Area forecast discussion
National Weather Service Burlington Vermont
746 am EDT Monday may 20 2013
Synopsis...
an active weather pattern is expected across the north country
this week...with several rounds of rain anticipated with a few
thunderstorms possible. Showers exit the region this
morning...with mainly dry conditions expected this afternoon and
tonight...but periods of rain return by Tuesday and continue right
through Thursday. High pressure and drier conditions return
Thursday night and continue into the weekend.
&&
Near term /until 6 PM this evening/...
as of 652 am EDT Monday...quick update to increase probability of precipitation slightly
across northern zones...otherwise previous forecast in good shape.
Still dealing with some isolated to scattered showers across
portions of the north country this morning as a frontal boundary
moving through the County Warning Area has stalled across our northern tier
counties. While this boundary will remain stalled across the area
through today...overall low/middle level moisture thins so expect
showers to generally dissipate as skies become partly/mostly
cloudy. Still a chance for a couple isolated showers across
central and southern Vermont this afternoon with forecast
soundings showing a few hundred joules of cape...but overall
conditions should remain fairly dry. Above normal temperatures continue
today with mean 925mb temperatures of +14-18c supporting highs in the middle
to upper 70s.
&&
Short term /6 PM this evening through Wednesday/...
as of 418 am EDT Monday...stalled frontal boundary remains over
the north country during the short term period and will be the
focus for periods of rain and possible thunderstorms through
Wednesday. Looking at a dry night tonight as an upper level ridge
builds into the region...but overall conditions will remain fairly
cloudy as low/middle level moisture increases as shortwave energy
ejecting out of a broad upper trough across the central Continental U.S.
Approaches. It will be quite a mild night with increasing
southerly flow and cloud cover contributing to lows only in the
50s to locally 60s in the Champlain Valley.
A prolonged period of rain begins Tuesday and continues into the
long term as several waves of low pressure move along the
aforementioned frontal zone draped from the Great Lakes through
the btv County Warning Area and into New Hampshire and Maine. Expected to see numerous
showers through the period with chances for thunderstorms during
the afternoon hours with surface instability increasing to over
1000 j/kg across portions of the area. A gradual warming trend is
expected through the period as well with Tuesday highs in the
lower to middle 70s warming into the upper 70s to lower 80s for
Wednesday. Mild overnight lows also continue Tuesday
night...generally in the 50s to near 60.
&&
Long term /Wednesday night through Sunday/...
as of 344 am EDT Monday...the long-term forecast period begins
active as positive tilt 500mb trough is expected across the Great
Lakes region Wednesday night with an area of low pressure across
southeastern Ontario along moderately strong frontal zone stretching west-southwest-
east-northeast just north of our international border. The overall evolution through the
extended is similar between the 00z GFS and 00z European model (ecmwf)...with the
00z European model (ecmwf) just a bit faster.
North country begins in the warm sector Wednesday night with surface low
tracking along frontal boundary near/just north of the international border.
Should make for a mild night with lows in the upper 50s to lower 60s.
Showers are likely...especially across northern Vermont and northern New York where probability of precipitation
are near 70 percent. Lower probability of precipitation across S-central Vermont further removed
from projected frontal zone.
During the day Thursday...frontal zone settles southeastward across the north
country as a cold front...and surface low tracks eastward into NH/Maine. 00z
GFS model indicates and the synoptic pattern supports at least weak
instability along the frontal boundary ... so carried a period of
likely probability of precipitation with a chance of thunderstorms with frontal passage. Highs
Thursday should generally be in the middle 70s...warmest across the CT
River Valley with later arrival of frontal boundary based on present
indications. Gradually clearing expected for Thursday night. May see
some patchy fog given wet conditions Tuesday-Thursday and radiational cooling
Thursday night. Lows Thursday night mainly in the 40s...with a few
lower 50s in the Champlain Valley.
Cooler and drier conditions return Friday as large area of high
pressure builds southeastward across Ontario and the Great Lakes region
bringing north-northwest low-level flow to the north country. Anticipate
clearing skies and generally pleasant conditions Friday with valley
highs 65-70f. High pressure should generally remain in control as it
drifts eastward across the region bringing mainly dry weather conditions through
next weekend. Weak shortwave trough in northwest flow brings a slight
chance of a shower Saturday afternoon or Saturday night...mainly across
northern/northestern Vermont. Don/T foresee anything significant in terms of precipitation
amts with this feature given expected dryness of low-level air mass.
Temperatures will remain near to slightly below climatological
averages with highs in the middle-upper 60s. Prospect for good
radiational cooling at night should bring lows low-middle 40s for most
areas...but locally down to 35f in the northern Adirondacks and the more
sheltered valley locations east of the Green Mountains
&&
Aviation /12z Monday through Friday/...
through 12z Tuesday...surface trough shifting southeastward across the
north country will bring scattered rain showers to the taf sites
through 16z. At krut...showers will remain possible as boundary
pushes into S-central Vermont this afternoon. Ceilings and visibility conditions
will be highly variable this morning...but trending VFR this afternoon
and through tonight.
Prevailing conditions are a mix of primarily VFR and MVFR
ceilings...with ceilings 1-2 kft currently at rut. Currently ovc008 at
slk...and these low ceilings will be maintained for another 2-3
hours. The low clouds begin to break up after 14-15z with daytime
heating/mixing...and have all sites trending VFR between 15-18z.
Winds initially SW early this am. A weak northwesterly wind shift will
occur during Monday afternoon with trough passage...with speeds
generally 5-7 kts. For Monday night...mainly looking at bkn060-100
with light wind conditions.
Outlook 12z Tuesday through Friday...active period of weather
Tuesday through Thursday. A warm front brings widespread rain with
embedded thunderstorms Tuesday afternoon and Tuesday night. Anticipate periods
of MVFR and brief IFR conditions during this time frame. Very warm
and moist air mass in place for Wednesday. Anticipate additional
round of thunderstorm activity Wednesday afternoon into Wednesday night
with periods of MVFR conditions. Should begin to dry out Thursday
night into Friday with mainly VFR conditions during the time frame
as dry low-level northwesterly winds develop.
&&
Btv watches/warnings/advisories...
Vermont...none.
New York...none.
&&
$$
Synopsis...lahiff
near term...lahiff
short term...lahiff
long term...banacos
aviation...banacos
