Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Buffalo New York
638 PM EST Tue Nov 19 2019
a weak upper level disturbance will cross the eastern Great Lakes
tonight and Wednesday, producing a few scattered light rain and snow
showers. Dry weather will return Wednesday night and Thursday as
high pressure builds into the area. A cold front will then cross the
region Thursday night and Friday, producing a few rain showers and
Near term /through Wednesday/...
radar imagery shows some light rain showers across the Niagara
Frontier early this evening. These will be very light, perhaps
just enough to wet the ground. Temperatures will generally
remain in the upper 30s through the evening hours, with the
exception of the north country where it will be a bit cooler.
Tonight and Wednesday a weak mid level trough axis will drift slowly
east across the eastern Great Lakes. Forcing will be weak and
diffuse with this system, but deep layer moisture will increase. The
combination of weak synoptic ascent, deeper moisture, and weak low
level northwesterly upslope flow may combine to produce some very
light precip. If this materializes, it would develop first across
Chautauqua County this evening, and then spread through the
remainder of western New York overnight before drifting towards the
western Finger Lakes and points southeast of Lake Ontario Wednesday
morning. Some high resolution guidance tries to develop some lake
enhancement, but the airmass does not appear cold enough to support
this with lake induced equilibrium levels remaining below 5k feet.
What remains of the light precip will fade away and end Wednesday
afternoon as the forcing and deep moisture break down and give way
to secondary cyclogenesis off the southern New England coast.
If light precip does materialize, precip type will likely be a mix
of light rain and wet snow, and possibly some drizzle given the
weak/shallow forcing regime. Surface temperatures will stay above
freezing across the majority of the area tonight and Wednesday
morning. The one exception may be across the higher terrain where
surface temperatures may drop to near or just below freezing later
tonight. There is some indication that the cloud bearing layer may
become warm enough late tonight to eliminate ice nuclei. If this
occurs and if precip does in fact materialize, there may be some
patchy freezing drizzle across the higher terrain late tonight and
early Wednesday morning. Not enough confidence in this scenario to
include freezing drizzle in the forecast, but the chance is non-zero.
Expect lows to be in the mid 30s tonight across lower elevations,
and around 30 across the interior southern tier and east of Lake
Ontario. Highs Wednesday will be in the lower 40s at lower
elevations, and mid to upper 30s for higher terrain.
Short term /Wednesday night through Friday night/...
dry conditions expected Wednesday night as surface high over the mid
Atlantic builds in and upper ridge moves overhead. Lows will range
from the mid and upper 20s across the higher terrain to the lower
and mid 30s across the lower elevations.
The surface high will press southeast into the Carolinas while the
upper ridge moves east over New England on Thursday in response to a
an area of deepening low pressure moving northeast across the
western Great Lakes. An associated warm front will move across the
forecast area Thursday afternoon and evening with fairly strong warm
advection. Aloft, a 45 to 55 knot low level jet will move overhead
Thursday afternoon and evening. Although it will become breezy late
in the day and into the evening, our region will remain in the warm
sector through at least the first half of Thursday night with stable
conditions in a warm air advection regime helping to to keep these
strong winds aloft from mixing down. A few showers may make it into
the western Finger Lakes region and points west during the afternoon
as the better forcing remains off to the northwest, otherwise expect
dry weather. Temperatures will reach into the 40s south of Lake
Ontario, while mid and upper 30s prevail east of Lake Ontario as
warmer will just be arriving here toward the end of the day.
As deepening low pressure moves northeast across Lake Huron, then
into Ontario and Quebec province Thursday night, an attendant strong
cold front will sweep across the area later Thursday night into
Friday morning. This will bring rain showers to the area
Thursday night into the first half of Friday as conditions
remain warm enough for all liquid through around midday Friday
before cold air deepens enough for some northwest flow lake
enhanced wintry precipitation by Friday afternoon, especially
across the higher terrain. Overall quantitative precipitation forecast amounts will remain low
for this event, while the wind will be the bigger story.
Speaking of wind, while the strongest winds aloft will be ahead
of the front and associated with the low-level jet as mentioned
earlier, cold air advection behind the front with around 40
knots still lingering off the deck now in a cold air advection
regime, will result in downright windy conditions from later
Thursday night through a good chunk of Friday. There will be
some lingering light upslope/lake enhanced snow showers east of
Lake Ontario early Friday night, otherwise it will be much
cooler as high pressure sliding south of the lower Great Lakes
will help to dry things out. High temperatures for Friday will
occur very early in the "day" Friday, with temperatures in the
lower to mid 40s just after midnight, falling into the 30s by
Friday afternoon area wide. Temperatures will continue to fall
Friday night, as lows bottom out in the 20s.
Long term /Saturday through Tuesday/...
overall, there are no major weather concerns or extremes expected
during this period.
Saturday will be mainly dry and cool as weak ridging stays in
control of our weather. Although, a few light rain and snow showers
may try to make it into the southern tier and Finger Lakes later in
the day as low pressure moves into the Ohio Valley. This area of low
pressure will track to the south of the area Saturday night, with
the northern fringe of associated precip possibly bringing some
light snow showers across the area. Some renewed cold advection in
the wake of low pressure moving off the southern New England coast
may be enough to produce some light lake enhanced rain and snow
showers east of the lakes Sunday and Sunday night on a westerly
flow. High pressure across the Ohio Valley and mid Atlantic will
ridge north across western and central New York for the start of the
work week. This will bring mainly dry conditions across the area for
Monday through Tuesday. Below average temperatures to start the
weekend will gradually warm to a bit above average by Tuesday.
Aviation /00z Wednesday through Sunday/...
a wealth of low level moisture will remain across the area this
evening through Wednesday, keeping skies mostly cloudy most of
the time. This will result in mainly MVFR flight conditions
across wny this evening, with cigs lowering to IFR at some
locations late tonight. IFR ceilings will become widespread across
the higher terrain. Very weak flow and the low sun angle will
likely allow these lower ceilings to linger most, if not all of
Some very light precip may develop this evening across Chautauqua
County, then spread through the rest of western New York tonight. What
remains will spread into the western Finger Lakes and areas
southeast of Lake Ontario Wednesday morning before fading away later
in the day. This will primarily be in the form of very light rain,
light snow, or light drizzle. There is a small chance of some patchy
freezing drizzle late tonight and early Wednesday across the higher
terrain of the western southern tier if surface temperatures fall
Wednesday night...VFR/MVFR in lingering stratus.
Thursday...mainly VFR with a chance of showers Thursday night.
Friday...MVFR/VFR with a chance of showers. Breezy. Saturday and
a weak pressure gradient will remain in place across the eastern
Great Lakes through Thursday morning, with winds generally 15 knots
or less and waves under 3 feet. A moderately strong area of low
pressure will then move from the upper Great Lakes Thursday
afternoon to southern Quebec by Friday, with a trailing cold front
crossing the eastern Great Lakes Friday morning. Southerly winds
will increase ahead of this system later Thursday afternoon and
Thursday night, then become southwest on Friday following the cold
front. This will likely produce a period of Small Craft Advisory
conditions on lakes Erie and Ontario.