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Area forecast discussion 
National Weather Service Burlington Vermont
328 PM EDT Fri Aug 26 2016

Synopsis...
fair and seasonably warm weather will prevail across the region into
Sunday as high pressure dominates the sensible weather pattern. The
next chance for scattered showers will occur by later Sunday into
Sunday evening as a weak front crosses the area. Behind this system
a return to fair and dry weather is expected for early next week.

&&

Near term /through Saturday/...
as of 245 PM EDT Friday...a quiet 24-hour stretch of weather is
expected across the area as surface high pressure across southern
Canada combines with deep subtropical upper ridging over the
southeastern states to provide broad-scale subsidence and mainly
clear skies. Other than some patchy mist/fog across favored
locales later tonight skies should be mainly clear through the
period with no rain expected. Temperatures generally a blend of
bias-corrected model output offering overnight lows in the 50s to
near 60 and highs on Saturday from 78 to 85 or so under moderate
humidity levels. Winds light.

&&

Short term /Saturday night through Sunday night/...
as of 327 PM EDT Friday...

The mid-level pattern beginning on Saturday night will
feature geopotential height rises from an anomalous ridge
centered over the mid--Atlantic states. Increasingly more neutral
to weak mid-level height falls are then anticipated later Sunday
into Sunday night associated with more unsettled weather.

Saturday night: much of the area should remain dominated
by subsidence associated with building 500 mb heights. The
one exception will be along the outer periphery of the ridge
primarily across St. Lawrence County and along the Canadian
border counties where at least mid to high-level cloudiness is
expected. Due to the spatial differences in cloud cover, expect
central and southern areas to remain locally cooler with more
radiative cooling versus the more cloud-covered areas. Lows
should run about +5 to +10 degrees warmer than normal - in the
50s to mid 60s.

Sunday: mid-level ridge axis begins to shift eastward with
variable cloud cover increasing through the day. I suspect that
precipitation chances through the first part of the day to be
limited given neutral heights and lack of a good trigger, with
chances ramping up into the high-chance range for the afternoon.
NAM-based instability values are in the 500 j/kg range with Li's
barely negative so there is a limited potential for thunder,
with mainly showers predominating. Since areas to the south are
likely to see more early breaks, i've raised highs up some in
this area and correspondingly lowered them to the north. Highs
should then range in the upper 70s to mid 80s, above 30-year
climo normals by a couple degrees.

Sunday night: ongoing showers and/or thunderstorms to
progress eastward through midnight with pops decreasing into the
slight chance range, with a weak/nebulous frontal passage
anticipated during the overnight. 925 mb temps still around +18c
by 12z Monday and mostly cloudy skies keep temperatures in the
upper 50s to mid 60s.

&&

Long term /Monday through Friday/...
as of 327 PM EDT Friday...

500 mb shortwave trough associated with frontal passage
moves through early Monday with lingering slight-chance pops
trending dry by Monday afternoon. 12z GFS/European model (ecmwf) guidance then
point to a pattern change in mid-levels across North America,
with amplified ridging building into central North America and a
cyclonic gyre setting up across the northeastern states beginning
around the end of August.Temperatures begin around 30-year climo
normals to end August,closing what has proven to be a warm
meteorological Summer across the north country, with a trend near
to below normal by early September as upper low and its thermal
trough overspread the area.The more active period of weather in
the extended is around Wednesday with a seasonably strong frontal
passage heralding the change toward cooler-than-normal temps.
Given the amplified nature to the upper-level pattern by mid-
week, I generally sided closer to the slower and cooler European model (ecmwf)
idea into Thursday and Friday.

&&

Aviation /19z Friday through Wednesday/...
through 18z Saturday...VFR through the period with mainly scattered
cumulus bases in the 035-045 above ground level range through 00z, then sky clear.
Patchy IFR/LIFR br/fg possible at kmpv/krut/kslk in the 06-12z
time frame tonight. Mixed signals on potential br/fg occurrence
given dry advection regime with MOS-based guidance most bullish.
Confidence moderate on occurrence but given morning rainfall, at
least some added low level moisture input will be present
overnight with light winds aloft. Winds generally light west to
northwesterly 5-10 kts through 00z, then light and variable
thereafter.

Outlook 18z Saturday through Wednesday...

18z Saturday through Wednesday...mainly VFR through the period
with high pressure. Two main threat periods for scattered showers
and brief MVFR conditions - Sunday afternoon/evening, then again
Tuesday afternoon/evening with weak trough passages.

&&

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

&&

$$
Synopsis...jmg
near term...jmg
short term...loconto
long term...loconto
aviation...jmg

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