Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 191850
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
150 PM EST Thu Jan 19 2017

.SYNOPSIS...
Low clouds and areas of drizzle come to an end as the axis of high
pressure crosses the area. A weak trough will cross the area Friday
with a period of rain showers during the afternoon and evening
across Western and Central NY. Mainly dry weather will then return
for the start of the weekend with temperatures remaining well above
average.

&&

.NEAR TERM /THROUGH FRIDAY/...
Low clouds and areas of drizzle will persist through the rest of the
afternoon. The clouds will finally erode as the high pressure
axis crosses  the region early this evening. This will result in a
period of partial clearing with a layer of high clouds spreading
across the region from southwest to northeast.

A mid level trough will move across the region with an increase in
mid clouds across the Western Southern Tier by 18Z Friday. There
will also be an increasing chance for rain later in the day and
early evening on Friday.

Temperatures will fall to the upper 20s to lower 30s across the
region tonight, especially colder in the areas with partial
clearing. High temperatures on Friday will climb to the mid to upper
40s across Western New York to the Finger Lakes region, with the
influx of warm air associated with the trough and southerly winds.
Highs across the North Country will be in the lower 40s as the
trough will slower to arrive, but the temperatures will hold nearly
steady or rise during the evening and overnight Friday night.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
The trough across the central plains today will become negatively
tilted and track toward the Great Lakes on Friday. The result will
be an area of rain moving into southwestern NY during the day
Friday, on the nose of the best moisture advection and frontogensis
ahead the upper-level trough. This trough and associated area of
frontogensis will become sheared out across central NY Friday
afternoon and evening, thus decreasing forcing and allowing rain to
become more scattered and fizzle out as it tracks toward the North
Country Friday evening. Have increased PoPs some more across the
western Southern Tier to near 100 percent, and brought categorical
PoPs farther north toward the Niagara Frontier. From the northern
Finger Lakes into the North Country, the rain will become much more
scattered, and have maintained chance PoPs there. Temperatures will
remain very mild on Friday with enhanced warm air advection an some
downsloping, bringing daytime highs well into the 40s. The rest of
Friday night, the showers associated with this feature will
gradually end... with skies remaining shrouded under plenty of low
cloud cover. Low temperatures will only bottom out around 40 in the
Lake Plains to mid 30s inland.

A progressive shortwave ridge will amplify over the Lower Great
Lakes on Saturday. This will provide us with a fairly nice day for
outdoor activities...as 850 mb temperatures rise to +5C over western
NY to +2C over North Central NY. This will allow daytime
temperatures to surge to low 50s for those in western NY, the
Genesee Valley and the Northern Finger Lakes, while the North
Country will remain in the low to mid 40s.

Sunday will largely feature more uneventful weather across our
region...as the high amplitude ridge will gradually exit across New
England. High temperatures on 850 mb temperatures fall slightly
ahead of the approaching low, but daytime highs will remain near 50
in western NY to the low 40s in the North Country.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Confidence remains very high in a period of precipitation across the
region from later Sunday night into Tuesday as an anomalous low
pressure system tracks northward through the coastal Atlantic
states. Despite maintaining very high confidence in precipitation,
there is decreasing confidence in the type of precipitation, as the
chance for snowfall across the region increases.

The eastward shift in the track of the low pressure system noted by
yesterday`s forecast discussion remains true with the 00Z model runs
this morning. As was noted previously, the eastward shift places
western and central NY on the cooler side of the system, increasing
chances for wintry precipitation. Since this storm system will lack
a tap to significant cold air, temperatures profiles will be
marginal and dynamical cooling process will be very important. While
the GFS thermal profiles remain overall uninteresting for wintry
precipitation in our area, the ECMWF, along with with ensembles, and
the Canadian are actually much more interesting. These models are
overall a few degrees colder, which makes all the difference near
the freezing mark. Dynamically cooling will play a vital role in the
wrap around precipitation as the low tracks up the coastline,
something the models typically seem to underrepresent. Also
supportive of the idea that the GFS thermal profiles may be too warm
is the CIPS analogs based on the GFS forecast itself. The top
analogs, all produced a swath of significant snowfall through NY
state. All of this points to increasing chances for potentially
significant snowfall, while the possibility of a cold rain remains
solidly on the table at this point as well. This storm system will
need to be watched closely as we move through this weekend, since if
the colder solutions verify, this would bring snowfall impacts to
the beginning of the work week.

A bit more on the daily details:

The mature storm system will drift to the Mid Atlantic region on
Monday. This will establish a deep easterly flow (40-50 kts) of
Atlantic moisture over our region where a strongly coupled H25 jet
will provide lift for increasingly widespread rain. This pcpn could
be moderate to heavy at times with some areas possibly receiving a
half to one inch of rain. High temps will be in the mid 30s to
near 40 for most areas.

The rain will continue and could begin to mix with or change to snow
across the region Monday night into Tuesday, as the storm system
will track north-northeast across New England. This is when things
could get interesting. Because of the more eastward track...colder
air will be able to work in behind the parent low. As mentioned, the
air could be cold enough to allow for a transition to wet snow,
especially across the higher terrain. In a worst case scenario, the
snow would change over at a point where significant accumulations
could occur.

Drier air will then work its way across our region later Tuesday
night and Wednesday...finally bringing an end to the pcpn event.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
Low clouds and areas of drizzle will keep ceilings and,
periodically, visibility in the IFR category through the rest of
the afternoon. The clouds will finally erode as the high pressure
axis crosses the region early this evening. This will result in a
period of partial clearing with a layer of high clouds spreading
across the region from southwest to northeast.

A mid level trough will move across the region with an increase in
mid clouds across the Western Southern Tier by 18Z Friday. There
will also be an increasing chance for rain later in the day and
early evening on Friday.

Outlook...

Friday...VFR through mid day...then MVFR/IFR with rain showers in
the afternoon.
Saturday and Sunday...Areas of IFR/MVFR in low stratus.
Monday and Tuesday...Areas of MVFR/IFR with rain or wet snow.

&&

.MARINE...
Winds and waves will slowly diminish into the evening as the
pressure gradient relaxes across the Lower Great Lakes. Relatively
light winds will persist through the end of the week and into the
weekend with mild temperatures and a weak pressure gradient in place.

&&

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

&&

$$

SYNOPSIS...WCH
NEAR TERM...WCH
SHORT TERM...CHURCH
LONG TERM...CHURCH
AVIATION...WCH
MARINE...WCH


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