Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
920 am EST Sat Mar 8 2014
high pressure over the north country will give way to a weak frontal
boundary today...clearing the region by tonight. This will be
followed by a couple quick moving lows in succession late Sunday and
on Monday. By midweek next week there is the chance for a coastal
low to affect much of the region.
Near term /until 10 PM this evening/...
as of 917 am EST Saturday...updated forecast to increase probability of precipitation across the
western slopes and northern dacks to likely. Current radar and surface
observation show light snow across southern Canada with Montreal at 9 am
showing 5sm -sn. Thinking as a weak surface cold front located near
the international border drops south this morning into early
afternoon...light snow shower activity will develop across the mountains
overall...moisture is limited so accumulations will be a dusting to
maybe an inch near Jay Peak. Otherwise...a few flurries will be
possible in the valleys with temperatures warming into the 20s mountain to 30s
Previous discussion...wide range of temperatures across the County Warning Area
this morning as high pressure will slowly give way to a weak
frontal boundary...currently across the southeast Ontario region. Temperatures
do range from the teens in eastern Vermont and portions of the
dacks...up to the u20s to middle to upper 30s in the cvly/slv. Areas
seeing hir temperatures still being affected by southerly winds despite
increase middle/high clouds from front to the west. With teens/20s behind
front in central Ontario...many areas here may see morning highs
as temperatures fall with frontal passage this aftnoon. It will also depend on how
quickly middle/high clouds over spread rest of County Warning Area this morning...but
will go a few degrees blw guidance today. With upper flow more
westerly compared to south-southwest surface flow...precipitation along front is scattered west/
models suggesting best dynamics near low to our north and across middle
Atlantic region in warmer area. As a result will be keeping chance
to sl chance probability of precipitation over area for light -SW and even possible --rw
in spots. Best chance S for -SW over hir terrain where 0.5"-1.0"
possible with little to none in valley locales. Precipitation will taper
off fairly quickly going into tonight with northerly flow setting
up behind front. Any additional light accumulate to be focused over hir
terrain northwest facing slopes. Overngt lows will after sunset with high
pressure/clring skies to be factor overngt. Staying close to model
guidance as some lingering clouds will not allow for total
radiational cooling. Looking for a range of 10-15f in cvly down to
the single numbers elsewhere.
Short term /10 PM this evening through Monday/...
as of 305 am EST Saturday...for Sunday on through Monday...high pressure
starts off this time frame providing area a nice day with temperatures
several degrees blw normal with highs only in the 20s. This ridge
overhead will be short lived as a pair of shortwaves...which models
have been showing over past few days...will move across the region
late Sunday and again on Monday. Both are fairly progressive through
the area...but current track does suggest light snowfall for
entire area for each system. Both of these should give County Warning Area a range
of 1-2" with hir amts over hir terrain and lower in valley locales.
Slightly warmer scenario for Monday for highs as County Warning Area will see
small time frame of south-southwest flow ahead of second shortwave that should
bring temperatures warmer than Sunday. Overngt lows Sun night will range
from 10-20f...with some outlier single numbers over hir terrain of NE
Long term /Monday night through Friday/...
as of 406 am EST Saturday...a weak clipper system will pass just
north of the region Monday night...so will go with chance probability of precipitation for
snow showers Monday night and a chance of rain and snow showers on
On Wednesday...GFS and Canadian global model do not phase the
northern and southern streams and both take a surface low moving
off the southeastern U.S. And take it well south of the benchmark
(40n 70w) Wednesday night. This would mean that the region would
remain mainly dry Wednesday and Wednesday night. The European model (ecmwf) model
takes moisture from the Ohio Valley and brings it into the region
by Wednesday afternoon into Wednesday night and has the surface
low moving off the southeast U.S. Coast passing near the benchmark
late Wednesday night and early Thursday. This track would bring
snow into the region late Wednesday afternoon and Wednesday night
and continuing into early Thursday. Have opted to keep in chance
probability of precipitation for Wednesday and Wednesday night given this uncertainty in
the track of the surface low at this time. Thus...forecaster
confidence is low from Wednesday through early Thursday. A ridge
of high pressure builds into the region Thursday night and
Friday...so have leaned toward a dry forecast at this time.
Aviation /14z Saturday through Wednesday/...
through 12z Sunday...mainly VFR conditions expected through the
period. A weak cold front will move south from Canada. Just
expecting an increase in cloud cover and lowering ceilings through
the period. Moisture rather limited with this front...so have not
included and mention of snow showers with this frontal passage and
latest guidance showing probabilities are low with this. So...have
opted to leave any mention of showers from the taf forecasts at
Outlook 12z Sunday through Wednesday...
12z Sunday through 00z Monday...VFR under weak high pressure.
00z Monday through 00z Wednesday...MVFR possible in snow showers.
00z Wednesday through 18z Wednesday...mainly VFR under high pressure.
18z Wednesday through 00z Thursday...possible MVFR/IFR in snow.