Area Forecast Discussion
Issued by NWS Burlington, VT-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KBTV 261912
Area Forecast Discussion
National Weather Service Burlington VT
312 PM EDT Mon Sep 26 2016
Nearly stationary upper level low pressure just north of Lake
Superior this afternoon will push and occluded front through the
North Country tonight, accompanied by some light rain showers.
Tuesday and Wednesday will be mainly dry behind the front with
temperatures warming to above seasonal normals. Greater chances
for rain return Thursday and into the weekend as the upper low
moves into the Ohio River Valley and Northeast.
.NEAR TERM /THROUGH TUESDAY/...
As of 224 PM EDT Monday...It`s a fantastic early fall day across
the North Country as we remain under the influence of high
pressure anchored just off the New England coast. Temperatures
have rebounded nicely from this mornings chilly start, and are on
track to top out in the low 60s east to near 70 west under partial
sunshine from an increasing high deck.
Moving on into this evening and the overnight hours, mid/high
clouds will continue to increase as an occluded front associated
with a deep vertically stacked and nearly stationary upper low
just north of Lake Superior approaches. Associated rain showers
are already moving into far western New York and should shift into
the BTV CWA shortly after 00z, and east of the Connecticut River
by sunrise Tuesday. Currently showers are very scattered in nature
along the boundary, and expect much of the same as it moves
through the North Country. Some local enhancement is expected on
southern and southwestern facing slopes due to a developing 40kt
jet at 925mb, while this feature will in turn limit QPF in the St.
Lawrence and Champlain Valleys. Overall not a big QPF event
though, with only a tenth to perhaps 2 tenths of rain expected.
With increasing winds and southerly flow, lows tonight will be
much milder than the past 2 nights, and generally range from the
mid/upper 40s across eastern Vermont and the Northern Adirondacks,
to low/mid 50s in the deeper Champlain and St. Lawrence Valleys.
Behind the front, a strong mid-level dry slot builds over the area
for Tuesday so after showers exit during the morning hours across
eastern Vermont, we should be looking at a generally dry day.
South/southwesterly flow persists behind the boundary, keeping
temperatures above seasonal normals and with 925mb temps averaging
around +13-15C we should see highs in the mid 60s to low 70s under
partly sunny skies. There remains though the outside chance for
some lake effect rain showers downwind from Lakes Ontario/Erie
tomorrow afternoon, but confidence is fairly low at this time and
latest hi-res guidance isn`t all that bullish either so I`ve
painted in just some low chance PoP`s during the afternoon up the
St. Lawrence River.
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
-- Changed Discussion --As of 312 PM EDT Monday...Dry slot moves into the North Country
behind the cold front, bringing an end to rain showers through the
early half of Wednesday night. Meanwhile, large closed 500mb low
sinks south and east into the Ohio river valley. Associated
surface low will be slow to align with upper low. Broad surface
low develops around the Carolinas with inverted trough extending
toward the 500mb low still over the Ohio Valley.
At the surface, east to NE flow will affect the North Country
with drier and cooler air. Expect Tuesday night and Wednesday
night temperatures in the 40s to around 50. Wednesday daytime
temps look to reach the 60s to around 70.
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.LONG TERM /THURSDAY THROUGH SUNDAY/...
-- Changed Discussion --As of 312 PM EDT Monday...Much uncertainty continues in the long
term as the 500mb closed low resides over the central/southern
Appalachians before gaining momentum northward late in the week.
Canadian surface ridge over Quebec, but secondary to the amplified
flow over the plains states, looks to impeded northern progression
of precip associated with the closed 500mb low. ECMWF and GFS show
mid-level ridge over the Atlantic blocks eastward progression of
the 500mb low, therefore the low eventually moves northward into
the eastern Great Lakes bringing showers to the North Country late
in the period. With such a meridional flow across North America,
expect high uncertainty in the details of the forecast to
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.AVIATION /19Z Monday THROUGH Saturday/...
Through 18Z Tuesday...VFR conditions this afternoon and evening
will trend towards MVFR in rain showers as an occluded front
traverses the area after 00z. Mid/high cirrus deck will gradually
lower through time, remaining VFR through about midnight across
northern New York, and 2-4AM across Vermont before lowering to
MVFR. Vsby remains largely VFR in the showers, with periods of
lowering to MVFR. After 12z, front exits the region to our east
with conditions gradually improving back to VFR by 18z. Winds
generally not an issue, less than 10kts, but a few gusts towards
18-22kts from the south will persist at KBTV and KPBG this
afternoon and evening.
Outlook 18z Tuesday through Saturday...
18z Tue - 00z Thu: Generally VFR, though an MVFR marine layer may
intrude from the east late Tuesday night through mid-day
00z Thu - 00z Sun: Mainly VFR with MVFR in rain showers possible,
especially on Saturday.
Funneling south winds ahead of approaching front will bring 15 to
25 knots and possibly higher gusts to Lake Champlain
tonight...already 20 knots at times this afternoon. After front
passes Tuesday morning, winds should begin to diminish.