Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
1030 am EDT Thursday Oct 23 2014
upper level low pressure off the New England coast will bring
periods of rain and showers to the region today into
tonight...especially from the Adirondacks eastward. Showers taper
off on Friday...but return by later Saturday into Saturday night
with the passage of additional energy. Drier and milder weather is
expected by early next week.
Near term /until 6 PM this evening/...
as of 1019 am EDT Thursday...late morning forecast refresh doesn't
have much in the way of forecast modifications. Radar & satellite
trends show that the much anticipated widespread rain is spreading
into the region from the east. Colder/deeper clouds are now over
much of eastern Vermont. Radar showing pretty solid coverage from
eastern Vermont across New Hampshire and into Maine. Thus the
going forecast for probability of precipitation to ramp up to 100% for most over Vermont
looks good. Northeast low level flow will continue to advect in
some drier air out across western sections of northern NY, so once
you get west of the Champlain Valley, chances for rain (and
overall amounts) will quickly decrease. At the same time, the low
is starting to slowly lift northeast and this will also limit the
ultimate westward extent of the deepest moisture and rainfall.
Have thus maintained a 30-40% pop out in the St Lawrence Valley
for the bulk of the afternoon.
Though the probability of precipitation will be high, the total rainfall does not appear
it will be all that heavy. Thus far the heaviest rains have stayed
south of the forecast area and area across massachussets. Will
stay with the lowering trend that rainfall amounts will stay in
the 0.5-0.9" range at the most.
Temperatures should remain fairly steady as well. Didn't make any
adjustments at this time. 40s will be common, with low 50s out in
the St Lawrence Valley due to less precipitation out there.
Short term /6 PM this evening through Saturday/...
as of 405 am EDT Thursday...by tonight today's slug of moisture
gradually loses its impetus as parent upper dynamics pull steadily
east-northeast and away from the region. Still looking at damp/wet conds from
the eastern slopes of the dacks east into Vermont...but precipitation character
should trend lighter and lessen in overall coverage as the night
wears on. Outside some evening showers...slv should trend mainly
dry from midnight Onward. Lows similar to this morning...upper 30s
to middle 40s under continued cloudy/northerly flow and neutral
By Friday...showers continue to pull away to the northeast as weak
high pressure slowly builds into the region. Highest coverage of
showers across NC/NE Vermont where some addl light totals will be
possible. Trending mainly dry from the Champlain Valley westward.
With lingering clouds and continued northerly flow did opt to lean
on the colder side of guidance in regard to temperatures...holding maximum
values in the upper 40s to lower 50s in most spots...perhaps middle 50s
in the slv where some afternoon partial sun will be possible.
Aforementioned weak high pressure continues to build into the area
for Friday night as pesky clouds slowly thin over time. Lingering
showers end northeast with low temperatures a tad cooler...middle 30s to lower
On Saturday models remain in overall good agreement suggesting
additional and rather robust northern stream shortwave energy will drop
quickly southeast into our area by the afternoon hours with a
renewed threat of showers. Given timing of the feature highest
probability of precipitation will occur across the western half of the forecast area. With
flow turning southerly ahead of this feature and a modestly mixed
planetary boundary layer...highs will be somewhat warmer for most spots...mainly 50s.
Long term /Saturday night through Wednesday/...
as of 354 am EDT Thursday...unsettled conditions return to the
north country for the later half of the weekend as a closed upper
level low tracks southeastward from James Bay into the northeast
Saturday night. Potent shortwave energy out ahead of a strong cold
front will develop showers across the region Saturday
night...transitioning to valley rain and mountain snow showers
Sunday and Sunday night with the low/middle level flowing turning to
the northwest and strong cold air advection moving in Post frontal passage. Temperatures at the
summits aren't incredibly cold...so likely only going to see a
dusting to maybe a couple of inches up there.
We'll still be under middle-level cyclonic flow to begin the work
week Monday so expect a good deal of clouds to be around and
possibly a few isolated mountain snow showers. A building upper
ridge over the central Continental U.S. And surface high across the
southeast will begin to shift eastward Monday night allowing for a
nice warming trend as we go into mid-week. While highs Monday will
be very seasonal in the upper 40s to low 50s...we'll see temperatures
rise into the upper 50s to lower 60s for Tuesday and Wednesday
with plenty of sunshine.
Late Wednesday evening into Thursday our next system approaches
though at this time models predict the low center passing well to
our north with only a weak ribbon of moisture along the trailing
cold front tracking into the northeast. Doesn't really look all
that threatening for any significant rain right now...but strong
cold air advection behind to front will bring our temperatures right back below normal
Aviation /14z Thursday through Monday/...
through 12z Thursday...low pressure off the middle-Atlantic coast
will bring deteriorating flight conditions to the area with
prevailing MVFR ceilings through the period. Rain moves in middle-
morning with some MVFR visibility possible...though upstream observation only
support VFR visibility. Exception on the rain will be kmss which will
likely remain dry...but will still see MVFR ceilings move in by middle-
morning. Winds will mainly be northerly at 8-12kts through the period
with gusts up to 25kts at times.
Outlook 12z Friday through Monday...
12z Thursday - 12z Friday...MVFR/IFR likely as low pressure lifts slowly
northeast along the New England coast.
12z Friday - 12z Sat...MVFR trending to VFR under brief high
12z Sat - 00z Tuesday...VFR trending to MVFR in valley rain showers
and possible mountain snow showers as cold low pressure tracks
across the region.
as of 405 am EDT Thursday...latest analysis suggests precipitation totals
from current system will be lighter than prior indications so no
hydrological concerns are expected for area rivers. 3-day totals
ending Friday morning are expected to range from 0.75 to 1.5
inches from the Champlain Valley eastward with locally higher
totals to near 2 inches possible along eastward facing slopes of
the Green Mountains further west totals should average from 0.25 to
0.75 inches in the Adirondacks...and less than 0.25 inches in the
as of 405 am EDT Thursday...northerly winds of 15 to 25 knots are
expected to continue across the Open Lake waters into this evening
before slowly subsiding later tonight into Friday. Thus a lake
Wind Advisory will remain in effect with this package. These
conditions will create choppy to locally rough waters today with
significant wave heights averaging in the 2 to 4 foot range.
Convergence of winds and waves due to topographical effects will
make conditions rougher on the southern half of the lake with
occasional gusts to near gale force possible. Caution is thus
advised to those planning to operate small craft on the lake today
into this evening.