Scientific Forecaster Discussion
fxus61 kbtv 210247
Area forecast discussion
National Weather Service Burlington Vermont
1047 PM EDT Thu Jul 20 2017
Friday will remain relatively dry, but an isolated afternoon
shower or two is not out of the question. Saturday into the
first part of Sunday will see more dry and seasonable weather
under high pressure. Sunday evening into Monday brings the next
chance of showers and thunderstorms as an upper level trough of
low pressure moves in.
Near term /through Friday night/...
as of 1034 PM EDT Thursday...showers and thunderstorms have moved
out of the area. Rest of the evening should be quiet with skies
becoming mostly clear. May see some patchy fog in the typcially
fog prone spots, especially any spots which had a shower roll
through this afternoon. Previous discussion follows.
Quiet and dry weather is expected tonight and for most of
Friday. There will be a trough moving across eastern Canada and
we should see some increase in dynamic support and combined with
additional forcing from the higher terrain and sufficient
instability. Because of that cannot rule out the possibility of
some very isolated showers or thunderstorms, mainly over the
northern Adirondacks and the northern third of Vermont. Again
this activity would be weak and disorganized. Overnight Friday,
high pressure takes hold again leading to another dry and quiet
High temperatures today and Friday will generally be in the
upper 70s to mid 80s while lows for Thursday and Friday will be
in the mid 50s to mid 60s.
Short term /Saturday through Sunday night/...
as of 314 PM EDT Thursday...looking for a relatively dry day on
Saturday with west-northwesterly mid-level flow and weak sfc
high pressure in place across New York and New England. Low-level wind
fields are quite weak with flat p-gradient, so winds areawide
should be less than 10 mph. The 850mb temps per 12z GFS/European model (ecmwf)
are near +13c at btv at 18z Saturday, and with partly to mostly
sunny conditions, should see daytime highs in the low-mid 80s.
Can't completely rule out a terrain driven shower/isold
tstm...especially vcnty of the nrn Adirondacks. There is a
slight chance mention (pops 15-20%) in the official forecast
during the mid aftn thru early evening period as a result.
Low pressure tracking ewd across the srn Great Lakes region will
be associated with ewd extending frontal zone, with developing
zone of 850-700mb warm advection across the srn half of the
forecast area during Saturday night. Some nwp differences with
12z GFS showing associated showers and warm air advection further north across
our region, with 12z European model (ecmwf) suppressed further south. At this
point, included 30-40% pops mainly late Saturday night for
showers and chance for an embedded elevated thunderstorm.
Will see continued chances for showers and isold thunderstorms
on Sunday into Sunday night, generally 20-40% pops Sunday and
50-60% pops Sunday night with highest pops across the srn half
of our forecast area. During this time frame, east-west baroclinic
zone will be situated across central New York into central New
England, with weak sfc low tracking ewd along the frontal zone.
It appears that better upper level support arrives Sunday night
into Monday with shortwave trough approaching from sern Ontario.
12z GFS model soundings at krut Sunday night indicate elevated
instability around 500 j/kg, so maintained slight chance
thunderstorms thru the overnight period. Should see high temps
mid-upr 70s Sunday, and upr 50s to around 60f for Sunday night
with mostly cloudy skies expected.
Long term /Monday through Thursday/...
as of 314 PM EDT Thursday...mid-level shortwave trough tracks
ewd thru the area Monday into Monday night, with continued
chances for showers. Abundant clouds likely Monday, keeping
daytime highs in the low-mid 70s. Should trend toward cooler and
drier weather mid-week as shortwave trough moves east of our
longitude later Monday night or Tuesday. Should see highs in the
mid 70s Tue/Wed. Kept lingering 30% pops Tuesday and down 10%
or less into Wed/Thu.
Aviation /03z Friday through Tuesday/...
through 00z Saturday...last vis imagery of the evening shows
mainly clear skies across our taf sites...as much drier air
advects into the region on northwest winds. Surface dwpts have
dropped into the upper 50s to lower 60s...which combined with
975mb to 900mb winds of 10 to 20 knots overnight will keep
atmosphere mixed and limit fog/br development. Have utilized
tempo btwn 08-11 for MVFR in br at mpv and MVFR cigs at slk
toward sunrise. Otherwise...VFR conditions prevail at all sites
with northwest winds 3 to 8 knots...becoming light and variable
Friday night: VFR. No sig weather.
Saturday: VFR. No sig weather.
Saturday night: VFR. Slight chance rain showers.
Sunday: VFR. Chance rain showers...slight chance thunderstorms and rain.
Sunday night: VFR. Chance rain showers...slight chance thunderstorms and rain.
Monday: VFR/MVFR. Chance rain showers...chance thunderstorms and rain.
Monday night: VFR/MVFR. Chance rain showers.
Tuesday: VFR/MVFR. Chance rain showers.