Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 190033

Area Forecast Discussion
National Weather Service Buffalo NY
733 PM EST Sat Feb 18 2017

High pressure will generally provide our region with fair weather
through early next week, with a chance of some drizzle east of Lake
Ontario on Sunday as a weak backdoor cold front moves south out of
Canada. It will be quite windy this afternoon, especially northeast
of Lake Erie. Meanwhile temperatures will rise to well above normal
levels this afternoon...with warmer than average readings then
expected to continue right through the upcoming week. The first
chance of rain will not arrive until late Tuesday when a weak front
crosses the area.


Satellite imagery this evening continues to show widespread clear
skies across the forecast area. While the clear skies will prevail
through the rest of tonight for much of the forecast area, we may
see clouds develop across the Saint Lawrence valley and the North
Country late tonight in advance of an approaching back door cold
front.  With the clear skies and diminishing winds, temperatures
will drop back into the upper 30s in most areas, with mid 30s
in the North Country.

On Sunday the weak backdoor cold front will continue to move slowly
south across the area. The combination of added moisture from the
front and westerly flow off Lake Ontario will bring plenty of low
stratus to areas east of Lake Ontario. The moisture may become deep
enough to support areas of drizzle as well for the eastern Lake
Ontario region, especially across the Tug Hill and western foothills
of the Adirondacks with an added boost from upslope flow.
Temperatures aloft cool under weak cold advection through the day,
but don`t get cold enough to support ice nuclei in the cloud bearing
layer, forcing the drizzle sounding.

Across the rest of the area, expect some morning sunshine across
western NY to fade behind increasing stratus as low level moisture
increases along and behind the weak backdoor cold front.
Temperatures will be knocked back considerably from today with the
increased clouds, weak cold advection, and much weaker mixing.
Expect highs in the upper 40s across the western Southern Tier, mid
40s from the Niagara Frontier to Rochester and the Finger Lakes. The
North Country will be cooler, with lower 40s at lower elevations and
mid 30s across higher terrain.


High pressure builds in across the region Monday with the ridge axis
still to our west. Temperatures will be lower on Monday, but still
above seasonal averages, as the cool air mass behind a departing
shortwave linger across the region. Temperatures will be coolest
across the North Country, closer to the center of the cold airmass,
and will top out in the mid to upper 30s. However, WNY will see warm
air advection increasing by the afternoon as the ridge axis moves
toward the lower Great Lakes. High temperatures will push into the
mid to upper 40s. Otherwise, expect fair weather and mostly sunny

Models have trended a bit faster with the approaching progressive
shortwave, with the consensus now bringing it across the area during
the day Tuesday. This will bring increasing cloud cover early
Tuesday morning, with rain showers likely crossing the area during
the day Tuesday, and tapering off from west to east Tuesday night.
With no real cold air source to the wave, Tuesday will see highs in
the upper 40s in the North Country to mid 50s in WNY, mainly limited
by the cloud cover and any precipitation that falls.

Ridging will quickly follow on Wednesday brining more fair weather.
Wednesday will see temperatures surge back to around 50 in the North
Country, to the lower 60s in WNY, continuing the stretch of very
mild weather across the region well into next week.


Temperatures will remain solidly above normal during this period...
as a blocked flow will persist across the northern hemisphere. The
main feature within the obstructed flow will be a Rex Block that
will be anchored between Alaska and the Hawaiian Islands. This will
naturally keep a trough over the western half of the country while
general ridging will be found further downstream (over the east).
While the pattern will attempt to break down towards the end of this
forecast period with the trough broadening across the country...any
semblance of winter will be short lived as the various ensemble
packages are suggesting that the longwave trough will then
become re-established over the west.

In terms of day to day weather...the upper level pattern described
above will be very conducive for `cutter` type storms to make their
way from the high plains to the Upper Great Lakes. This storm track
will keep the storm systems to our west...further enhancing the mild
weather with periodic injections of warmth from the GOMEX. Such will
be the case Friday and Friday night when a sub 990mb low will direct
some late winter sub tropical warmth (H85 temps 10 to 12c) across
the Lower Great Lakes.

While there is high confidence of the general pattern and its
corresponding impacts on our temperatures...the same cannot be said
about the timing of the individual storm systems. This will lead to
some broad brushing of chc pops...especially later in the period.
Will thus refrain from getting too specific with the use of likely


Widespread unlimited VFR conditions in place across the forecast
area this evening will prevail for most areas through the rest of
tonight, with the exception of the North Country, where increasing
low level moisture will pool along/ahead of an approaching back door
cold front. This is expected to generate MVFR cigs across the North
Country from 08-09Z onwards. Moisture, combined with upslope
westerly flow may be enough to generate some areas of drizzle across
the North Country by Sunday afternoon. In addition, there will be a
threat of LLWS this evening across the Southern Tier, owing to
decoupling winds in the lowest levels of the atmosphere from a
weakening 40+kt low level jet. The jet is also expected to weaken
this evening, with the LLWS threat diminishing after 03Z.

Elsewhere, aforementioned moisture and associated stratus is
currently expected to expand southwards across the forecast area
after 15Z on Sunday, with MVFR cigs expected to be widespread across
area terminals by 18Z.

Monday...Stratus and MVFR CIGS improving to VFR.
Tuesday and Tuesday night...Chance of showers with areas of MVFR.
Thursday...Mainly VFR with a chance of showers.


Low pressure will continue east across Quebec and reach the Canadian
Maritimes later tonight. Moderate southwesterlies will diminish on
Lake Erie this evening with winds and waves dropping below Small
Craft Advisory criteria. On Lake Ontario, west to southwest winds
will continue in the 15-20 knot range tonight through Sunday. Waves
may approach Small Craft Advisory conditions on the east half of
Lake Ontario, but given the marginal setup have kept the forecast at
2-4 feet for now. Lighter winds will return for early next week as
high pressure builds into New England.





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