Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
708 PM EST Tuesday Nov 24 2015
lake effect clouds off Lake Ontario and Lake Erie will thin and
dissipate overnight as warming aloft and surface high pressure build
across the region. This will also bring a stretch of warmer and dry
weather for Wednesday and Thanksgiving day. A cold front will likely
bring rain showers to the region Friday and a cooling trend for the
Near term /through Wednesday/...
high pressure will continue to build northward overnight from the
Middle Atlantic States. Ktyx radar shows some weak lake effect snow
showers southeast of Lake Ontario. These are expected to taper off
overnight as the building high pressure suppresses lake induced
equilibrium levels from near 9kft at 8pm to below 5kt early Wednesday.
Surface observations also reporting some patchy fog east of Lake
Ontario. The fog is likely a result of higher dewpoints moving over
a light fresh snow pack east of Lake Ontario. This fog will remain
though the overnight hours as dewpoint depressions are forecast to
remain low. Otherwise satellite imagery shows low clouds are eroding
from Lake Ontario inland toward the southern tier so expect this
trend to continue...leaving just scattered middle and high clouds as an
elevated upper level jet remains oriented over the Great Lakes.
Temperatures are forecast to drop into the 20s across the
region...the colder low 20s inland and closer to 30 along the
The high pressure across the region will provide nearly clear skies
and sunshine across the area on Wednesday. High temperatures will
rise to middle to upper 40s under the influence of southeast winds...
with some lower 40s across the hills of the southern tier.
Short term /Wednesday night through Friday night/...
Wednesday night will be a quiet prelude to the Thanksgiving Holiday
as the lower Great Lakes will be on the western fringe of high
pressure that will be centered near Nova Scotia. While skies should
remain mostly clear...high clouds will begin to filter in from the
west as a few pieces of upper level energy cross the area ahead of a
cold front that will be taking shape to our west across the western
Great Lakes. It will be breezy Wednesday night and on into Thursday
as the pressure gradient tightens between the high off the East
Coast and low pressure to our northwest near James Bay. Winds mixing
down from a strengthening low level jet will bring gusts of 20-35 miles per hour
to much of the forecast area on Thursday.
In addition to bumping the winds up across the region...the
tightening pressure gradient and consequent increase in southerly
flow will boost temperatures back up average for the Thanksgiving
Holiday. Temperatures will warm from morning lows in the 30s to
lower 40s to afternoon highs in the 50s. A few spots in the Genesee
Valley may even see readings climb into the upper 50s courtesy of
downsloping. Otherwise...the Holiday should remain uneventful as a
developing front will remain hung up to our west across the upper
Great Lakes...though cloud cover will continue to increase through
the day and into Thursday night. Warm air surging northwards ahead
of the front will produce a seasonably mild night Thursday night
with lows in the 40s across most areas with upper 40s along the
downsloping lake plains.
The main event of the period will occur on Friday as the
aforementioned front is finally kicked east across the region by a
clipper that will be tracking along the US-Canada border. The front
will pivot southeast across the forecast area Friday into Friday
evening bringing periods of rain. The latest runs have shifted the
focus of ideal upper level support farther to the north across the
Saint Lawrence valley...nonetheless still expect to see frontally
driven precipitation across the majority of the forecast area...though have
backed off quantitative precipitation forecast to the neighborhood of a quarter inch. As the front
moves through and cold air surges across the area...we may see a
brief changeover to snow on the back edge of any precipitation as
the boundary layer rapidly cools below freezing Friday
night...however any accumulations should be negligible as the very
dry Arctic airmass advecting into the region out of the north should
rapidly shut off any lingering precipitation. Regarding
temperatures...highs in the middle to upper 50s Friday ahead of the
front will come crashing down into the 20s by early Saturday morning
behind the front.
Long term /Saturday through Tuesday/...
in the wake of Friday night's cold frontal passage it should be a
largely uneventful weekend across western and north-central New York
as an elongated area of high pressure encompassing the Great Lakes
shifts across the region. The cold Arctic airmass will make for a
chilly day on Saturday with highs only expected to reach into the
upper 30s across most areas...though mainly sunny skies and light
winds should make up somewhat for the cool temperatures. The light
winds and mostly clear skies will create a good set up for
radiational cooling Saturday night with lows that will easily fall
into the 20s with some of the colder spots in the north country and
southern tier possibly falling into the teens.
Conditions should remain quiet on Sunday as high pressure lingering
across the lakes should keep a weak area of low pressure over the
Ohio Valley well to our south with only an increase in clouds and
the slightest chance of a shower or two near the PA border. The
latest runs are starting to come into better agreement as we move
into next week as a large upper low translates from the northern
rockies into the Great Plains...driving a deepening upper low across
the upper Great Lakes. Warm moist air surging north ahead of this
low will begin to increase temperatures along with shower chances
starting Monday with Tuesday increasingly looking like a wet and
Aviation /00z Wednesday through Sunday/...
scattered VFR lake effect snow showers and patchy MVFR/IFR fog are
found east of Lake Ontario this evening. IFR at kart at 00z. The
snow showers should dissipate overnight as high pressure builds
overhead. The fog is likely a result of higher dewpoints moving over
a light fresh snow pack east of Lake Ontario. This will likely
remain in place through the overnight hours as dewpoint depressions
are forecast to remain low.
Otherwise VFR in dissipating low clouds across western New York
overnight leaving VFR scattered middle/high clouds on Wednesday with
southerly winds. Low level wind shear will become possible toward
00z Thursday as a strong low level jet approaches western New York.
Will not include in this taf cycle but expect it in the 06z taf
Wednesday night and Thursday...VFR. Low level wind shear possible Wednesday night
into Thursday morning.
Friday...VFR deteriorating to MVFR with rain showers likely then
changing over and ending as some snow showers Friday night with IFR
Saturday and Sunday...VFR.
high pressure and light winds will bring fair conditions on the
lakes through Wednesday. An expected increase southwesterly flow
Wednesday night and Thursday has lead to issuance of a Small Craft
Advisory on the east end of Lake Ontario Wednesday night and
Marine...Small Craft Advisory from 10 PM Wednesday to 7 PM EST Thursday