Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 200257
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1057 PM EDT Thu Apr 19 2018

.SYNOPSIS...
A large upper-level trough will pinwheel across New England keeping
a supply of cool air in place across the region through Friday.
Meanwhile, a wave will track just south of the Great Lakes while
merging with the upper-level trough Friday, producing periods of
snow showers, but minimal accumulations through Friday. High
pressure will build across the region this weekend into early next
week finally bringing drier weather and moderating temperatures.

&&

.NEAR TERM /THROUGH FRIDAY/...
Upper level trough over the northeast CONUS will maintain a moist
northwest flow across the region overnight. The mainly diurnally
driven snow/rain showers have been transitioning to more of
lake enhanced/upslope snow showers. This trend will continue
overnight. Outside of these lake enhanced/upslope regions, snow
showers will continue to diminish. Accumulations may be enhanced
at higher elevations, but should be less than an inch or two.
Overnight temperatures will drop into the 20s and lower 30s
near the lake shores, with northwest winds remaining elevated.

There is an end in sight as the upper-level trough that brought us a
cold, snowy week moves east of Lake Ontario Friday. Clearing will
move into the Great Lakes but areas inland will stay mostly cloudy
as northwest flow continues and clouds and scattered snow showers
persist. Snow showers will be more confined to the higher elevations
and little to no accumulation is expected. The start of warmer
weather begins Friday with temperatures slowly climbing into the low
40s.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH MONDAY/...
Friday night lingering troughing over the Canadian Maritimes will
slide eastward and further away from our area...while sprawling high
pressure and drier air continues to build eastward from the Upper
Great Lakes. The resultant decrease in moisture and cyclonic flow
will allow lingering upslope flow-driven cloudiness to slowly
scatter out from west to east...with an otherwise dry and quiet
night anticipated. The above clearing trend...lightening winds...
and our cold dry airmass will set the stage for a cold night...
with lows ranging from the lower to mid 20s across our normally
colder interior portions of the Southern Tier and North Country
to around 30 right along the lakeshores.

Saturday and Sunday the aforementioned ridge will settle directly
across our area...with attendant subsidence and plentiful dry air
promoting dry weather along with mostly sunny skies by day...and
mainly clear conditions at night. Meanwhile the strong April sun
will help to considerably modify our resident airmass...such that
we will experience a steady day to day warming trend. Expect highs
on Saturday to range from the mid 40s across the higher terrain
and in areas of lake influences to the upper 40s and lower 50s
elsewhere...with readings on Sunday then reaching into the lower to
mid 50s...with the immediate lakeshores again running a bit cooler
due to a developing onshore flow. Meanwhile lows Saturday night will
again range mostly from the mid 20s to lower 30s with the high
centered directly overhead and thereby providing ideal conditions
for radiational cooling.

Sunday night and Monday the center of the ridge will drift eastward
and off the New England coastline...while a rather broad surface
low/closed upper low meanders its way across the Deep South and
Lower Ohio Valley. The developing modest return flow in between
these two features will allow for some warmer air to advect into our
region from the Ohio Valley...and this in tandem with continued
airmass modification by the strong April sun will allow highs to
climb to above normal levels in the upper 50s and lower 60s in areas
away from any lake influences. Meanwhile...the slowly departing
ridge will also maintain dry weather and mainly clear/mostly sunny
skies...with just the leading edge of some thin cirrus from the
aforementioned low pushing into the Southern Tier later Monday
afternoon.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
Closed low over the deep south will continue to slowly track
northward and begin to interact with an approaching northern
stream short wave tracking across the Great Lakes. This will
likely bring to our region increasing moisture and chances for
precipitation for the middle to later half of this period.
However, before this system arrives surface high pressure will
maintain dry conditions Monday night and a majority of Tuesday
before exiting off the New England coast. Tuesday, it will feel
more spring like across the forecast area as southerly return
flow around the high helps to push temperatures into the 60s
everywhere. Although, it will remain cooler near the lake shores
of Erie and Ontario (water temps: Erie 34F and Ontario 38F).

As the aforementioned low tracks towards the region during the day
Tuesday, look for increasing cloudiness and chances for showers by
Tuesday night and then especially Wednesday. After Wednesday, lots
of uncertainty creeps up in the latest guidance package. Have kept
low end chance POPs Thursday depending on how fast this system exits
the forecast area and subsequent frontal passage. Otherwise, again
highs will climb into the 60s Wednesday then cooler Thursday behind
the front.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Mainly low-end VFR conditions expected through the overnight hours.
Snow showers will continue in favored northwest upslope regions,
mainly away from any TAF sites. Until the snow shower activity
completely focuses on the higher elevations, there may be a
brief period of MVFR cigs/vsbys in snow showers at KBUF and
KROC.

NW flow continues into Friday and flight improvements are
expected with the exception of KJHW where snow showers and MVFR
cigs may develop in the upslope flow.

Outlook...

Saturday...Mainly VFR.
Sunday through Tuesday...VFR.

&&

.MARINE...
Winds will remain elevated into Friday as a low pressure system
moves off the New England coast. Small craft conditions will
continue across the lakes tonight and linger well into Friday.

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

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 2 AM EDT Friday for LEZ040-041.
         Small Craft Advisory until 8 PM EDT Friday for LOZ043-
         044.
         Small Craft Advisory until 2 PM EDT Friday for LOZ042.
         Small Craft Advisory until 5 PM EDT Friday for LOZ045.

&&

$$

SYNOPSIS...Church/TMA
NEAR TERM...HSK/TMA
SHORT TERM...JJR
LONG TERM...AR
AVIATION...HSK/TMA
MARINE...Church/HSK/TMA


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