Area Forecast Discussion
Issued by NWS Burlington, VT
FXUS61 KBTV 200934
Area Forecast Discussion
National Weather Service Burlington VT
534 AM EDT Thu Oct 20 2016
Strengthening surface low pressure system will bring widespread
rain to the North Country Thursday afternoon through Sunday.
Occasionally heavy rainfall expected, especially this evening into
early Friday. As the front pushes east of the area by early next
week a return to seasonably cooler weather is expected.
.NEAR TERM /THROUGH FRIDAY/...
As of 510 AM EDT Thursday...Today looks to be the beginning of a
pattern change as 500mb trough continues to dig south and
gradually east over the central USA. Rain will encroach upon the
St Lawrence Valley and Adirondacks in the early afternoon
associated with frontal system moving in from the SW. 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.
Strong low level deformation associated with front moves into St
Lawrence this afternoon into tonight, leading to heavier rainfall
for Nrn NY, 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
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 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.
.SHORT TERM /FRIDAY NIGHT 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 WEDNESDAY/...
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 /09Z Thursday THROUGH Monday/...
Through 06z Friday...VFR conditions except at KSLK with IFR to
VLIFR possible this morning. MPV could see brief period of
LIFR/VLIFR centered around 10Z. In the late morning ceilings
lower to around 4000-5000 feet as a front will bring rain showers
to most terminals. Expect rain to affect MSS/SLK/PBG/BTV by early
afternoon. Possible periods of MVFR with confidence of MVFR cigs
and vsbys at MSS/SLK around 19Z onward. PBG/BTV/MPV could see MVFR
conditions after 00Z Friday.
Winds vary greatly due to proximity to front. Overall expect
southerly winds, possibly gusting at times in the afternoon as low
level jet moves over the North Country late this afternoon into
evening. Cannot rule out possible LLWS, especially heading into
Outlook 06z Friday through Monday...
06z 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.