Area Forecast Discussion
Issued by NWS Burlington, VT-- Highlight Changed Discussion --
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FXUS61 KBTV 181442
Area Forecast Discussion
National Weather Service Burlington VT
942 AM EST Sat Feb 18 2017
High pressure slides to the east today, putting the North
Country in south to southwest flow. Temperatures will moderate
considerably, with valley high temperatures in the upper 30s to
lower 40s for both Saturday and Sunday. Also, a weak upper level
disturbance will bring increasing clouds, with a slight chance
for light rain or snow showers, mainly Saturday night into
Sunday. The next chance for widespread precipitation will arrive
the middle of next week.
.NEAR TERM /THROUGH SUNDAY/...
-- Changed Discussion --As of 939 AM EST Saturday...Have made some upward adjustments to
wind gusts and temperatures from the Champlain Valley wwd based
on observational trends. It appears the models are having
difficulty with low-level WAA over the snowpack, keeping lapse
rates too stable and not realizing the extent of the turbulent
mixing in the PBL already this morning. Have seen observed
gusts to 26kt at BTV, and should continue to see gusts 25-28kt
in the Champlain Valley thru mid-afternoon. Consistent with
that, raised afternoon high temperatures another degree or two,
going with 46F this afternoon at BTV and generally low-mid 40s
areawide. Skies will remain mostly sunny with just passing - and
mostly thin - cirrus.
Previous Discussion...Clouds eroding from W to E this morning.
Will likely see some sun before more clouds move in. Above
normal temperatures as strong 850-700mb WAA develops in
southwest flow. Expect winds to increase and become gusty this
afternoon especially in the Champlain and St. Lawrence Valleys
with gusts up to 20-30 mph. Under this WAA, expect max
temperatures in the upper 30s to mid 40s today - even with some
clouds from a weak northern stream shortwave trough. This
shortwave will also bring a chance for a few sprinkles/mtn snow
showers tonight into Sunday. Min temperatures tonight will range
in the low-mid 30s in the valleys and upper 20s above
1000-1500ft elevation. Winds are expected to subside overnight
as well, shifting west towards Sunday morning.
Mid level vorticity looks to push southward across portions of
the North Country on Sunday, especially in the afternoon,
keeping the chance of showers over the mountains.
-- End Changed Discussion --
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 350 AM EST Saturday...Mid/upper level flow will be
west/northwest during this time period as weak surface cold
front pushes across our region. The combination of upper level
energy in the jet stream winds aloft...along with a narrow
ribbon of mid level moisture will interact with upslope flow to
produce chance pops on Sunday Night mainly in the mountains.
Thermal profiles cool enough to support mostly snow...with
maybe an inch or two accumulation by Monday...especially
northern Greens. Otherwise...modest low level cold air advection
occurs on Sunday Night into Monday with progged 850mb temps
dropping between -10c and -12c...supporting highs mid 20s to mid
30s Monday. Surface analysis shows 1030mb high pres nosing into
our region Monday Night...supporting clear skies and light
winds...with ideal cooling expected. Thinking lows will range
between 0f and +15f depending upon location...with strong low
level inversion developing as warming aloft occurs.
.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 350 AM EST Saturday...High confidence in much above
normal temperatures during this time period...resulting in
significant snowmelt...especially across the valleys. Next
chance of valley rain showers and mixed rain/snow in the
mountains will be Tuesday into Weds. Weak short wave energy in
the fast flow aloft...along with narrow axis of enhanced 850 to
500mb moisture will move from west to east across our cwa
between 06z and 18z Weds. QPF will generally be between 0.10 and
0.25 with no hydro issues anticipated. Plenty of uncertainty
with regards to magnitude and timing of our next system late
next week into next weekend. We still have plenty of time to
sort out the details over the next 5 to 7 days...associated with
thermal profiles and mid/upper level trof evolution...along
with eventual track of surface low pres.
Progged 850mb temps between 2c and 4c on Tuesday support highs
well into the 40s to near 50f...but with ridge of high pres
directly overhead...mixing will be limited so have kept temps in
check. If we had no snow pack and better mixing...thermal
profiles would support highs well into the 50s on Tuesday with
plenty of sunny. Still mid/upper 40s in the valleys with sun and
light winds will feel really nice...with mid 30s to lower 40s in
the mountains. Minor cooling with more clouds hold temps mainly
in the mid 30s to mid 40s on Weds...before more warming occurs
for Thursday into Friday. Developing southwest flow and progged
850mb temps between 3c and 5c...support highs well into the 40s
with a few 50s possible in the warmer valleys with lows mainly
in the mid 30s to lower 40s Thursday into Friday. Expecting much
less snow depth in the valleys by the end of the week...with
some increases on local waterways.
.AVIATION /15Z Saturday THROUGH Wednesday/...
Through 12z Sunday...VFR conditions persist through at least
the next 12 hours. Winds will start light out of the S-SE, then
shift S-SW during the daylight hours on today, with increasing
gusts of 15-25kts through this evening. Otherwise MVFR cig
expected to develop as warmer air moves in over cold snowpack.
This will likely result in MVFR stratus developing during the
evening/Eal overnight hours. Winds are expected to subside after
06Z as the low level jet begins to weaken and exit east.
Outlook 12z Sunday through Wednesday... Will see periods of HIR
TRRN OBSCD through 12Z Monday. Any precipitation will be light,
mainly isold/sct light rain or snow showers during Saturday
night into early Sunday. Significant precipitation is not
expected during the outlook period.