000
FXUS61 KBTV 310539
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
139 AM EDT Fri Mar 31 2023

.SYNOPSIS...
A strong frontal system with bring a light wintry mix to the region
Friday afternoon, which will change mainly drizzle and rain Friday
night into Saturday morning. Windy and warm conditions follow mid-
morning to early afternoon on Saturday, with a line of strong
showers and potentially some thunder expected for the late afternoon
into the evening. More seasonable temperatures along with drier
conditions return for Sunday into early next week.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 130 AM EDT Friday...Peaceful weather continues, with clear
skies over the region. Variable cooling has taken place under
these conditions, and the temperature grids are holding up well.
With the TAF update, did sharpen the PoP gradient some for
Friday. All remains on track. Previous discussion follows
below:

Surface high pressure building across the Northeast today will
crest over the region tonight with skies trending clear towards
midnight and remaining so until the pre-dawn hours Friday where
high clouds will approach ahead of our next system. Gusty
northwesterly winds will generally abate, though not go
completely calm which will slightly limit the amount of
radiational cooling we see. Nevertheless, it will be a chilly
night, well below normal with lows ranging from 10-20 degrees.

For Friday, the forecast remains on track for low pressure pressure
over the northern Plains to push an elongated warm front stretching
from Iowa to the central Appalachians northward towards the region.
Shortwave energy riding east along this feature and in fast westerly
flow aloft will provide support for warm advection precipitation to
develop in the afternoon, which will mainly fall as a wintry mix of
rain and snow. Thermal profiles will support some light snow
accumulations from around 1000 feet to the summits up to 2", but in
the valleys little to no accumulation is expected with temperatures
in the mid 30s to low 40s.

&&

.SHORT TERM /SATURDAY NIGHT/...
As of 355 PM EDT Thursday...Continuing on from above, as the
aforementioned warm front lifts north of the Canadian border
Friday night, precipitation will become lighter in intensity,
more drizzly in fact, but some areas such as the higher summits
and Northeast Kingdom may see some freezing drizzle and snow
continue through midnight before the continued warm air
advection in the warm sector wins out warming the boundary layer
above freezing and changing all ptypes to liquid. Towards day
break as the core of the upper low approaches from the west,
another round of more moderate rain is expected to traverse the
region through sunrise, but thereafter for mid-morning to early
afternoon, guidance continues to increase the strength of a mid-
level dry slot working into the region. In fact, we`ve lowered
PoPs to low chance for a good portion of the day with skies
becoming partly sunny. This clearing reinforces the potential
for mixing and as such, we`ve bumped high temperatures and wind
gusts up for the day. Looking for highs well into the 50s with
locally low 60s in the Champlain, St. Lawrence and Connecticut
River Valleys with winds gusty in the 20-35 mph range from the
south.

Finally for the tail end of the system, hi-res guidance continues to
hone in on the potential for a strong convective line preceding the
attending cold front. This feature looks to swing into western
portions of northern New York Saturday afternoon, and rapidly
through Vermont in the evening. Progged SBCAPEs of a few hundred
J/Kg support the idea of some isolated embedded thunder, and given
the strong low level jet preceding the front, there will be some
potential for convectively driven enhanced wind gusts. Behind the
front, much drier air works into the region with gusty west-
northwest winds aiding in a brief period of upslope snow showers
along the western slopes through midnight, but thereafter low levels
dry out rapidly with precipitation waning towards Sunday morning.
Lows Saturday night will be winter-like again in the teens to mid
20s.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 355 PM EDT Thursday...Aside from a cold and sunny Sunday,
the long term period looks mild or warm with unsettled weather.
The continental US will be dominated by another Colorado low,
and this spring storm will likely track northeastward into the
western Great Lakes region midweek. After a relatively weak
frontal system bringing a round of showers late Monday into
early Tuesday, temperature spreads in our region become rather
large in the midweek period. While this suggests our
deterministic forecast is subject to change, potential for 60
degree temperatures exists for both Wednesday and Thursday out
ahead of a large low pressure area. With high confidence in this
potent spring storm to our west, we will also have an
opportunity for increasingly windy conditions along with the
warm weather.

Chances of rain showers at this point looks reasonable Wednesday
through Thursday given increasing moisture advection in a deep,
southwesterly flow. In contrast to temperature, ensemble model
spread is small in precipitable water on Wednesday, suggesting high
likelihood of good moisture availability (median PWAT near 1"
would be well above the 75th climatological percentile).
Depending on the status of our rivers and streams after
Saturday`s weather system, we will again need to monitor our
region`s hydrology given additional snow melt and potentially
substantial rainfall. The latest data suggests a cold front
passes through somewhere in the late Wednesday to Thursday
timeframe, and prior to its passage we also could have a round
of thunderstorms - any convection would enhance the flood
potential. A slower timing of the system`s cold front would
support temperatures approaching 70 in our warmest spots for the
first time this spring on Thursday, but is a low (25%) chance
outcome at this time. For what it`s worth, today`s 12Z ensemble
guidance is most clustered around the more amplified/slower
system idea. As a result, our region would be on the cooler side
of temperature outcomes for Wednesday and warmer side of
possibilities for Thursday.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
Through 06z Saturday...VFR conditions should prevail much of the
next 12 to 15 hours under clear skies or passing cirrus at or
above 15000 ft agl. Winds will become south to southeast at 4 to
8 knots beyond 12z. Moisture begins moving in from the west
about 15z, with a gradual reduction in ceilings and the
development of some light rain or snow. The heaviest activity
should be mostly between 18z and 02z. A few areas should
transition to snow, with visibilities falling towards 1-4 SM and
ceilings towards 1000-2500 ft agl. It`s possible some sleet may
mix in at KSLK, and we should see flow become northeast to east
at KMSS. Otherwise, after 02z, a transition to light drizzle
should take place, along with a increasing southwest flow at
2000 ft agl from the south. So do have a mention of LLWS for
KSLK, KRUT, and KMSS, and would expect it to expand north beyond
06z Saturday.

Outlook...

Saturday: Mainly VFR, with local IFR possible. Windy with gusts
to 35 kt. Definite RA, Chance SHRA, Slight chance TSRA.
Saturday Night: Mainly VFR, with areas MVFR possible. Chance
SHRA, Chance SHSN.
Sunday: VFR. NO SIG WX.
Sunday Night: VFR. NO SIG WX.
Monday: VFR. Chance SHRA, Chance SHSN.
Monday Night: Mainly VFR, with local MVFR possible. Slight chance
SHRA.
Tuesday: Mainly VFR, with local MVFR possible. Chance SHRA.

&&

.HYDROLOGY...
As of 355 PM EDT Thursday...The combination of storm total
precipitation amounts of 0.75-1.25" Friday through Saturday
night, and warm temperatures in the 50s and 60s on Saturday will
combine to add a significant amount of water to area rivers and
streams this weekend. Additional contributions from snowmelt
are modeled to be in the 1-2", so total liquid amounts entering
area waterways will be in the 2-3" range, which will cause
moderate rises. Probabilistic data continues to support several
rivers approaching bankful, and we will continue to monitor main
stem rivers for the potential for any minor flooding. It may be
that we see some field flooding or ponding over natural flood
plains that end up being mostly beneficial for our local
farmers.

For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.

&&

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

&&

$$
SYNOPSIS...Lahiff
NEAR TERM...Haynes/Kremer/Lahiff
SHORT TERM...Lahiff
LONG TERM...Kutikoff
AVIATION...Haynes
HYDROLOGY...Lahiff