Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 170228
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1028 PM EDT Mon Apr 16 2018

.SYNOPSIS...
Sprawling low pressure draped across our region will gradually
consolidate while slowly pushing northeastward into Quebec and New
England tonight and Tuesday. This system will keep unsettled weather
and well below normal temperatures across our region right through
Tuesday, with occasional rain and wet snow, which will produce some
minor snow accumulations at times. Another low pressure system will
then bring another round of rain and a little wet snow Wednesday
night into Thursday, before drier and quieter weather arrives for
the end of the week and upcoming weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
Radar imagery showing widespread light snow across Western NY late
this evening, with a mix of rain and wet snow for areas southeast of
Lake Ontario and the eastern Lake Ontario region. The steady snow
across Western NY will continue for a few more hours before breaking
down overnight as the axis of deformation weakens. Expect additional
accumulations of around an inch for the Niagara Frontier, with 1-2
inches possible across the higher terrain east of Lake Erie where
some modest lake enhancement and upslope will develop later tonight.
East of Lake Ontario 1-2 inches may fall locally across the Tug Hill
from upslope, with just a slushy coating across lower elevations.
The Genesee Valley and western Finger Lakes can expect a light
slushy coating overnight.

On Tuesday moist cyclonic flow will continue across the eastern
Great Lakes as low pressure moves east across Southern Quebec. This
will continue to produce scattered to numerous snow showers, which
will mix with rain at lower elevations in the afternoon. Expect
another 1-2 inches of accumulation across the higher terrain east of
Lakes Erie and Ontario where some lake enhancement will also occur.
Any accumulations at lower elevations will be minimal. Most of the
accumulations will be in the morning when air and surface
temperatures are coldest. High temperatures will only be in the
upper 30s to lower 40s at lower elevations, and mid 30s for higher
terrain. West-southwest winds will also continue to gust in the 30-
35 mph range, producing some wind chill.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
Cyclonic large scale flow will continue over the area through
Tuesday night as the decaying system that is trudging into Lake
Ontario today will have only moved northeastward a couple hundred
miles by that point as it continues to decay with its frontal
structure becoming further occluded. The fact that multiple mid-
level vort maxima will be doing the Fujiwhara will not help matters
any either, as the large scale pattern seems fully content to really
not evolve much at all. Even still, with modest cold advection
continuing over the region and deeper surface moist layer remaining,
especially over the north country, snow showers downwind of the
lakes will continue. Given marginal boundary layer temperatures,
light accumulations really should only be expected in the higher
terrain.

By Wednesday, even while northwesterly large scale flow continues
over the north country, deeper moisture from warm advection will be
advancing northward from the Ohio Valley. In the interim, there
looks to be an exceedingly short window during which layer RH values
fall off enough that we should see some amount of clearing during
the second half of the day Wednesday. However, this will be fleeting
as moisture from the southwest will quickly increase into the
evening.

With southwesterly flow increasing, the atmosphere should become
sufficiently warm such that general light rainfall will develop from
southwest to northeast on Wednesday night and continue into
Thursday. Most of the forcing with this system will be from 500 hPa
on downward as upper jet dynamics really do not look to play a
part and the pronounced theta-e ridge at 850 hPa does all of the
heavy lifting. That said, PWAT values with this upcoming system
are about a half an inch lower than the one that moved through
over the weekend, so far lighter QPF is expected.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Cold advection in the wake of Thursday`s system will again allow for
northwesterly large scale flow snow shower chances to return. This
mid-week system does not look to be carrying a large pool of cold
air behind it, however. Thus, snow shower chances taper off fairly
quickly into the end of the work week.

Ridging will finally start to edge into the Great Lakes by the
weekend. This will allow for drier conditions to become very common.
The sun should also start to make its cameo across the region. That
said, the ridge axis on basically all ensembles fails to really
advance through the area, thus while moderating temperatures and
clearing will be common, substantiating warming even to values
above normal looks unlikely during the long term period.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Widespread snow will continue through the first half of tonight
across Western NY with IFR conditions. Farther east, rain showers
will gradually transition to rain and wet snow showers overnight
with a mix of MVFR and IFR conditions. On Tuesday the steadiest snow
showers will be found across the higher terrain east of Lakes Erie
and Ontario, where periods of IFR will continue. Across lower
elevations (including KBUF, KROC, and KIAG) expect mainly MVFR
conditions with a few rain and wet snow showers.

Outlook...
Wednesday...Lingering rain/snow showers and IFR/MVFR east of Lake
Ontario diminishing...otherwise mainly VFR.
Wednesday night and Thursday...MVFR/IFR in rain...which may initially
be mixed with some wet snow across the North Country.
Friday...Mainly VFR with a chance of rain/snow showers.
Saturday...Mainly VFR.

&&

.MARINE...
Low pressure draped across our region this evening will gradually
consolidate and drift northeastward across Quebec and New England
through midweek. In its wake...a brisk southwesterly flow of colder
air will continue to support fairly widespread Small Craft
Advisories through Tuesday night...and into Wednesday across eastern
portions of Lake Ontario.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 11 PM EDT Tuesday for LEZ020.
         Small Craft Advisory until 5 AM EDT Wednesday for LEZ040-
         041.
         Small Craft Advisory until 11 PM EDT Tuesday for
         LOZ030.
         Small Craft Advisory until 11 AM EDT Wednesday for LOZ042-
         043.
         Small Craft Advisory until 8 PM EDT Wednesday for LOZ044-
         045.

&&

$$

SYNOPSIS...Hitchcock/JJR
NEAR TERM...Hitchcock/JJR
SHORT TERM...Fries
LONG TERM...Fries
AVIATION...Hitchcock
MARINE...Hitchcock/JJR



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