Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 232053

Area Forecast Discussion
National Weather Service Buffalo NY
453 PM EDT Thu Mar 23 2017

High pressure ridged across the lower Great Lakes will continue fair
weather through late evening. A warm front will then bring a period
of rain to western New York with some mixed wintry precipitation
from the western Finger Lakes to the eastern Lake Ontario region
late tonight and Friday. Expect much warmer temperatures on Friday
behind the front. The front will stall across the region this
weekend, with several disturbances moving along the front and
bringing periods of rain over the weekend and into the first half of
next week.


High pressure will continue to drift east off the Mid Atlantic coast
through this evening, with a ridge extending northward into New
England and the eastern Great Lakes. Subsidence associated with the
ridge will continue to support mainly clear skies into this evening
with just a modest increase in thin cirrus clouds from west to east.

Surface ridging will keep us dry through much of tonight with mainly
increasing and lowering clouds. Temperatures will bottom out around
midnight in the low 30s across western New York with 20s across
central New York. After midnight, increasing southerly flow will
help temperatures begin a slow climb ahead of a warm front lifting
across the Ohio Valley. Models show an axis of 925-700mb moisture
being lifted ahead of the warm front and on the nose of a 40-50kt
jet. Precipitation will begin to overspread western NY between 09-12z
where surface temperatures will be very critical on p-type at the
ground. Using a warm layer tool which produces a p-type based on a
warm layer aloft and looking at surface temperatures, have included
some freezing rain across the extreme interior southern Tier into the
western Finger Lakes for a few hours before changing quickly over to
plain rain as surface temps rise above freezing. Have issued a
Winter Weather Advisory to cover the areas most likely to see a
trace to a tenth of an inch of ice. There may be some sleet too but
the more dominant p-type will be freezing rain. This idea matches
very well to ensemble guidance from the SSEO/NCAR/SREF. All other
areas of western NY appear to have surface temps above freezing when
the rain arrives including Jamestown to Buffalo to Rochester. Total
liquid QPF will run around a quarter of an inch.

As the warm front approaches then crosses western NY on Friday,
expect precipitation to begin to overspread the eastern Lake Ontario
region around Sunrise where temperature profiles support some Snow
changing to sleet and freezing rain before switching to plain rain
around Noon. Up to two inches of snow are possible here along with
up to a tenth of an inch of ice which also lead to a Winter Weather
Advisory. Total liquid QPF after the mixed precip here will also
run around a quarter of an inch.

As the warm front shifts across western NY, expect rain to
taper off to a chance of some more spotty showers by noon with a
possibility that much of the region south of the front may in
fact see drying with some breaks of sun through the afternoon.
Temperatures will warm nicely into the 50s across western NY
behind the front with 40s for Highs east of Lake Ontario where
the front may stall leaving rain in the forecast through the


By Friday night a sharp frontal boundary will be in place
across the Great Lakes from southern WI to northern New England
as broad southerly return flow around high pressure stationed
off the Eastern Seaboard and a large, vertically stacked low
over the southern Plains encounters an anticyclonic flow of cold
and dry air moving down from the north out of Canada. A broad
swath of precipitation will be in place along this front Friday
night thanks to aforementioned convergence and frontogenetic
forcing along and north of the boundary. Latest model consensus
places the axis of this precipitation primarily north of the
Thruway, with the bulk of the precip falling across Ontario and
the North Country. Precip type should remain all rain, as
virtually all of the forecast area should stay on the warm side
of the frontal boundary, with lows ranging from near 50 along
the PA border to the mid 30s in the St. Lawrence valley.

The frontal boundary will shift south across the forecast area on
Saturday as the high over Canada shifts position eastward across
James Bay. A low-level northeasterly flow of colder air will ooze
back into the forecast area from the northeast during the
day...depressing temperatures across the area, with highs barely
budging from overnight readings. Temps should only top out in the
mid 50s along the PA border, with low 40s across the Buffalo-
Rochester metros, and upper 30s in the St. Lawrence valley. Precip
should taper off in intensity/coverage as we move through Saturday,
as upper level forcing diminishes with the departure of an upper
level jet max over eastern Ontario/Quebec.

The arrival of shallow cooler air from the northeast will once again
present precip type issues Saturday night into Sunday morning, as
temperatures fall below freezing across the North Country, bringing
back a potential for freezing rain from the Tug Hill north to the
St. Lawrence River. Precip should stay as rain elsewhere though, as
temperatures should range from the mid 40s along the PA border to
the mid 30s along Lake Ontario. With upper level ridging amplifying
across the area, precipitation should taper off to showers
overnight, before precipitation ramps up again Sunday into Sunday
night, as the upper level low that will be drifting across the
Midwest during the first half of the weekend approaches the Great
Lakes. Strengthening southerly flow with the approach of this
feature and its attendant surface low will shove the cold front back
to the north, with highs running from the 50s in Western NY to the
low 40s in the North Country. Lows Sunday night will run in the 40s,
meaning that precip should once again fall entirely as rain.

Regarding flooding concerns, while warming temperatures will
accelerate melting of remaining snowpack across the forecast area,
the axis of heaviest rainfall Friday night should fall primarily
across Canada. There will be enough of a break in the steady
rainfall Saturday/Saturday night to allow for some recovery in
stream levels before the next round of rain arrives Sunday.  All
told, current MMEFS hydro ensemble guidance suggest that area
streams may rise to action stage, but no flooding is currently


A stalled frontal boundary will remain near or over the forecast
area through mid next week. Several rounds of showers are possible
through this period as various disturbances ride along the boundary.
Temperatures will remain variable, as the front ripples through the
region, with generally more mild to above normal temperatures for
locations south of Lake Ontario, while locations east of the Lake
and along the Saint Lawrence valley will likely remain cooler as
colder air on the north side of the front flows into the region from
a strong Canadian high pressure system. By Tuesday, global models
are in better agreement that a strong trough will track along the
boundary, sending warmer air northward all the way through the Saint
Lawrence valley and bringing an organized widespread rain event.

Finally by mid-week, mid-range models show some hope for a drier
stretch of weather a large scale ridge finally builds in across the
Great Lakes. However, this would also bring in some slightly below
normal temperatures.


High pressure ridged across the region will continue dry/fair
weather through late this evening with increasing high clouds this
evening yielding to a lowering mid level deck overnight.

A warm front will lift across the Ohio Valley tonight with rain
overspreading western then central NY. All TAF sites in WNY should
see plain rain beginning 09-11z but some interior airfields toward
the western Finger Lakes could see some light freezing rain at the
start before changing over to rain. This will also bring in MVFR

The front will lift across western NY through the morning on Friday
with KART seeing some SN/PL/FZRA with IFR VIS and MVFR cigs around
12z before changing over to plain rain by around 15z. There also
looks to be a risk for LLWS Friday morning across WNY as a 40-50
knot low level jet arrives. Some IFR cigs could arrive at KJHW/KART
Friday afternoon.


Friday night through Tuesday...MVFR/IFR cigs with rain likely at


High pressure ridged across the lower Great Lakes will maintain
light winds and negligible waves through late this evening.

South to Southwest winds will increase Friday as a warm front lifts
into the eastern Great Lakes. Winds will approach small craft
criteria across eastern portions of Lake Erie and Ontario but waves
look to remain below 4 feet. After this, a warm frontal boundary
will stall across the region, with a northeasterly flow likely on
Lake Ontario and variable winds on Lake Erie. This may require small
craft headlines on Lake Ontario at times this weekend.


NY...Winter Weather Advisory from 6 AM to noon EDT Friday for
     Winter Weather Advisory from 5 AM to 11 AM EDT Friday for



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