Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
816 PM EST Thursday Jan 29 2015
a storm system will track across the eastern Great Lakes region this
evening spreading light snow across the area tonight and tomorrow.
Greatest snowfall totals will be found across the higher terrain
east of both lakes. Another area of high pressure will then bring a
return of fair...but cold weather for the start of the weekend.
Near term /through Friday/...
a broad area of low pressure will pass across the lower Great Lakes
this evening and this will produce fairly widespread light snow
across all of western and north central New York. As the overnight
progresses...the relatively weak storm system will exit across the
Adirondacks. While the bulk of the synoptic lift will push off to
the east as well...continued height falls and the onset of cold
advection in the wake of the low should continue to support more
snowfall. Accumulations from this event are not expected to be
significant...especially by late January standards. Snowfall rates of
less than an inch per hour will result in overnight totals of a
couple inches in most areas...with 4 to 6 inch amounts possible
across parts of the southern tier and east/southeast of Lake Ontario
where lake enhancement will come into play. Will thus keep the
winter weather advisories in place for the latter.
Temperatures will fall after midnight behind the area of low
pressure with readings dropping off into the lower teens across wny
by dawn tomorrow...and upper teens east of Lake Ontario. The cold
northwest flow within cyclonic flow aloft will maintain light snow
showers south of Lake Ontario through much of the day Friday...with
a couple inches of snow possible across the Chautauqua ridge and
Boston Hills east of Lake Erie...and to the southeast of Lake
Ontario. Temperatures will be notably colder tomorrow with single
digit temperatures across a good portion of the region by middle
Short term /Friday night through Sunday/...
Friday night low pressure will move east through the Gulf of Maine.
Cold northwest flow in the wake of this system will continue to
produce some very limited lake effect snow showers southeast of Lake
Ontario. Despite the cold air...inversion heights will remain
relatively low around 5k feet...and the short fetch and lack of
upstream lake connection will prevent anything more organized.
Expect spotty additional amounts of around an inch from Monroe
County into the northern Finger Lakes. There may still be a few
flurries or light snow showers across the western southern tier from
upstream Lake Huron moisture and limited moisture from the thin
spots on Lake Erie...but this should remain very light with just a
Temperatures will continue to drop Friday night with lows in the
lower single numbers on the lake plains and single numbers below
zero farther inland. East of Lake Ontario will get much colder with
no off-lake flow and some possible clearing late. Expected lows of
15 to 20 below across the north country. There will still be a
breeze especially during the first half of the night...and this will
produce wind chills of advisory criteria east of Lake Ontario and
also across the western southern tier...with a lesser chance of
advisory wind chills elsewhere. After coordinating with surrounding
offices and having agreement that this is a high confidence wind
chill forecast...have issued a Wind Chill Advisory for Friday night
into Saturday morning.
On Saturday any lingering light lake effect flurries or snow showers
southeast of Lake Ontario should end by midday as a surface ridge
crests over the lower lakes. Warm advection in the middle levels will
bring an increase in high clouds from west to east. After a cold
start to the day temperatures will recover into the low 20s by late
afternoon across western New York...but stay in the single digits across
the north country deeper into the cold airmass.
Saturday night and early Sunday morning a re-enforcing Arctic front
will move quickly south across the area. The front may be
accompanied by a quick burst of snow showers...which may also pick
up some enhancement off Lake Ontario and the limited open water on
Lake Erie...and also from upslope flow east of the lakes. This may
produce a quick inch or two of accumulation in some spots. On Sunday
boundary layer flow will quickly become northwest...with light lake
effect snow showers lingering south and southeast of Lake Ontario
with some very minor additional accumulations. A fresh batch of
colder air will keep highs only in the middle teens in most areas with
single numbers across the north country.
Long term /Sunday night through Thursday/...
uncertainty still abounds in the forecast for Sunday night and
Monday. The 12z GFS and European model (ecmwf) are consistent with the trend of
keeping a weaker and farther south solution with the low forecast to
move out of the lower Ohio Valley into the middle Atlantic...although a
slight northward shift and stronger surface low is noted in the 12z
European model (ecmwf). The Canadian Gem which had been hanging onto the system over
the past few runs has abandoned it with the 12z run...taking a much
weaker low well south of the area. A look through the individual 12z
gefs ensemble members show a majority similar to the operational
GFS...although there are still several runs with a much stronger and
farther north solution. With the ongoing ensemble uncertainty and
the fact that the energy which will produce this system is still
over Alaska...there will probably still be some future model changes
with the timing and track. Even the current GFS and European model (ecmwf) solutions
may brush the southern tier with some light snow...and cold
northerly flow to the north of the system would likely produce some
limited lake effect snow showers south of Lake Ontario Sunday night
and Monday. With this in mind...have maintained Middle Range chance
probability of precipitation through the period.
Regardless of the track of the system...another strong push of cold
air will arrive early next week...with highs on Monday possibly not
getting out of the single numbers in many areas. Lows Monday night
may drop below zero in most areas and possibly colder than 20 below
across the north country especially if skies clear.
Otherwise a series of weak clipper systems will cross the Great
Lakes region Tuesday through Thursday...with both the GFS and European model (ecmwf)
suggesting the strongest will be on Wednesday. If this stronger
solution verifies it would briefly bring a push of milder
temperatures Wednesday before another Arctic surge by Thursday.
There will also be some opportunity for lake effect snow by Thursday
as flow appears to align better at that time than earlier in the
Aviation /01z Friday through Tuesday/...
broad low pressure will push across the region during the first half
of tonight...and this will produce fairly widespread snow with visibilities
ranging from 1-3sm. Meanwhile ceilings will range from 800-1500 feet
over the western counties and east of Lake Ontario...with ceilings of
1500-2500 feet across the Genesee Valley and Finger Lakes.
On Friday...MVFR conditions will prevail across much of the region
with widespread snow showers occasionally reducing visibilities to less
than 2 miles.
Friday night...a chance of snow showers southeast of the
Saturday...no significant weather expected.
Sunday and Monday....areas of MVFR in a chance of snow showers
south of Lake Ontario.
Tuesday...areas of MVFR with a chance of snow showers.
a broad area of low pressure will pass over the lower Great Lakes
during the first half of tonight. Southerly winds ahead of the
system will veer to westerly by midnight then northwesterly
tomorrow. Winds will reach 15 to 25 knots on the lake tonight and
tomorrow...and this will generate waves up to 7 feet Friday
afternoon. Such...Small Craft Advisory will be in place through Friday night.
New York...Winter Weather Advisory until 10 am EST Friday for nyz004>008-
Wind Chill Advisory from 7 PM Friday to 9 am EST Saturday for
Wind Chill Advisory from 4 PM Friday to 9 am EST Saturday for
Marine...Small Craft Advisory from 1 am Friday to 7 am EST Saturday for