030
FXUS61 KBTV 061900
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
300 PM EDT Mon May 6 2024

.SYNOPSIS...
Beautiful weather conditions is expected. After a foggy and cool
morning tomorrow, temperatures will rise into the mid 60s to mid
70s again under clear, blue skies. By Wednesday, rain chances
will return to the forecast with a trend towards cool
temperatures struggling to rise above 60 over the weekend.
Friday appears most likely to be the wettest day. Temperatures
will begin to moderate at the start of next week.

&&

.NEAR TERM /THROUGH TUESDAY NIGHT/...
As of 256 PM EDT Monday...With moisture out of the region, we`re left
with fair weather cumulus and thin cirrus. Observed temperatures
are in the 60s to lower 70s with a light breeze out there.
Truly a gorgeous spring day. Efficient cooling is expected
underneath surface high pressure and ample mid-level dry air. In
fact, parts of Ontario Province were below freezing last night.
With that, it seems highly likely the Adirondack Airport at
Saranac Lake hits 32 tonight. Elsewhere, mainly upper 30s to mid
40s is expected with upper 40s near Lake Champlain. There`s
plenty of ground moisture available, and this should produce
valley fog across climo favored spots.

Another great weather day should unfold tomorrow. Temperatures
should be a couple degrees warmer compared to today due to
somewhat drier air in place. There will be some more wind
tomorrow afternoon out of the northwest, but nothing that should
exceed 15 mph. Overnight, a compact surface low will approach
the region with rain chances increasing from the southwest.
Initially, skies will be partly cloudy, and we could observe
brief radiational cooling before clouds and southeast flow
develop ahead of the low and precipitation. Temperatures will
likely be in the 40s Tuesday night into Wednesday.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
As of 256 PM EDT Monday...On Wednesday morning, the omega block
breaks down, allowing for a piece of shortwave energy from a huge
meandering upper level closed upper low out west to approach our
region. PWATs rise from 0.4 to 1.1 inches, which is equivalent to
the 25th and 90th percentile of SPC sounding climatology for the
Albany, NY upper air site. Expect shower coverage to become more
widespread by Wednesday morning. 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. A belt of 7 to 7.5C/km
mid-level lapse rates cross the area around mid day into the
afternoon hours from west to east.

While the best chance for organized convection and stronger storms
should remain south of our CWA, CAMs forecast soundings (namely the
12z NAM 3km since we are just getting into the CAM time range for
Wednesday afternoon) hint at the potential for some marginally
severe storms capable of isolated large hail and perhaps some wet
downburst across the southern zones of our CWA. The main limiting
factors include the marginal and conditional surface-based
instability and dew points in the low to mid 50s. But with surface
to 6km shear in the 40-50 kt range as well as 0-1km storm relative
helicity of over 100 m2/s2, an isolated strong to perhaps severe
storm cannot be totally ruled out. Nonetheless, given the
conditional nature of the storms, have kept with the mention of
slight chance of thunderstorms. The key take home message at this
time remains to monitor the forecast for Wednesday afternoon if you
have outdoor plans. Heading into overnight Wednesday, any
thunderstorms and locally heavy downpours will taper off and mainly
dry conditions should prevail after midnight. Given plenty of
moisture trapped in the boundary layer up to 750mb, patchy fog is
possible in sheltered locations overnight Wednesday into early
Thursday morning.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 256 PM EDT Monday...We briefly get into zonal flow on Thursday
but there remains plenty of moisture trapped under an inversion at
the 850-700mb level and cool light northerly or northeasterly flow
below 925mb level owing to a weak surface low off the New England
coast. So expect isolated to scattered showers and plenty of clouds
on Thursday, although no washouts are expected. There remains the
possibility for breaks in sunshine and where they do occur, current
forecast daytime highs would be a tad too cool. Heading into Friday,
global guidance shows a sub-550mb upper low shifting east from the
Ohio River valley into the interior Atlantic seaboard. There remains
considerable differences in the evolution of the upper low and how
far south it digs. At this time, most of the ensemble members have
it too far south for any organized convection, although another
round of garden variety thunderstorms is certainly on the table for
Friday. What we can be currently more confident is the potential for
anomalously cool temperatures to prevail across North Country Friday
afternoon into at least the first part of the weekend. The sub-550mb
upper low moves overhead with unseasonably cold temperatures aloft.
For perspective, the sub-freezing 850mb temperatures late Friday
into Saturday would be around the 10th percentile of SPC sounding
climatology for the Albany, NY upper air site for middle of May. So
hikers could certainly encounter snow showers for the High Peaks of
the Adirondacks above 4500 ft elevation Friday afternoon into
Saturday.

Highs on Friday or Saturday could struggle to get out of the 50s for
the valleys and 40s in the higher elevation. For reference, typical
highs for North Country are in around 62 to 68, so a day with highs
around 10-15F below normal is on tap. Unsurprisingly, the CPC 8-14
day temperature outlook favors below normal temperatures for our
region. As for rainfall and hydrologic considerations, 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 rise but remain below action stage. Typically flashy
basins such as East Branch of the Ausable River (ASFN6) could
experience sharp water level rises late Friday into Saturday but
remain below action stage or bankfull. 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 given the unseasonably cool regime as depicted
by the upper level pattern. Therefore, the rainfall is expected to
be mainly showery and manageable in nature. As for a sneak peek into
the weekend, after an anomalously cool start to Saturday, a brief
period of drier and warmer conditions are possible for at least
parts of the weekend before a deeper and broader 540mb upper low
anchors itself somewhere across the eastern U.S. For warm weather
lovers, unfortunately the odds do favor an extended period of cooler
weather but it does look like severe weather potential remains
negligible to nil.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
Through 18Z Tuesday...Clouds continue to scatter across the
region. Mostly VFR conditions are expected the next 24 hours,
outside nighttime fog. Winds are still in the process of
shifting in areas like KBTV and KRUT as a weak boundary
continues eastward, but west to northwest winds should prevail
at 5 to 10 knots today, and trend light and variable or terrain
driven after 00z. Fog appears likely across favorable river
valleys impacting KSLK and KMPV probably between 08z and 12z,
with lower chances at other terminals with no explicit mentions
noted at this time. Beyond 12z, mainly clear skies prevail with
north to northwest winds steadily increasing at 5 to 8 knots.

Outlook...

Tuesday Night: VFR. Likely SHRA.
Wednesday: Mainly MVFR, with areas VFR possible. Definite SHRA,
Slight chance TSRA.
Wednesday Night: Mainly MVFR, with local IFR possible. Slight
chance SHRA.
Thursday: Mainly VFR, with areas MVFR possible. Chance SHRA.
Thursday Night: Mainly VFR, with areas MVFR possible. Likely
SHRA.
Friday: Mainly MVFR, with areas VFR possible. Likely SHRA.
Friday Night: Mainly VFR, with areas MVFR possible. Chance SHRA.
Saturday: Mainly VFR, with local MVFR possible. Slight chance
SHRA.

&&

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

&&

$$
SYNOPSIS...Haynes
NEAR TERM...Haynes
SHORT TERM...Chai
LONG TERM...Chai
AVIATION...Haynes