Area Forecast Discussion
Issued by NWS Burlington, VT-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KBTV 291444
Area Forecast Discussion
National Weather Service Burlington VT
1044 AM EDT Fri Jul 29 2016
-- Changed Discussion --A quasi-stationary front along the international border will
settle southward across the North Country today. This front
combined with an upper level disturbance across southern New
England will bring a chance of showers and slight chance of
thunderstorms, mainly across south-central portions of Vermont.
Elsewhere, light north winds will usher in drier air from Ontario
and Quebec, with skies becoming partly to mostly sunny across
Northern New York and Vermont this afternoon. Canadian high
pressure will bring dry weather tonight through Saturday. High
temperatures on Saturday will range from the upper 70s to lower
80s, with pleasantly low humidity levels. The next upper level
disturbance approaching from the Great Lakes will bring the next
chance for showers for Sunday into Monday.
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.NEAR TERM /THROUGH SATURDAY/...
-- Changed Discussion --As of 1044 AM EDT Friday...Only change was addition of slight
chance of thunderstorms for southeast VT with this update. Morning
sounding data at ALB adjusted for afternoon heating shows
potential CAPE values up to 900 J/kg this afternoon with 1.71"
precipitable water and tall narrow CAPE profile. This in line with
blend of model CAPE forecasts. RAP shows 925-850mb thermal axis
SW-NE across central VT associated with nearly stationary front.
This also aligned with right entrance region and axis of 80 kt
300mb jet moving into the gulf of ME. Noted a couple of shower
cells earlier this morning with little movement and up to 1.50" of
dual- pol estimated rainfall, so something to keep an eye on.
Previous discussion....Surface frontal boundary across far nrn NY
marked primarily by higher surface pressures across swrn Quebec
and sern Ontario will shift slowly southward during the daylight
hours today reaching srn VT by 00z this evening. Have noted N-NW
wind shift at PBG/MSS/Potsdam past 1-2 hours associated with this
frontal passage. Separate mid-level shortwave trough across
e-central NY is associated with widespread light rain across sern
NY and much of southern New England, and this precipitation shield
will remain well south of the North Country today. Will be
monitoring s-central VT for development of a few showers late this
morning into this afternoon as frontal zone shifts
swd...consistent with high resolution model guidance from NAM4KM,
BTV-4km WRF and 10Z HRRR. Up to 0.10" rainfall possible, but
generally confined to Rutland/Windsor/srn Orange counties with
PoPs 30-40% in these areas. Drier air moving in from
Quebec/Ontario and passage of mid-level trough to our south will
generally result in decreasing cloud cover across nrn NY and nrn
VT, especially as we head into the afternoon hours. Temperatures
are starting mild (mid-upr 60s) in most spots early this morning
with cloud cover in place, so should see highs in the low-mid 80s
with good insolational heating this aftn. 2-m dewpoints in the
low-mid 60s will begin to fall into the mid-upr 50s across nrn
half of the forecast area this afternoon, with north winds
increasing to around 10 mph.
Generally quiet conditions tonight with light N-NW winds and
mostly clear skies. Should see min temps a bit cooler than recent
days with advection of lower dewpoints/clear skies/good radiative
cooling. Lows mainly in the 50s. May see some patchy fog develop
in the favored river valleys of central and eastern VT, and also
across the valley locations within the northern Adirondack region.
Pleasant conditions for Saturday with weak surface high pressure
across southern Quebec providing light north winds and sfc
dewpoints in the low-mid 50s. The 00Z GFS indicates 850mb
temperatures of +11 to +12C, which should translate to afternoon
highs in the upr 70s to lower 80s with nearly full sun. PoPs nil.
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.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/...
As of 354 AM EDT Friday...A slow moving upper level trough of low
pressure will gradually move into the region. We should start to
see increasing chances of showers after midnight Saturday night
and especially on Sunday. The clouds and showers will also hold
down high temperatures Sunday with readings in the 70s to around
80. Areas with the best chance for seeing precipitation will be
over the northern Adirondacks of New York and the central and
southern sections of Vermont.
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 354 AM EDT Friday...Trends in the data suggest upper trough
moving into the region Saturday night into Sunday will be slow to
clear the region and will not exit until late Monday into Tuesday.
Thus looking at a continuation of the showers Sunday night through
Monday before gradually tapering off from west to east Monday
night into Tuesday. Clouds...precipitation...and cooler 925 mb
flow suggest highs only in the 70s on Monday. A warming trend will
begin on Tuesday as clouds and precipitation move out of the
area...but we will still be in northwest flow aloft. Should be at
seasonal normals on Tuesday then better warming for Wednesday and
Thursday with highs getting into the 80s for much of the area. Dry
weather is expected Wednesday and Thursday.
.AVIATION /15Z Friday THROUGH Tuesday/...
Through 12Z Saturday...Areas of LIFR fog/ceilings will continue
through 13-1330Z at RUT/BTV/MPV, but daytime mixing and drier air
moving in from the north wil bring conditions back to VFR
thereafter. Overall, looking for clearing skies mid-late morning
from NW-SE as a front settles southward across the area and as
mid-level trough departs to the south and east across srn New
England. May see isold -SHRA across s-central VT/KRUT late
morning into the aftn, with dry weather elsewhere. Light and
variable winds generally becoming N 5-10 kts late morning through
afternoon. Mostly clear with light winds tonight...may lead to
localized LIFR radiation fog MSS/SLK/MPV after 06Z Saturday.
Outlook 12z Saturday through Tuesday...VFR/mainly clear Saturday
with light winds. This will be followed by periods of showers
Sunday into Monday with slow moving upper trough moving ewd from
the Great Lakes. May see intervals of MVFR conditions SUN-MON.