Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
1044 PM EDT Sat Mar 28 2015
high pressure will bring clearing skies and cold temperatures
overnight. A sunny Sunday is expected but with temperatures still
below normal. To start the work week a cold front will bring a
chance of rain and snow showers to the area. After a brief cool
down Tuesday and Wednesday a warming trend will lead to temperatures in
the middle 40s to low 50s by the end of the week.
Near term /until 9 am Sunday morning/...
as of 1044 PM EDT Saturday...current forecast in good shape at
this time...so no changes have been made.
Short term /9 am Sunday morning through Monday night/...
as of 359 PM EDT Saturday...high pressure will dominate our
weather Sunday with plenty of sun and temperatures still below
normal in the 30s. Late Sunday night/early Monday morning an
Alberta clipper system will quickly push into the region with
decent qg forcing from 06z-18z. It will bring a slight chance of
snow showers Sunday night over northern New York before
overspreading into Vermont by early morning on Monday. Expect the
temperatures in the boundary layer to support complete melting of the
precipitation in valleys by 15-18z before changing back to snow by 00z in
the evening. Models showing steep low-level lapse rates and even
some low values of cape, so some gusty rain or snow showers may
accompany the cold front as it move through later in the day.
Temperatures during the day will warm into the low to middle 40s under
moderate and gusty south westerly flow of 25 to 30 kts with
Monday night...colder Post frontal northwest upslope flow
develops and with Froude numbers expected above 1 most of the snow
shower expected at the summits and slightly on the Lee side of The
Greens. A dusting to couple inches possible with a bit more on the
mountain summits. Lows in the 20s.
Long term /Tuesday through Saturday/...
as of 343 PM EDT Saturday...changeable weather in the extended
period. Dry Tuesday and Wednesday then warming and warm air
advection rains Thursday followed by a cold front Thursday night.
Post frontal snow showers through Friday then a more southern
track system for Saturday yet to be resolved. There were some
model differences between the GFS and European model (ecmwf) for the Thursday night
frontal passage and warmth or lack of for Friday however 12z European model (ecmwf)
has come in line with the cooler GFS.
Tuesday starts with familiar long wave trough over the eastern US
and northerly low level flow behind a departing surface low.
Carrying slight chance probability of precipitation in the mountains Tuesday with lingering
snow showers possible with reinforcing shot of cold air behind a
shortwave trough moving by mainly to south late Tuesday. Dry
Wednesday/Wednesday night with brief surface ridging and a
shortwave ridge at 500 mb.
Southerly flow returns Thursday in advance of next upper low
moving in northwest flow out of Canada...and surface low passing
by to north. Area will be clipped by warm air advection rainfall
Thursday, followed by cold front passage Thursday night/Friday
morning. As noted by previous forecaster gusty winds possible
Thursday into Thursday night in strong pressure gradient,
especially channeling in Champlain and St. Lawrence valleys. Area
will be will into the warm air for a 24 hour period from 12z
Thursday to 12z Friday with 850 mb temperatures maxing out near +3 to
+5c. Quick hit from precipitation and brief warmup will give US
minimal Hydro concerns for excessive runoff from precipitation or
snowmelt. Rivers should be able to contain any rises with little
if any ice breakup. Cold front drops things back below freezing
Friday night, and then a second vorticity maximum rounds the bottom of the
500 mb trough on Saturday. GFS a little further south with this
feature tracking it across southern New England while European model (ecmwf) seems
a little too far north taking the surface low across northern
Temperatures start off below normal with highs in the 30s and lows in the
teens to 20s Tuesday and Wednesday. Much warmer Thursday in strong
southerly flow with highs in the 40s to near 50. From Friday
Onward temperatures trend back down toward normal.
Aviation /03z Sunday through Thursday/...
through 00z Monday...VFR expected through the period. Any
lingering clouds will dissipate this evening with sky clear
expected through tonight and into Sunday with only a few high
clouds increasing Sunday afternoon. Winds become light and
variable overnight and into Sunday morning with some southwesterly
return flow developing by Sunday afternoon...so winds 5-10 knots
out of the south/southwest expected after 15z...with some gusts
to 20 knots at mss.
Outlook 00z Monday through Thursday...
00z Monday through 06z Tuesday...periods MVFR ceilings/visibility in rain
or snow showers with low pressure system moving west to east out
of Great Lakes. 06-12z Monday south to southwest wind gusts of 25
kts possible in advance of approaching low pressure system.
06z Tuesday through 00z Wednesday...mainly VFR conditions...but
localized MVFR with scattered mountain snow shower activity (possibly
including slk/mpv)...diminishing late in the day Tuesday. Hir
terrain obscured at times.
00z Wednesday through 00z Thursday...mostly clear with high
pressure in place.
00z Thursday through 00z Friday...MVFR ceilings/visibility in light snow
changing to rain during the day ahead of approaching low pressure