of northern New York and the Champlain Valley this
afternoon with localized gusts 45 to 50 mph being observed near
the lake. In addition, these winds have bumped very warm airmass
into the slv with temperatures approaching 70f this aftn. For
tonight, we continue under moderate 925mb to 850mb waa
associated with 45 to 55 knots south/southwest flow. Progged
850mb temps approach 12c by 06z Friday with 925mb temps btwn
13-15c. The combination of winds and clouds will hold temps
mainly in the upper 40s to mid/upper 50s in most locations,
except cooler conditions east of The Greens. Water vapor shows
several weak embedded short waves in the fast progressive flow,
with deepest 850 to 500mb rh fields from northern New York into
northern VT, so have continued to mention chc/likely pops.
General qpf will be 0.10 to 0.20 in the heaviest activity. Have
not mention thunder, but would not be surprised of a rumble or
two over northern NY, as weak elevated instability develops by
Short term /Saturday night through Sunday night/...
as of 343 am EDT Friday...a vertically stacked low will be
pulling through the mid Atlantic region Saturday night into
Sunday. As it does a dry slot will push into parts of northern
New York and Vermont. This should lead to a brief window overnight
where the rain lets off and conditions start to quiet down a
bit early Sunday morning.
As the low pressure system starts to tighten up a bit Sunday
afternoon, we could see some redevelopment of some shower
activity which would move through northern New York into
Vermont but we'll have to wait and see whether the forcing would
be strong enough.
Both Saturday evening and Sunday will be be warm. Expect lows
each night in the upper 40s to low 50s and highs on Sunday in
the mid to upper 60s under mostly cloudy skies. These warm temps
will likely continue to melt snow into the river so while the
rate of rise will be significantly less, we'll still
unfortunately be adding some snow melt runoff to some of the
northern river basins.
Long term /Monday through Thursday/...
as of 343 am EDT Friday...the beginning of next week will start
off showery as the upper level low pressure system starts a
slight north easterly push. Guidance is still a bit all over the
place with how this unfolds but the general idea is that we'll
see some scattered showers through Monday and Tuesday while the
middle of the week is starting to look a bit drier. As high
pressure returns for the middle of the week we'll also see temps
return much closer to normal with highs through the middle of
the week back in the low to mid 50s and lows pushing back
towards freezing. Median date for the last Spring freeze is may
1 for the Champlain Valley so is a bit early any frost/freeze
worries, however any ambitious folks in the Champlain Valley may
need to take precaution to protect sensitive crops.
Aviation /08z Friday through Tuesday/...
through 06z Sunday...variable aviation conditions expected
across the area over the next 24 hrs. Currently mainly VFR
conditions with some IFR/localized LIFR ceilings over central
and eastern Vermont. Slow moving frontal boundary north and west
of the forecast area will sag south today, leading to moderate
to locally heavy rainfall and generally deteriorating flight
conditions. St. Lawrence Valley will see precipitation onset
and associated MVFR conditions between 10-12z, Champlain Valley
and northwestern Vermont 16-19z, and southern and central Vermont after
21z. Gusty southerly winds 10-20 kts with gusts 20 to 30 kts in
the Champlain Valley will lessen to 5-15 kts overnight. The
exception to this will be kbtv, which will see gusts 20 to 30
kts continue through 10z. There are some areas of low-level wind
shear through 12z as a 50+ kt low level jet moves through the
area. Winds after 12z will generally be 5-12 kts and of variable
directions as a slow moving front wavers over the area.
Saturday: MVFR/IFR conditions possible. Chance rain showers.
Saturday night: mainly VFR, with local MVFR possible. Chance
Sunday: VFR. Chance rain showers.
Sunday night: VFR. Chance rain showers.
Monday: VFR. Chance rain showers.
Monday night: mainly VFR, with local MVFR possible. Chance rain showers.
Tuesday: mainly MVFR, with local IFR possible. Chance rain showers.
as of 332 PM EDT Thursday...a Flood Watch continues for the
entire north country.
We continue to expect a moderate to locally heavy rainfall
event heading into the weekend, especially northern New York into
northern VT, with sharp rises anticipated on many rivers and
streams. Several main Stem rivers are expected to reach minor
flood stage with the potential for moderate flood stage for some
of the northern rivers with higher snow melt. In addition,
embedded higher rainfall rates could produce an isolated flash
flood threat during this time period, especially across complex
terrain of the Adirondacks into mountains of Vermont.
Specific river rises will be dependent on exactly where the
heavy rainfall occurs so please follow the latest rainfall and
river forecasts for flooding. Main Stem rivers most at risk
for flooding include the Passumpsic, the Wells, the missisquoi,
the LaMoille, the Winooski, the ausable, and the Saranac rivers.
Sharp river rises will begin Friday afternoon, with most rivers
expected to crest on Saturday.
Additionally, Lake Champlain continues to slowly rise with current
levels over 99 feet. With strong southerly winds today, there
may be some minor splash over effects due to wave action.
Additionally its possible that Rouses Point could reach minor
flood stage this afternoon as the seiche occurs. With the
additional rain fall and snow melt this weekend the Lake
Champlain level will likely approach or exceed 100 feet this
weekend or early next week.
Those with interests in low-lying or flood prone areas should
continue to monitor the latest forecasts.
Vermont...Flood Watch from this evening through Sunday morning for
New York...Flood Watch from this evening through Sunday morning for