341
FXUS61 KBTV 060519
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
119 AM EDT Mon May 6 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 TUESDAY/...
As of 112 AM EDT Monday...No significant changes were needed
with this update. Our first batch of rain has moved well to our
south and east; now we await scattered showers to develop along
a weak cold front which currently lies poised just on the other
side of the St Lawrence Valley. With light winds and ample low-
level moisture, expect patchy fog will develop as we head toward
daybreak. Cloud clover will linger as well, and this will serve
to keep temperatures from cooling much more than a few degrees
beyond current readings (mid 40s to mid 50s). The forecast has
this all pretty much covered, so only change was to increase
cloud cover to cloudy pretty much areawide through the remainder
of the overnight hours.

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 NIGHT 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 /05Z MONDAY THROUGH FRIDAY/...
Through 06Z Tuesday...Currently a mix of MVFR and IFR ceilings
across the region. Scattered showers will slowly cross from west
to east early in the period as a cold front pushes through, and
IFR ceilings are expected at all terminals as this occurs,
roughly 07z-12z. The lone exception is KPBG, which should stay
just barely MVFR. Visibilities will be reduced 3-5SM at times in
rain and fog. The front exits to our southeast by 14z, and
expect gradual improvement thereafter, with ceilings lifting to
MVFR and eventually VFR at all terminals by late in the TAF
period. Winds light and mainly terrain driven overnight, turning
toward the north/northwest around 5-8 kt once the front moves
through.

Outlook...

Tuesday: VFR. NO SIG WX.
Tuesday Night: VFR. Chance SHRA.
Wednesday: Mainly VFR, with areas MVFR possible. Definite SHRA,
Slight chance TSRA.
Wednesday Night: Mainly VFR, with local IFR 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.

&&

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

&&

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