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Area forecast discussion
National Weather Service Buffalo New York
516 PM EST Sat Nov 16 2019

Synopsis...
an Arctic air mass will remain over the region through tonight
resulting in record or near record cold. Dry and cold
conditions will continue through Sunday night, as high pressure
gradually moves eastward across northern New England. A coastal
storm is expected to bring a wintry mix or rain to portions of
the region Monday through Monday night.

&&

Near term /through Sunday/...
an area of high pressure currently north of Lake Ontario along the
Quebec/Ontario border will slowly shift southeast and center over
the St. Lawrence Valley this evening before shifting northeast to
northern Maine by Sunday afternoon. This area of high pressure and
its placement have resulted in a northeast flow over the area, that
will gradually shift to the east through the night tonight. This
will also result in any remaining lake clouds also shifting north
through the day today. With this area of high pressure centering
over the northern parts of the region, dry weather is expected for
the rest of the day today. As the area of high pressure shifts, and
wind direction changes, some weak warm air advection aloft will
begin. 850 temperatures will warm from a morning low of around -9c
to around -4c this evening. Temperatures today will be in the upper
20s to low 30s for most of the area with some cooler temperatures in
the mid to upper 20s east of Lake Ontario. Winds will be around 10
to 15 miles per hour across the area.

Overnight, dry weather will continue across the area and with a
light snowpack on the ground and mostly clear skies, temperatures
will drop down to the low to mid teens across the area, with single
digits and near zero temperatures expected east of Lake Ontario and
in some of the valley location of western New York.

Sunday, with the area of high pressure shifting northeast toward
Maine through the day, winds will veer toward the southeast. This
will result in continued warm air advection, with 850 temperatures
warming from around -3c Sunday morning to around +2c by the evening.
Sunday will be another dry day as the area of high pressure
continues to provide subsidence over the region, resulting in the
lack of precipitation and clouds. Cloud cover will slowly increase
starting in the mid-afternoon as the area gets sandwiched between
two different areas of low pressure, one to the east, the other to
the west. Temperatures will be in the mid to upper 30s for Sunday
across the area and in the low to mid 30s for areas east of Lake
Ontario.

&&

Short term /Sunday night through Wednesday night/...
the axis of the mid level trough working into the Great Lakes
takes on a slight negative tilt Sunday night into Monday. At
the same time, an offshore low near North Carolina will deepen
and ride north toward southern New England. Dry air in place
from exiting high pressure should keep Sunday night dry in
between these two system.

The effects from the coastal low should begin in parts of our area
by mid day on Monday. Some light precipitation will be possible
along the northwest fringe of this system through the day Monday and
Monday night across mainly the east half of the area, and especially
across the north country. The forecast confidence is low at this
time, due in part to track/evolution of the coastal cyclone and also
the complex thermal profile. Thermal profiles, with a warming layer
aloft, will result in mixed precipitation, with the possibility of
some sleet and freezing rain.

The upstream mid level trough will push through Tuesday and Tuesday
night bringing a round of light rain/snow showers with some limited
lake enhancement as the low level flow turn west to northwest
Tuesday night into Wednesday.

&&

Long term /Thursday through Saturday/...
Thursday will be the warmest day of the next seven with daytime
highs possibly reaching a little above average, before the next shot
of cooler air sends temperatures back below average for the tail end
of the work week into the start of next weekend. It will be wet to
start the period, with ptype eventually trending more toward snow or
a mix of rain and snow toward the latter half of the period as
colder air moves in. Breezy to windy conditions can also be expected
throughout a good majority of the period. The details...

Thursday may start out dry across the forecast area, but will become
wet from west to east through the day. As mentioned above,
temperatures will warm to around or just above average. However as
is almost always the case this time of year that will come at a
price, as rain and wind will be on the increase.

A cold front will then sweep across the area sometime Thursday night
into the first part of Friday. Cooler air behind the front will
change the ptype back to mainly snow across the higher terrain
beginning sometime on Friday, with snow the predominant form Friday
night for all areas. Despite it being plenty cold enough aloft to
support snow as the ptype, surface temperatures at lower elevations
will be above freezing during the day both Friday and Saturday, so
either rain or a mix of rain and snow is expected across these
locations. There are some signs with the latest guidance that even
colder air may be in the cards for the second half of this period.
If this trend continues, more of the precipitation could fall as
snow across the region. Stay tuned...

Aside from first rain then wintry weather, wind be the other main
story during this time frame. It will be come breezy to downright
windy Thursday night, and pretty much remaining that way for much of
the remainder of the period. Low pressure moving northeast across
Michigan and the Central Lakes will be deepening as it passes by to
our west later Thursday and Thursday night, which is one key
component looked at for seeing stronger winds across our area. That
said, despite a 40-50 knot low level jet poised to move across the
area Thursday afternoon/night, it will be difficult to fully mix
this jet down to the surface as it resides ahead of the surface cold
front in the warm air advection regime. There is also upward
vertical motion (lift) in the low levels ahead of the cold front.
Would like to see downward vertical motion and cold air advection in
this layer, which would help to force the stronger winds to surface.
All that said, it will still be quite windy. A strong pressure
gradient and cold air advection regime will keep breezy to at times
windy conditions going for Friday through Saturday.

&&

Aviation /22z Saturday through Thursday/...
VFR cigs through Sunday as lake clouds move north over Lake Ontario.
Winds will veer from the northeast to the east through tonight.

Outlook...

Monday and Tuesday...mainly MVFR/VFR with a chance of showers.
Wednesday...mainly VFR with a chance of showers.
Thursday...MVFR/VFR with a chance of showers.

&&

Marine...
high pressure moving from the St Lawrence Valley to the Canadian
Maritimes during the next 36 hours will result in veering winds
across the lower Great Lakes...with an easterly flow becoming
southeasterly later tonight through Sunday night. While winds will
initially be moderately strong...the easterly component will direct
the highest wave action and choppiest conditions into Canadian
waters.

Winds and waves will remain safely flow Small Craft Advisory levels
Monday and Monday night...as a weak trough will cross the region.

&&

Climate...
an unseasonably cold airmass will remain across our region
tonight. This will not only keep temperatures 20 to 25 degrees
below typical mid-November averages but also bring the
likelihood for additional new low temperature records. This will
especially be the case at Watertown.

Record low minimums for Sunday November 17th...

Buffalo..........13f (1959)
Rochester........15f (1959)
Watertown........13f (1995)

&&

Buf watches/warnings/advisories...
New York...none.
Marine...none.

&&

$$

Synopsis...SW
near term...rsh/SW
short term...tma

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