000
FXUS61 KBTV 270221
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
1021 PM EDT Sat May 26 2018

.SYNOPSIS...
A backdoor cold front will drop south of the North Country this
evening as high pressure builds into northern Vermont overnight.
This will result in cooler temperatures and mainly dry conditions
overnight into Sunday with lows mainly in the mid 40s to upper 50s
and highs mid 60s to mid 70s on Sunday. A few showers with a
rumble of thunder is possible across the Saint Lawrence Valley
on Sunday afternoon. A few additional showers are possible on
Monday with temperatures mainly in the 70s.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
As of 1021 PM EDT Saturday...A few sites reporting fog at the
moment. There is some mid-level drying in forecast soundings and
a building surface high, so more patches of fog developing is
not out of the question, especially where recent light rains
have fallen. Cloud cover and forecast increase in winds
overnight should prevent most regions from seeing any widespread
or thick fog. Any lingering fog will quickly dissipate with
sunrise around 09Z. Other than adding patchy fog across all of
northern New York and Vermont, the rest of the forecast is
roughly on track with some tweaks to temperatures and dewpoints.

Previous Discussion...
Water vapor shows confluent northwest flow aloft across the ne
conus with subsidence/dry air building toward our northern cwa.
meanwhile...surface analysis shows boundary over southern VT
with building 1027mb high pres over northern Maine. This high
pres combined with weakening sfc boundary will create a brisk
925mb to 850mb east/southeast flow tonight into Sunday across
our central/eastern cwa. This flow will help to advect in
cooler/maritime airmass with low clouds possible, especially
east of the greens tonight into Sunday. Some patchy drizzle/br
is possible in the higher trrn. Otherwise...a widespread in
temps are anticipated with lows from the mid 40s with some
clearing nek to upper 50s cpv/southern slv. Developing southeast
winds of 10 to 20 mph with localized gusts to 25 mph likely
along the western slopes and parts of the eastern cpv toward
morning.

Sunday...The forecast challenge will be convective potential across
the Saint Lawrence Valley as guidance is still not in good agreement
with regards to heating/instability. The combination of sfc
convergence and weak embedded 5h vort in the flow aloft will
interact with some cape of 500 to 1000 j/kg over the slv to help
generate showers/isolated storms. Once again the lack of forcing and
instability will limit the areal coverage/intensity of convection on
Sunday. NAM shows northeast flow down the slv with temps only in the
60s, while GFS indicates southwest flow developing with some breaks
in the overcast, helping to warm/destabilize atmosphere. We will
continue to mention chc pops with schc for thunder on Sunday. Temps
will range from the mid/upper 60s eastern VT to mid 70s southern SLV
near Edwards. Thinking BTV starts near 60F at 7 AM and warms to near
70F by 2 PM on Sunday with southwest winds 10 to 15 mph with gusts
up to 20 possible. Expect dry conditions from the eastern dacks into
the cpv and all of vt on Sunday.

Sunday Night...surface analysis continues to show a cold air damming
signature with high pres located over northern Maine. This combined
with an inverted sfc boundary/warm front over the slv with some
energy aloft will mention schc pops west. Overall, expecting most
areas to be dry with the lack of forcing aloft and limited moisture.
Temps will be tricky with some clouds around, but lows generally in
the mid 40s east to 60f west.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
As of 336 PM EDT Saturday...Memorial Day looks to be quite on the
unsettled side as scattered showers and thunderstorms look
likely. On Monday, there will be a series of two shortwaves that
will pass across the international border of Northern Vermont
with both of these systems tracking across the region around
peak heating (18Z to 00Z). Temperatures will warm into the mid
70s to lower 80s during the early afternoon hours which will
help develop anywhere between 500 J/kg to 1000 J/kg of CAPE.
This CAPE combined with upper level support from the shortwaves
will help produce the aforementioned scattered showers and
thunderstorms. The one limiting factor will be a surface
boundary that will remain north and west of the North Country.
This feature would help pool moisture across the region but with
it being too far north and west, it looks looks like the
overall coverage of shower/t-storm activity will likely be
limited meaning that not everywhere will see precipitation on
Monday. There is also a small chance of a severe thunderstorm on
Monday, mainly across northern VT and northern NY, as those
locations should maximize moisture, lift and instability. The
shower and thunderstorm activity will taper off Monday night as
a stout upper level ridge will build across the area following
the second shortwave.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 336 PM EDT Saturday...Tuesday through Thursday look like
fantastic days across the North Country. If you find yourself
hanging around following the marathon this weekend, you will be
treated to sunny skies with high temperatures in the mid 70s on
Tuesday and warming into the upper 70s to mid 80s by Thursday.
Conditions will begin to deteriorate on Friday as the remnants
of subtropical storm Alberto will begin to influence our region.
Throughout the upcoming week, the remnants will track across
the Mississippi River Valley and then take a turn NE toward Ohio
and move toward the North Country on Friday. While models
continue to vary on the overall track, there is definitely a
common trend. All deterministic and ensemble means show the
remnants impacting us during the weekend at some point. The big
question is to how organized the precipitation associated with
this will be. There won`t be any super impressive boundaries or
anything but it looks like the moisture will latch onto a cold
front and move across the North Country over the weekend. With
PWAT values likely between 1.5 and 2.0 inches, it wouldn`t be
surprising to see some areas receive some locally heavy
rainfall. However, with the lack of organization by the time it
reaches us, it doesn`t look like a widespread heavy rainfall at
the moment. This does bare watching over the next week and we
will continue to know more with each subsequent model run.

&&

.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Through 00Z Monday...Other than some periods of MVFR/IFR
ceilings and visibilities at KPBG/KBTV/KMPV through 04z...VFR
conditions are expected through the period. Showers have come to
an end early this evening and next chance for any showers will
come after 18z at KMSS and KSLK. Winds will generally be under
10 knots tonight and then have an easterly component to
them...with gusts in the 15 to 25 knot range across Vermont.

Outlook...

Sunday Night: Mainly VFR, with local MVFR possible. Slight chance
SHRA.
Memorial Day: Mainly VFR, with local MVFR possible. Chance SHRA,
Slight chance TSRA.
Monday Night: Mainly VFR, with local IFR possible. Chance SHRA,
Slight chance TSRA.
Tuesday: VFR. NO SIG WX.
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. NO SIG WX.
Wednesday Night: VFR. NO SIG WX.
Thursday: VFR. Slight chance SHRA.

&&

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

&&

$$
SYNOPSIS...Taber
NEAR TERM...Evenson/Haynes/Taber
SHORT TERM...Clay
LONG TERM...Clay/SLW
AVIATION...Evenson/Taber