Area Forecast Discussion
Issued by NWS Buffalo, NY

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200
FXUS61 KBUF 220641
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
141 AM EST Thu Feb 22 2018

.SYNOPSIS...
A weak storm system passing south of New York will bring some mixed
precipitation to the Southern Tier overnight followed by some
accumulating snowfall through daytime today. Another low pressure
system will then bring another round of mainly rain to our area on
Friday. A third storm system will bring more rain and some wind for
Sunday. Otherwise, temperatures will remain above normal through the
weekend.

&&

.NEAR TERM /THROUGH TODAY/...
Strong Canadian high pressure is spread across the Great Lakes early
this morning. Further south, a wave of low pressure is lifting north
across the southern Appalachians. Radar mosaic shows this wave of
low pressure is generating widespread precipitation across the Ohio
Valley into western PA with some echoes also extending north across
western NY. These echoes across WNY remain elevated near 1am with
some drier air remaining near the surface. We continue with a
forecast expecting an initial brief wintry mix of freezing rain and
sleet early this morning a little later this morning. Following
this, cooling thermal profiles will lead to a quick shot of light to
moderate accumulating snowfall across the Southern Tier. Areas
further to the north will only see the chance for a little light
snow given what should be a rather sharp northern edge to the
steadier precipitation.

A Winter Weather Advisory remains in effect for Chautauqua,
Cattaraugus and Allegany counties for a short-lived round of
light icing followed by a general snowfall of 2-4"/ 3-5" through
mid afternoon. Snowfall amounts and probabilities then quickly
diminish with increasing northward extent across the remainder
of the region with some lighter snowfall accumulations of 1-3"
likely from Southern Erie and Wyoming counties eastward across
interior portions of the Finger Lakes and just a chance for some
light snow/spotty light rain and little if any accumulation
found further to the north.

With respect to temperatures...continued steady cold air advection
overnight will allow temperatures to drop back to the lower to mid
20s areawide...with highs later today then ranging through the 30s.
In spite of the much colder airmass...such readings will still
actually be a little above average for this time of year.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
The prevailing flow aloft Thursday night through Saturday night will
feature a SW-NE oriented jet stream generally stretching from the
Desert Southwest into the Central Great Lakes region.  The result at
the surface will be a number of relatively weak troughs/lows.

The first feature will already be east of the region by Thursday
night while surface high pressure moves from the Northern Great
Lakes region east across Southern Ontario and Quebec.  This will
result in a temporary break in any precipitation across Western and
Central NY for Thursday night with weak subsidence in place.

The break will be short-lived however as another feature moves in.
Although the surface pattern looks relatively weak, moisture will
will be tapped from the Gulf of Mexico, with the potential for
another decent precipitation event at least toward the NY/PA line.
Although the details will likely change, overall it looks like some
areas could briefly start out with snow or a very brief period of
freezing precipitation before quickly changing over to rain on
Friday.

Another surface high pressure system follows with a dry period
expected for most of Friday night and Saturday.  A more significant
synoptic low should have developed by this time over the plains.
This low, a result of the upper level disturbance currently moving
down the BC coast, should deepen as it moves toward the Northern
Great Lakes Saturday night.  The result will be increasing chances
for rain, with widespread rain expected Saturday night.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
A low pressure system will eject from the four corners region
Saturday across the Great Lakes by Sunday. The result should be a
chance of widespread rainfall Sunday ahead of the approaching low
pressure system. As the low passes by to our northwest, expect
decent southwest winds to pick up behind in the cold advection
behind the front. Forecast models continue to advertise the
possibility (last several runs of the GFS and today`s 12Z EC) of a
strong or high wind event for the typical areas northeast of Lake
Erie on Sunday behind the cold front passage. Have added the mention
to the HWO for now.

Quiet and drier weather returns Monday with surface high pressure
building over the Ohio Valley. Highs will remain above climo (+5F -
+10F) with the daytime highs in the mid and upper 40s likely for
most locations for the first half of next week. Sunday will likely
be the warmest day, so long as we briefly break into the warm
sector, with at least 50s possible.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
VFR remains in place across our region ahead of some incoming wintry
weather. Expect IFR to MVFR cigs possible across the Southern Tier
later this morning but have continued with a rarely used NIL TAF for
KJHW due to observation equipment that has not been reporting for
several days. Safety concerns play a major role in this
decision...especially given the erratic cigs and potential for mixed
precipitation at this elevated site during the TAF period.

North of the Southern Tier, VFR should remain through today. Some
light snow may edge toward or over KBUF-KROC midday but otherwise
remain dry. VFR expected much of tonight with a possible late
reduction to MVFR with a chance of some rain toward 12z Friday.

Outlook...
Friday...Deterioration to MVFR with rain developing...with a
very brief wintry mix possible at the onset.
Saturday and Sunday...VFR/MVFR with additional periods of rain
developing...which may be mixed with a little snow across the
North Country. Monday...Mainly VFR.

&&

.MARINE...
Winds have diminished and veered to northerly/northeasterly this
morning as high pressure is centered over the Great Lakes. Moderate
northeasterlies to easterlies will persist across Lake Ontario
through today before increasing and potentially leading to another
round of advisory-worthy conditions across the western half of the
lake tonight.

Southerly winds will veer to westerly Friday as a weak storm
system passes over western NY. This will keep highest waves on the
northern half of Lake Ontario. High pressure will build briefly back
over the Great Lakes Saturday before a strong low pressure cuts
across the Great Lakes Sunday. This should bring a round of higher
end Small Craft Advisory conditons.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory until 4 PM EST this afternoon for
     NYZ019>021.
MARINE...None.

&&

$$

SYNOPSIS...SMITH
NEAR TERM...JJR/RSH/SMITH
SHORT TERM...ZAFF
LONG TERM...CHURCH
AVIATION...JJR/RSH/SMITH
MARINE...SMITH



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