Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 161054

Area Forecast Discussion
National Weather Service Buffalo NY
654 AM EDT Fri Mar 16 2018

Northwest flow in the wake of low pressure over the Canadian
Maritimes will continue to produce a few snow showers this morning
before ending from west to east this afternoon. High pressure will
then build into the region for the weekend, with mainly dry weather
and cool temperatures. The cool and dry weather will last into early
next week as another high pressure builds into the Great Lakes.


Low pressure will remain in place across the Canadian Maritimes
today. Cyclonic flow and deep moisture aloft will relax through the
course of the day across the eastern Great Lakes, allowing for
improvement to sensible weather during the afternoon.

Radar imagery showing a wealth of snow showers across the region
south of Lake Ontario early this morning. These show showers are
being forced by a combination of low level convergence from a
passing trough, DPVA from a mid level shortwave, some lake
instability, and upslope flow. The WSW to ENE oriented trough is now
moving into the western Southern Tier and western Finger Lakes,
carrying the most concentrated area of snow showers with it. The
snow showers will continue through early to mid morning before
steadily tapering off from west to east during the midday and
afternoon as synoptic scale moisture and ascent quickly decrease
across the area. Additional accumulations will be limited to a
coating to an inch in most areas, with a few spots across the higher
terrain south of Buffalo and areas southeast of Lake Ontario seeing
1-2 inches locally. The decrease in moisture should allow for some
partial clearing this afternoon, first on the lake plains and last
across higher terrain. Temperatures will continue to run well below
average, with highs in the upper 20s to lower 30s on the lake plains
and mid 20s for higher terrain. WNW winds will continue to be brisk,
with gusts of up to 30 mph common today, and even 35 mph along the
south shore of Lake Ontario.

Tonight a sharp mid level closed low will swing across southern
Quebec and northern New England, with an associated low level trough
reaching the Saint Lawrence Valley by early Saturday morning. This
feature will bring a modest increase in moisture and large scale
ascent to the eastern Lake Ontario region late tonight. There may be
just enough forcing, when combined with westerly flow and some
marginal contribution of lake moisture, to produce increasing clouds
and a few scattered light snow showers east of Lake Ontario late
tonight. Otherwise the rest of the area will be dry as surface high
pressure builds into the central Great Lakes and upper Ohio Valley,
with associated subsidence and drying bringing mainly clear to
partly cloudy skies overnight. Temperatures will drop back into the
low to mid 20s on the lake plains, and mid to upper teens across the
Southern Tier valleys and Lewis County.


Saturday morning a 500mb vort max diving southward through northern
New England will drag a weak frontal boundary across the eastern
Lake Ontario region. While mostly moisture staved, the combination
of steep lapse rates and upslope enhancement may help produce a few
isolated to widely scattered bursts of moderate snow showers. These
showers will be possible through late morning before rising heights
aloft and high pressure building in from the upper Great Lake wins
out with subsidence and clearing skies. For western NY this should
be a dry weak frontal passage. Temperatures will slowly rebound on
Saturday, topping out in the low to mid 30s in western NY, with mid
20s in the North Country.

High pressure will continue to build across the region Saturday
night and Sunday, with cool night likely in the North Country with
good radiational cooling. Lows will range from the teens in western
NY to the single digits in the North Country. Sunday will be mainly
dry, however, another shortwave diving from Canada across New
England in the cyclonic flow there will drag another weak and
moisture starved boundary across the region Sunday afternoon and
evening. The result will be a few more isolated to widely scattered
snow showers mainly for the eastern Lake Ontario region. Highs on
Sunday will be a few degrees warmer than Saturday, with mid 30s in
western NY to upper 20s in the North Country.

Expect more cool nights Sunday night and Monday night, with high
pressure building back across the region behind the weak frontal
passage. Lows will range from the teens in WNY to the single digits
in the North Country each night. Monday will remain dry as high
pressure crosses the region, highs will be in the low 30s in WNY to
the mid 20s in the North Country.


Global models remain steadfast in lee side cyclogenesis of a low
pressure system in Colorado Sunday night, which then tracks eastward
across the central US toward the mid-Atlantic by Tuesday night,
passing south of the forecast area. Forecast models have show run-to-
run inconsistencies on how far north/south the low will track. While
recent operational runs have held a southward trend over the last
day, there remain numerous ensemble members that maintain a more
northward track. A farther north (closer to the forecast area) track
would increase snow chances by Tuesday, however a farther south
track could mean almost no precipitation at all on Tuesday. Forecast
models then transfer the low to the coast, with a coastal low
becoming dominate and tracking off the northeast coastline Wednesday
into Thursday. With this track, it is possible the eastern portions
of the forecast area could see some snow chances Wednesday into
Thursday on the western edge of the precipitation shield. Continue
to maintain chance PoPs through much of this period due to the
uncertainty in the track of the storm system. The slightly below
normal temperatures will continue through this period.



Northwest flow will continue to produce areas of lake effect and
upslope snow showers through mid morning across much of the region
south of Lake Ontario with areas of IFR VSBY. Drier air builds into
the region this afternoon, with snow showers ending from west to
east. Areas of MVFR CIGS with local IFR for higher terrain will
continue through late morning before improving to VFR during the
afternoon. Mainly VFR will then prevail tonight, with the exception
of some local MVFR CIGS east of Lake Ontario.

Saturday through Tuesday...Mainly VFR.


Low pressure over the Canadian Maritimes and high pressure over the
western Great Lakes will maintain moderate to strong northwest winds
today tonight, with the strongest winds on Lake Ontario. This will
continue to support Small Craft Advisory conditions on both lakes.
High pressure will then build slowly east and closer to the region
later Saturday and Saturday night, with winds and waves slowly
subsiding from west to east.


MARINE...Small Craft Advisory until 11 PM EDT this evening for LEZ040-
         Small Craft Advisory until 8 PM EDT Saturday for
         Small Craft Advisory until 2 PM EDT Saturday for LOZ042.



NEAR TERM...Hitchcock
LONG TERM...Church
MARINE...Hitchcock is the U.S. government's official web portal to all federal, state and local government web resources and services.