Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
639 am EST sun Mar 1 2015
light snowfall accumulations are expected across the area from
this afternoon through Monday with a weak system passing through
New England. High pressure ridges back over the area from Monday
night through early Tuesday. Another low pressure system passes to
our west on Tuesday night bringing a wintry mix of precipitation
to the area from Tuesday afternoon through Wednesday afternoon.
Another ridge of high pressure builds over the area towards the
end of the week.
Near term /until 7 PM this evening/...
as of 624 am EST Sunday...did not make any significant changes
for 630 update this morning. Precipitation continues to spread
northeastward and is on track to move into our region this
afternoon. Previous discussion follows.
Increasing clouds this morning ahead of approaching light
precipitation moving northeastward from the Ohio River valley.
Warm front lifts north across our forecast area and warm air
advection light snowfall is expected to be widespread across the
north country. Deeper moisture and heavier precipitation will
remain across southern New England. Quantitative precipitation forecast totals for our area will
range from around a tenth of an inch to a few tenths of an inch.
Expect some downsloping effects in the Champlain Valley due to
shadowing with the southwesterly flow coming across the
Adirondacks. Maximum temperatures today will be in the 20s across
the area...steadily increasing through the day on the warm air
advection. Generally an inch or less of snowfall can be expected
Short term /7 PM this evening through Tuesday/...
as of 410 am EST Sunday...during the overnight hours wave of low
pressure will pass south of our forecast area into southern New
England. Steady light snow will continue through 7am. Generally
one to three inches of snow can be expected overnight and
temperatures will be mild with overcast skies across the area.
This will be the only forecast period of the short term with above
normal temperatures. Trailing upper level trough will cross the
north country during the daytime hours on Monday...flow will veer
to northwesterly and some upslope northwest flow snow showers are
expected. An additional inch or two of snow is expected...best
chance in the higher elevations especially the northwest facing
slopes. Southwest flow aloft will provide the region with
relatively mild daytime hours...maybe a degree higher than Sunday.
From Monday night through Tuesday a ridge of surface high pressure
will build over the area and mainly dry weather is expected. Very
cold temperatures Monday night with clear skies and decent radiational
cooling...single digits above and below zero. During the day
Tuesday surface high will slide eastward and next low pressure
system will approach from the southern Great Lakes. Increasing
clouds and chance for light snow through the day from west to east
across our forecast area. Aside from tonight...temperatures will
remain below seasonal normals.
Long term /Tuesday night through Saturday/...
as of 338 am EST Sunday...low pressure will be tracking from the
central Great Lakes region Tuesday evening up through the St
Lawrence Valley across southern Ontario/Quebec Tuesday night into
Wednesday. Good moisture advection into forecast area in advance
of this system with precipitable water values climbing to near
0.75 inches. Bulk of the precipitation is slated to occur Tuesday
night when best forcing will occur...in association with strong
warm warm air advection. The intrusion of warmer air will make for
some precipitation type issues...but it does appear as if most of
the precipitation will fall during initial burst of overrunning
through about 06z Wednesday...in the form of snow with several
inches expected. Southwest jet of around 50 knots at 850 mb will
bring in warmer air overnight however...with 850 mb temperatures prognosticated
to climb to around 0c northern areas and to +2-3c south. This will
result in snow mixing with or changing to sleet/freezing rain
across much of the area before tapering off towards morning. At
this time...it appears as if any ice amounts will be quite light.
During Wednesday surface low tracks up across southern Quebec.
After a brief period in the warm sector...cold front will move
across the north country during the day. Expect some areas of
light mixed precipitation early in the day...then scattered
rain/snow showers with maximum temperatures in the middle 30s to lower 40s.
Lingering snow showers Wednesday night as upper trough and
secondary Arctic boundary move across region...with temperatures dropping
into the single numbers and lower teens by Thursday morning. High
pressure then dominates the north country weather Thursday through
Friday as the center passes south of our area. Look for dry and
cold conditions with temperatures about 10 degrees below normal. Temperatures
moderate next Saturday back to more seasonal levels...and there
will be a chance of snow showers as a weak trough moves across the
Aviation /12z Sunday through Thursday/...
through 12z Monday...increasing clouds this morning with lowering
VFR ceilings. Conditions deteriorate rapidly between 17z-20z to
MVFR/IFR in light snow and these conditions will persist through
tonight. Greatest impacts at rut/mss/slk/mpv with least at pbg/btv
due downsloping southwesterly flow. Surface winds today will
strengthen out of the south to 5-15 knots...with gusts up to 20
knots at btv. Winds shift to westerly after 06z Monday.
Outlook 12z Monday through Thursday...
1z Monday-00z Tuesday...variety of flight categories in snow
showers. Greatest chance of IFR at mpv/slk.
00z Tuesday-18z Tuesday...VFR conditions under high pressure.
18z Tuesday-00z Thursday...MVFR/IFR in mixed precipitation as low
pressure system tracks up through St Lawrence Valley.
00z Thursday Onward...mainly VFR with areas of MVFR/IFR in snow