Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 181826

Area Forecast Discussion
National Weather Service Buffalo NY
226 PM EDT Wed Apr 18 2018

A large upper-level trough will pinwheel across New England while
keeping a supply of cool air in place across the region through
Friday. Meanwhile a western wave will track from the Rockies to just
south of the Great Lakes while merging with the upper-level trough
tonight and Friday. Expect widespread light snow with minor
accumulations mainly over higher terrain. High pressure will build
across the region this weekend into early next week finally brining
drier weather and moderating temperatures.


A broad upper-level low pinwheeling across New England is
keeping a parade of shortwave troughs training across the
forecast area along with below average temperatures. This
morning, a shortwave trough can be seen in WV imagery moving
south across NYS, while generating a loosely organized area of
snow east of Lake Ontario. KTYX radar shows locally enhanced
returns over the Tug Hill, as the moist northwesterly flow
upslopes. Given this, the winter weather advisory in place for
the Tug Hill looks on track. Expect general accumulations of 3
to 5 inches over the higher terrain with locally up to 6 inches
possible, with this accumulation mainly coming through mid-day
with snow tapering off this afternoon. Lower elevations around
the Tug Hill will likely see much less snow accumulation, only
around an inch or two.

Behind this shortwave passage, snow will taper off today from west to
east, with snow ending east of Lake Ontario by this afternoon as a
subtle ridge axis crosses the forecast area. The mainly dry
afternoon with westerly winds in place will allow temperatures to
range from the low 40s downwind of the lakes, to the mid 40s in the
Genesee Valley and Northern Finger Lakes regions.

Tonight, a wave ejecting from the Rockies will track toward the
eastern Great Lakes while merging with the large upper-level low
over New England. The wave will phase just south of the forecast
area while the surface reflection tracks across PA. The result will
be a system largely cold enough to support snow, although a mix of
rain at precipitation onset cannot be ruled out. Enough warm air
aloft may reach near the PA state line in the far Southern Tier for
a brief wintry mix, however as the wave continues eastward the
column will cool enough to support all snow there as well. The
highest snowfall rates will be found across the Southern Tier near
this transition line, with a quarter to a half inch per hour briefly
possible tonight. Meanwhile snowfall will be much lighter for areas
just south of Lake Ontario, with only a tenth or two per hour
likely. The overall result will be an inch or less of accumulation
across the lake plains tonight, with 1 to 2 inches of snow expected
across the higher terrain of the Southern Tier east to the Finger
Lakes. Expect impacts and snowfall amounts to remain below winter
weather advisory criteria.


Following the passage of Thursday`s system...lingering upper level
troughing and a cold cyclonic upslope northwesterly flow will help
to produce some additional snow showers and minor accumulations of
another inch or two across the higher terrain Thursday night...
while any accumulations elsewhere remain under an inch. The activity
will then wind down altogether from west to east Friday and Friday
evening as high pressure and drier air build into the region...with
skies also showing a corresponding gradual decrease in cloud cover
through Friday night. With respect to temperatures...these will remain
solidly below average with lows ranging between the mid 20s and lower
30s...and daytime highs on Friday failing to reach above the upper
30s to lower 40s.

After that...sprawling high pressure centered over the Upper Great
Lakes will steadily build southeastward across our region through
the remainder of the period...with plentiful dry air and subsidence
attendant to the high providing our region with fair dry weather
and the beginning of a welcome long-duration day-to-day warming
trend. During the first couple days of this warmup...we can expect
daytime highs to recover first into the mid and upper 40s on
Saturday and then into the lower to mid 50s on Sunday...with
even warmer readings then expected to arrive early next week...
details on which are provided in the long term section below.


Building 500mb heights and surface ridging moving overhead will
continue a significant warming trend across the region early next
week. On Monday, highs will finally climb above normal with
temperatures expected in the U50s to near 60F...with readings
then climbing into the L60s everywhere Tuesday.


Snow showers will focus on and near the Tug Hill east of Lake
Ontario through morning. Expect mainly MVFR Cigs across the
region except for IFR at JHW and over the Tug Hill in steadier

Snow showers will taper off today, with gradually improving
conditions during the day. By early evening, another weather system
will spread rain to mainly snow across the region and bring a return
to MVFR/IFR conditions.


Thursday...MVFR/IFR in rain or snow.
Friday...Mainly VFR with a chance of rain/snow showers.
Saturday...Mainly VFR.


A southwest to west wind will continue across the lakes this
morning, generally in the 15 to 25 knot range, before diminishing
from west to east this afternoon and evening. Tonight winds will
turn to the north while increasing into Thursday morning. Winds will
likely reach SCA levels on Thursday in northwesterly flow.

A period of more tranquil conditions will likely come this weekend
into early next week as high pressure moves over the lower Great


MARINE...Small Craft Advisory until 5 PM EDT this afternoon for LEZ040-
         Small Craft Advisory from 2 PM Thursday to 9 PM EDT
         Friday for LOZ043-044.
         Small Craft Advisory from 11 AM Thursday to 2 PM EDT
         Friday for LOZ042.
         Small Craft Advisory until 11 PM EDT this evening for



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