893
FXUS61 KBTV 052344
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
744 PM EDT Sun May 5 2024

.SYNOPSIS...
Once we clear precipitation tomorrow morning, a couple days with dry
and warm weather will unfold. Quiet weather is expected, with foggy
conditions possible early Tuesday morning. By Wednesday, rain
chances will return to the forecast alongside a trend towards
cool temperatures struggling to rise above 60 over the weekend.
Friday appears most likely to be the wettest day.

&&

.NEAR TERM /THROUGH MONDAY NIGHT/...
As of 653 PM EDT Sunday...As expected, the subtle upper trough
is shifting east this evening, pushing rain east as well. This
dry period is expected to be short lived tonight though, as a
frontal boundary will produce more rain showers across the
forecast area from northwest to southeast during the early hours
of Monday morning. In terms of updates, high resolution models
are depicting a minor shift slower than previously, and
precipitation is expected to be much more scattered and showery
than today`s rain was due to drier air. There is the potential
for a couple lightning flashes with elevated instability
available overnight tonight, but generally the potential is too
low to even put in the forecast. The atmosphere should begin to
stabilize after midnight, allowing for some mist or patchy fog
to develop in the usual spots. Winds on Lake Champlain continue
to run around 20-25 knots out of the north or south, depending
on location. Temperatures remain on track to fall into only the
mid 40s to lower 50s under plenty of sky cover. Previous
discussion below:

Previous discussion...Rain from moist, tropical air overriding
the cool maritime air at the surface has yielded a soggy day
alongside an incoming upper vort. As we head towards evening, the
subtle upper trough will shift east with sunset helping rain to also
diminish. It`ll be this time frame we see winds around 2000-4000
feet above the ground pick up from the south. Winds will become
increasingly gusty near Lake Champlain up to 30 mph over the
next several hours, but will likely have little impact on the
rest of the region. Abundant clouds and rain have generally kept
us in the 50s today with a few readings stuck in the upper 40s.
Little cooling is expected tonight while we await a weak cold
front, with mid 40s to lower 50s likely to hold steady.

Overnight, a weak cold front characterized mostly by its moisture
gradient will move southeast and there will a brief uptick in shower
activity between about 4 AM and 10 AM Monday associated with it.
Rising pressures and dry atmospheric conditions afterwards
should allow clouds to clear out into a gorgeous day.
Temperatures will climb into the 60s for most, with spot 70s
across our lower valleys. Surface high pressure slides overhead
Monday night. With relatively high dewpoints and recent rain,
this seems the opportunity for fog development with a cool
morning in the upper 30s to mid 40s, though still upper 40s near
Lake Champlain.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
As of 258 PM EDT Sunday...Tuesday is shaping up to be a gorgeous
early May day by North Country standards. We briefly get into an
omega block in between an upper low out across the Northern Rockies
and another one across Newfoundland. Surface high pressure noses in
from south of Hudson Bay, and given all the recent rains, it should
be a picture perfect day with the leafing process kicking into high
gear and mostly sunny skies. Forecast soundings show the potential
for the boundary layer to mix up to 800mb, so there could be some
localized northwest gusts of 15 mph. Lower dew points from aloft
could also mix down to the surface, but given the recent wetting
rain and green up, the 30s dew points would increase outdoor comfort
rather than fire danger. Given the relatively deep mixing and
potential downsloping northwest flow off the Adirondacks, have
utilized the 75th percentile of temperature guidance for afternoon
highs on Tuesday. Expect highs 68 to 75 areawide, except 58-64
across the higher terrain of the Adirondacks and Green Mountains.
Get outside and enjoy what should be the pick of the week if you
can!

Quiet weather should continue into Tuesday evening and even the
first half of the overnight hours. However, the omega block breaks
down, allowing for a piece of shortwave energy from the huge
meandering closed upper low out west to approach our region. PWATs
rise from 0.4 to 0.9 inches, which is equivalent to the 25th and
75th percentile of SPC sounding climatology for the Albany, NY upper
air site. Expect shower coverage to become more widespread during
the latter half of the overnight hours into the Wednesday morning
hours. Then the upper level pattern gets a little more complicated.
Models show that upper low over Newfoundland retrograding into New
Hampshire/Maine. As it interacts with the aforementioned relatively
weak shortwave energy from out west, there are some signals it
becomes a neutrally to even slightly negatively tilted H5 trough.
Looking at the 250mb level, there is a small window parts of New
England gets into the favorable left exit region of an anomalously
strong 110 kt jet. At this point, however, it does look like the
best jet dynamics are to the south of our CWA, so the most probable
weather risk at this time are garden variety thunderstorms on
Wednesday afternoon with locally heavy downpours. Nonetheless, there
still remains plenty of time in the model world for our southern
zones to get into more organized convection. Overall, the key take
home message at this time is to monitor the forecast especially for
Wednesday afternoon given the potential for thunderstorms.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 258 PM EDT Sunday...From Wednesday night onwards, the overall
weather pattern can be described as unsettled with no real
significant warm up or impactful weather. Unsurprisingly, the CPC
8-14 day temperature outlook favors below normal temperatures and
leans towards above normal rainfall. For reference, typical highs
for North Country in early May are in the low to mid 60s, while
average overnight lows are in the mid 30s to low 40s. Global models
show a rather active northern stream upper level pattern, with a
train of quick-hitting shortwave troughs originating from northern
Canada crossing our regions every 2-3 days. While the most
aggressive members of the Model-Based Ensemble Forecast System
(MMEFS) guidance are hinting at a non-zero chance of river flooding
in the Friday/Saturday time frame, the consensus of members is for
area rivers to remain below action stage. The probability of
widespread convection, which is required to drive the rainfall rates
for flooding to be a concern, is extremely low and mainly confined
to the south of our CWA. Therefore, the rainfall is expected to be
mainly showery and manageable in nature. Outside of rainfall
concerns, while the forecast has shower chances almost every single
day, it does not mean that it will be a washout every day. In fact,
that would probably be extended dry periods although it is difficult
to time those breaks in rainfall and clouds this far out. So largely
stuck to blended guidance from Wednesday onwards.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
Through 00Z Tuesday...Currently MVFR CIGS prevail at all sites
except VFR conditions at PBG. As subsidence on water vapor moves
across our region tonight, expect a slow lowering of CIGS to IFR
with highest confidence at SLK/MPV and RUT. Have used a tempo
group to show transition from MVFR to IFR as cigs may jump up
and down btwn MVFR and IFR for several hours before becoming
prevailing btwn 04-06z. Also, less confidence 30 to 40% of IFR
cigs at EFK/BTV and MSS toward 06z with intervals of IFR
possible btwn 06-12z. Conditions slowly improve to MVFR by 14z
and mostly VFR by 16z on Monday. South/southeast winds of 10 to
20 knots will become southwest 4 to 8 knots by 06z, before
shifting to the west/northwest by morning. Some scattered
showers are likely from time to time overnight into early Monday
morning, which was covered by VCSH. Some lowering of sfc vis
possible toward morning also, especially at SLK/MPV.

Outlook...

Monday Night: VFR. Patchy BR.
Tuesday: VFR. NO SIG WX.
Tuesday Night: VFR. Chance SHRA.
Wednesday: Mainly VFR, with local MVFR possible. Definite SHRA,
Slight chance TSRA.
Wednesday Night: Mainly MVFR, with areas VFR possible. Slight
chance SHRA.
Thursday: Mainly MVFR, with areas VFR possible. Likely SHRA.
Thursday Night: Mainly MVFR, with areas IFR possible. Likely
SHRA.
Friday: Mainly MVFR, with areas IFR possible. Likely SHRA.

&&

.MARINE...
South winds have been trending towards 20 to 25 knots over the
course of the morning and early afternoon. It is expected that
sustained winds to 25 knots, especially across the broad lake
will become more persistent late this afternoon and evening. A
Lake Wind Advisory is in effect, and waves up to 4 feet will be
possible. After 10 PM or so, winds should begin to subside
across the lake.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.

&&

$$
SYNOPSIS...Haynes
NEAR TERM...Haynes/Storm
SHORT TERM...Chai
LONG TERM...Chai
AVIATION...Taber
MARINE...