FXUS61 KBTV 221818
Area Forecast Discussion
National Weather Service Burlington VT
218 PM EDT Wed Mar 22 2023
A warm front will lift northward towards our region today,
followed by a cold frontal passage on Thursday. Widespread
rainfall is expected for Thursday. Below normal temperatures
will settle back into the region on Friday ahead of an
elevationally dependent snowstorm anticipated for the weekend.
.NEAR TERM /THROUGH THURSDAY/...
As of 218 PM EDT Wednesday...Shallow northerly flow has held
tough in our northern valleys under influence of surface high
pressure to our north, which is stronger than the one to our
east. As a result, surface temperatures have become rather
inverted this afternoon with values still in the 30s in these
locations while central and southern areas and elevations
generally above 1000 feet in the mid and upper 40s. In fact,
some southern portions of the western Adirondacks and southern
Vermont are well into the 50s. The cloud forecast is playing out
better with high clouds lowering and thickening with time and
no further changes needed.
Surface and upper level ridging will be in place over our
region today. Will have variably cloudy skies and high
temperatures reaching the mid 40s to lower 50s. Clouds will
increase later in the day and limit extent of daytime heating
somewhat as a warm front lifts into our region from the south.
Light winds this morning will become southerly as the day wears
on with warm air advection in place ahead of next approaching
low pressure system as surface high pressure slides eastward and
away from the region. Some light showers will pass mainly north
of the international border tonight, with just a chance of
showers across our northern zones. Surface and upper level
troughs will pass well to our north across Ontario and into
Quebec. Surface cold front will drag across our forecast area on
Thursday, and widespread rainfall is anticipated for our
region. Precipitation will spread west to east across our area.
Rainfall totals will range from around a tenth of an inch to six
tenths of an inch. Bulk of the rain will fall during the
daylight hours on Thursday. High temperatures on Thursday will
reach the upper 40s to lower 50s areawide. Combination of warm
temperatures and rainfall will lead to some rises on area rivers
and streams, but at this time not anticipating river flooding.
Will continue to monitor this potential.
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 337 AM EDT Wednesday...A relatively quiet period of wx
anticipated as sfc cold frnt is departing our cwa and we are
left with some lingering trrn driven precip on Thurs Night. Have
noted some minor differences in qpf btwn GFS/ECMWF and NAM
solutions for Thurs night with ECMWF most aggressive, while NAM
is the driest. For now have lingering likely pops for the mtns
of central/northern VT thru 03z, before quickly tapering
coverage by 06z, as deeper moisture and better lift shifts east
of cwa. Any qpf on Thurs evening with be light with just a minor
snowfall possible, as pw values are quickly falling to 0.20 to
0.30 associated with drier air from sfc high pres. Modest 925mb
to 850mb caa develops behind cold frnt on Thurs night into Fri
with 850mb temps btwn -8C and -10C, but gradient remains in
place. Given advection type thermal profiles, I have placed
coldest values at summits and warmers temps in deeper/wider
valleys with lows ranging from upper teens to lower/mid 30s on
Thurs Night. Friday is quiet with intervals of sunshine likely
given deep dry layer in place with temps ranging from the upper
20s to lower/mid 40s, which is very close to normal for late
March. For Friday Night primary challenge wl be temps, given
potential for a non-diurnal temp profile with coolest values
eastern VT, including the NEK. Initially deep dry layer is in
place with sfc ridging nosing into northern CWA, which helps to
drop sfc dwpts. However, winds shift to the south/southeast aft
06z and moisture wl begin to advect north toward our southern
CWA by 12z Saturday. For now have a large range in temps from
lower teens SLK/NEK to mid 20s SLV and parts of the CPV.
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 337 AM EDT Wednesday...A widespread precip event is
expected Saturday into Sunday acrs the FA, with minimal change
noted in the 00z guidance with regards to synoptic scale
features. The general idea of sub-990mb low pres lifting ne from
the MS River Valley toward the central Great Lakes is still
anticipated, while weak secondary low pres develops along the
SNE coast on Sat Night. The uncertainty in the fcst remains with
thermal profiles/ptype and impacts of strong llvl winds on
precip fields. Have continued with the general idea of
measurable precip is expected Sat aftn into Sat Night associated
with axis of strong 850 to 700mb fgen forcing and good moisture
advection on deep southerly flow, which results in pw values
btwn 0.70 and 0.90. Given strong 850mb southeast to southwest
jet of 45 to 60 knots, expect trrn driven precip fields
associated with this system. The heaviest qpf wl be on the se
upslope regions of the central/southern Greens and eastern
Dacks, while a relative minimal is anticipated over the northern
Dacks and parts of the CPV, including the Western Slopes. The
general idea of qpf values ranging from 0.25 to 0.75 with
localized higher amounts looks reasonable, given guidance output
and overall system evolution. Next question wl be ptype, given
sharpening trrn driven thermal profiles anticipated for this
event. Soundings show deep layer in place as precip develops on
Saturday, so expect the evaporational cooling process should
result in any light rain changing to a period of wet snow, even
the CPV/SLV, while mtns are all snow. However, as southwest jet
of 45 to 60 knots around 850mb develops, a warm nose of >0C air
advects into parts of northern NY and VT overnight Saturday into
Sunday, as bl profiles hover within a few degrees of freezing.
Thermal profiles stay mostly below 0C east of the Greens and
acrs upslope regions of the eastern Dacks, supporting mostly
snow with some sleet possible, with a change to a cold rain
likely for the downslope regions of the western/northern Dacks
and parts of the CPV on Saturday Night into Sunday, especially
as the heavier precip rates shift away from our cwa. Bottom line
an advisory type snowfall is mostly likely scenario for the
eastern Dacks and locations east of the Greens, with a sloppy
few inches possible in the CPV and parts of the western
Dacks/SLV. We wl continue to fine tune the fcst, especially as
event becomes better sampled by high res data in the upcoming
days. Have some localized gusts in the 35 to 45 mph range acrs
the northern Dacks and parts of the northern CPV for now, but
this wl need to be adjusted as higher resolution data becomes
available. Temps warm into the mid 30s to lower 40s Saturday and
only cool back into the upper 20s to mid 30s Sat night, before
climbing back close to normal on Sunday. These profiles with
accumulating snowfall in the mtns, should minimize any potential
hydro related issues this weekend acrs our cwa.
For next week a rather unsettled pattern prevails with at or
slightly below normal temps anticipated. Have continued with chc
pops for late Monday night into Tues associated with another
system. Still plenty of uncertainty on overall upper lvl
evolution and track of sfc low pres attm and potential impacts
acrs our cwa. Have continued with chc pops for rain or snow
based on sfc temps for now with best chc for snowfall acrs the
mtns, while warmer temps would result in more rain in the
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
Through 18z Thursday...VFR conditions are expected at all
terminals through at least 00Z. Have added FZRA at MSS between
02Z and 06Z when best chance for light precipitation occurs
with surface below freezing. Elsewhere, any light showers will
be plain rain through the period, becoming widespread after 12Z.
With strong low level moistening, rain showers will also
coincide with lowering ceilings with MVFR conditions trending
locally IFR towards 18Z.
North/northeast winds near 10 knots at PBG and MSS trend light
and variable in the 01Z to 06Z period, then southerly at PBG
after 10Z. At BTV/EFK/SLK, light northerly flow will gradually
trend southerly as well, roughly 21Z at BTV, 05Z at EFK, and
towards 10Z at SLK. Farther south and east at MPV/RUT, variable
winds will trend southeasterly by 00Z. Some LLWS is possible
late in the period at RUT as directional shear increases with
increasing southwest flow aloft.
Thursday Night: Mainly VFR, with local IFR possible. Chance SHRA.
Friday: Mainly VFR, with local MVFR possible. NO SIG WX.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. Definite RA, Chance SN.
Saturday Night: Mainly MVFR and IFR, with local VFR possible.
Windy with gusts to 30 kt. Definite SN, Definite RA, Likely SHRA,
Sunday: Mainly MVFR, with local IFR possible. Chance SHRA, Likely
Sunday Night: Mainly MVFR, with areas VFR possible. Slight chance
Monday: Mainly VFR, with areas MVFR possible. Chance SHRA.