Area Forecast Discussion
Issued by NWS Burlington, VT-- Highlight Changed Discussion --
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FXUS61 KBTV 201950
Area Forecast Discussion
National Weather Service Burlington VT
350 PM EDT Thu Oct 20 2016
-- Changed Discussion --Strengthening surface low pressure system has started bringing widespread
rain to the North Country and will continue to do so through
Sunday. Occasionally heavy rainfall expected, especially this
evening into early Friday, especially in the St Lawrence Valley
and Western Adrondacks. As the front pushes east of the area by
early next week a return to seasonably cooler weather is expected.
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.NEAR TERM /THROUGH FRIDAY NIGHT/...
-- Changed Discussion --As of 343 PM EDT Thursday...Rain showers are making their way
through the North Country. Expect a short break late this
afternoon before showers resume at a much stronger and widspread
pace as the next band of mositure south of Lake Onterio moves
quicking into the CWA.
The 500mb trough continues to dig south and east over the central
USA. The rain has been slightly more widespread, mainly in the St
Lawrence Valley and Adirondacks but Western VT is also seeing
precip moving through rather quickly from the SW. The main
question remains how far north and east it will spread before the
deepening trough and surface low riding up the frontal boundary
causes area of rain to pivot north and west sometime on Friday.
The HRRR continues to have the best handle on the near term precip
for the St Lawrence Valley, have adjusted the PoPs and QPF
slightly to show the heightened band of precip making it`s way
Strong low level deformation associated with front moves into St
Lawrence later this afternoon and into tonight, leading to
heavier rainfall for Nrn NY overnight, before weakening on
Friday. Another consideration for Friday is sub- tropical system
weakening as it heads north far off the Carolina coast, but
moisture looks to get absorbed or wrapped into the low affecting
the Northeast, and could result in resurgence of heavier precip
over eastern VT late Friday into Friday night, per the 00Z ECMWF.
This may be dependent on when the 500mb trough becomes more
neutral or negatively tilted late Friday.
Winds another concern as strong low level jet enters the region
this afternoon. Southerly jet of 40-55kts at 850mb stays over the
North Country through Friday. This will lead to strong winds
across the higher terrain. Best chances for strong winds to mix
into the valleys would be early Friday as the precip shield pivots
slightly NW, allowing for breaks in precip over VT. Have gusts up
to 15-25kts across most of the area on Friday, before the surface
low tracks over the area.
In summary, cloudy and wet pattern expected throughout the near
term with temperatures in the mid 50s to mid 60s today as we
remain in the warm sector. Tonight temperatures remain mild in the
mid 40s to upper 50s. Forecast max temperatures will be very tricky
on Friday as the surface low and associated front traverse across
the North Country. Timing of FROPA will dictate wind shift of NW-N
and colder air filtering in, especially through the valleys and
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.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 534 AM EDT Thursday...Models in good agreement with
bringing abundant moisture into the north country through the
period. Have gone with categorical pops for Friday night and
Saturday. Expecting precipitation to become more showery Saturday
night, as surface low pressure area moves north into Quebec
Saturday night. Models showing a closed upper low will move into
the region late Saturday and Saturday night which will produce
dynamical cooling aloft, so expecting rain to change to snow over
the higher elevations of the Adirondacks and Green Mountains late
Saturday into Saturday night. Some locally heavy snow is possible
over the higher summits of the Adirondacks and Green Mountains
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 534 AM EDT Thursday...Expecting rainfall amounts from
Thursday through Sunday to be around 2 to 4 inches across the
north country. Some locally heavy snowfall is possible Sunday over
the higher summits of the Adirondacks and Green Mountains on
Sunday. The region will remain under cyclonic flow from the
surface low pressure area over eastern Canada Sunday through
Monday night, so have chance pops for rain and snow shower in the
forecast. A high pressure area over the western Great Lakes on
Tuesday will build slowly east and bring mainly fair and dry
weather to the north country Tuesday night and Wednesday.
.AVIATION /20Z Thursday THROUGH Tuesday/...
Through 12z Friday...VFR conditions will give way to MVFR and IFR
for Western stations. Rain is moving into the region and is
overall light with embedded heavier spots. Expect cigs to lower
to MVFR in the next few hours for MSS/SLK and late afternoon for
PBG and BTV. Rain will be heavy at times, with MVFR/brief IFR
possible, especially in the overnight hours. Widespread MVFR
expected after to persist 00Z/Friday and persisting throughout the
Light Southeasterly winds will give way to gustier winds after 00Z
at 10-20 knots. There looks to be a lull in the early morning
hours which could open the door for wind shear conditions at all
stations except KRUT/KMSS between 09Z-11Z.
Outlook 18z Friday through Monday...
18z Friday through 00z Monday: A prolonged period of unsettled
conditions is expected with widespread MVFR/IFR in periods of
00z Monday through 00z Tuesday: A mix of VFR/MVFR...with VFR/IFR
possible in showers.
As of 510 AM EDT Thursday...A widespread and long duration
rainfall of 2 to 4 inches with isolated higher amounts expected to
start midday Thursday and ending Sunday. There will be some breaks
throughout the event, especially across portions of Vermont. Given
most of the region is in moderate to severe drought...we are not
anticipating any widespread hydro issues. However...some minor
urban and street flooding is possible associated with the heavier
rainfall rates on Friday with leaves clogging storm drains.
Otherwise...some modest rises in local rivers and streams are
likely this weekend...but no widespread flooding is anticipated.