Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 172133
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
433 PM EST Sat Feb 17 2018

.SYNOPSIS...
High pressure sliding off the New England coast this afternoon
is making way for a low pressure system passing south of Long
Island and outside the benchmark. Light snowfall is expected
across Southern Vermont and along the spine of the Greens,
generally 1 to 4 inches. A significant warming trend is expected
Monday through Wednesday of next week, along with increasing
chances for rain. Near record high temperatures are possible
Tuesday into Wednesday, with highs well into the 50s and
possibly lower 60s.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
As of 430 PM EST Saturday...As high pressure moves away from
the region this evening, a low pressure system will be skimming
the New England coast to the South. Some light snow will spread
into Vermont after about 11pm. Very progressive mid-level flow
is in place, and will push this system east of the region pretty
quickly. All snow should fall by about 8am. Snowfall totals
will range from around an inch or less across Northern New York
to two to five inches in Southern Vermont. There may be some
higher totals along the spine of the Greens as well. Clouds and
snow will keep overnight temps mild, ranging through the 20s.
Another ridge of surface high pressure will build into the area
Sunday and Sunday night from the South. Will take a bit to push
the rest of the moisture eastwards on Sunday, but we should see
some sunshine by the afternoon, especially in the Champlain
valley. We may also see some upslope snow showers lingering
through the morning hours in the NW facing slopes of the Greens.
Temperatures will be above normal again on Sunday with some
upper 30s in the Champlain and Saint Lawrence valleys with lower
to mid 30s elsewhere. Gusty NW winds upwards of 20 mph at times
during the afternoon. Sunday night high pressure center drifts
eastward and pressure gradient will be increasing with a
southerly return flow developing. Sunday night will also feature
temperatures well above seasonal normals with mid 20s in the
valleys and teens in the higher elevations.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
As of 347 PM EST Saturday...High pressure will continue to exit
to our east on Monday, placing the region under deep southwest
flow. Hence we`ll see increasing warm advection and moisture,
leading to a period of precipitation Monday and Monday night.
It`ll take a bit for the dry air at the surface to saturate, so
precipitation will mostly hold off until Monday afternoon, and
temperatures will be above freezing in most areas by then. So
expect most locations will see the precipitation start out as
rain, though a bit of snow may mix in across the higher terrain
of the Adirondacks and northern Greens at the onset. The rain
will be steadiest overnight Monday night as a warm front lifts
across the region. This will also allow temperatures to rise
much of the night after a brief drop in the evening east of the
Greens. Overall, 24 hour rainfall amounts will be about a
quarter to a half inch, with the Champlain and Connecticut River
valleys seeing the least due to shadowing in the southwest
flow.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 347 PM EST Saturday...The focus for this term becomes
very warm, near record warm temperatures, along with potential
rainfall placement. The warm front looks to become nearly
stationary north of the Saint Lawrence Valley through Wednesday
morning, with waves of low pressure traveling along it. This
will bring periods of rain, particularly across northern
sections. There are still some model differences in frontal
placement and the extent of the associated precipitation, but
the consensus of the guidance shows 0.50-1.50 inches will be
possible through Wednesday with the heaviest amounts along the
border. In addition, temperatures will warm considerably through
the period, approaching record highs on Tuesday and Wednesday.
With temperatures well into the 50s to around 60, and Tuesday
night`s low staying well above freezing, runoff from snowmelt
and rainfall will be a concern. See the hydrology section for
more details.

The mild spell comes to an end later Wednesday with a cold
front quickly crossing the region. Cooler and drier air will
return under high pressure through Friday. However, temperatures
will remain above seasonal normals, with highs remaining in the
30s to around 40 both Thursday and Friday. The threat of
precipitation returns Friday night and Saturday with another
surge of warmer air, though not nearly as mild as what we`ll see
earlier in the week. Note that there are considerable
differences in model solutions for next weekend, so have stayed
close to a model blend to account for the uncertainty.

&&

.AVIATION /21Z SATURDAY THROUGH THURSDAY/...
Through 18Z Sunday...Increasing cirrus from west to east
through the day continues. After 00Z Sunday, low clouds and snow
will advance from the south associated with coastal low
pressure, lowering ceilings to MVFR at all sites except KPBG and
KMSS, and vsby to IFR at KMPV and KRUT. Snow exits after 09-10Z
with vsby lifting to VFR, but MVFR ceilings remain. Winds trend
southerly after 14Z at 5-15 knots.

Outlook...

Sunday Night: VFR. NO SIG WX.
Washingtons Birthday: Mainly VFR, with local MVFR possible.
Chance SHRA.
Monday Night: MVFR. Definite RA.
Tuesday: Mainly MVFR, with local IFR possible. Likely RA.
Tuesday Night: Mainly MVFR, with local IFR possible. Likely RA,
Chance SHRA.
Wednesday: Mainly MVFR, with local IFR possible. Likely RA,
Chance SHRA.
Wednesday Night: Mainly MVFR, with areas VFR possible. Chance
SHRA, Chance SHSN.
Thursday: Mainly VFR, with local MVFR possible. NO SIG WX.

&&

.HYDROLOGY...
As of 355 AM EST Saturday...A 48-hour period of anomalously
warm temperatures will affect the region from Monday through
Wednesday. Periods of rainfall, modest winds and dewpoint
temperatures climbing into the 40s to lower 50s will foster
rapid snowmelt across the entire area. Still some variability
shown with this afternoon`s modeled 48-hr QPF, though the
general consensus is for two day totals averaging from 0.5 to
1.5 inches, heaviest north. Taking this all into account, modest
to substantial river rises look highly probable starting Monday
night and continuing through Wednesday, supported by NAEFS/SREF
MMEFS hydrograph data. While widespread open water flooding is
not expected, several rivers may approach minor flood. Given the
numerous ice jams in place from the substantial thaw this past
January, localized high water/flood concerns near these features
will also remain a concern. As future data helps hone the
forecast in the coming 36-hours, a Flood Watch will likely be
necessary for most if not all of the forecast area during this
period.

&&

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

&&

$$
SYNOPSIS...Neiles
NEAR TERM...Neiles
SHORT TERM...Hastings
LONG TERM...Hastings
AVIATION...Neiles
HYDROLOGY...JMG


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