FXUS61 KBTV 220735
Area Forecast Discussion
National Weather Service Burlington VT
335 AM EDT Tue May 22 2018
Cloudy skies and periods of showers are expected today into
this evening as weak low pressure crosses the region. A cold
front will cross the area by Wednesday afternoon with little
fanfare other than a few showers or perhaps an isolated storm
across northern counties. Behind this front fair and seasonably
warm weather is expected through the remainder of the work week.
.NEAR TERM /THROUGH WEDNESDAY/...
As of 335 AM EDT Tuesday...Kind of a "meh" day on tap for our
area as we continue to watch weak low pressure and associated
moisture streak east/northeast from the eastern Great Lakes and
Ohio Valley this morning. While we`ll maintain higher chance to
likely pops across our area by this afternoon, several factors
argue for a low impact event with generally light QPF expected.
These are namely 1) a fairly dry boundary layer through early
afternoon, 2) anticyclonic, confluent flow aloft, and 3) a
general lack of large-scale forcing for upward vertical motions.
As such, while aforementioned pops will top out in the 50-70%
range this afternoon and early evening our latest QPF has been
reduced significantly, in some cases by as much as 50% from
prior forecasts. This suggests 18-hr totals ending by midnight
or so to generally range from a tenth to one quarter inch with
locally lighter totals in portions of the broader valleys. Any
thunder threat will remain well south of our area. Highs today
will be significantly cooler than yesterday given widespread
cloud cover and shower activity - mainly 60s under light south
to southwesterly flow.
Scattered to numerous evening showers then gradually shift east and
end overnight as surface high pressure noses into the area.
Skies will trend partly cloudy over time, especially north and
west as low temperatures range from 46 to 54 or so. Some patchy
fog will also be possible, mainly in the Adirondacks.
By Wednesday a well advertised cold front will drop southward
through the region as flow veers from southerly to
north/northwesterly by afternoon. As mentioned last night, we`ll be
on the back side of this front and parent upper trough with better
moisture and attendant forcing generally lying off to our northeast.
This morning`s 00Z guidance still advertises a lower end threat for
a few showers across far northern counties, especially northern VT
by later in the morning and afternoon as the front passes through
with southern counties remaining largely dry. Low level lapse rates
will remain quite steep with a mid level instability layer
developing between 850 and about 600 mb where a weak capping layer
will likely take shape. Whether any updrafts can become robust
enough to generate in-cloud graupel and thunder remains in question.
However, given modest convergence along the boundary, lower-end CAPE
values of a few hundred J/Kg and blended MOS thunder progs from 10-
18% I`ll maintain an isolated storm threat across mainly
northeastern VT counties accordingly. High temperatures will trend
warmer once again due to higher coverage of partial sunshine -
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
As of 338 PM EDT Monday...No real big changes from the previous
forecast thinking for the middle to end of the work week with
models remaining very consistent. Overall big picture highlights
an upper trough with some modest shortwave energy tracking
through ME/NH skirting our northeast zones on Wednesday,
followed by high pressure for Thursday and Friday. Outside of a
few showers and perhaps an isolated thunderstorms across
northern areas Wednesday, the rest of the week will be dry with
temps ranging through the 70s on Wednesday, cooler in the upper
60s to low 70s for Thursday, and significantly warmer in the
upper 70s to low 80s on Friday.
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
As of 338 PM EDT Monday..Still a ton of uncertainty for the
holiday weekend with little model run to run consistency. Latest
GFS and Canadian GEM show a frontal zone and digging upper
trough over central Quebec dropping southward into the Northeast
Friday night through Saturday, with an upper level ridge and
surface high pressure building in for Sunday and Monday. This is
in stark contrast to previous runs, while the ECMWF has
remained more consistent showing the trough well farther
northeast over the Canadian maritimes. The ECMWF still
highlights a frontal zone moving over the region Friday night
into Saturday, but without the trough to kick it out, wetter and
warmer conditions prevail through the weekend. Moderate
forecast confidence at this point that we`ll see some rainfall
Friday night into Saturday, but beyond that confidence is very
low. Stay tuned.
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
Through 06Z Wednesday...VFR through 18Z, then deteriorating
conditions thereafter as areas of showers push into the region
with approach of weak low pressure and associated moisture from
the Great Lakes. During this period conditions lower to MVFR
with patchy IFR in favored locales, especially from the 20-23Z
time frame onward. Winds light and generally less than 10 kts
through the period.
Wednesday: VFR. Slight chance SHRA, Slight chance TSRA.
Wednesday Night: VFR. NO SIG WX.
Thursday: VFR. NO SIG WX.
Thursday Night: VFR. NO SIG WX.
Friday: VFR. NO SIG WX.
Friday Night: VFR. Chance SHRA.
Saturday: Mainly MVFR, with local IFR possible. Chance SHRA.
As of 335 AM EDT Tuesday...A Lake Wind Advisory is in effect
for today, with the main period of stronger winds occurring this
afternoon and early evening. During this period southerly winds
will average from 15 to 25 kts with occasional gusts to near 30
kts on portions of the broad lake from the Charlotte Ferry
crossing northward. Bays and inlets with southerly exposures
will also see enhanced winds with a light chop expected. These
conditions could prove hazardous to inexperienced mariners,
especially those with small craft such as kayaks and canoes. The
southerly winds will abate later this evening.