Forecast Discussion

Forecast Discussion for BUF NWS Office
096
FXUS61 KBUF 210827
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
427 AM EDT Wed Apr 21 2021

.SYNOPSIS...
Low pressure will pass just south of the region today, producing
widespread accumulating snow across the region. Colder air will
bring some lake effect snow showers to areas southeast of Lake Erie
and Lake Ontario tonight into Thursday morning. Dry and warmer
weather will return on Friday.

&&

.NEAR TERM /THROUGH THURSDAY NIGHT/...
Regional radars showing main band of snow entering western New
York aligned well with the very tightly packed southwest to
northeast thermal gradient at 850 mb. 850 mb low looks to be
entering southwest New York with snow on the cold side of the
low. Mixed precipitation showing up underneath the low across
northern Pennsylvania into Cattaraugus and Allegany counties.
Little if any precipitation on the warm side of the 850 mb low
and mainly in the form of rain.

Nearly all model guidance keeps the 850 mb low to the southeast of
the area today as it tracks through the region so expected any
mixed precipitation and rain to change over to snow this
morning.

Main band of snow just entering western New York will gradually
work through the area fairly quickly this morning. Upstream
observations suggesting we will be looking at about a 2-3 hour
period of at least the possibility of moderate snow at times.
Grassy surfaces could see another 2-3 inches, with lesser but
still a slushy covering on warmer paved surfaces.

The widespread snow will taper off quickly from west to east
starting late this morning through the afternoon, to be replaced by
a few snow showers as cold air pours into the eastern Great Lakes in
the afternoon. Lake effect and upslope snow showers will become more
widespread tonight through Thursday morning as the core of the
coldest air aloft crosses the region. Northwest flow will direct
most of this into the western Southern Tier off Lake Erie, and from
Orleans County eastward across Rochester to Oswego County and down
into the Finger Lakes off Lake Ontario. Upslope flow will also keep
more widespread snow showers going across the higher terrain east of
Lake Ontario. All of this may produce localized additional
accumulations of 1-3" tonight.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
Ridging aloft and at the sfc will provide dry and tranquil weather
Friday and Friday night. It will also turn notably warmer as warm
advection processes modify the airmass over the eastern Great Lakes.
Look for temperatures to be 15F-20F warmer than Thursday with
highs ranging from the low to mid 50s to near 60F across Western New
York into the Finger Lakes region. Again, it will be a bit cooler
east of Lake Ontario with readings found in the 40s across the Tug
Hill to low and mid 50s at lower elevations. Lows areawide
Friday night will bottom out in the 30s by day break Saturday
morning.

The next chance of precipitation arrives by late Saturday afternoon
and then continues through Saturday night. A complex scenario
unfolds Saturday as low pressure tracks up through the Mid-Atlantic
States and then interacts with a northern stream shortwave trough
moving east through the Upper Great Lakes. Deep moisture being drawn
northward will result in widespread precipitation overspreading the
Lower Lakes by Saturday evening and then will continue through the
night. This go around, precipitation will be in the form of rain
as a mild air mass will be in place. In terms of temperatures, highs
on Saturday will climb well into the 50s to low 60s across the
forecast area. Lows Saturday night will only drop back into the 40s.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
The complex low pressure system gradually pulls away from the
region on Sunday with precipitation chances diminishing from west to
east. In it`s wake, a brief shot of cooler air will filter into the
Lower Lakes with highs anticipated only in the upper 40s to low
50s on Sunday. However, it doesn`t appear to last very long as
the air mass again quickly modifies as we head into the new work
week. Sfc high pressure builds in for Monday with dry weather
expected for the rest of this period. Of which, may even extend
well beyond the middle of the week as an Omega block develops over
the eastern half of the CONUS. Stay tuned!

Otherwise, it appears that highs may climb well above normal by the
middle of the work week with upper 60s to low 70s.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
Low pressure will move from the Ohio Valley to southern New England
this afternoon. A shield of widespread precipitation will continue
to spread to the north of the low track. Most of the precipitation
will be snow with any lingering mixed precipitation changing to all
snow this morning, with widespread snow lasting through this
morning before tapering off from west to east this afternoon.

The snow will produce widespread IFR conditions today. The snow may
become moderate for a couple hour period early this morning, with
VSBY possibly to near a half mile at the TAF sites. Expect
improvement to MVFR/VFR from west to east in the afternoon as
the snow tapers off.

Outlook...

Tonight and Thursday...MVFR/local IFR with scattered snow showers
and some lake effect snow showers southeast of the lakes. Windy.
Friday and Saturday...Mainly VFR.
Sunday...VFR/MVFR with a chance of showers.

&&

.MARINE...
Low pressure will move east across Pennsylvania will move to New
England by this afternoon. Northeast winds will increase as
this low approaches, then become northwest and increase further
this afternoon and tonight as cold air pours into the eastern
Great Lakes behind the departing low. A long period of Small
Craft Advisory conditions is expected on Lakes Erie and Ontario
from today into Friday. The strongest winds will occur on
Thursday, when sustained winds may approach 30 knots on Lake
Ontario.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory until 5 PM EDT this afternoon for
     NYZ007-008.
     Winter Weather Advisory until 2 PM EDT this afternoon for
     NYZ001>003-010>013-019>021-085.
MARINE...Small Craft Advisory until 10 PM EDT Thursday for LEZ040-041.
         Small Craft Advisory from 8 AM this morning to 8 AM
         EDT Friday for LOZ043-044.
         Small Craft Advisory from 8 AM this morning to 2 AM EDT
         Friday for LOZ042.
         Small Craft Advisory from 11 PM this evening to 8 AM EDT
         Friday for LOZ045.

&&

$$

SYNOPSIS...Hitchcock/TMA
NEAR TERM...Hitchcock/TMA
SHORT TERM...AR
LONG TERM...AR
AVIATION...Hitchcock/TMA
MARINE...Hitchcock/TMA

NWS BUF Office Area Forecast Discussion