Area Forecast Discussion
Issued by NWS Burlington, VT

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056
FXUS61 KBTV 240801
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
401 AM EDT Tue Oct 24 2017

.SYNOPSIS...
A deep trough of low pressure over the Ohio Valley this evening will
shift into the Great Lakes tonight and Tuesday providing the
North Country with a windy and wet Tuesday and Tuesday night.
The rain will end from west to east during the early morning
hours on Wednesday, with total rainfall in the 1 to 2 inch range
over much of the area.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 129 AM EDT Tuesday...Overall forecast in good shape with
just a few tweaks to match the current conditions. Otherwise
will mainly see clouds increase...winds increasing...and
eventually precipitation chances increasing through the early
morning hours which is covered nicely in the going forecast.

Previous Discussion...
Big picture highlights strong high pressure anchored off the
eastern seaboard while a deep upper trough is digging into the
Ohio Valley this afternoon. As the low strengthens and shifts
north/northwestward into the Great Lakes, the attending frontal
boundary will tap into sub-tropical moisture from the Gulf of
Mexico, readily seen on today`s blended TPW products. Some of
this deeper moisture is already working into the region this
afternoon with surface dewpoints rising into the mid 50s, and a
low marine stratus layer working up the southern Champlain and
Connecticut River valleys. As the front tracks through the
region late tonight through Tuesday, the deep moisture combined
with strong surface to mid-level winds paralleling the front
will develop a band of moderate to locally heavy rain moving
over northern New York during the morning hours, and Vermont in
the afternoon and evening.

Ahead of the front, winds will continue to become increasingly
gusty with the mean 925mb flow from the south/southeast
strengthening to 40-50kts. With a more southerly component to
the direction versus southeast, true downslope effects won`t be
realized despite gusts in the 30-40mph range. The wind combined
with falling leaves could present an issue with clogged drains
in urban areas, especially considering QPF should be fairly
widespread in the 1-2" range. Rivers should be able to handle
the QPF, so don`t think we`ll have any concerns there.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 350 PM EDT Monday...Models continue to show the back edge
of precipitation associated with cold front exiting central and
eastern VT on Wednesday. With the 500mb trough lagging behind
flow will generally be parallel to the front, making for a more
gradual end to rain showers across central and eastern VT. SW
flow behind the front could also filter in moist air and clouds
from Lake Ontario with just a slight to low chance of some
showers over the Adirondacks into the Champlain Valley late
Wednesday into Wednesday night. The aforementioned 500mb trough
looks to swing through the area sometime Thursday, keeping
chance of showers over the North Country.

Temperatures running 5-10 degrees above normal Wednesday and
Wednesday night will cool to near to slight above normal on
Thursday.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 400 AM EDT Tuesday...Lingering showers/light rain will
then slowly exit eastern VT Thursday night as frontal wave pulls
through Maine to north of Quebec City by sunrise Friday.
Additional QPF of a tenth to a quarter inch will be possible in
these areas with mainly dry conditions across northern New York
as low tempertures range from the upper 30s to mid 40s.

Dry weather returns area-wide by Friday into Sunday morning as
expansive high pressure builds back across the eastern quarter
of the nation and into the western Atlantic waters. Partly
cloudy skies should be the general rule with best probabilities
of full sunshine occurring Friday afternoon. Temperatures will
remain mild, though not to the extent of our recent near-record
warmth as highs generally range from 56 to 64 and overnight
lows hold mainly in the 40s.

This morning`s global models continue to suggest that our next
system in the pipeline will arrive by later Sunday into Monday
as a slow moving frontal zone interacts with another deep
subtropical moisture plume bringing widespread rainfall,
possibly heavy, to the area. The 00Z ECMWF deterministic run
and corresponding Euro MOS guidance was unavailable for this
package, though leaned toward it`s 10/23/12Z idea showing a
slightly slower arrival of the main precipitation shield given
the meridional nature of the mean synoptic flow. Temperatures
will cool slightly given clouds and rainfall - mainly mid 50s to
lower 60s for highs and overnight lows Sunday night in the 40s.
Similar to today`s system, gusty south winds look probable once
again at some point Sunday afternoon/night.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
Through 06Z Wednesday...VFR conditions will continue overall
across the region through 12Z Tuesday, with the exception being
KMPV where marine MVFR stratus advecting northward will build
into eastern Vermont. After 12Z, lowering cigs shift into
portions of northern New York with band of heavier
showers shifting through KMSS from 16-20Z and KSLK from 18-22Z.
This band will continue to slowly advance eastward into the
early evening hours reaching KPBG/KBTV/KRUT after 20Z and KMPV
by 22Z or so. Rain will be quite heavy at times within this band
with MVFR cigs and MVFR/brief IFR visibilities. Isolated thunder
is also possible within the band but confidence remains low at
this time. Winds will continue to be very gusty south to
southeasterly from 12 to 22 kt and gusts from 25 to 40 kts ahead
of the band of heavier showers, especially east of KMSS in the
12-20Z time frame. This will create enhanced low level
turbulence on arrivals/departures, though runway-aligned flow
should preclude any crosswind threat.

Outlook...

Wednesday: VFR. Chance SHRA.
Wednesday Night: VFR. Chance SHRA.
Thursday: VFR. Chance SHRA.
Thursday Night: VFR. Slight Chance SHRA.
Friday: VFR. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. Slight Chance SHRA.

&&

.MARINE...
A lake wind advisory is in effect through at least Tuesday.
Winds will be from the south at 15 to 30 knots tonight, but
increase into the 25 to 35 knot range on Tuesday. Winds of this
magnitude will create rather choppy conditions, especially on
the northern portions of the lake, and waves will build into the
4 to 6 foot range by Tuesday.

&&

.EQUIPMENT...
MPV is not transmitting due to a communications outage. FAA is
aware of the problem. We do not have an estimated return to
service.

&&

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

&&

$$
SYNOPSIS...Lahiff
NEAR TERM...Evenson/Lahiff
SHORT TERM...KGM
LONG TERM...JMG
AVIATION...JMG
MARINE...Evenson
EQUIPMENT...BTV



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