Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 151444

Area Forecast Discussion
National Weather Service Buffalo NY
944 AM EST Mon Jan 15 2018

High pressure will bring dry weather through most of today. Low
pressure will move through the Great Lakes region tonight and
Tuesday, with periods of snow and minor accumulations. Some
lake effect snow will develop following this clipper Tuesday
night through Wednesday night.


Arctic high pressure is advancing across southern Quebec this
morning, yet still continues to bring a cold morning across our
region with many areas in the single digits to low teens. Thin
cirrus across WNY this morning will continue to spill eastward today
and thicken ahead of a storm system across the Western Great Lakes.

Warm air advection ahead of this system will bring in more
cloud cover during the day today. Regional radars showing a large
band of warm air advection driven light snow across the upper Great
Lakes/Midwest and Ohio Valley. Leading edge of this will arrive into
western New York by the end of the day.

Increasing southerly flow and associated warm advection will
yield an uptick in temperatures today, with highs in the lower
to mid 20s, with slightly cooler readings in the upper teens to
around 20 degrees in the North Country/Saint Lawrence Valley.

Light snow will continue to overspread across the remainder of the
area tonight. Forcing is fairly weak as this clipper tracks into
region. Both the surface low and mid level low shear out during this
time period as additional energy sinks into the base of the
longwave trough. Forecast soundings show rather weak lift with
nearly isothermal temperatures through the saturated layer.
Some better low level lapse rates develop, but this will not be
until Tuesday as colder mid level air fills in. Broad isentropic
ascent looks to be the driving force behind the snow. Expecting
small flakes size limiting accumulation potential. Model
consensus of 0.15 to 0.2 inches of water equivalent looks
reasonable as the system has arctic origins with no connection
to moisture from the GOMEX. We are looking for mainly 1-2 inches
of snow across the whole area.


The dry slot of the clipper-type low will be moving into Western NY
Tuesday morning. Widespread snow showers will be ending from west to
east by Tuesday afternoon. Additional accumulations of an inch is
possible Tuesday morning making the storm total between 1-3 inches
across the region. In the wake of the cold front, lake effect bands
will form off Lakes Erie and Ontario as -15C 850mb air moves over
the lakes Tuesday. Lake induced equilibrium levels will increase to
8K feet Tuesday afternoon. Snow showers are expected to begin east
of the lakes by Tuesday afternoon. Due to a nearly frozen Lake Erie,
lake snows will likely be more intense off Lake Ontario. Flow will
begin as southwest Tuesday/Tuesday night before becoming west on
Wednesday. Accumulating snow is expected with the best chance for a
winter headline east of Lake Ontario.

High temperatures Tuesday will be in the low to mid 20s. Low
temps Tuesday night and Wednesday night will range in the single
digits to teens with Highs on Wednesday forecast to run in the
teens to 20s.


Lake snows will taper off into Thursday as ridging and warm air
advection moves over the region. Mostly sunny on Thursday with high
temps will be in the mid 20s. A fast moving clipper system is
forecast to move near the Great Lakes Thursday night-Friday. This
system will speed by the region with very little moisture. At this
time, this system is forecast to move south of the region. This will
cause the best forcing to be south of the eastern Great Lakes
therefore mostly dry conditions are expected at this time.

A warm-up will begin Friday with temperatures reaching the low 30s.
Zonal flow is expected through much of the weekend and southerly
flow will allow temperatures to climb into the 40s and potentially
50s by Sunday. A deep trough is expected across the Rockies Sunday
while ridging occurs across the east. A Colorado low is expected to
form Sunday-Monday and track northeastward into the Great Lakes
early next week. This will bring the chance of rain and snow showers.


High pressure will gradually move out of the region over the next 12
hours. While VFR conditions will persist for the bulk of the period,
high clouds across the region will thicken/lower into a mid-level
deck during the day Monday, as a low pressure system approaches the
region. Light snow will develop across far western New York early
Monday evening in association with this low, resulting in MVFR
conditions at KBUF/KIAG/KJHW after 23Z Mon.

Monday night...Light snow with areas of IFR.
Tuesday through Friday...A chance of snow showers with spotty MVFR
to IFR, especially east of the lakes with local lake effect snow.


Winds will remain relatively light today as high pressure drifts
slowly east down the Saint Lawrence Valley. Winds will increase on
Lake Ontario later tonight and Tuesday, but the ESE wind direction
will direct the greater wave action into Canadian waters.

A clipper system will then cross the eastern Great Lakes late
tonight and Tuesday. This will bring an increase in winds on Lakes
Erie and Ontario, with Small Craft Advisory conditions possible from
later Tuesday through Wednesday.





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