-- Discussion containing changed information from previous version are highlighted. --
897
FXUS61 KBTV 181706
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
106 PM EDT Sat May 18 2024

.SYNOPSIS...
A weak upper level trough traversing the region today will provide
mostly cloudy skies this morning and partly sunny this afternoon
with a few isolated showers possible. On Sunday, a strong upper
level ridge will build into the region and take residence into early
next week with temperatures rising well above normal to more summer-
like levels. The next best chance for appreciable rainfall comes
next Wednesday or Thursday with a potential cold front passage.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 1155 AM EDT Saturday...Another update to increase pops and
qpf acrs northern VT into portions of the NEK late this morning
into the early aftn hours. Web cams, sfc obs, and radar
indicate light rain showers prevailing acrs this region with
Derby webcam showing a rather wet day with rainfall amounts of
0.09 at North Troy site. Have high chc pops with qpf up to 0.10
of an inch possible. Meanwhile, clearing skies have developed
over northern NY with temps warming into the upper 60s to lower
70s with MSS at 73F as of noon. This sfc heating and steepening
lapse rates and lingering pockets of higher bl dwpts wl help in
the development of some fair wx cumulus clouds. But no precip is
anticipated. Clearing line wl continue to slowly work toward
the CPV with areas of sunshine expected to increase in areal
coverage this aftn. Highs range from the mid 60s NEK/eastern VT
to mid 70s SLV.

Previous Discussion...Overall trends for the forecast today
have been towards drier conditions in the guidance as a weak
shortwave trough traverses the region and interacts with
Atlantic moisture streaming northeastward into central/southern
New England. Consensus amongst short-range hi- res guidance is
for the bulk of the marine moisture to remain east of the
Connecticut River Valley with perhaps some isolated showers
developing for a short period this afternoon across eastern
Vermont. Considering a general lack of strong forcing feel the
majority of the region should be dry today with cloudy skies
this morning trending partly sunny from west to east this
afternoon and highs seasonal in the mid/upper 60s east to to
low/mid 70s west.

Tonight and Sunday feature a strong mid/upper level ridge building
into the region with strong subsidence aloft supporting nil PoPs.
Skies will continue to clear through the evening and overnight, and
considering recent high soil moistures and calm winds, some patchy
river valley fog certainly seems plausible. Sunday begins sunny but
will see an abundance of fair weather cumulus develop outside of the
wider valleys in the afternoon. It will also be the first day of a
warming trend going into next week with highs widespread in the 70s
with near 80 degrees in the Champlain and St. Lawrence Valleys.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY/...
As of 330 AM EDT Saturday...Quiet weather is expected for this period
with surface high pressure prevailing across the Northeast. With
light winds and mostly clear skies, expect overnight lows in the 50s
with a few upper 40 degree readings in the typically colder spots.
Then we begin our warming trend on Monday, with mid 570 Dm heights
nosing in from the southwest. With 925mb temperatures forecast to
reach +17 to +20C, expect daytime highs in the mid 70s to low 80s.
A few mid 80s readings are not out of the question. Light winds and
plentiful sunshine should make a rather decent day to be outdoors.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
As of 330 AM EDT Saturday...Tuesday looks to be the warmest day of
the season with little relief overnight Tuesday. 925mb temperatures
reach +21 to +24C, or 2 standard deviations above normal. For
reference, typical highs for mid to late May are in the upper 60s to
mid 70s. Global guidance hints at the potential for some embedded
shortwave energy in the building H5 ridge east of the Ohio River
valley on Tuesday, so there remains questions how efficient the
daytime heating and boundary layer mixing can get. Adding 8C to the
forecast 925mb temperatures get us into the mid to upper 80s range,
so still quite toasty with marginal to minor heat risk concerns
since the population would not have been acclimated. If we do get
more clouds than sun on Tuesday, then overnight lows Tuesday night
might have a hard time falling below 70 here in the Champlain
valley. Additionally, there are indications the cold front could be
delayed till late Wednesday or even overnight Wednesday, allowing
for yet another day of mid to upper 80s on Wednesday. Bottom line,
it would likely be quite toasty and perhaps uncomfortably warm on
Tuesday into Wednesday so prepare accordingly.

Heading into Thursday, we do get a reprieve from the heat. While
there is a good chance for thunderstorms given the contrasting air
mass and cold front, it is far from a slam dunk we will get any kind
of severe weather. The main upper low remains over the Upper
Midwest, with pieces of weaker shortwave energy peeling off from the
parent low and giving our region a glancing blow overnight
Wednesday. This setup is not favorable for severe weather across
North Country since the best forcing is directed to our north. Given
the model differences on the timing of the cold front, have
generally kept PoPs in the chance category (less than 54 percent).
It will be a rather significant cooldown for this time of the year,
with highs on Friday into Saturday 15 to 20 degrees lower than on
Tuesday and Wednesday.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
Through 18Z Sunday...Light rain showers will exit EFK and MPV
in the next 1 to 2 hours with VFR conditions prevailing into the
evening hours. Agree with previous forecaster patchy fog is
possible (40-50%) on Sunday morning, especially at locations
that received rainfall today, such as EFK. Also, have noted
slightly higher dwpts at SLK, supporting greater potential for
going below cross over temp tonight to support some localized
fog/br. Have continued with previous forecaster idea of 1SM in
BR for now at SLK/EFK and MPV, which is supporting by model
sounding data showing a shallow thermal inversion with saturated
sfc conditions. Highest confidence of fog/br potential will be
btwn 07-11z. Elsewhere, VFR conditions persist, except a small
chance <10% of some shallow fog at MSS, however confidence too
low to mention attm. Winds are generally light and variable thru
the next 12 to 24 hours.

Outlook...

Sunday: VFR. NO SIG WX.
Sunday Night: VFR. NO SIG WX.
Monday: VFR. NO SIG WX.
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. Slight chance SHRA.
Tuesday Night: VFR. Slight chance SHRA.
Wednesday: VFR. Chance SHRA, Slight chance TSRA.
-- End Changed Discussion --

&&

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

&&

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