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000
FXUS61 KBTV 212300
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
700 PM EDT Sun Apr 21 2024

.SYNOPSIS...
A period of mostly dry weather is expected across the region through
Tuesday. A cold frontal passage tonight will bring cooler weather
for Monday, but we`ll see a warm up on Tuesday. Rain chances
increase Tuesday night and Wednesday, with sharply colder conditions
returning by Thursday.

&&

.NEAR TERM /THROUGH MONDAY NIGHT/...

As of 700 PM EDT Sunday...Other than tweaking the sky cover
for the next few hours to better reflect the trends observed on
the visible satellite, the forecast remains very much on track.
See previous discussion below.

PREVIOUS DISCUSSION...Abundant cloud cover blankets the region
this afternoon, which has helped to keep temperatures a little
cooler than anticipated. These clouds will dissipate this
evening as the sun sets and we lose daytime heating. Our cold
front can be seen approaching from the north, accompanied by a
band of showers and followed by cooler and drier conditions.
This feature will cross the region overnight, moving into the St
Lawrence Valley 9-11 pm and shifting southeastward through
early Monday morning. Shower activity with the front will wane
as it crosses our region, so expect most areas will remain
fairly dry, especially as one heads south from the international
border. The northern mountains will have the best chances for
seeing precipitation, and given the dry airmass, expect most
precipitation will fall as snow or a rain/snow mix. Some light
accumulation is possible in the higher terrain. For most, the
front will simply be an increase in clouds, followed by a wind
shift and temperatures dropping sharply into the lower to mid
30s. Skies will clear as we head toward daybreak Monday, and
lows will range from the lower to mid 20s in the northern
mountains to around 30 in the wider valleys.

Monday will be sunny but cool with highs only in the 40s in most
locations. The airmass will be very dry, with dewpoints dropping
into the single digits. Mixing will be fairly steep as we see
daytime heating, so winds will become a little breezy in the
afternoon, blowing out of the northwest with gusts of 15 to 25
mph. Given that we are pre-green up, the low relative humidity
and breezy conditions will make for some fire weather concerns
during the afternoon, and could make any fires difficult to
control. The dry weather continues Monday night, though flow
will start to shift toward the south/southwest as the ridge axis
moves to our east. Lows will be coldest east of the Greens
where south winds will be last to reach. Mid to upper 20s will
be common there, with upper 20s to mid 30s elsewhere.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
As of 339 PM EDT Sunday...Tuesday is still on track to be the warmest
day of the week. Strong southerly flow will maintain seasonably mild
air across the area ahead of an incoming cold front. The front`s
surface low initially will track northeastward well north of the
region tomorrow night, which reduces forcing for heavier
precipitation in our region. That being said, shower chances will
enter northern New York towards sunset and spread eastward
overnight. Mid-level temperatures look too warm to see much in the
way of instability with the showers, but the upper level divergence
associated with the incoming trough and focusing mechanism of a pre-
frontal trough should support widespread showers. The dry low level
air ahead of the showers will cause temperatures to drop several
degrees with rain cooled air, but the mild air mass will otherwise
signal a mild night with temperatures in the 40s for most locations.
A significant southwesterly low level jet will cut into
precipitation amounts and duration in the Champlain Valley and
somewhat in the Connecticut River Valley. High temperatures Tuesday
have ticked upwards with low to mid 60s common in the valleys. These
highs look reasonable assuming 850 millibar temperatures peak near 3
Celsius; model guidance shows relatively low spread which increases
confidence in these forecast high temperatures.

All together, Tuesday will be another day with some fire weather
concerns, although overlap of low humidity and strong winds is not
quite a slam dunk. While relative humidity should be less extreme
than on Monday, another day of insolation and deep mixing will cause
drying conditions. Minimum relative humidity could drop below 30%,
especially in eastern Vermont. The low level winds will produce
noticeably strong gusts at times from Tuesday afternoon through much
of the overnight hours, especially along and west of the Green
Mountains where frequent gusts above 25 MPH can be expected. We have
increased peak gusts substantially in this forecast, especially in
the St. Lawrence and Champlain Valleys where mean momentum transfer
suggests some 40 MPH wind gusts are not out of the question amongst
many 30-35 MPH gusts during the period. Especially given the lack of
warm days recently and increasingly windy conditions during the
afternoon, we would like to emphasize cold water safety if venturing
out onto area lakes and rivers as water temperatures remain
dangerously low in the 40s.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 339 PM EDT Sunday...Impactful weather featuring an unseasonably
strong and sharp cold front is now expected during the daytime on
Wednesday, followed by relatively benign weather for the rest of the
week. The threat of heavy snow is basically zero as the GFS and its
ensemble members no longer indicate a deep closed low cutting off
over our region, instead being well to our east Wednesday night into
Thursday such that dry air will quickly follow a frontal passage.

That being said, we still need to watch for a short period of
difficult travel immediately behind the front during the day
Wednesday. A zone of surface low pressure will sweep eastward
through our region Wednesday morning. Very cold low level air will
rapidly funnel in following a sharp wind shift with precipitation
ongoing due to a trailing upper level trough. The greatest risk of
flash freeze conditions seems to be over northern New York.
Generally looks less likely in Vermont with relatively mild
temperatures ahead of the front and slightly less rapid temperature
falls during the day. However, with low level temperatures
plummeting, any post-frontal precipitation will be in the form of
snow, so expect some poor visibilities before precipitation tapers
off. Have erred on the cautious side for snow accumulations with
some light accumulations indicated for most locations, thinking a
brief accumulation could occur even with initially warm surface
conditions due to aggregation of snowflakes and well below freezing
air aloft. Another reason for concern is possible blowing snow, as
winds will be rather gusty out of the northwest with another bout of
30-35 MPH wind gusts suggested by model forecast soundings.

This bout of winterlike weather will relax on Thursday with regards
to winds as high pressure looks to nose in from the west. Still,
temperatures will be unseasonably cool and enough of a wind chill
will make one appreciate a coat even with plenty of sunshine
indicated by low variance in NBM sky cover. Friday then looks like a
complete lock for sunny and tranquil conditions across the region.
In fact, if we were in the growing season, Friday morning would be a
concern with frosty conditions and sub-freezing low temperatures
looking favored with a pattern of high pressure and strong anti-
cyclonic flow. For the weekend, Saturday looks like another
beautiful day with seasonably mild temperatures, and then generally
the chance of showers increases Saturday night, especially as you go
westward with the approach of a weakening shortwave. It will be
riding northeastward along the periphery of warm dome of air
building across much of the eastern US, where temperatures this
weekend will reach the 70s and 80s. To the north, in our region
highs will probably stay in the 60s through the weekend.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
Through 18Z Monday...VFR conditions currently prevail across
all terminals and with the exception of a quick frontal
passage and local MVFR ceilings, VFR will persist throughout
the forecast period. BKN ceilings across the region are
generally 4000 to 6000 ft, briefly becoming SCT-FEW toward 00z
as we lose daytime heating. Sharp cold front will move from
north to south 03z-08z, which will briefly increase clouds as it
moves across terminals. MVFR ceilings expected at
KEFK/KSLK/KMSS. Widely scattered snow or rain showers will be
possible as well, mainly at KMSS/KPBG/KBTV/KEFK; brief MVFR or
even IFR visibility will be possible in any snow showers. Skies
quickly clear behind the front, and all terminals return to VFR
by 09z. Winds will generally be from the west/southwest with
gusts up to 25 knots through this evening. Winds briefly abate
after 00z, but will turn to the northwest and become gusty again
after the frontal passage.

Outlook...

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

&&

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

&&

$$
SYNOPSIS...Hastings
NEAR TERM...Chai/Hastings
SHORT TERM...Kutikoff
LONG TERM...Kutikoff
AVIATION...Hastings