Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 010241

Area Forecast Discussion
National Weather Service Burlington VT
1041 PM EDT Fri Sep 30 2016

Upper level low pressure over the Ohio Valley will weaken as it
slowly lifts across New England over the upcoming weekend. Mostly
cloudy skies and scattered showers will result, though pronounced
periods of dry weather are also expected. With the abundance of
clouds temperature ranges will be narrower than normal with
seasonably cool daytime highs and relatively mild overnight lows
through Monday.


As of 1038 PM EDT Friday...Light rain/sprinkles continue to fall
from the mid-cloud deck (cloud bases 10-12kft AGL) across far nrn
NY at 0230z, with generally overcast skies elsewhere across the
North Country. Mid-level moisture has advected nwd across the
region, but blocking high across Quebec/Maine and relatively dry
PBL conditions will continue to limit rainfall coverage and
amounts overnight. Area observations indicate a few hundreths
across the nrn NY (0.04" at KSLK). East-west 850-700mb
deformation axis across central NY into wrn MA will lift nwd after
midnight, and bring a chance for light showers or sprinkles across
s-central VT during the pre-dawn hours. There are some higher PW
values south of this deformation axis, with 00z ALB sounding
showing PW values of 1.63". So, some increase in rain chances
across s-central VT (Rutland/Windsor counties) is anticipated.

Low temperatures should be similar to last night given thickening
upper cloud cover will limit radiational processes - mainly upper 40s
to lower 50s.

By tomorrow a mainly persistence forecast will be offered as upper
low pressure will remain nearly stationary across the Ohio Valley
allowing modest south to southeasterly flow to continue into our
area. Deeper moisture and better threat for scattered light showers
will be tied to either 1)a weak plume across central/upstate New York
on the upper low`s eastern periphery, or 2)across
southern/southeastern New England where a maritime airmass with PWATs
to 1.5 inches will reside. Further north across the intl border and
northern Champlain Valley conditions should again remain largely dry.
Only notable larger-scale change was to lower high temperatures by
several degrees over prior forecast. This is consistent with over
half of the consensus blended output and in closer agreement with
latest MOS guidance which show values mainly from the mid 50s to
lower 60s (perhaps a few mid-60s in the SLV).


As of 249 PM EDT Friday...

Little substantive change noted in today`s 12z guidance suite
pertaining to the forecast for Saturday night through Sunday night.
A very slow-evolving upper low over the Ohio Valley begins to pivot
north-northeastward through the period, and beginning to deamplifyas
it does so. The system will continue to advect Atlantic moisture
northward, but will run into lingering weak subsidence associated
with a weak ridge across our northern counties. Forecast challenge
remains timing a period when PoPs may be highest. While PoPs are
generally in the Slight Chance to Chance range through this
period, overall forecast QPF is kept very low - on the order of a
few hundreths. It looks at this point that Saturday night may be a
period where a greater coverage of showers may exist, with a break
Sunday before ramping up late Sunday night. While temperatures
still trend above-normal compared to 30-year normals, blanket of
overcast skies through the weekend will lead to narrow diurnal
ranges with cooler highs and "milder" lows. Highs Sunday in the
60s, though may struggle to climb much above 60 in eastern VT.
Lows Saturday night in the 40s to lower 50s and Sunday night upper
40s to mid 50s.


As of 249 PM EDT Friday...

Continuing a trend with last night`s 00z global guidance, today`s
12z guidance suite continues to indicate that Monday would offer the
best chance at widespread, if light, rain. This is as the
deamplifying upper-level low from the previous period evolves into
an open wave trough and gets entrained in the broader belt of
westerlies. While PoPs are the highest in the Monday period - high
Chance to low Likely - precipitation is expected to be showery
driven mainly by cold pool aloft and any weak instability that can
be generated. Temps still in the 60s for highs and lows in the
40s/around 50.

A period of generally dry conditions is then anticipated Tuesday
through the remainder of the period, as CONUS 500 mb pattern becomes
more amplified with a large upper level ridge over the eastern third
of CONUS with a digging trough over the central US. Anticipating
more sunny skies and larger diurnal temperature ranges (milder than
normal highs in the mid 60s to low 70s and cooler but seasonable
lows 40s to low 50s). Will be looking at how Matthew evolves over
the next several days in the Caribbean/Bahamas, but at this point
in time guidance does not suggest any impact to our area. See the
latest forecasts at NHC`s website for more details on Matthew`s
current and forecast evolution.


.AVIATION /03Z Saturday THROUGH Wednesday/...
Through 00Z Sunday...Generally OVC mid-level clouds and VFR cigs
over the next 24 hours as upper low pivots to our distant
southwest. Ceilings generally above 10 kft thru 12Z, but should
see some lowering into 5-10kft range during the daylight hrs
Saturday. A few sprinkles light rain showers expected
overnight...mainly nrn NY...and then s-central VT/KRUT after 06Z.
All in all, not expecting any significant reduction in sfc vsby or
ceilings heights with this very light pcpn. Winds generally light
and variable overnight, except SE around 10kts at RUT. Winds generally
becoming SE areawide 6-10kts daylight hrs Saturday, except locally
NE 5-7kt MSS/SLK.

Outlook 00Z Sunday through Tuesday...

00Z Sun - 12z Tue: Mainly VFR with brief bouts of MVFR/sct
showers as upper low drifts into the region while weakening over
time. Much of the period will remain dry.

12z Tue onward: Mainly VFR with building high pressure.




SHORT TERM...Loconto
LONG TERM...Loconto
AVIATION...Banacos/JMG is the U.S. government's official web portal to all federal, state and local government web resources and services.