Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
1241 am EST Friday Mar 6 2015
a strong ridge of high pressure will move across the
north country overnight...resulting in clear skies...light
winds...and cold temperatures. Lows will be below zero in many
location by Friday morning. A sunny but chilly day is expected on
Friday...before our next weak clipper system arrives with snow
showers on Saturday and breezy south winds.
Near term /until 7 am this morning/...
as of 1238 am EST Friday...clear skies...light winds...and
subsidence with surface ridge in place providing excellent radiational
cooling for the remainder of the night. Looking at low
temperatures well below zero in most sections including around
-20f in the northern Adirondacks and colder valleys of far northestern Vermont and
-3f to -8f in the Champlain Valley.
Short term /7 am this morning through Saturday night/...
as of 300 PM EST Thursday...water vapor continues to
show the northeast Continental U.S. Being influenced by the northern stream
jet...which will result in below normal temperatures and chances for light
precipitation events. On Friday...surface high pressure overhead at 12z...will
shift into eastern New England with a return southerly flow
developing by evening. Prognosticated 850 mb temperatures warm from -20c to -14c by
00z Saturday...with full sun will support highs in the l/M 20s
warmer valleys to M/u teens in the mountains have trended a couple
degrees warmer than guidance...based on good mixing associated with
plenty of March sunshine. Next northern stream short wave energy and
associated ribbon of enhanced 850 to 500mb moisture approaches our
western County Warning Area by 06z Saturday. As with many clipper like
systems...moisture will be limited with precipitable waters values between 0.20 and
0... in a light accumulating snowfall. Snowfall will
range from a dusting to several inches in the mountains. Will
mention likely probability of precipitation northern dacks into the mountains of
central/northern Vermont...with chance elsewhere.
NAM/GFS show prognosticated 850 mb winds of 30 to 40 knots from the
west/southwest ahead of this system...resulting in downslope
shadowing in the cpv. Also...expect some enhanced channeling of
the surface winds...especially across the Saint Lawrence and
central/northern Champlain Valley. Temperatures will be tricky on Friday
night...with developing southerly winds and clouds...thinking
early evening lows...with temperatures warming after midnight. Coldest
values near -10f will be in the Northeast Kingdom with +10f in the
southern Saint Lawrence valley. Highs Saturday will warm into the
20s most locations with maybe a spot 30f in the warmer urban areas
of the Champlain and Saint Lawrence valleys. Cooler temperatures return
for Saturday night into Sunday...with departing snow showers and
Long term /Sunday through Thursday/...
as of 312 PM EST Thursday...still looks like a rather uneventful
extended period with a few weak shortwave troughs moving through
Sunday/Monday producing a little light snow, followed by dry
weather and a another taste of Spring for mid-week.
Overall, the upper level pattern becomes less amplified moving
through the weekend which results in a more zonal and fast flow
aloft. Several shortwave troughs zip through the flow, specifically
a weak one Sunday and a slightly stronger one on Monday, both likely
producing some light snow but with a lack of moisture snow totals
will be on the low side. After Monday, the north country will get a
nice taste of Spring as high pressure develops over much of the middle-
Atlantic and northeast states and slowly drifts eastward. The
resulting southerly return flow will usher in temperatures at and
above normal for Tuesday through Thursday with highs in the 30s and
40s under partly cloudy skies.
While i've gone with a dry forecast for middle-week, it should be noted
that we'll be on the edge of a middle-level thermal boundary with
energy passing just north of the international border both Wednesday and
Thursday. Can't rule out some light precipitation occurring, but will go
more optimistic for now.
Aviation /06z Friday through Tuesday/...
through 06z Saturday...VFR conditions persist with only exception
at kslk having chance for ice crystals forming and deteriorating
visibilities to MVFR. Have included a tempo from 08z-10z. Otherwise,
ridge axis over the region keeps mostly clear skies over the
region with winds of 10kts or less through middle day. Kmss will
develop increasing gusts up to 20kts Friday afternoon in SW flow.
Increasing high and middle level clouds expected in the evening
Outlook 06z Saturday through Tuesday...
O6z Saturday - 12z Saturday...VFR under high pressure.
12z Saturday - 06z Tuesday...periods of MVFR/IFR in light snow as
several systems track through the region.
06z Tuesday - 00z Wednesday...VFR under high pressure.