Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Burlington Vermont
408 am EDT Sat Jul 30 2016
low humidity levels, mostly clear skies, and pleasantly warm
temperatures will characterize Saturday, as Canadian high pressure
controls our weather through tonight. Thereafter, a slow moving
upper level disturbance and associated rich moisture moving out
of the Ohio Valley will bring periods of rain showers Sunday into
Monday, possible lingering into early Tuesday. High temperatures
will reach the low 80s today, but then generally in the low to
mid 70s for the Sunday through Tuesday time frame with abundant
cloudiness. High pressure returns Wednesday through Friday with
warmer and more humid conditions.
Near term /through tonight/...
as of 317 am EDT Saturday...tranquil and pleasant weather
conditions through the near-term period. Dry northerly low-level
airstream continues east of 925mb anticyclone centered across swrn
Quebec. This will continue to provide the north country with
relatively low humidity (2-M dewpoints in the 50s) today. Early
am valley fog will dissipate by 13z, and then skies will be mostly
sunny thru the day. With 850mb temps of +11c to +13c at 21z per
00z GFS, looking for highs generally in the upr 70s to lower 80s.
10-meter winds 14-22z generally north 5-9 mph, except locally NE
across far nrn New York. Pops none.
Continued quiet tonight, though will see some mid-upper level
clouds increasing from SW-NE after midnight as slow-moving 500mb
trough shifts newd from Ohio into PA/wrn New York. Included slight chance
of showers S-central Vermont toward 12z Sunday, but most likely
scenario is that associated shower activity remains south of the
entire forecast area until during the day Sunday. Overnight lows
mid-upr 50s, except locally around 60f S-central Vermont valleys where
clouds inhibit radiative cooling. Some patchy valley fog is
possible nrn valleys after 06z Sunday.
Short term /Sunday through Monday night/...
as of 354 am EDT Saturday...the 00z suite of guidance remains
consistent with the general idea of a broad slow moving upper
level trough crossing the Great Lakes region Sunday afternoon into
the north country by late Monday. The surface low that develops
will be south of the forecast area but guidance is still quite
disparate between solutions. Where the surface low sets up and the
convergence boundary develops will have dramatic effects on the
area that ends up being the bulls eye for precip. The GFS and Gem
models have a 2-3 inch bulls eye along the Saint Lawrence River
where as the European model (ecmwf) has the 3 inch bulls eye over the Massachusetts/CT/NY
border, and the NAM has a 2 inch Hot Spot over near Binghamton New York.
So in essence, its still a bit difficult to Pin Point where the
heaviest rain will fall. So I went with a consensus blend of 50%
new guidance and 50% previous forecast to trend the quantitative precipitation forecast towards
the latest guidance. I ended up with a broad 1-2inch swath of
precip across much of the area from Sunday afternoon into Monday.
With that moderate to occasionally heavy rainfall, there will be
some ponding of water in low lying areas and in areas of poor
drainage. Given the lack of continuity in location, I dont have
confidence in any sort of flood hazards especially due to the
potential for much of the precip to fall over areas in drought
Temps will warm into the mid to upper 70s and with dewpoints in
the upper 50s to near 60, instability isn't great. As such I
continued the idea of mainly rain showers with an isolated chance
of thunder across the area. Overnight lows will be warmer with the
rainfall but are still expected to drop into the mid 60s. With
precip still falling and overcast skies expected, Monday should
be below normal with highs only in the upper 60s to low 70s.
Long term /Tuesday through Friday/...
as of 404 am EDT Saturday...early in the morning Tuesday there
may be a few lingering wrap around rain showers as the trough
swings through. Northerly to northwesterly winds should keep much
of the precip isolated to higher terrain locations. Then by mid
week a ridge builds in and heights rise. 925mb temps warm
throughout and by Thursday they are in the 24-26c range based on a
warm GFS solution. That may be a tad overdone but even so thats
supportive of Max temps Thursday and Friday into the lower to mid 90s.
With that trend continuing from both the previous 00z and 12z
forecasts I continued to trend warmer in the extended by bumping
up our locally produced "superblend" of models to show Max temps
each day in the upper 80s to near 90 in the CT River Valley.
Aviation /08z Saturday through Wednesday/...
through 12z Sunday...localized LIFR fog slk/mpv thru 12z Sat,
then sky clear-few250 with light north-NE winds daylight hrs areawide.
Continued VFR tonight with increasing mid-upr level clouds mainly
after 06z Sunday. Some chance of localized early am fog slk/mpv
once again 06-12z Sunday.
Outlook 12z Sunday through Wednesday...
12z Sunday-00z tuesday: mainly VFR early Sunday, but then
intervals of MVFR in shower activity Sunday afternoon through
Monday with slow moving upper trough.
00z Tuesday through wednesday: upper trough brings lingering
showers Monday night into early Tuesday with periods of MVFR and
brief IFR possible. Then clearing with VFR conditions as high
pressure returns Tuesday afternoon through Wednesday. May see
areas of nocturnal fog 06-12z Wednesday slk/mpv with localized