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Area forecast discussion 
National Weather Service Burlington Vermont
444 am EDT Wednesday may 27 2015

Synopsis...
there is a chance for rain showers across the north country this
morning. Strong to severe thunderstorms are likely across Vermont
and northern New York this afternoon. Some thunderstorms will
produce locally heavy rainfall...strong gusty winds...small hail
and frequent lightning. There is a chance for rain showers on
Thursday as a cold front moves through the region. Drier weather
is expected across the north country Thursday night and Friday.

&&

Near term /until 6 PM this evening/...
as of 432 am EDT Wednesday...composite radar loop already showing
some scattered showers across the northern Champlain Valley and
northern Vermont at this time. Expecting conditions to destabilize
by early this afternoon with convective available potential energy values ranging from 500-1500
j/kg this afternoon. 0-6km bulk shear will be around 30-40 knots
this afternoon. Also...BUFKIT forecast soundings showing
precipitable water values will range from 1.5 to 1.9 inches across
the region this afternoon...so locally heavy rainfall will be
possible with these thunderstorms. Strong gusty winds will also be
the main threat with any thunderstorms that develop. Wet bulb zero
levels are above 11000 feet...so feel any hail reaching severe
criteria looks marginal at this time. Have used the btv 4km model
for timing as to when thunderstorms will develop and move through
the region this afternoon. Storm Prediction Center has the region in a slight risk for
severe thunderstorms today.

&&

Short term /6 PM this evening through Thursday night/...
as of 432 am EDT Wednesday...expecting any thunderstorm activity
to be mainly over eastern and southern Vermont early this evening.
Expecting a lull in shower activity overnight...before more shower
activity develops toward daybreak on Thursday as a cold front
moves through the region. Expecting temperatures to be mainly in
the 70s for highs on Thursday under cloudy skies. Have gone a bit
above MOS guidance for min temperatures tonight...as air mass will
still be warm and fairly humid. Have also gone with a slight
chance for thunderstorms on Thursday from the Champlain Valley
eastward. A ridge of high pressure will build in the region
Thursday night and Friday...with fair and dry weather expected.

&&

Long term /Friday through Tuesday/...
as of 430 am EDT Wednesday...another active day is expected on
Saturday afternoon/evening associated with surface cold front and potential
for showers and thunderstorms. The magnitude/intensity of storms
will depend upon frontal passage time...which models still
disagree on. GFS is showing frontal passage during peak heating Saturday
afternoon with surface based cape values between 1000 and 1500 j/kg...while
European model (ecmwf) is 6 to 12 hours slower and has less instability. Will
continue to mention chance to low likely probability of precipitation for this time
period...with the potential for some strong to severe
thunderstorms. Latest trends off the GFS continue to show the best 500 mb
vorticity associated with digging middle/upper level trough...approaching our
western County Warning Area during maximum instability...along with a sharp surface cold
front. If this timing would verify...a line of storms would be
likely...with wind profiles suggesting bowing line segments as the
primary convective Mode. Will continue to monitor latest timing for
potential changes in the forecast...but Sat afternoon/evening looks active.
Still some lingering showers on Sunday morning...before surface high
pressure builds into our County Warning Area. This will result in surface boundary
dropping south of our forecast area...into the Middle Atlantic States along with
best forcing/moisture. Will keep Sunday afternoon through early next
week dry at this time. Prognosticated 850 mb temperatures between 14-16c support highs well
into the 80s on Saturday...but will drop sharply by Sunday into
Monday...as prognosticated 850 mb temperatures fall back into the single digits.
Have noted latest mex has a 28f for slk on Monday morning...which
looks reasonable given clear skies...light winds...and prognosticated low level
thermal profiles. Some frost highlights maybe needed.
Otherwise...temperatures will rebound to near normal levels by middle week
with highs back into the 70s to near 80f.

&&

Aviation /09z Wednesday through Sunday/...
through 06z Thursday...scattered strong to severe thunderstorms
will impact our taf sites this afternoon. VFR conditions will prevail
overnight into Wednesday morning...with a light shower possible at
slk/mss. Expect showers/storms to increase in areal
coverage/intensity after 16z today...with periods of IFR ceilings/visible
in the heavier storms. In addition...any storms will be capable of
strong and gusty outflow winds...which will create areas of low
level turbulence and wind shear. Dangerous cloud to ground and
cloud to cloud lightning will accompany the storms this afternoon.
Expect activity to shift east of our terminals by 00z
Thursday...with generally improving conditions expected. Some
patchy fog/br will be possible toward 04z at slk/mpv.

Outlook 06z Thursday through Sunday...
additional storms will be possible Thursday across our
central/southern taf sites of mpv/rut/btv with a period of
MVFR/IFR conditions. Surface high pressure with VFR conditions develop on
Friday...before another front with more storms occur on Sat afternoon
into Saturday evening. These storms will contain localized gusty
winds...brief heavy down pours...and frequent lightning.

&&

Marine...
as of 432 am EDT Wednesday...strong to severe thunderstorms will
develop across the region this afternoon. Some thunderstorms may
produce locally heavy rainfall...strong gusty winds...small hail
and frequent lightning. A lake thunderstorm advisory for Lake
Champlain may be needed this afternoon. If threatening weather
approaches...seek safe Harbor immediately. Winds and waves will be
locally higher in the vicinity of any thunderstorms. There is also
a chance for some rain showers this morning.

&&

Btv watches/warnings/advisories...
Vermont...none.
New York...none.

&&

$$
Synopsis...wgh
near term...wgh
short term...wgh
long term...Taber
aviation...Taber
marine...wgh

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