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000
FXUS61 KBTV 180534
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
134 AM EDT Thu Apr 18 2024

.SYNOPSIS...
A weakening area of surface low pressure moving into the Great Lakes
region combined with embedded shortwave energy aloft will bring a
period of light rain to the forecast area late tonight through
Thursday. Dry conditions follow for Friday morning, but a cold front
passage in the afternoon and evening will bring an additional round
of light rain. Mostly dry conditions and seasonally cool
temperatures are expected for the weekend.

&&

.NEAR TERM /THROUGH FRIDAY/...
As of 129 AM EDT Thursday...Radar is showing light rain showers
trying to enter our sw cwa, but sfc obs indicate very little
precip is reaching the ground as cloud heights are still very
high. Have made some minor tweaks to pops/qpf based on these
trends, otherwise rest of fcst in good shape.

PREVIOUS DISCUSSION...

Overall the forecast for tonight through Thursday night remains
on track with a weakening are of surface low pressure tracking
into the Great Lakes region being the main feature of interest
for weather across the North Country and Vermont. Shortwave
energy ejecting out of the parent mid/upper level trough on
southwest flow will provide the support for showers to develop
late tonight through Thursday as a ribbon of enhanced low to mid
level moisture moves in on the nose of a modest 925-850mb jet.
Ahead of the precipitation, southeasterly winds look more robust
compared to the previous forecast with good mixing ahead of the
precipitation and 925mb winds in the favored downslope prone
regions topping out around 45kts. Think areas along the western
slopes of the Adirondacks and Green Mountains will see gusts in
excess of 35mph for a short period after midnight through midday
Thursday before the areal coverage of showers increases and the
low levels stabilize. Showers may linger into the first half of
Thursday night as well with low clouds and moisture potentially
supporting some areas of drizzle through the night as well.
Overall the basin average QPF will be light though, with
generally 0.2" or less across Vermont and up to a third of an
inch possible across northern New York. Min temps tonight and
Thursday night will be on the mild side of normal in the upper
30s to mid 40s, and highs won`t be much warmer on Thursday in
the mid 40s to low 50s.

&&

.SHORT TERM /FRIDAY NIGHT/...
As of 310 PM EDT Wednesday...As we transition further into Spring,
days like Friday will become increasingly common. Slated for Friday
will be a one-two combo with a prefrontal trough during the
afternoon and the actual front coming through after sunset. The
highest chances for showers will be Friday afternoon, but most
forcing will come from isentropic upglide. Overall, the better
dynamics are to our north, and the frontal boundary is diffuse.
Precipitation amounts will be at or less than 0.10" favoring
northern New York and the northern Greens. Breezy south to southwest
flow will yield wind gusts of 15 to 25 mph, especially in the
northern Champlain Valley and northern slopes of the Adirondacks.
High temperatures will mainly be in the 50s, with a few spot 60s in
warmer locales within the St. Lawrence and northern Champlain
Valley. Cold air before the front could bring a few summit snow
showers as temperatures sink into upper 30s to lower 40s at low
elevations, 30s in the Adirondack wilderness, and Mt. Marcy and
Whiteface into the upper 20s.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 310 PM EDT Wednesday...There are several vigorous shortwave
troughs that will traverse the region over the weekend into the new
week. However, none of them really tap into a tropical moisture
feed. The strongest one will swing through on Saturday. Although
surface moisture will be decreasing from a recent frontal passage
and surface pressures are rising, the vorticity advection with the
trough is quite strong and there will be steep low level lapse rates
with up to 100 J/kg of CAPE. It is difficult to say whether
precipitation can reach the ground. Forecast soundings depict very
dry near surface conditions. What this may do is produce virga that
also create gusty winds as the steep low-level lapse rates aid in
the acceleration of downdrafts in convective activity. For now, the
forecast depicts the highest precipitation chances along the
international border where the shortwave tracks and keeps conditions
dry south with wind gusts generally 25 to 30 mph, locally up to 35
mph.

The next shortwave trough moves in almost immediately behind the
previous system, racing through Saturday night. Ultimately, this
system will likely have too little moisture and will reinforce cool
air that should keep the region around seasonal norms. The next
upper trough will descend over Quebec Province late Sunday evening
into Monday, but the front is so diffuse and it will again be
moisture starved. Upper level troughiness gets briefly interrupted
by a weak ridge and south to southwest flow to produce some warmer
temperatures. However, by late next Tuesday evening into next
Wednesday, there is another trough. This one should have some more
moisture with it and have a larger impact on sensible weather
conditions with shower activity sliding in for the middle of next
week.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
Through 06Z Friday...Radar is showing a band of light rain
showers south of a MSS to SLK to RUT line with no impacts to vis
or cigs. Have continued with VFR conditions prevailing at all
sites thru 12z Thursday, before a slow trend toward MVFR cigs
occurs at SLK/MSS. In addition, as better moisture and forcing
arrives, we could see localized MVFR vis in the heavier showers
toward 18z. These showers should spread into the CPV taf sites
by 18z and thru our region by 00z Friday. Winds are mostly light
and variable, but some localized channeled flow may produce
gusts 15 to 20 knots at RUT/MSS and PBG overnight into Thursday.
Most locations wl experience winds in the 5 to 15 knot range on
Thurs with some localized gusts 20 to 25 knot.

Outlook...

Friday: VFR. Chance SHRA.
Friday Night: VFR. Chance SHRA.
Saturday: VFR. Chance SHRA.
Saturday Night: VFR. NO SIG WX.
Sunday: VFR. NO SIG WX.
Sunday Night: VFR. NO SIG WX.
Monday: VFR. NO SIG WX.

&&

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

&&

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