Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
643 am EST Wednesday Nov 25 2015
high pressure will build across the region through Thanksgiving...
bringing increasingly mild temperatures and dry conditions. Black
Friday will start off mild and dry before a cold front arrives for
the second half of the day bringing rain showers and a cooling trend
for the weekend.
Near term /through tonight/...
high pressure will move from New England this morning to off the New
England coast by this evening... increasing the warmer southerly
return flow across the region. Any lingering lake clouds and
flurries east of Lake Ontario will dissipate and lift northward out
of the area this morning as drier and milder air takes charge.
850 mb temperatures will rise to around +4 to +6c by this
afternoon... and when combined with some light downslope flow should
amount to daytime highs in the middle to upper 40s. A few locations may
even see 50 today. The downslope flow will further help to scour out
any remaining low-level moisture / clouds resulting in a mostly
sunny to sunny day. Temperatures wont fall much overnight with
continuing weak warm air advection and southerly downslope flow keeping lows in the
middle to upper 30s... and setting the stage for a mild Thanksgiving
ahead on Thursday.
Short term /Thursday through Friday night/...
western and north central New York will settle within a deepening
middle level southwest flow for the Thanksgiving Holiday...positioned
between upper ridging draped across the southeast Continental U.S. And an
expanding region of height falls encompassing the western Continental U.S.. a
strengthening warm air advection pattern will send temperatures
Thursday into the 50s. A few spots in the Genesee Valley may even
see readings climb into the upper 50s courtesy of downsloping. The
tightening pressure gradient and consequent increase in southerly
flow will produce rather breezy conditions.
Western New York will remain along the immediate downstream side of
the emerging frontal zone marking the edge of the stronger height
falls Friday. Northward low-middle level moisture transport will
increase through this time under continued/strengthening deep layer
south-southwest flow. This will translate into an increasingly mild
and moist environment. Temperatures Friday will push well into the
50s to near 60 degrees.
The strongest ascent tied to frontal dynamics will hold off until
late Friday and Friday night...leaving precipitation chances largely
dictated by the prospects of less defined lower amplitude shortwaves
lifting through the southwest flow augmenting a background of weak
but persistent moist isentropic ascent. Positioning of the primary
moisture transport vectors will focus greater precipitation
potential northwest of the region Friday.
Northern piece of energy shearing through the upper Great Lakes will
drive the cold front through Friday night. Solid period of low-middle
level frontal forcing beneath favorable upper jet support and a pre-
conditioned existing moist profile will favor a solid widespread
rainfall event late Friday and Friday night.
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 /12z Wednesday through Sunday/...
scattered lake effect flurries with some patchy fog continues east
of Lake Ontario. This will likely remain for a couple more hours
early this morning. After sunrise... increased mixing and
increasing southerly flow should help to scour out this fog in the
north country. Otherwise... expect a pleasant VFR flying day ahead
today across the taf sites.
Tonight... low level wind shear is expected to develop as a 40+ knots
low level jet shifts over western and central New York ahead of a
slowly approaching cold front. This has been included in the 06z taf
Wednesday night and Thursday...VFR. Low level wind shear Wednesday night into
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 today. An expected increase in southerly flow Wednesday night
and Thursday has lead to issuance of a Small Craft Advisory on the
east end of Lake Ontario and Lake Erie Wednesday night and Thursday.
Marine...Small Craft Advisory from 10 PM this evening to 7 PM EST
Thursday for lez040-041.
Small Craft Advisory from 7 PM this evening to 7 PM
EST Thursday for loz045.