951 
FXUS61 KBUF 022023
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
323 PM EST Tue Feb 2 2021

.SYNOPSIS...
A strong low will move slowly northward along the east coast through 
tonight, reaching the Canadian Maritimes Wednesday. Accumulating 
snow will spread westward and back into most of the region into 
tonight, with the greatest accumulations across Central NY and the 
western Finger Lakes. The snow will end from west to east later 
tonight and Wednesday as high pressure builds into the eastern Great 
Lakes. A brief warming trend will arrive Thursday and early Friday 
before much colder air moves back into the region for the weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Radar update at 145 PM shows widespread moderate snow from the 
St. Lawrence River valley across the North Country and across 
much of central NY. Light to moderate snow is as far west as 
Niagara county. Two main concerns remain into this evening. 

First issue at hand is problematic strong mesoscale band that keeps 
forming off and on across North Country on west edge of mid-upper 
low which is currently vcnty of New York City. Models not handling 
it well and per radar algorithm and reports from the earlier 
iteration of this band, it is likely producing snowfall rates of 1-2 
inches per hour. Based on radar trends seems like this will break 
down in the next two hours, but am very uncertain given how the 
models, even the HRRR, are not handling it well. This heavy snow 
that has already occurred along with additional snow overnight 
tonight as another wave of moderate to heavy snow works in from 
northern New England has led to upgrading Lewis and Jefferson 
counties to winter storm warning. That warning will run through 15z 
on Wed. 

Second issue is from mid afternoon through early evening concerning 
a period of heavy snow for especially Monroe, Wayne and Ontario 
counties. This would include Rochester Metro and specifically the 
commute home this afternoon. All high-res models very insistent on 
backing swath of moderate to heavy snow over North Country and also 
eastern Lake Ontario over this area during this time. Based on above 
comments though, probably should have at least some caution in that 
idea if the stronger band persists east of Lake Ontario. If this 
heavier snow moves in though, snowfall rates 1-2 inches per hour 
would be likely which will result in a very rough commute in the 
Rochester area. Already started messaging this potential with SPS 
and on social media for now. We probably will fall just short of 
warning criteria (7"/12 hours), but wanted to have additional 
messaging out in addition to the going advisory in place. Appears 
period of moderate to heavy snow for these areas will last through 
around 7-8 PM before starting to taper off by late evening.

Otherwise, light snow with pockets of moderate snow is expanding 
across rest of western NY with steadiest snow across northern 
reaches of the Niagara Frontier. Expect the mainly light snow to 
linger through late evening before diminishing after midnight as 
primary shortwave rotating around upper low slides off to the 
southeast. Rising heights aloft and limited cold air behind the 
system will lead to improvement from west to east on Wednesday. Snow 
will persist the longest in the upslope higher terrain areas 
southeast and east of Lake Ontario. Most additional snow late 
Wednesday morning through Wednesday afternoon will be light. 

From west to east here at expected *additional* snow accumulations 
late this afternoon through Wednesday morning: western NY less than 
2 inches, Genesee Valley including Rochester Metro 4-6 inches, 
northern Finger Lakes into Oswego county 4-6 inches (most over 
Wayne/Ontario counties) and east of Lake Ontario another 4 to 6 
inches.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
Low pressure will finally exit across the Canadian Maritimes 
Wednesday night, meanwhile ridging at the surface and aloft will 
build across the Ohio Valley and eventually nudge into Western New 
York. There may be a few lingering snow showers east of Rochester 
Wednesday evening, but after this the high pressure ridge will crest 
across the region and provide dry weather through Thursday. Low 
temperatures Wednesday night will generally be in the teens, but 
single digits are possible across the Southern Tier if the high 
builds in a bit more quickly. Expect warmer weather Thursday with 
some breaks of sunshine allowing temperatures to climb well into the 
30s. 

A vertically stacked 976 mb surface low will track across Michigan 
Thursday night before moving north of the Great Lakes on Friday. 
This will force a series of frontal boundaries across our area. The 
initial will be a warm front with associated mid-level warm air 
advection supporting a round of fairly steady precipitation which 
will enter Western New York late Thursday night. This will quickly 
be followed by a cold (or occluded) front which will move from west 
to east across the area on Friday. Forecast thermal profiles are 
marginal, suggesting mainly rain across the lake plains where a 
southerly flow will result in downslope warming. A bit more tricky 
across the Western Southern Tier and east of Lake Ontario where it 
will be cold enough to support snow for much of the time. Could see 
a few inches accumulation, but likely sub-advisory amounts. Some 
mixed precipitation, such as freezing rain or sleet, cannot be ruled 
out but suspect increasing winds should help scour out the cold air 
at the surface resulting in non-diurnal temperature trends Thursday 
night. Warmest temperatures will be just ahead of the 2nd front 
Friday morning, then expect temperatures will quickly drop below 
freezing Friday afternoon behind the front. Expect most of Western 
New York to remain dry behind the front, with the exception of 
northeast of Lake Erie where some lake effect snow showers may begin 
to develop.

This system has the potential to produce a period of gusty winds 
just behind the cold/occluded front Friday, especially northeast of 
the lakes. How strong the winds are depends on the track of the 
surface low, which is forecast to move due north of Michigan, 
keeping it further away from the area. However, would not be 
surprised to see a few hours with advisory level gusts to 50 mph 
across the Niagara Frontier on Friday.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...

...COLD WEATHER AND SIGNIFICANT LAKE EFFECT SNOWS POSSIBLE INTO NEXT 
WEEK...

Low pressure will weaken as it gradually gets absorbed by longwave 
trough across Canada. 850 mb temperatures will drop to around -16c 
behind the front Friday night resulting in lake induced instability. 
Meanwhile shortwave will provide ample moisture to support a period 
of moderate to heavy lake effect snow northeast of the lakes Friday 
night. This shortwave will exit into New England Saturday, with lake 
snow expected to taper off Saturday afternoon and evening. This has 
the potential produce several inches of snow or more, with advisory 
or even warning amounts possible. Time will be a limiting factor 
since the moisture provided by the shortwave will be temporary. 
Slightly warmer air aloft, diminishing synoptic moisture, and 
increasing shear will cause lake effect snows to diminish Saturday 
night. 

The core of arctic air will drop across Western Ontario province on 
Sunday. As its associated trough axis dives across the Great Lakes, 
a surface low will pass to our south, with some model disagreement 
on its track and strength. This could bring a light general snow on 
Sunday, but in its wake it definitely will be colder heading into 
next week. GFS/GGEM both drop 850mb temperatures to around -25c, 
with the 'warmer' ECMWF down to around -20c. This supports highs in 
the teens for Monday and Tuesday, and even that may be optimistic in 
some areas if the colder guidance verifies. Bitterly cold wind 
chills can also be expected.

In addition to the cold, this will establish a pattern favorable for 
lake effect snow. Wind direction and moisture will be key, and its 
too far out to pin down the details. In general, a prevailing WSW 
flow will place the traditional snow belts east of the lakes at the 
greatest risk. However, bands will meander, with the potential to 
impact the cities of Buffalo and Watertown at times. The WSW flow 
will diminish the risk for heavy snow for counties immediately south 
of Lake Ontario, including the Rochester area.

&&

.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
Snow is spreading from east to west across the region this afternoon 
as the circulation around a mature east coast low expands. The 
moderate snow has reached the lower Genesee Valley, and will 
continue to spread slowly southwestward rest of afternoon. IFR VSBY 
and MVFR CIGS will become widespread across most of the region as 
the snow expands. IFR CIGS will be found across the higher terrain 
today. The heaviest snow and lowest VSBY is expected to focus from 
KROC eastward to the eastern Lake Ontario region. There will be a 
few periods of 1/4SM heavy snow at KROC (20-24z), but most of the 
time VSBY will stay above airfield minimums. 

The snow will reach its westernmost extent late this afternoon, 
reaching KBUF, KIAG, and KJHW for at least a few hours. The snow 
will then taper off from west to east tonight as the coastal low 
continues to move northeast towards the Canadian Maritimes. Expect a 
gradual improvement from IFR VSBY to VFR VSBY from west to east 
tonight. Areas of MVFR CIGS will linger overnight after the snow 
ends.

Outlook... 

Wednesday...Light snow east of Lake Ontario with MVFR/IFR VSBY at 
times. Otherwise areas of MVFR CIGS.
Thursday...VFR.
Thursday night and Friday...Mainly MVFR. Rain and snow showers 
likely.
Saturday...IFR possible in lake effect snow northeast of Lakes 
Erie and Ontario.

&&

.MARINE...
High pressure will remain anchored from James Bay to central and 
northern Quebec through Wednesday. To our east, a deep east coast 
low will move slowly northward just offshore of New England through 
tonight, reaching the Canadian Maritimes Wednesday.

Moderate northeast winds will continue to back to the north this 
afternoon, and northwest tonight and Wednesday as the coastal low 
moves slowly northward. This will maintain Small Craft Advisory 
conditions on Lake Ontario through Wednesday night. Winds are 
somewhat lower on Lake Erie, but will still be strong enough to 
produce Small Craft Advisory conditions through late tonight. High 
pressure will build into the eastern Great Lakes Thursday with 
diminishing winds. 

Next period of stronger winds occurs Friday into Friday night with 
southwest gales looking likely on Lake Erie and a return to Small 
Craft Advisory conditions for the rest of the waters.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Storm Warning until 10 AM EST Wednesday for NYZ007-008.
     Winter Weather Advisory until 10 AM EST Wednesday for NYZ006.
     Winter Weather Advisory until 7 AM EST Wednesday for NYZ004-
     005-014.
     Winter Weather Advisory until 4 AM EST Wednesday for NYZ003-
     013.
MARINE...Small Craft Advisory until 7 AM EST Wednesday for LEZ040-041.
         Small Craft Advisory until 7 AM EST Wednesday for 
         LOZ030.
         Small Craft Advisory until 7 AM EST Thursday for 
         LOZ042>044.
         Small Craft Advisory until 10 PM EST Wednesday for LOZ045.

&&

$$

SYNOPSIS...Hitchcock
NEAR TERM...JLA
SHORT TERM...Apffel
LONG TERM...Apffel
AVIATION...Hitchcock/JLA
MARINE...Hitchcock/JLA