Thursday, November 22, 2018

Arctic Express arrives

Area Forecast Discussion
National Weather Service Buffalo NY
443 AM EST Thu Nov 22 2018

Arctic high pressure will settle across our region today, bringing
record or near record cold along with slowly diminishing snow
showers. The bitter cold will be short lived, as a significant
warm up will begin on Friday and continue through the weekend.

Arctic high pressure will continue to build into the region and
bring an unseasonably cold day today. Light intensity lake effect
snow showers south and southeast of the lakes early this morning
will diminish through the morning, before ending entirely by mid day
or early afternoon. Outside of the snow shower activity conditions
will be partly to mostly sunny, but unseasonably cold. High
temperatures will range from the mid teens across interior portions
of the Southern Tier/North Country to the lower 20s across the lake
plains. These readings are some 25 degrees below normal, with daily
record low maximums likely to be set.

Very cold temperatures will persist tonight as the high settles over
the area. Widespread low temperatures in the single digits and
teens are expected.

While mid winter temperatures will greet Black Friday shoppers
early Friday morning...fair dry weather can be expected throughout
the day. The large Arctic high responsible for the January like
temperatures will push off the coast during the afternoon...and the
clockwise circulation on its backside will allow for more tolerable
temperatures to end the day as the mercury will climb well into the
20s east of Lake Ontario with readings reaching well above freezing
over the far western counties. All in all though...good weather will
be in place for holiday shoppers/travelers.

Continued warm advection will be found across our forecast area
Friday a southerly flow will deepen between the exited
surface high and an approaching `storm system` over the Ohio and
Tennessee Valleys. Clouds will increase and thicken over the region
ahead of this next system...but we should maintain our dry weather
through the overnight. In regards to will not be
nearly as the stronger southerly flow will guarantee that
temperatures will be a solid 15 deg higher than those from
Thanksgiving night. Lows will range from the teens in Lewis county
to around 30 near Lake Erie...and those should be experienced before
midnight with slowly rising temperatures during the wee hours of
the morning.

Conditions will rapidly deteriorate across the forecast area on a complex frontal system and developing surface low
will push to the east across the Lower Great Lakes and Mid Atlantic
region. A robust 50kt low level jet will combine with a little help
from some H25 jet dynamics to lift a deepening moisture field to
generate fairly widespread rain...particularly over the western
counties. There will be the risk that some of the precipitation will start
off as a mix of sleet wet snow during the morning...but there is no
doubt that this will be a rain event with daytime basin average
rainfall forecast to range from a few hundredths across the North
Country to as much as a half inch across the Southern Tier. Its
worth noting that the southerly flow should encourage a little
downsloping north of the NYS Thruway between BUF and SYR...and this
will help to hold down the rainfall numbers by some 20 percent. Not
a big deal though given the projected rainfall totals. It will also
feel somewhat milder with max temps generally in the low to mid 40s.

The complex system within a supporting negatively tilted trough will
continue to advance across the Eastern Lake Ontario counties
Saturday night. This will allow the rain to become more widespread
in that area...while the steadier rain will taper off and end as
nuisance showers over the western counties. Again...the precipitation should
fall as no winter related travel issues are anticipated.

A short lived ridge will quickly pass over our region on Sunday.
This will provide us with fair dry weather...although a few leftover
showers will be possible early in the day for sites east of Lake
Ontario. It will be relatively the mercury will climb into
the mid and upper 40s for the bulk of the region.