Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 231146
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
646 AM EST Thu Jan 23 2020

.SYNOPSIS...
Dry conditions and above normal temperatures will last through
Friday as high pressure anchored along the east coast remains in
control of our weather. Low pressure over the lower Mississippi
Valley today will then track northeast to Michigan by late Friday,
before a secondary area of low pressure forms over the Delmarva and
tracks northeast along the New England coast over the weekend. This
will initially bring rain and mixed precipitation from very late
Friday into Saturday, then transition to a mainly wet snow for
Saturday night and Sunday as somewhat cooler air works into the
region.

&&

.NEAR TERM /THROUGH FRIDAY/...
Dry weather and light winds will continue through at least Friday
afternoon with just a gradual increase in the mid and upper cloud
decks through the period as high pressure remains in control of our
weather across all of Western and North Central NY. Deeper moisture
will approach from the southwest during the latter half of Friday as
an area of low pressure tracks slowly northeast into Michigan. This
will bring a chance for some light rain showers to far Western NY by
late in the day Friday.

Temperatures will remain solidly above average through the period.
Highs today will range from the mid 30s east of Lake Ontario, to the
upper 30s to around 40 elsewhere. It will be a tad warmer Friday
with highs mainly in the lower to mid 40s, with upper 30s reserved
only for the interior higher terrain.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
Rain and or a wintry mix gradually switching to lake enhanced
snow is one theme of the weekend while the other main theme is
limited cold air (surprise, surprise) resulting in snow amounts
that will be highly dependent on elevation. Total snow amounts
from Friday night through later Sunday night as the event
finishes up could exceed 6 inches in the higher terrain areas
from the Chautauqua Ridge to the hills in Southern Erie and
Wyoming county along with the higher terrain of the Tug Hill
Plateau region. However, at the lower elevations, including much
of the Buffalo metro and in Rochester, total snow accumulations
may struggle to reach just a couple inches as temps remain
marginal for accumulating much snow through the weekend.

Starting Friday night, vertically stacked sfc and upper lows will be
sliding northeast through the Ohio Valley toward the Lower Great
Lakes. Low-level jet and warm air advection in lowest 5kft will
bring a swath of mostly rain over much of the area. May see snow mix
with the rain where temps are near freezing, over parts of the
Southern Tier and in the higher terrain east of Lake Ontario. NAM
does indicate warm layer would ride over sfc temps below freezing.
Suspect the NAM may be too cold with the degree of warm air
advection excepted so leaned toward warmer blyr of GFS and Canadian
so essentially more of a rain/snow issue instead of freezing rain.

On Saturday, upper low only makes its way to vcnty of Lake Erie
while the initial sfc low lifts through the central Great Lakes.
Eventually another sfc low takes shape toward the Mid Atlantic
States as stronger jet energy slides southeast of the upper low.
Daytime on Saturday will be the time of transition across our area
as this evolution in sfc lows is occurring. Carried mix of rain and
snow, but temps in the mid to upper 30s due to the warm air
advection occurring since Friday night and as initial low
should still be northwest of here will result in ptype staying
rain in the lower elevations.

Eventually as the low along the coast becomes the primary low by
late Saturday night, temps aloft settle more toward -6c and
soundings indicate blyr cools sufficiently to turn most mixed precip
over to snow across all the forecast area. With deeper moisture to
H7-H6 in the area (as evidenced by slower trend to depart the upper
low) and delta t/s to 8-9c off both Great Lakes, think a period of
lake enhancement develops Sat. night and continues into good part of
Sunday. Blyr wind direction from the nw will favor higher terrain
over western Southern Tier and to east of Lake Ontario for the most
snow as with marginal sfc temps this should turn into a upslope
terrain enhancement event. However, with the cyclonic side of the
upper low in the vcnty and cooling temps, even the lower elevation
locations will probably see some snow accumulation late Saturday
night into midday Sunday before temps warming into the mid 30s limit
additional accums into Sunday afternoon. One of the bigger changes
to the forecast was to increase pops Sunday and Sunday night, most
notable over the higher terrain areas favored by nw winds.

Later Sunday evening and certainly by Monday, upper low exits toward
Maine and Nova Scotia and the lake enhancement shuts down. Once the
deeper moisture departs, temps at top of 5kft inversion, remaining
only as low as -6c are not sufficient for pure lake effect snow. May
be some lingering upslope light snow showers on into Monday with
maybe some rain mixing in over the lower elevations as temps reach
the lower to mid 30s.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
Looks quiet once this system departs on Monday. Even though we are
entering into when we should be a climatological min for temps, we
will be far from it for this week as strongly positive Eastern
Pacific Oscillation (EPO) teleconnection pattern favors strong jet
pushing into western North America off the eastern Pacific which
keeps coldest air bottled up well to the north, across even northern
Canada. Weak little shortwave may bring some isold rain and snow
showers or sprinkles/flurries Tuesday, but looks dry otherwise in a
non eventful zonal flow. Yet another warmer system in the southern
stream lifting along the northeast coast late in the week will bring
the next chance of precipitation to the region.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
High pressure anchored along the East Coast will maintain fair VFR
flight conditons and light winds throughout our region through at
least tonight. Only `weather` to speak of will be just a general
increase in mid and upper level cloud decks through the end of the
TAF period.

Outlook...
Friday...VFR conditions.
Saturday...MVFR/IFR conditions possible with rain and wet snow.
Saturday night through Monday...MVFR/IFR conditions possible due to
snow.

&&

.MARINE...
Headline free conditions will be found throughout the Lower Great
Lakes through at least Friday morning, as high pressure remains in
control. Light south winds through midday will then back to the
southeast and east winds for later today and tonight.

Easterly flow will freshen (especially across the western half of
Lake Ontario) Friday through Saturday ahead of the next storm
system. This will bring possible SCA conditions across the western
Lake Ontario nearshore zones from Friday afternoon through Saturday
evening. A return to below SCA conditions can then be expected for
the second half of the weekend into early next week.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...JM
NEAR TERM...JM
SHORT TERM...JLA
LONG TERM...JLA
AVIATION...JM
MARINE...JM


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