Scientific Forecaster Discussion
fxus61 kbtv 230755
Area forecast discussion
National Weather Service Burlington Vermont
355 am EDT Mon Sep 23 2019
a low pressure system moving through the Great Lakes will bring
periods of showers and perhaps some rumbles of thunder to the north
country today along with gusty winds. Somewhat drier weather is
expected tonight, before conditions take a turn for the worse on
Tuesday with scattered showers redeveloping and much cooler
temperatures expected as low pressure moves overhead. Dry weather
and seasonable temperatures return Wednesday under brief high
pressure, with showers returning for Thursday.
Near term /through Tuesday/...
as of 354 am EDT Monday...forecast remains generally on track for
today through Tuesday with the main weather feature being an
occluding upper low moving from the Great Lakes region this morning
to directly over the north country on Tuesday. For today, showers
will be developing ahead of the occlusion around daybreak across the
St. Lawrence Valley and shift across northern New York into Vermont
during the mid-day hours. Behind this initial batch of precip,
surface instability will increase to around 400-600 j/kg helping to
develop some additional convective showers this afternoon, but
coverage will be widely scattered and many parts of the region will
likely remain dry. Some rumbles of thunder are certainly possible in
this airmass as well, but don't think we'll see many cg's. In
addition, surface winds will remain gusty from the south/southwest,
strongest across northern New York this morning in the 20-30 mph
range, with 10-20 mph elsewhere. Highs will continue to be mild for
early fall, and run only slightly cooler than yesterday in the mid
70s to low 80s.
Occlusion/cold front moves through the forecast area this evening
with a strong mid-level dry slot shifting in behind it helping to
reduce coverage of precipitation for the first half of the night. As
the dry slot shifts east of the area after midnight, the core of the
upper low begins to shift in, first redeveloping scattered showers
across the Adirondacks early Tuesday morning, then across the entire
forecast area during the day as low/mid level lapse rates steepen
and the low centers overhead. It will certainly feel more like fall
after the past couple days of Summer-like temperatures, with
somewhat mild lows in the 50s tonight, followed by highs only in the
60s for Tuesday.
Short term /Tuesday night through Wednesday/...
as of 354 am EDT Monday...fallish, upper low lifting east-northeast allowing a
shortwave ridge to move in on Wednesday. Any remaining shower
activity early Tuesday evening will be exiting with gradual clearing
Wednesday with nek being the latest. Highs will be at or above (aoa)
seasonable levels in the 60s/70.
Long term /Wednesday night through Sunday/...
as of 354 am EDT Monday...after a week of ridging the active pattern
that began Monday-Tuesday will continue for the rest of this period
with a disturbance basically every other day. It's been dry lately
and although we'll be getting a chance of rainfall, the amounts
during this period are nothing that great. Meanwhile temperatures
will largely stay at or above seasonable levels for the period.
Wednesday night...upper level ridge already departing with SW flow
ahead of northern stream shortwave and surface cold front that will
approach Thursday. Whatever convective feedback issues on the GFS
calling for very strong lift and precipitable waters have disappeared. There will
be some decent lift but much is lifting north-northeast across Canadian border
and unfavorable timing may limit any chance of T-storms.
This system departs with southeast Continental U.S. Ridge attempting to build into the
northeast but New York/Vermont should stay in northern periphery and more
zonal flow thus allowing influence from northern stream or ridge
Friday looks dry with surface high pressure nosing across the area
with temperatures in the 60s to l70s. A weak disturbance along the
periphery of the ridge threatens Saturday.
Currently, timing differences doesn't allow US to elaborate an
all day threat or just in the afternoon. The GFS appears more
aggressive in a southerly push across the area with the
northern stream then the other medium range models. Given the
semi- permanent nature of this southeast Continental U.S. Ridge, i'm leaning
toward a less progressive, thus milder solution.
By Sunday...the above disturbance should be out of the region for
mainly dry conditions.
Aviation /08z Monday through Friday/...
through 00z Tuesday...southwest flow aloft continues ahead of
approaching system with increasing mid/upper level clouds
developing from west to east. These clouds, along with 925mb to
850mb winds of 25 to 40 knots will prevent fog/br from
developing at taf sites overnight, as all sites experience VFR
conditions. Sfc winds generally in the 5 to 10 knot range, but
with some periodic gusts up to 15 to 18 knots possible, at
btv/mss. Clouds continue to lower on Monday with some scattered
showers arriving mid to late morning from west to east. Thinking
generally VFR conditions with some brief periods of MVFR
cigs/vis in the stronger active during the aftn hours. Winds
continue at 5 to 15 knots with some localized higher gusts
possible, along with some turbulence and shear likely near the
higher trrn of the dacks and green mtns.
Monday night: VFR. Chance shra, slight chance thunderstorms and rain.
Tuesday: mainly VFR, with areas MVFR possible. Chance rain showers.
Tuesday night: mainly VFR, with local IFR possible. Slight chance
Wednesday: mainly VFR, with local MVFR possible. No sig weather.
Wednesday night: VFR. Slight chance rain showers.
Thursday: VFR. Likely rain showers.
Thursday night: mainly VFR, with local MVFR possible. No sig weather.
Friday: VFR. No sig weather.