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000
FXUS61 KBTV 250804
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
404 AM EDT Thu May 25 2017

.SYNOPSIS...
Gusty downslope winds are expected today, especially across the
southern and central western slopes of the Green Mountains with
isolated power outages possible. A band of light rain will lift
from south to north across the North Country today...with
rainfall amounts generally less than a quarter of an inch.
Steadier rain will redevelop tonight and continue into Friday.
The upcoming weekend with feature a dry Saturday with some
scattered showers possible late Sunday into Monday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 402 AM EDT Thursday...Wind advisory in effect from 11 AM Thursday
to Midnight for localized gusts to 50 mph along the central and
southern western slopes of the Green Mountains.

Forecast concerns today are winds...followed by timing of light rain
showers. Water vapor shows deep closed full latitude mid/upper level
trof across the Ohio Valley with strong feed of deep layer moisture
over the eastern conus. Surface analysis places 994mb low pres over
central Ohio this morning...with developing gradient associated with
departing 1015mb high pres and increasing 925mb to 850mb wind
profiles.

Winds are tricky today...as local btv 2 and 4km...along with the
latest 3km NAM show some uncertainty in magnitude and areal coverage
of strongest wind fields. Unlike the wind event on May 5th, the
925mb to 850mb winds are 10 to 15 knots weaker on all
solutions...along with weaker low pres and departing high pres. BTV
2km and Nam 3km continue to show strongest core of 925mb winds of 45
to 55 knots across central/southern Greens between 18z-00z today.
Investigating sounding data closely shows bottom of the mix layer
around 40 to 42 knots at Rutland...but thinking with some downslope
warming and better mixing...some slightly stronger gusts are
possible. This thinking also matches the surface gust potential off
the NAM 3km...which shows values between 40 and 45 knots across the
central/southern western slopes of the Green Mountains...but values
quickly taper off over the northern Greens...as core of strongest
925mb winds weakens. Thinking gusts between 45 and 50 mph looks good
from just east of Danby to Wallingford to just east of Rutland to
East Middlebury with 35 to 45 mph for Nashville/Underhill areas.
Some isolated power outages possible...along with some downed small
trees and limbs...but less impact than the May 5th event.

Models in good agreement with band of warm air advection rain
showers lifting from south to north across our cwa between 15z and
20z today. Expecting a 2 to 4 hour window of mainly light rain
showers...which will be highly terrain driven in terms of qpf
placement...given the low level wind fields. Qpf will range from
<0.10 along the downsloping regions of the western slopes/eastern
CPV/NEK and western dacks...with a 0.25 or so on the southeast
upslope areas of the eastern dacks/southeast greens. The initial
surge of favorable lift/upper level divergence will be north of our
cwa by 20z today...resulting in much less areal coverage of precip
and mainly over the se upslope regions.

Meanwhile...water vapor shows potent 5h vort in the flow aloft over
central NC...will help to enhance shower/storms across the mid
Atlantic States this aftn. This deeper moisture and stronger lift
will help to redevelop another round of rain showers aft 06z
tonight. Expecting heavier qpf values with amounts between 0.25 and
0.50...mainly CPV and points east.

Temps mainly upper 50s to upper 60s today and holding in the 50s
overnight with clouds/precip.

&&

.SHORT TERM /FRIDAY/...
As of 445 PM EDT Wednesday...During the day Thursday, vertically
stacked low pressure system will slowly track from the Ohio
river valley Northeastward towards our CWA. Light rain will
spread southwest to northeast across our forecast area,
especially after 15z. Low pressure system then tracks off the
coast of New England overnight and into the Gulf of Maine on
Friday. Two areas of deeper low level moisture will miss us, one
to our Northwest and one to our Southeast. Have lowered rainfall
totals a bit, mainly a third of an inch to an inch of rain is
expected. GFS is showing an evident dry slot moving across our
area from 18z through about 03-06z. During this time will see
some winds mix down to the surface on strong low level
east/southeast jet, strong Easterly flow will cause downsloping
in Rutland County as well as Eastern Addison and Eastern
Chittenden counties. Have issued a wind advisory, please see
NPW. As low pushes east off the New England coast Friday best
forcing goes with it and precipitation will become more showery.
Temperatures will remain mild through the period, generally 50s
at night and 60s during the day.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
As of 340 PM EDT Wednesday...The synoptic pattern will be
shifting towards a more pleasant weekend as vertically stacked
low pressure system will be pulling off the New England
coastline. This leaves a few scattered showers over the eastern
portion of Vermont as the moisture will be decreasing through
the evening hours. The more welcomed portion of the forecast
will be the high pressure that builds in for Memorial Day
weekend. As ridging occurs at the surface there may be a stray
shower or two but otherwise we can expect highs in the upper 60s
to lower 70s with partly cloudy skies with a few breaks in the
that areal coverage.

The latest trends in the guidance has been to slow down how
quickly the next system is to move into the region. In the broad
sense, an upper level low pressure system will track west of
the Great Lakes and lift a warm front through the North Country
and then later on will swing a cold front through. The timing on
this has been even further delayed such that we may get through
much of Sunday with quiet weather and nice conditions to be
outdoors or perhaps going for a run.

Towards Sunday evening and into Monday morning, expect that
warm front to lift north and bring a chance for scattered
showers into Monday. By Monday mid-morning early afternoon a
pre- frontal trough will swing through with shortwave energy
aloft and bring showers with perhaps some embedded
thunderstorms. The GFS depicts decent instability with marginal
elevated instability along with decent 0-6km shear and moderate
lapse rates. So the idea of some showers with embedded
thunderstorms looks good based on the 12z guidance timing.
Heading into the rest of the mid week we should see a break on
Tuesday before the actual front swings through on Wednesday
renewing our chances for showers.

Temps through the period will be depend on the timing of the
fronts but the general idea is upper 60s to lower 70s for high
and lows starting off in the upper 40s over the weekend and
gradually warming to the low to mid 50s by mid week.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
Through 06Z Friday...Aviation concerns will be gusty southeast
winds at Rutland today...followed by lowering cigs with some
mvfr conditions expected by this evening. As low pres
approaches...gusty southeast winds will develop with localized
gusts to 40 knots possible at Rut between 17z-01z today. Expect
areas of moderate to severe turbulence...especially near the
terrain. Meanwhile...a ribbon of rain will move from south to
north across our taf sites btwn 15-21z with mainly vfr
conditions...trending toward mvfr cigs at mpv/mss/pbg by 00z
this evening. As winds shift to the north...expect lowering cigs
at btv/rut by 06z Friday. Downslope southeast flow will keep
vfr conditions at rut/btv through today. Additional showers are
expected to redevelop aft 04z tonight and continue into Friday.

Outlook...

Friday: VFR/MVFR. Likely SHRA...RA.
Friday Night: VFR. Slight Chance SHRA.
Saturday: VFR. Slight Chance SHRA.
Saturday Night: VFR. NO SIG WX.
Sunday: VFR. Chance SHRA.
Sunday Night: VFR. Chance SHRA...TSRA.
Memorial Day: VFR/MVFR. Chance SHRA...TSRA.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Wind Advisory from 11 AM this morning to midnight EDT tonight
     for VTZ011-017>019.
NY...None.

&&

$$
SYNOPSIS...Taber
NEAR TERM...Taber
SHORT TERM...Neiles
LONG TERM...Deal
AVIATION...Taber