Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 241506
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
1106 AM EDT Thu May 24 2018

.SYNOPSIS...
High pressure will provide dry weather today, then warm and
summery conditions on Friday with partial to full sunshine. A
cold front approaching from the north later Friday may spark a
late day shower across the far north. This front will sag into
the area for the upcoming weekend with cooler temperatures and a
more widespread threat of showers.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 1106 AM EDT Thursday...Mid-level clouds have eroded
rather quickly over the past couple of hours and most areas are
experiencing sunny or mostly sunny conditions. Still some clouds
upstream over central Quebec, but with upper trough moving east
the bulk of these clouds should not reach the area with only the
Northeast Kingdom of Vermont having a chance to see a little
increase in clouds. Rest of forecast remains unchanged.

Previous discussion...An outstanding, chamber of commerce day
is on tap for our area as surface high pressure builds eastward
and lingering upper troughing aloft lifts out to the northeast.
Other than some scattered high clouds plenty of sunshine is
expected as temperatures top out in the upper 60s to mid 70s.
Light northwesterly winds this morning will back to
south/southwesterly over time by this afternoon. Pops nil.

Mainly clear skies continue tonight with winds light southerly to
near calm. Flow atop the nocturnal boundary layer holds in the 10 to
20 kt range so no fog is expected given expected mixing processes.
Indeed, quite a nice surge of westerly flow (30-40 kts) in the 925-
850 mb layer does push into the region overnight heralding the
arrival of a much warmer airmass from the Central and Northern
Plains for Friday. Low temperatures to range mainly through the 50s
though some Northeast Kingdom sites may drop into the upper 40s
while mildest spots in the St. Lawrence and Champlain Valleys
will hold around 60F.

For Friday a warm, summerlike day is still in the cards as
aforementioned continental airmass advects atop the region on
gusty west/southwest flow of 20 to 30 mph and partly to mostly
sunny skies. Have leaned toward a blend of MOS and bias-
corrected GEM/SREF/downscaled NAM output for high temperatures
showing values ranging from the upper 70s to mid 80s, warmest in
the Champlain Valley where the westerly flow will aid in
downsloping/compressional effects. Plattsburgh, NY tends to
outperform most sites under this type of regime, and as such
I`ve offered a spot high of 87F for KPBG. The only fly in the
ointment will be an outside shot of a stray shower across the
far northern tier later in the afternoon as a backdoor cold
front begins to encroach from the north/northeast and a push of
higher moisture aloft sweeps eastward. With such dry air in the
boundary layer (Td values to 30F), rather marginal mid level
lapse rates and only lower-end instability I feel anything that
does occur will be scattered at best through sunset. As such
only lower-end chance pops will be offered in this area and
mainly after 300 pm. Areas south of a KSLK-KBTV-K1V4 line look
to remain largely dry.

&&

.SHORT TERM /FRIDAY NIGHT/...
As of 350 AM EDT Thursday...A cold front will be sagging south
along the international border and will bring showers to parts
of northern New York and northern Vermont. Timing and how far
the front sags south is still yet to be determined. The EC/GFS
bring the front to the international border while the NAM sags
the front all the south into central NY. The best forcing should
remain near the international border and so I`ve largely kept
the best chances for precip north with only a slight chance for
rainfall across southern Vermont Friday night into Saturday
morning.

By mid day Saturday I do anticipate showers moving south and
covering most of the North Country. Even with PWATs relatively
high, I dont anticipate significant precip on Saturday.
Currently the thinking is that we`ll see between a quarter to a
third of an inch of rainfall north with around a tenth across
central and southern Vermont.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 350 AM EDT Thursday...The backdoor front will continue to
be a challenge on Sunday as models are still struggling with
the placement of where the boundary stalls. The growing
consensus as noted by the previous forecaster is that its going
to be wetter over Northern New York rather than Vermont on
Sunday. A marine airmass will push in from the east but the
wedge doesn`t look like it will make it past the Adirondacks. So
there`s going to be a pretty strong baroclinic zone across the
Saint Lawrence Valley on Sunday. That combined with a surge in
PWATs will lead to the potential for some fairly heavy rainfall.
While flooding is not an immediate concern we`ll need to
continue to monitor for any potential hazards.

The upper level trough finally swings through on Monday and
Monday night so our period of unsettled weather should come to
an end on Tuesday. Temperatures moderate as high pressure starts
to build in and we see slightly above normal temps with highs
in the upper 70s and lows in the 50s.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
Through 12Z Friday...VFR as occasional scattered to broken mid
level cigs in the 100-150 AGL range trend SKC by later this
afternoon. No precipitation is expected. Winds gradually back
from 5-10 kts west/northwesterly to south/southwesterly in the
14-20Z time frame today. After 00Z winds generally light
south/southwesterly from 5 to 10 kts, though LLWS from 35-40
kts becoming likely at many terminals from 03-06Z onward with
surge of westerly flow aloft. Exception will be at KBTV where
developing channeled low level southerly flow will likely keep
lower levels more well mixed.

Outlook...

Friday: VFR. Slight chance SHRA.
Friday Night: VFR. Chance SHRA, Slight chance TSRA.
Saturday: Mainly VFR, with areas MVFR possible. Chance SHRA.
Saturday Night: Mainly VFR, with local MVFR possible. Chance
SHRA.
Sunday: Mainly VFR, with local MVFR possible. Chance SHRA, Slight
chance TSRA.
Sunday Night: Mainly VFR, with local MVFR possible. Chance SHRA,
Slight chance TSRA.
Memorial Day: MVFR. Chance SHRA, Slight chance TSRA.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.

&&

$$
SYNOPSIS...JMG
NEAR TERM...Evenson/JMG
SHORT TERM...Deal
LONG TERM...Deal
AVIATION...JMG



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