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Area forecast discussion 
National Weather Service Buffalo New York
132 am EST Tuesday Mar 3 2015

clearing skies tonight will allow for temperatures to fall into the
low teens and single digits overnight. Clouds will thicken later
overnight from west to east as a storm system nears the
eastern Great Lakes region from the Midwest. This system will spread
snow across the region tomorrow afternoon with precipitation quickly
changing to a wintry mix and then to rain Tuesday a brief
push of warmer air moves into the area. Colder air and gusty winds will
move back into the region Wednesday in the wake of this system with
well below average temperatures again later in the week.


Near term /through today/...
cloud cover is waning across the forecast area this evening as high
pressure and drier air are working their way across the region.
Lingering lake effect showers southeast of Lake Ontario will
continue to diminish over the next couple of hours as the high
shifts overhead. The clearing skies and light winds will allow
temperatures to drop precipitously this evening...potentially as low
as the single digits in places by midnight. However will need to
keep a close eye on warm advective middle/high clouds that are rapidly
approaching from the these will significantly retard
any temperature falls should they arrive sooner than expected.

For Tuesday...a Colorado low will advance from the Central Plains
Tuesday morning to the central Great Lakes by Tuesday evening. A
strong low level jet of 60 knots will bring both milder
temperatures...but also moisture northward through the day. This
moisture lifted isentropically...which with added low level
convergence on the nose of the low level jet will produce
precipitation...first across the southern tier in the early
afternoon and spreading over the remainder of the County Warning Area by early
evening. Using a model consensus of boundary layer to 850 hpa
temperatures expect precipitation to start in the form of snow.
After several hours of snow...increasing temperatures around 850 hpa
will transition the snow over to sleet...and then freezing rain.
Expect the northern reach of the freezing rain Tuesday afternoon to
reach near the New York state thruway. North of the thruway precipitation will
remain snow...or a snow/sleet mixture through the day.

As temperatures warm the snow liquid ratio will be falling...such
that a 8 to 10:1 ratio yields about an inch of snow across western
New York...and lesser amounts east of Lake Ontario where the snow
will start later.

Warming temperatures tomorrow will reach near freezing across
wny...while upper 20s and lower 30s will remain east of Lake


Short term /tonight through Thursday night/...
strong low pressure will move across northern Ontario and James Bay
Tuesday night while a secondary triple point low moves through the
Central Lakes Tuesday evening. Strong dynamics will spread east
across the area Tuesday evening...with the primary forcing being
strong isentropic upglide ahead of the system driven by a 50+ knot
low level jet. The system will be able to tap into a deeper field of
moisture as Gulf moisture spreads north towards the Ohio Valley. The
combination of strong dynamics and moisture will bring a solid...
albeit brief period of widespread steady precipitation later Tuesday
afternoon and evening across the entire region.

The initial snow which develops on the leading edge of the precipitation
shield Tuesday afternoon will have already changed to freezing rain
and perhaps a little sleet across western New York by early Tuesday
evening. Across the north country snow may last a little longer into
Tuesday evening...but even here some mix is likely Tuesday night as
the nose of warmer air aloft moves into the area. A brief...strong
push of low level warm advection just ahead of the cold front should
allow just about the entire County Warning Area to rise above freezing Tuesday
night...first in the west by middle to late evening...then east of Lake
Ontario well after midnight. This will change the freezing rain to
just plain rain overnight before tapering off. A few spots in Lewis
County and the Saint Lawrence valley may struggle to rise above the
freezing mark...and keep a mix of even just snow for much of the
night. One note with this setup...the ground is very cold so there
may still be freezing rain for an hour or two after the air
temperature rises above freezing...with ground temperatures often lagging
behind the air temperatures when it has been this cold for this long.

Total snowfall looks to be generally 1-2 inches before the
changeover...with 2-4 inches east of Lake Ontario and possibly up to
5 inches across the higher terrain of the Tug Hill with a later
changeover to a mix and upslope enhancement. Ice amounts should
generally run around a tenth of an inch...except up to a quarter
inch in some of the southern tier valleys where low level cold air
is typically difficult to dislodge. With this in mind winter weather
advisories are up for the entire County Warning Area mainly for the mix.

Rain amounts following the freezing rain should be relatively
light...with a tenth to a quarter inch at most. The deep snowpack
across the area will tend to absorb much of the rain and freezing
rain...limiting runoff. It will not be warm enough for a long enough
period of time to be concerned about any flooding or ice jams...the
creek ice should remain in place.

The rain will quickly taper off from west to east overnight as the
strongest warm advection driven dynamics spread into New England.
This will leave just a few sprinkles or light showers overnight. The
cold front will pass through late...with moderate cold advection
bringing falling temperatures during the day Wednesday. Any precipitation that
remains will be very light and scattered in nature...and will change
back to snow as temperatures fall through the 30s and into the 20s on
Wednesday. It will be breezy to borderline windy Tuesday night and
Wednesday with gusts in the 30-35 miles per hour range.

Wednesday night and Thursday some very limited lake effect snow will
develop east and southeast of Lake Ontario as much colder air floods
back into the region. Lake induced equilibrium levels rise to around
8k feet on Thursday...but diurnal influences of the strong March sun
angle and northwest fetch should keep this somewhat limited. In
addition to lake effect...expect moisture from upstream lakes to
combine with the strong March sun to produce scattered snow showers
in many areas...similar to what we have seen today. The GFS and
European model (ecmwf) continue to suggest a secondary wave moving along the frontal
zone as it sags into the Middle Atlantic States...but the majority of
model guidance keeps this system too far south to have any influence
on our area other than some middle/high clouds.

It will be much colder again on Thursday with highs only in the
lower to middle teens...with some of the hills possibly not getting out
of the single numbers. Lows Thursday night will be very cold...with
low single digits on the lake plains and single numbers below zero
across the colder interior locations. At least some limited lake
effect snow will linger southeast of Lake Ontario but lowering
inversion heights and drying low levels should keep this limited.


Long term /Friday through Monday/...
temperatures will remain below average through the long term period
as the longwave trough remains in place across eastern North
America...although not as extreme as what we have seen. A few weak
systems will move through the northwest flow aloft and bring a
chance of some light snow and reinforcing shots of colder air.

Looking at the details...on Friday high pressure will build from the
Ohio Valley into the middle Atlantic with a ridge extending northward
towards the lower lakes. This should keep the bulk of the area
dry...although westerly flow off Lake Ontario may still produce a
few snow showers east of the lake.

On Saturday both the GFS and European model (ecmwf) bring a weak middle level and
surface trough through the region with a chance of a few snow
showers. This is followed by high pressure on Sunday before another
trough and clipper low moves through the Great Lakes Monday with a
chance of light snow.

Looking a little farther ahead...medium range guidance and ensemble
members continue to suggest the potential for a pattern change
around the middle of the month. Both the GFS and European model (ecmwf) bring a
trough into the West Coast...forcing strong downstream height rises
and warm advection spreading into the central Continental U.S. By around March
11th or 12th. This should progress east towards the middle of the
month. Beyond that...gefs ensemble members suggest more of a typical
March pattern developing with swings up and down in temperature as
more progressive systems move east across the nation.


Aviation /07z Tuesday through Saturday/...
VFR conditions and diminishing will prevail through the overnight
hours as high pressure slides across the region. A warm front will
push into the region on Tuesday with ceilings lowering through the
morning hours...though remaining in VFR range through the early
afternoon. By 18z however conditions will deteriorate through MVFR
and possibly to IFR as -sn develops as the warm front lifts north.
Precipitation will likely change over a mix of -sn/pl and possibly even
freezing rain before changing over to rain around/after 00z.

Tuesday night...MVFR/IFR with a wintry mix changing to rain...then
possibly back to snow late. Becoming windy.
Wednesday...breezy. MVFR with a chance of snow Showers. Lake
effect snow likely east and southeast of Lake Ontario.
Thursday...MVFR with a chance of snow Showers. Lake effect snow
likely southeast of Lake Ontario.
Friday and Saturday...mainly VFR.


south-southeasterly winds will strengthen Tuesday evening as a low
pressure skirts north of the lake...resulting in another round of small
craft advisories. Fresh westerlies will develop later Tuesday
night into Wednesday in the wake of a cold frontal passage with
Small Craft Advisory conditions lasting on Lake Ontario through
Wednesday night. High pressure crosses the area once again
Thursday...providing a brief respite before southwesterlies
freshen again Friday as low pressure once again passes to the
north of the lakes.


Buf watches/warnings/advisories...
New York...Winter Weather Advisory from 3 PM this afternoon to 4 am EST
Wednesday for nyz006>008.
Winter Weather Advisory from 2 PM this afternoon to 1 am EST
Wednesday for nyz003>005-013-014.
Winter Weather Advisory from noon today to 1 am EST Wednesday
for nyz001-002-010>012-019>021-085.
Marine...Small Craft Advisory from 7 PM this evening to 8 am EST
Wednesday for loz043-044.
Small Craft Advisory from 11 PM this evening to 7 PM EST
Wednesday for loz042.



near term...Thomas/wood
short term...Hitchcock
long term...Hitchcock


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