Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 211749

Area Forecast Discussion
National Weather Service Buffalo NY
1249 PM EST Sun Jan 21 2018

A warm front will push north across the Ohio Valley today
bringing a chance for light drizzle or sprinkles into Western
New York. More significant rainfall is expected Monday, as a
large storm system tracks into the Central Great Lakes, with
temperatures warming well into the 40s ahead of this system. A
cold front will then bring back more typical winter weather late
Tuesday into Thursday. Another warm up is forecast Friday into
next weekend.


A cold front stretches roughly from just north of Lake Ontario to
Northern New York and east across southern Maine. A warm front
runs from low pressure over Colorado east to just north of the
Ohio River. The cold front is forecast to generally remain
stalled in place today with a zonal flow aloft while an
increasing southerly flow over the Ohio Valley will shift the
warm front north to near the NY/PA border.

Satellite imagery and surface observations show extensive cloud
cover across much of western and central New York with moisture
pooling ahead of the warm front. Radars are clear now, but cant
rule out a slight chance of some drizzle or sprinkles
afternoon. Temperatures today should warm generally into the
upper 30s to mid 40s despite extensive cloud cover. Patchy fog
also possible today into tonight as dewpoints rise above
freezing in areas with lingering snow pack.

Tonight, we remain cloudy with the warm front lifting further
toward or into the western Southern Tier. Chances of hit/miss
showers increase and spread north and east across western into
central NY. Light snow/flurries would be the P-type across the
cooler North Country. Steadier rain will become most likely
across the western Southern Tier late tonight. Fog due to the
warm air moving over lingering snow pack should become more
widespread overnight. Temps will range from the mid-upper 30s in
western NY to the upper 20s to low 30s in the North County.


The main feature of significance during the first half of the week
will be a vertically stacked upper low that will be tracking from
the lower Missouri valley Monday, across the central Great Lakes and
southern Ontario by Tuesday, and to the Gulf of St. Lawrence by
Wednesday. A warm front will lift across the region in advance of
this system on Monday, bringing precipitation to western and north-
central New York as it moves across the area from south to north.
For most areas, this precipitation should fall as rain, however
persistent northeasterly flow up the St. Lawrence Valley will likely
keep sub-freezing air locked in across the area longer than the
models suggest. This should result in precipitation falling as sleet
and freezing rain in that area during the day on Monday before
temperatures climb above freezing Monday evening. A winter weather
advisory may be needed for this sleet/freezing rain potential.

The initial round of warm frontal precipitation should only last for
a few hours, as the area becomes engulfed in the warm sector of the
approaching low. Temperatures will climb into the 40s on Monday and
remain in the 40s Monday night as warm air continues to surge across
the region ahead of the low. Expect rain to move back in Monday
evening, as a pre-frontal trough moves across the area from west to
east. There will likely then be another break in precipitation as a
dry slot moves across the area Tuesday morning before wraparound
moisture brings yet another round of precipitation later in the day
on Tuesday. Expect temperatures to be falling during the day on
Tuesday as a cold front moves through, causing rain showers to
chance over to snow showers as aforementioned wraparound moistures
works its way across the forecast area. As temperatures aloft
continue to fall Tuesday night, expect lake effect snow showers to
develop on WNW flow, though increasingly dry conditions and
shortwave ridging aloft will likely keep lake effect activity

Wednesday will feel more like mid-winter again, as 850mb temps drop
to around -15C, translating to highs in the 20s. Scattered lake
effect snow showers will be ongoing southeast of the lakes into
Wednesday evening, though as mentioned above, a lack of moisture
will significantly limit accumulations. Wind chills will likely fall
into the single digits across many areas Wednesday night on
continued brisk northwesterly flow.


Any lingering lake effect snow showers should dissipate on Thursday
as a broad area of high pressure encompassing the eastern half of
the country moves over the region. The high pressure should also
allow for many areas to see decent sunshine, however temperatures
will remain below average, with highs in the 20s, with teens in the
North Country, thanks to continued cold northwesterly flow on the
front side of an approaching upper level ridge. With light winds and
clearing skies underneath high pressure, expect Thursday night to be
the coldest night of the week, with lows in the teens across western
New York, and readings possibly dipping below zero in the North

Quiet weather will continue on Friday and persist through Friday
night as the aforementioned high moves across the region.
Temperatures will begin to rebound on Friday as the center of the
high moves off to the east and anticyclonic southerly flow begins to
advect warmer air back into the Great Lakes. This should allow
temperatures to climb back into the mid to upper 30s across most
areas, with the exception of the North Country.

The progressive regime will continue as we move into next weekend,
as the upper level ridge moves across the eastern U.S. and a deep
trough digs across the Great Plains. The meridional flow currently
forecast should yield seasonably warm temperatures on Saturday, with
temperatures climbing back into the 40s, as warm air surges poleward
ahead of a low pressure system tracking across the upper
Midwest/western Great Lakes. Looking a little further ahead, we may
end up seeing a very wet conclusion to the weekend and start to next
week as GOMEX moisture surges across the region ahead of the
vigourous upper level trough. However, at this point it appears that
the rain should hold off at least until Saturday night.


Low cigs in place at all terminal except KROC, with patches of
IFR fog due to warm air spreading over our snow pack. The
northward lifting stratus deck will reach KROC by 19z. Cigs will
then remain MVFR at all sites into tonight. KJHW will hold in
IFR CIGs and VIS through tonight. Some rain showers likely
moving near KJHW during the evening, but becoming more likely
across all of WNY during the late overnight as a warm front
lifts north.


Monday and Monday night...MVFR/IFR with widespread rain.
Tuesday...MVFR/IFR with rain showers changing to snow showers before
ending...then areas of lake effect snow also developing east of the
lakes Tuesday night.
Wednesday...VFR/MVFR with a chance of snow showers.
Thursday and Friday...Mainly VFR.


High pressure reaching across the Eastern Great Lakes region will
promote light winds and wave action on the eastern Great Lakes
through tonight.

Northeasterly winds will re-freshen on Monday, as a large area of
low pressure tracks from the lower Missouri valley towards the Great
Lakes. This will likely generate more small craft advisory
conditions on the western half of Lake Ontario. This low will then
track across the Great Lakes on Tuesday, sweeping a cold front
across the lower Great lakes late Tuesday into Tuesday night and
bringing a potential for gales on Lake Ontario behind the front
Tuesday night into Wednesday morning.


NY...Flood Watch from Monday afternoon through Tuesday evening for



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