-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBTV 281409
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
1009 AM EDT Sun Apr 28 2024

.SYNOPSIS...
Expect scattered to numerous rain showers with embedded thunder
today. A cold front brings cooler temperatures and partial
sunshine on Monday before the next chance for widespread
rainfall arrives Tuesday. The rest of the work week features
mainly dry weather and a warming trend before unsettled weather
possibly returns next weekend.

&&

.NEAR TERM /THROUGH MONDAY/...
-- Changed Discussion --
As of 1002 AM EDT Sunday...Morning showers with embedded rumbles
of thunder associated with warm frnt feature has exited our
eastern cwa this morning. A few reports of pea size hail near
Waterbury, with rainfall amounts generally a tenth to five tenths
of an inch in the heavier convective elements. Have adjusted
pops to quickly dry fa out this morning based on crnt radar.
However, expecting additional showers with embedded rumbles to
redevelop toward 18z acrs northern NY/VT ahead of weak cold
frnt. Some breaks in the clouds should help temps warm quickly
into the upper 60s to lower 70s over parts of our cwa ahead of
boundary, supporting a weak axis of instability with CAPE values
in the 250-500 J/kg range. This instability, combined with
additional forcing should be enough to support scattered to
numerous showers with embedded rumbles this aftn, but activity
wl remain below strong/severe limits. Temps are tricky today,
especially with clouds, but already 68F at Potsdam, supported by
progged 925mb temps btwn 14-16C, so have thinking with some
breaks highs should reach at least the upper 60s to lower 70s,
but might struggle east of the Greens and acrs portions of the
NEK in the upper 50s to lower 60s. All depends upon amount of
sunshine. Have tweaked hrly temps to match crnt obs and also
delayed additional pops toward 18z, instead of 15-16z, based on
timing of s/w and boundary. Rest of fcst in good shape this
morning.

Previous discussion below:
While we are currently in a lull in rainfall, the next feature
of interest associated with a cold front is showing up on radar.
A line of thunderstorms is seen near Ottawa, Ontario. RAP
mesoanalysis shows an axis of rather steep 2-6km AGL lapse rates
of up to 7.5C/km. So thinking that the thunderstorms should
hold themselves together and reach portions of northern NY and
northern VT during the pre-dawn into early morning hours.
Locally, there are also some returns along the western slopes of
the Greens due to some localized convergence. So blended in
some hi-res guidance to better reflect the PoPs in the next 6
hours. There is nothing strong or severe, but don`t be surprised
to hear some rumbles of thunder and see brief locally heavy
downpours first thing this morning.

This morning, a 1004 mb surface low pressure tracks northeast from
the southern tip of Hudson Bay to Nunavut this morning. As it does
so, it will be weakening but has just enough dynamics to drag a weak
cold front across the northern Adirondacks and northern Vermont.
Accordingly, these areas have the best chance for most widespread
coverage of convective showers and higher rainfall amounts by later
this afternoon. And you might feel it is quite a bit muggier
compared to 24 hours ago. And it is about to get even more so today
with dew points rising into the 50s and even around 60, especially
across the St Lawrence Valley and west of the Adirondacks in
northern NY. As for Vermont, we start out Sunday with dew points in
the 40s but 50s dew points will also overspread the state by mid day
into the afternoon hours. This would result in a few hundred joules
of CAPE, so have maintained a slight chance of thunder across much
of our CWA this afternoon. With a bit of sunshine, temperatures are
expected to rise into the mid 60s to low 70s with even a few 73-75
readings not out of the question. That being said, areas across
northern Vermont that has the most widespread rain coverage could
see slightly cooler daytime temperature readings. However, we are
also in late April so the high sun angle will allow temperatures to
warm rather efficiently. As for outdoor activities today, while
there would likely be rain drops to dodge, it would not be exactly a
washout either. If anything, the rainfall would be beneficial in
this pre green-up environment and help keep the fire danger at bay.
For warm weather and summer lovers, the uptick in humidity and
possible rumbles of thunder would serve as a reminder that summer is
not too far away.

Tonight, sub-freezing 925mb isotherms nose into the northern
portions of our CWA. Showers become much more isolated in nature
with temperatures falling into the upper 30s to mid 40s, except low
to mid 50s across far southern Vermont. Monday looks to feature
partly sunny conditions, with best chance for mostly sunny skies
across Vermont. With a 1032 mb surface high across northern Quebec,
it will help lock in a cool northerly flow with temperatures only
rising into the mid 50s to near 60, except mid to upper 60s across
the far southern zones of our CWA. For comparison, the typical high
temperatures for North Country in late April are in the upper 50s to
mid 60s, so a tad below normal for most to start the new work week.
-- End Changed Discussion --

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/...
As of 334 AM EDT Sunday...A ridge remains overhead Monday night into
Tuesday. Warm advection overnight will keep temperatures above
seasonal norms in the 40s to even lower 50s in St. Lawrence County.
A theta e ridge axis crests overhead, and moisture will begin to
spill back into the region. A weak surface low will attempt to
develop during the day on Tuesday and produce widespread
precipitation over the North Country. Behind it will be some cooler
air, but there`s some question as to how far south cold air sags and
stuck to a blended approach with 50s north and 60s south.
Eventually, another surface low will develop across the Mid-Atlantic
and precipitation from it will lift north later in the afternoon and
evening hours.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
As of 334 AM EDT Sunday...After the ridge briefly breaks down, a new
and stronger ridge will take its place. We`ll observe precipitation
stay mainly north for a few days with warm temperatures pushing the
70s by Thursday and Friday. However, can`t rule out some
precipitation near the international border. Eventually, the center
of the upper high will shift towards Bermuda and a surface
reflection will develop. As with such a summer-type pattern, we`ll
likely have scattered showers and thunderstorms towards the weekend
followed by an incoming upper low to the west by next Sunday.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
Through 12Z Monday...Currently all TAF sites are seeing VFR
conditions. Winds are currently from the south, but are
expected to switch to more southwesterly in the 18-21z Sunday
time frame. Most sites should see sustained winds of 5-10 kt,
but gusts of 20 kt are likely for KBTV, KMSS, and KSLK through
00z Monday. A line of thunderstorms is affecting KSLK, KPBG,
KBTV and KMPV through 13z. Another round of thunderstorms is
possible between 18-23z time frame but confidence is not high
enough to include TS with this TAF update. Scattered rain
showers are expected to impact all terminals through 00z Monday.
Increasing atmospheric moisture profile during the day on
Sunday should yield a lowering of ceilings to MVFR and locally
IFR between 03-08z Monday.

Outlook...

Sunday Night: Mainly VFR, with local MVFR possible. Chance SHRA.
Monday: VFR. NO SIG WX.
Monday Night: VFR. Chance SHRA.
Tuesday: Mainly VFR, with local MVFR possible. Chance SHRA.
Tuesday Night: Mainly MVFR, with areas VFR possible. Chance SHRA.
Wednesday: Mainly MVFR, with areas VFR possible. Slight chance
SHRA.
Wednesday Night: Mainly VFR, with areas MVFR possible. Slight
chance SHRA.
Thursday: Mainly VFR, with local MVFR possible. Slight chance
SHRA.

&&

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

&&

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