157
FXUS61 KBTV 182317
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
717 PM EDT Wed Jul 18 2018

.SYNOPSIS...
High pressure building over the region continues to bring dry
and seasonable weather through the end of the week. A chilly
night is anticipated tonight with lows in the mid 40s to mid
50s. Temperatures return to above normal values by the end of
the week, along with increasing chances for rain showers by
Sunday.

&&

.NEAR TERM /THROUGH THURSDAY NIGHT/...
As of 717 PM EDT Wednesday...Current forecast remains in great
shape as we head into the evening hours. Only appreciable change
was to reduce the time frame and areal coverage of mist/fog
later tonight in favored river valleys/hollows of the
Adirondacks and eastern VT. Perusal of data suggests most spots
will have trouble reaching crossover T thresholds and with only
marginally supportive hydrolapse rates feel that coverage will
be fairly minimal. Have a great evening.

Prior discussion...
Large ridge of surface high pressure will continue to ridge
into the North Country overnight, and crest over the area on
Thursday during the daytime hours. This results in dry and quiet
weather for our area through the near term. Tonight we will
have clear skies and light winds, and temps will drop quickly
following sunset. With sharp low level thermal inversions in the
coldest pockets of the Dacks and Northeast Kingdom, the coldest
spots will drop into the upper 30s. Most of our area will have
low temps bottoming out on the mid 40s to mid 50s, around 60
closer to Lake Champlain. Some spots should still hit cross over
despite afternoon dewpoints dropping into the 30s now,
especially Saranac Lake area. Think it will generally be some
patchy fog in some of the typically fog prone spots. Dry weather
will continue on Thursday with almost a repeat day of today.
Surface high will crest overhead on Thursday, so winds will be a
bit lighter than Wed. Anticipate mostly sunny skies Thursday,
generally upper 70s to lower 80s. Thursday night will also be
dry and clear, with mainly light winds. High pressure begins to
slide eastward though, so not as cold as tonight, temperatures
will generally be in the mid 40s to mid 50s.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
As of 332 PM EDT Wednesday...High pressure will continue to be
the primary influence for Friday`s weather with dry conditions
prevailing. Thicknesses will continue to rise and 925mb temps
will climb to about 23C. This will translate to high
temperatures in the upper 80s across the St. Lawrence/Champlain
Valley with 80s elsewhere, excepting the higher mountain areas
where highs will be in the 70s. Friday night lows will be warmer
than Thursday night as southerly winds slowly increase the
dewpoint. Expect lows in 50s across the Adirondacks and in the
Northeast Kingdom and upper 50s/lower 60s across the valleys.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 332 PM EDT Wednesday...After another dry day on Saturday,
high pressure will begin to yield to a large upper low digging
from the Dakotas into the Ohio River Valley. Heights will begin
to fall as the upper low approaches, but the upper low begins to
meander as it becomes cut-off. Forecast depictions of the
dynamical tropopause beautifully show the stratospheric air and
the associated PV anomaly induce stronger southerly flow ahead
of the upper low and influence the development of a surface
feature along the east coast. The upper low weakens into an open
wave as it barely moves across the area with our CWA also
positioned at the periphery of an anomalously strong Bermuda
High.

This will lead to an enhanced stream of moisture with
disturbances cycling northward ahead of the upper low. The first
passes nearby on Sunday with a surface feature and a warm front
that gets dragged northward. Some uncertainty regarding this
feature remains with the latest GFS, ICON, and FV3 runs sending
the disturbance further eastward, which will likely keep the
best precipitation chances to our east with the initial surge of
moisture. Not much instability is currently forecast with the
first system on Sunday with the main forcing mechanism being the
developing warm front and isentropic upglide. So no mention of
thunder there for now. From there, the unsettled weather pattern
will continue through at least Wednesday with the weakening
upper trough replaced by a new upper trough, helping to maintain
moist, southwesterly flow. There will be some instability, so
storms can be expected Monday through Wednesday, with the
greater chances during the daylight hours.

Temperatures will remain above average, especially overnight
low temperatures. Somewhat cooler conditions are expected Sunday
as southeasterly flow brings in some cooler maritime air and a
warm front is lifted northward. Temperatures will then warm
again Monday with Tuesday and Wednesday looking similar to
Monday.

&&

.AVIATION /23Z WEDNESDAY THROUGH MONDAY/...
Through 00Z Friday...Prevailing high pressure will maintain
VFR and generally SKC all terminals. Only exception could be
brief nocturnal fog at MPV/SLK; carried tempo groups for 1SM BR
at those two sites only, from 07-11Z Thursday. Winds will
become light and variable after sunset. At BTV, will see winds
become 260-280deg around 7kt after 15Z and persisting thru the
daylight hrs on Thursday.

Outlook...

Thursday Night: VFR. NO SIG WX.
Friday: VFR. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. NO SIG WX.
Saturday Night: Mainly VFR, with local MVFR possible. Chance
SHRA.
Sunday: Mainly MVFR, with areas VFR possible. Chance SHRA.
Sunday Night: Mainly VFR, with areas MVFR possible. Chance SHRA.
Monday: MVFR/IFR conditions possible. Chance SHRA, Chance TSRA.

&&

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

&&

$$
SYNOPSIS...Neiles
NEAR TERM...JMG/Neiles
SHORT TERM...Haynes
LONG TERM...Haynes
AVIATION...Banacos