Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 241100
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
700 AM EDT Fri Mar 24 2017

.SYNOPSIS...
A warm front will bring a period of rain to Western New York with
some mixed wintry precipitation to a few spots this morning.
Temperatures will be much warmer this afternoon behind the front.
Then front will meander southward tonight and stall across the
region, with cooler temperatures north of the boundary and several
disturbances bringing periods of rain over the weekend and early
next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
A warm front will lift across the region today with associated
mid- level warm air advection leading to a period of widespread
rainfall. Radar shows an area of precipitation across Western
New York around daybreak, which will move from west to east
across the region this morning. The precipitation should last a
few hours in most areas, totaling about a quarter inch.

Temperatures are above freezing for areas west of the Genesee
River so will drop the winter weather advisory for these areas. A
winter weather advisory remains in place for eastern portions
of the cwa, mainly due to the potential for some freezing rain
at the onset. The coolest temperatures are across the Eastern
Lake Ontario region where thermal profiles support a wintry mix
this morning before temperatures warm and change this to all
rain. Here, some light icing up to a tenth of an inch is
possible. For other areas remaining in an advisory, any icing
should be very light with only trace amounts.

Temperatures will warm significantly this afternoon, with
temperatures expected to rise into the upper 50s to around 60 south
of Lake Ontario where the boundary should push through. It will
become windy northeast of Lake Erie with southwest winds
gusting to 35 mph. Winds aloft could support stronger gusts, but
these should not mix down well due to persistent cloud cover.
Outside of the cloud cover it should be mainly dry outside of a
few scattered showers. The boundary will stall across the North
Country with lingering rain and cooler temperatures this
afternoon.

Model consensus drops the boundary back southward tonight. By
12Z Saturday expect the boundary to extend roughly from Dunkirk
to Dansville. Also, forecast temperatures was `sharpened`
considerably to reflect the sharp thermal gradient which will be
along the frontal boundary.

Steady rain will spread back southward to the I-90 corridor from
Buffalo to Rochester this evening and remain there for most of the
night. Tonight will be cool and rainy along and north of the
front, with diminishing chances for rain and warmer temperatures
south. This pattern is also likely to result in fog along and
north of the boundary. Temperatures may cool enough for precipitation
to change back to snow or sleet across the North Country late
tonight.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
An unsettled pattern will continue this period as a frontal
boundary oscillates across the Lower Great Lakes.

Saturday morning a frontal boundary will be found across areas just
south of Lake Ontario, with a broad area of high pressure near James
Bay, and deepening surface low over the middle Mississippi Valley
strengthening the baroclinicity of the front. The arctic high
pressure supplying cold air to the north of this frontal boundary
should deepen the subfreezing layer upwards towards 700 hPa which
would support primarily snow, or sleet through the morning hours
across the Eastern Lake Ontario region. A northerly flow off Lake
Ontario will likely bring areas of low clouds and fog along the
southern shoreline, with activity expanding towards the thruway.
Through the day Saturday this frontal boundary will sag southward,
with lower level forcing also shifting southward. Aloft, the right
entrance region of a 120 knot jet over Quebec Canada will slide
eastward. This should bring a diminishment to the precipitation
through the day Saturday, with waning rain showers shifting
southward along the frontal boundary. Overall rain Saturday will
average between a quarter and a third of an inch.

Saturday night the frontal boundary will be pushed southward by the
James Bay arctic high pressure, with the boundary dipping towards
northern Pennsylvania. Rain may become scattered for a period of
time Saturday evening, before an increase in rain occurs as the
frontal boundary begins to lift northward as the surface low over
the western mid-west states nears our region.

This surface low will drift northward across Michigan Sunday night,
and carry a warm front across our region Sunday and Sunday evening.
Another period of rain will occur along the warm front, with again a
quarter to a third of an inch possible. Across the Eastern Lake
ONtario region the cold air will be shallower than the previous
morning, allowing for a heighten risk of freezing rain Sunday
morning.

There should be enough of a break between the Saturday rain, and
this next slug of rain to limit any widespread or river flooding
risk. Following this warm front there will continue to be chances
for rain showers, but activity will have more of a convective
element to it, with activity broken in nature through the remainder
of the period. There may even be a rumble of thunder late Sunday
across the western So. Tier, though the better instability will
remain just to the southwest across OH/PA.

Temperatures will widely vary across the region this period, with
afternoons and evening reaching the low to mid 50s south of the
boundary, with highs only in the upper 30s to lower 40s to the north
of the boundary. Saturday night will be the coldest of the two
nights, with many areas dropping down into the 30s. A few areas
across the North Country will  likely reach the upper 20s, while
closer to the frontal boundary across the So. Tier temperatures may
remain in the lower 40s overnight. Sunday night should feature a
mild night with lows primarily in the 40s, with a few upper 30s
across the North Country.

Regarding flooding concerns, while warming temperatures will
accelerate melting of remaining snowpack across the forecast area,
rainfall through the day Saturday will likely not be heavy and
produce quick rises on larger creeks and rivers. There will be
enough of a break in the steady rainfall 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 continues
to suggest that area streams may rise to action stage, but no
flooding is currently expected.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
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.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
Precipitation will move across Western NY this morning with
a warm front. Most of the precipitation will fall in the form
of rain with a brief period of mixed precipitation at ART. This
will also bring a mix of VFR/MVFR cigs this morning.

Expect most TAF sites to remain VFR this afternoon, with patchy
MVFR or lower clouds across higher terrain of the Southern Tier
and the Eastern Lake Ontario region. After this, the frontal
boundary will slowly drop southward late this afternoon and
evening. This will shift winds to the northeast, which will
result in IFR or lower conditions following the wind shift this
evening. This flow will typically produce low cigs and fog with
widespread IFR or lower conditions expected to develop south of
Lake Ontario tonight.

Low level wind shear will be widespread for much of the day as
the warm front stalls nearby and a low level jet crosses the
area.

Outlook...

Saturday...IFR or lower cigs in rain and drizzle.
Saturday night through Tuesday...MVFR/IFR cigs with rain likely
at times.

&&

.MARINE...
South to Southwest winds will increase today as a warm front lifts
into the eastern Great Lakes. Winds will approach small craft
criteria across eastern portions of Lake Erie and northeast Lake
Ontario but waves look to remain just below 4 feet. After this, the
boundary will shift slightly southward tonight and then stall across
the region over the weekend. This will result in 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.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory until noon EDT today for NYZ006>008.
     Winter Weather Advisory until 11 AM EDT this morning for
     NYZ004-005-014-021.
MARINE...None.

&&

$$

SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...THOMAS
LONG TERM...CHURCH
AVIATION...APFFEL
MARINE...APFFEL


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