Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 211356

Area Forecast Discussion
National Weather Service Burlington VT
956 AM EDT Fri Jul 21 2017

A sunny start is expected for the North Country today...but the
threat of some showers or storms will exist this afternoon...
especially over northeast New York and the northern third of
Vermont. Any showers or storms will have the potential to
produce gusty winds before coming to an end this evening. A dry
day is expected for Saturday. Eventually we will transition to
a wetter pattern Sunday into Monday. Expect one more day of
above normal temperatures today...then a transition to at or
below normal temperatures for the weekend and early next week.


As of 951 AM EDT Friday...Nocturnal fog has dissipated from the
deeper valleys of central/ern VT, leaving mostly clear skies
from the Champlain Valley ewd at 1345Z. Low-level SW flow
generating some upslope cloudiness across the nrn Adirondacks.
Have made some forecast adjustments for prevailing nrn NY
cloudiness, but should see these clouds mixing out as PBL
deepens with continued insolational heating thru the late
morning and early aftn hours.

Should see a good deal of sun through midday before trough
moves across eastern Canada and helps to move a front down into
our area. This should enhance the potential for some showers and
storms this afternoon...although areal coverage should be
isolated in nature. It looks like northeast New York and the
northern third of Vermont will have the best chance of seeing
these isolated showers or storms. Instability is not strong but
it is sufficient for thunder potential. Deep layer shear will
also be increasing as the afternoon wears on and the drier low
levels mentioned earlier indicate some increased downdraft
potential. Have included the mention of gusty winds with any of
the storms over the northern third of Vermont where forecast
soundings support this idea. High temperatures today will be in
the upper 70s to mid 80s. The mid 80s will be most common on the
Vermont side of the Champlain Valley as downsloping westerly
winds will help warm the temperatures more than other areas.

Any convection ends this evening and quiet weather is expected for
the overnight hours. Much of Saturday should remain dry too with
west to northwest flow aloft over the area. Highs will be a few
degrees cooler than Friday with readings in the mid 70s to lower
80s. Cannot rule out the possibility of some showers moving in late
in the day on Saturday over parts of northern New York and the
southern half of Vermont...but the bulk of the precipitation should
remain south of our area.


As of 358 AM EDT Friday...Trend in the latest NWP guidance for
the latter half of the weekend is trending drier, though I will
note that could easily change. The forecast largely depends on
how low pressure evolves out of convection expected to fire up
over the Wisconsin/Minnesota area this afternoon and night, and
where the mid-level thermal packing sets up downstream. There`s
a general consensus that the boundary will set up south of the
BTV forecast area, with a comparison of the 00Z NAM/ECMWF/GFS
showing the GFS as the outlier with the most northern track and
deeper low. Don`t want to totally discount it, so I`ve offered a
blended forecast for PoPs, trending towards the drier
NAM/ECMWF. This results in low chance PoPs across our southern
zones Saturday night, with only a slight chance north. Anything
that does affect the area overnight will dissipate by Sunday
morning with a mainly dry day expected, though chances for more
widespread showers increases from the southwest in the afternoon
as our next system approaches.


As of 358 AM EDT Friday...Sunday night through Tuesday
continues to look like the main active period of the next 7 days
as medium range guidance is in good agreement highlighting an
upper trough digging through the Great Lakes Sunday night and
across the Northeast through Tuesday with a series of embedded
shortwave troughs bringing periods of precipitation to the North
Country. Best dynamical forcing shifts over the CWA Sunday
night into Monday morning with a decent plume of PWATs around
1.5" skirting southern areas and modest mid-level lapse rates
around 6 C/km supporting the idea of some thunder, but overall
convective threat is rather low. Additional showers continue
Monday afternoon right through Tuesday as the trough shifts over
and east of the region by 00Z Wednesday. By Tuesday night
surface high pressure and ridging aloft build into the area with
sunny/clear conditions expected for Wednesday and Wednesday
night. A weak cold front approaches for Thursday renewing
chances for showers along our northern border.


Through 12Z Saturday...Expect VFR conditions through much of the
period. The only exception will be at KSLK and KMPV where
periods of IFR/LIFR conditions may exist through 13z due to low
clouds and fog. Some wind does exist just off the surface and
this may limit the areal extent of fog early this morning. A
front will move toward the region this afternoon and we will see
winds become more west with time at speeds around 10 knots
before tapering off after 00z. With the front there may be the
potential for some showers/storms over northeast New York and
the northern third of Vermont between 18z and 00z...but still
looking at VFR conditions as any showers or storms will be
isolated in nature.


Saturday: VFR. NO SIG WX.
Saturday Night: VFR. Slight Chance SHRA...Slight Chance TSRA.
Sunday: VFR. Chance SHRA...Slight Chance TSRA.
Sunday Night: VFR. Chance SHRA...Slight Chance TSRA.
Monday: VFR. Chance SHRA...Chance TSRA.
Monday Night: VFR/MVFR. Chance SHRA.
Tuesday: VFR/MVFR. Chance SHRA.




NEAR TERM...Banacos/Evenson
LONG TERM...Lahiff
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