Area Forecast Discussion
Issued by NWS Buffalo, NY

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705
FXUS61 KBUF 252351
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
651 PM EST Sat Feb 25 2017

.SYNOPSIS...
Behind a strong cold front, temperatures will continue to fall
overnight. Lake effect snow will bring minor accumulations east of
Lakes Erie and Ontario tonight into early Sunday before tapering off
later in the day. Temperatures will warm to well above normal again
by the middle of next week before winter cold returns by the end of
the week.

&&

.NEAR TERM /THROUGH SUNDAY/...
Cold air continues to advect across the region this evening, with
the boundary layer becoming conducive for snow. Within this cold air
advection winds remain gusty, and will continue the wind advisory,
though peak gusts have likely already occurred with the core of the
LLJ now shifting east of the advised areas.

Tonight, the central pressure of the deepening surface low will
continue to fall below 980mb while shifting north across Quebec.
Strong cold air advection and wrap-around moisture will advect in
behind the systems cold front. The incoming cold air will change
post-frontal scattered rain showers over to snow showers along with
development of some modest lake effect snows east of Lakes Erie and
Ontario.

Temperatures at 850 hPa will drop to around -14C supporting lake
induced equilibrium heights rising to around 8kft feet tonight into
Sunday afternoon. East of both lakes, the lake effect snow showers
will peak from late this evening into Sunday morning then taper off
Sunday afternoon first off Lake Erie as surface ridging builds
across the forecast area. Lake Ontario lake effect snow showers
could weakly persist into Sunday evening. Expect total amounts
through Sunday east of Lake Erie to run of 1-3 inches from the
Chautauqua Ridge east across the higher terrain. Totals east of Lake
Ontario will run 2-4 inches from tonight through Sunday mainly
across the Tug Hill and portions of Oswego County.

In addition to the lake snows, winds will remain quite gusty through
Sunday as the tail end of an 850mb jet lingers over the eastern
Great Lakes. Gusts in the 20s and 30s mph will be common. Low
temperatures tonight will dip down into the low to mid 20s tonight
then rebound only into the low to mid 30s Sunday.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
Sunday night a weak surface trough will move through southern
Ontario and Quebec, with a 50kt 850mb low-level jet crossing western
and central NY. While winds will run in the 10-20 knot range, point
soundings indicate a shallow inversion should keep any high gusts
from reaching the surface. A few snow showers cannot be ruled out
overnight east of Lake Ontario as the surface wave may force some
limited moisture up into the Tug and western Adirondacks.
Temperatures will likely not fluctuate too much with early overnight
temps in the upper 20s to low 30s warming to the low to mid 30s by
Monday morning.

Monday through Monday night, a general zonal mid level flow with
surface ridging and weak warm air advection will support mainly
cloudy skies with low to slight chances for some isolated showers or
sprinkles. Southwest flow will help temps rise into the 40s for most
on Monday then will dip down to the mid to upper 30s Monday night.

On Tuesday, low pressure will be developing over the Central Plains
with models showing an associated warm front and possible surface
wave shifting across our region. This will keep a chance for rain
showers Tuesday increasing to likely POPs across western NY Tuesday
night with warm air advection ahead of a strengthening low level jet
shifting into the Ohio Valley. Warm air ahead of this low will bring
back a midweek stretch of very mild temperatures with highs on
Tuesday running in the upper 40s to low 50s then only slipping back
into the low 40s across western NY and upper 30s east of Lake
Ontario Tuesday night.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Very mild temperatures will remain for Wednesday ahead of the next
low pressure system and associated cold front. Abundant
moisture will continue to be drawn northward into the region
with precipitable water values nearing an inch, some 2 to 3
standard deviations above normal. This will bring a period of
widespread showers during the day Wednesday as the cold front
interacts with the mild and moisture laden airmass. Expect
temperatures once again to push into the upper 50s, and even the
60s for some on Wednesday.

Wednesday night into Thursday, a strong upper level disturbance will
push east over the area and pushing the surface cold front through
the area. This will bring a return to normal winter conditions by
end the week.

Upper trough digging into the Great Lakes will send 850 mb
temperatures down into the negative teens celsius later Thursday
through Friday. This will bring a threat for accumulating lake
effect snows, especially Thursday night through Friday night for
favored west-northwest flow areas. High pressure begins to
build into the area Saturday.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
For the 00Z TAFS VFR flight conditions are becoming common as post
frontal precipitation is tapering off, with just some lingering
scattered rain/snow showers east of Lake Ontario with MVFR CIGS.

As we progress through the night, temperatures aloft will continue
to cool, and lake effect snow will become established east of both
lakes. Lake snows will impact KJHW at times through the night with
IFR flight conditions, with activity likely just to the south of
KBUF airfield. East of Lake Ontario steering winds will likely keep
lake effect snow just to the south of KART.

Winds will remain gusty through the TAF cycle from the west.
Strongest gusts upward to 30 to 35 knots will be early in the TAF
cycle, with gusts within the 20 knot range continuing through the
remainder of the TAF cycle.

Outlook...

Sunday night...VFR.
Monday...VFR, possible MVFR with chance of -SHRA/-SHSN.
Tuesday...VFR/MVFR with a chance of showers.
Wednesday...MVFR/IFR with showers likely.
Thursday...Mainly VFR. A chance of snow showers.

&&

.MARINE...
A strong cold front will sweep from west to east across the Lower
Great Lakes this morning and early afternoon. West winds will
increase in the wake of the cold front and peak during the late
afternoon on Lake Erie, and this evening on Lake Ontario. Both lakes
appear to peak just below gale force, with sustained winds reaching
30 knots for a few hours. This will bring high end Small Craft
Advisory conditions to both lakes. Stronger winds will continue
through Sunday night before the pressure gradient relaxes on Monday.

&&

.HYDROLOGY...
Multiple flood warnings remain in effect for the Eastern Lake
Ontario region. Thunderstorms moved across the area around noon,
with variable rainfall amounts, followed by a steady half inch
of moderate rain. Meanwhile, temperatures rose into the lower
60s as advertised resulting in rapid snow melt. NYS Mesonet
site webcams show this rapid snow melt as well.

The initial issue will be areal flooding, which is expected to
develop through this evening. The most vulnerable streams and
creeks will be those with source regions across the Tug Hill and
Adirondacks. There also may be flooding in many low- lying
areas.

It will take a bit longer for rivers to respond, but flooding is
expected at all 3 forecast points in the Black River basin.
Crests will occur first at McKeever and Boonville, with a much
later crest at Watertown. Expect an extended period of high
flows on the Black River from Lowville to Watertown. The
forecast only goes out through Tuesday, but Watertown may be
above flood stage for several days, with a crest expected on
Tuesday. Minor flooding is forecast for all 3 points, but it is
possible that Watertown and Boonville will approach moderate
flood stage. Flooding is also possible on non-forecast point
waterways such as the Beaver River and the Salmon River.

High flows will occur elsewhere, with some of the Buffalo Creeks
reaching action stage. With little if any snow pack left in
place, no river flooding is expected in any other basin besides
the Black River.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Flood Watch through Sunday evening for NYZ006>008.
     Wind Advisory until 10 PM EST this evening for NYZ001>003-
     010>012-019-085.
MARINE...Small Craft Advisory until 1 AM EST Sunday for LEZ020.
         Small Craft Advisory until 7 AM EST Monday for LEZ040-041.
         Small Craft Advisory until 1 AM EST Sunday for LOZ030.
         Small Craft Advisory until 1 PM EST Monday for LOZ043>045.
         Small Craft Advisory until 10 AM EST Monday for LOZ042.

&&

$$

SYNOPSIS...APFFEL/HITCHCOCK/THOMAS
NEAR TERM...APFFEL/SMITH/THOMAS
SHORT TERM...SMITH
LONG TERM...TMA
AVIATION...THOMAS
MARINE...APFFEL
HYDROLOGY...APFFEL



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