Area Forecast Discussion
Issued by NWS Burlington, VT-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KBTV 290759
Area Forecast Discussion
National Weather Service Burlington VT
359 AM EDT Thu Sep 29 2016
A closed upper low over the western Great Lakes will move slowly
south into the Ohio River Valley overnight, and will linger there
through Saturday. Meanwhile, a ridge of high pressure over eastern
Quebec and Labrador will slowly build southwest into the region
through Friday, with mostly fair and dry weather expected over the
North Country. As the closed low moves back north into the Great
Lakes this weekend, there will be increasing chances for rain
showers from Friday night through this weekend.
.NEAR TERM /THROUGH TONIGHT/...
As of 159 AM EDT Thursday...Forecast in good shape at this time,
so no changes have been made.
Previous discussion from 1015 PM Wednesday...Somewhat of a wide
range of temperatures have developed over the area tonight based
on clouds versus no clouds. Have fine tuned grids to account for
this...but overnight lows are still on track. No other changes
needed at this time.
For tonight, the upper low currently over the southern tip of
Lake Michigan only dives slightly south into the Ohio River
Valley, while a dirty ridge of high pressure over eastern Quebec
and Labrador builds over portions of the northeast. I call it
"dirty" because it won`t be your classic high pressure providing
clearing skies, rather easterly flow off the Atlantic will
persist with variable cloudiness expected through the overnight.
This will make for a tricky min temp forecast as areas with more
clouds will be warmer than those that are clearer. Have opted for
a model blend approach, which will offer min temps generally
close to climo ranging through the 40s in general, except a few
upper 30s in the colder hollows of the Adirondacks and Northeast
Thursday will be almost a repeat of today in regards to temps as
southeasterly areas will once again only be in the low/mid 60s and
areas northwest pushing into the low 70s. We`ll be under the ridge
I mentioned above which will keep us dry, and most areas should
see about the same amount of sunshine or more than we saw today.
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
-- Changed Discussion --As of 345 AM EDT Thursday...The forecast challenge during this
period will be northern extent of precip shield...along with
impacts clouds will have on temps. Models in good agreement with
closed 5h/7h cyclonic circulation over the Ohio Valley with
building ridge of high pressure develops over southern Canada.
This will continue to produce a east to northeast flow across our
region...with mid/upper level moisture trying to advect in from
the south. Based on 70% and greater 1000 to 500mb RH fields
staying to our south and pw values < 1.0...along with best upper
level forcing located to our south...will continue to mention just
low chc pops across southern VT zones on Friday. Better moisture
tries to make a run into our central cwa on Saturday...but weakens
as it encounters dry air associated with ridge of high pres.
Thinking a few isolated to scattered light rain showers are
possible across our central/southern cwa on Saturday...but qpf
will be light and generally under 0.10" Temps will be tricky with
highs clouds on Friday...along with some low clouds again across
eastern section...and even more clouds areawide on Saturday. Based
on yesterday`s cloud impacts on temps...will mention a similar
type profile for Friday with highs near 60s eastern cwa...to near
70 Saint Lawrence Valley and downslope parts of the Champlain
Valley. With more clouds anticipated Saturday...thinking highs
mainly in the upper 50s mountains to mid 60s warmer valleys...with
lows generally in the 40s to lower 50s.
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.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
-- Changed Discussion --As of 345 AM EDT Thursday...The deep closed 5h circulation over
the Ohio Valley will slowly lift toward the ne conus and weaken by
early next week. As cold core aloft and associated energy/moisture
move directly overhead by Monday...expect scattered showers. Once
again...best chance for precip with the highest pops will be dacks
and mountains of vt...with generally light qpf values under 0.25".
System will be replaced once again by a large dome of high pres
both at the surface and aloft by midweek. Still some uncertainty
on timing of high pres and potential lingering moisture/pops on
Tuesday...but Wednesday and Thursday look dry. A general warming
trend is anticipated...especially daytime highs with more sun
anticipated and progged 850mb temps near 8c. This supports highs
mid 60s to lower 70s with lows mainly in the mid 30s to upper
40s...depending upon elevation and closeness to Lake Champlain.
Overall expect a large diurnal swing in daily temps by midweek
due to the expected very dry air mass in place.
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.AVIATION /08Z Thursday THROUGH Monday/...
Through 06Z Thursday...Mainly VFR conditions expected through the
period as a surface ridge of high pressure builds southwest from
Quebec into the region through the period. Expecting increasing
high and mid level clouds moving into the region today from the
mid Atlantic states. These clouds are associated with the closed
upper low over the Ohio valley today. Expecting surface winds
today to turn into east and northeast today as the ridge of high
pressure build southwest from Quebec.
Outlook 06z Thursday through Monday...
06z Thu - 12z Sat: VFR under an increasing mid/high deck.
12z Sat - 00z Tue: Mix of VFR/MVFR in scattered rain showers, mainly
from 00z Sun onward.