Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 kbtv 221758 

Area forecast discussion
National Weather Service Burlington Vermont
1258 PM EST Wed Feb 22 2017

much above normal temperatures continue into the weekend with
scattered showers and areas of fog possible...especially tonight
into Thursday. A strong cold front will produce gusty winds and a
line of showers on Saturday afternoon and evening...with much cooler
temperatures by Sunday. The combination of snow melt and
precipitation will result in localized ice jam threat with the
potential for isolated low lying flooding as we head into the


Near term /through Thursday/...
as of 1134 am EST Wednesday...forecast in good shape with just
some mid and high level clouds over the area for this afternoon
and temperatures continuing to warm into the mid 40s to lower
50s. No precipitation is expected for the rest of this

Previous discussion...
fast westerly flow aloft continues today...while low level
winds are from the south/southwest resulting in moisture and
warm air advection. Have noted plenty of low clouds and fog
upstream associated with higher moisture content and warm air
moving over cold snow pack...especially Michigan. Soundings indicating
the threat for fog/br increases by tonight...especially
deeper/protected mountain valleys and this trend may continue
into Thursday. Progged 850mb temps warm between 2-4c today...but
with all the clouds mixing maybe will keep temps
mid 40s to lower 50s most locations. An isolated shower cannot
be ruled out over the terrain...but any precip will be light.

Tonight...the potential for fog/br increases as temps cool back into
the 30s and lower 40s...but surface dewpoints continue to increase
on southerly winds. Will continue to mention patchy to areas of
fog/br...given sounding profiles...with mostly likely locations the
slv/northern dacks and parts of central/northern Vermont valleys.

Thursday...temps become very tricky as we continue to be under
moderate low level warm air advection on gusty south/southwest
winds. However...these winds continue to advect higher moisture into
our region with surface dew points in the upper 30s to mid
40s...supporting areas of low clouds and fog...which may limit
surface heating. Area soundings show lots of moisture between
surface and 850mb on Thursday...associated with strong moisture
advection on 925mb to 850mb winds of 35 to 45 knots. Soundings
support localized wind gusts btwn 30 and 35 knots in the
slv...dacks and parts of the cpv on Thursday afternoon. Areas of
drizzle will be possible in the mountains on Thursday. For temps
will fall high resolution 2m temps...which support mid 40s mountain
valleys to l/M 50s warmer valley locations. A weak surface boundary
along with increasing mid level moisture will increase the threat
for showers on Thursday precipitable water values
surge between 0.75 and 0.95. Have mention chance to low likely
pops...but best forcing associated with 5h vort and better
moisture looks to pass just to our north. Quantitative precipitation forecast will be <0.10.


Short term /Thursday night through Friday night/...
as of 412 am EST Wednesday...Friday brings with it an increase
in clouds and precipitation as a passing upper ridge gives way
to an upper through and a warm front from an associated rapidly
developing low over the Midwest US late in the day. Light
precipitation should move throughout the later part of the day
through the region, although quantitative precipitation forecast looks to only be about .10 on
average for most locations. Slightly cooler temps are expected
for Friday as increased cloud cover along with the late
influence of the advancing warm front will see daytime highs in
the mid 40's while temps should continue to rise in central and
western parts of the County Warning Area while the eastern portion should see
some cooling overnight, leading to overnight lows ranging in the
mid 40's to upper 30's.


Long term /Saturday through Tuesday/...
as of 412 am EST Wednesday...Saturday afternoon/evening should
see the precipitation ramping up just ahead of the passage of a
cold front from the associated occulded system pushing to the
north and west of our area. Most of the County Warning Area should see a half
to three quarters on an inch of precipitation during this
timeframe. Winds out ahead of the front could lead to a narrow
band of gusty conditions and advisory level winds especially
across the Champlain and St Lawrence valleys as the 00z GFS
continues to indicate 850mb winds reaching 65 and 70 knots in
the respective valleys Saturday afternoon. After frontal
passage, rain will switch over to snow showers late Saturday
night/Sunday morning with moderate cold air advection. Very warm
temperatures are expected Saturday ahead of the cold frontal
passage. Temperatures overall look to be in the mid to upper 50s
with the Champlain and St Lawrence valleys pushing a record
breaking 60. The sharp cold front will drop temps quickly back
into the upper 20s and lower 30's late Saturday night. Flash
freeze issues are possible in some locations with temperatures
dropping so sharply after a moderate rainfall. Next week see a
return to more seasonable and quiet weather Sunday through
Tuesday before another system moves in at the end of the period
on Wednesday.


Aviation /18z Wednesday through Monday/...
through 18z Thursday...have continued with mention of br
overnight at all taf sites. Surface dewpoints to increase and
winds will decouple...allowing for areas of low clouds and
fog/br to develop as warm/moist air moves over cold snow pack.
Expecting IFR with LIFR conditions possible...especially given
all the fog/br upstream over the Ohio Valley and Michigan early Wed
morning. Winds begin to increase toward sunrise on
fog/br may transition into an IFR stratus deck before lifting.
Have vcsh mentioned for mss and slk with some scattered light
rain showers expected overnight.

Outlook 18z Thursday through Monday... additional fog/br
possible Thursday night into weak backdoor front
results in a wind shift to the north. Very gusty southerly winds
develop...along with a line of showers with embedded heavier
rainfall for Sat. Localized areas of turbulence and shear
likely...along with MVFR conditions in the heavier showers.
Rain transitions to mountain snow showers with lingering IFR
vis possible at slk/mpv Sat night into Sunday. MVFR possible
again on Monday with more showers in the area.


as of 400 am EST Wednesday...above normal temperatures will
continue to melt a significant amount of snow this week into the
upcoming weekend. This runoff will cause rises on local
waterways with an increasing threat for localized ice jam
flooding...especially across northern New York and central and
northern Vermont rivers. A widespread rainfall on Saturday will
produce additional Hydro concerns over the weekend for the
potential of minor main Stem river flooding.


Btv watches/warnings/advisories...
New York...none.


near term...evenson/Taber

National Weather Service Glossary of Abbreviations