Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 251859
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
259 PM EDT Sat Mar 25 2017

.SYNOPSIS...
A frontal boundary will remain draped across the region through
tonight, before slowly lifting back north across the region as a
warm front Sunday and Monday. Several disturbances sliding along
this boundary will bring frequent rounds of precipitation through
the end of the weekend and early next week, with cooler temperatures
prevailing north of the boundary and milder temperatures to its
south.

&&

.NEAR TERM /THROUGH SUNDAY/...
Surface analysis shows the frontal boundary has dipped south of
the state line this afternoon, with temperatures now into the
upper 30s across portions of the Southern Tier, even into far
northern Pennsylvania. High pressure off to our north and
associated dry air advection really diminishing the band of
precipiation now located from the Thruway into northern portions
of the Southern Tier.

Latest mesoscale guidance continuing to support the idea that the
band of precipiation will continue to erode into this evening,
while continuing to drift a little further to the south. There
may even a several hour period early tonight with dry conditions
areawide.

The high to our north is forecast to shift off to the east later
tonight, and this will allow the front to our south to lift
back northward, with modest mid-level warm air advection
increasing chances for some light precipitation late tonight.
This should mainly fall in the form of rain, but there is a risk
of freezing rain late tonight across the Eastern Lake Ontario
region. Confidence in measurable precipitation is low, but this
may require another round of headlines for this region if the
precipitation becomes widespread.

Temperatures will not cool much tonight, before rising late in the
night as the frontal boundary lifts back northward into the
region. The exception is the North Country where skies should
clear out, allowing for some radiational cooling and temperatures to
fall into the lower 20s.

Precipiation looks to briefly wane during the day Sunday within
the warm sector. Closed/occluded low in the plains expected to
finally open up and advance up into the western Ohio Valley/lower
Great Lakes during the day. This will bring a northward bulge
of warmer air back up into western New York while opening up
that feed of Gulf moisture into the Great Lakes, spreading
precipitation back up through the region during the mid to late
afternoon. Temperatures in the west will approach or potentially
exceed 60 degrees.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
A large low pressure system than has been meandering through the
central plains over the last couple of days will finally eject
northeastward across the Great Lakes region Sunday night and Monday,
as it rejoins the mean mid-latitude flow. In the process, increased
moisture advection will bring Gulf of Mexico sourced air into the
region with ample synoptic forcing as the cold front and vorticity
advection ahead of the upper level low approach the area Sunday
night into Monday morning. This will bring an area of widespread
showers across the forecast area, and will maintain categorical PoPs
for that time period. By Monday mid-day and afternoon, height rises
behind the trough passage and drier low-level air will end the
widespread rain showers in favor of just some widely scattered
showers and lingering cloudiness. With respect to temperatures,
Sunday night will remain mild with downslope flow and warm advection
ahead of the wave, with lows ranging from the low 40s in the North
Country to around 50 in western NY. By Monday, the airmass in the
wake of this largely cut-off low pressure system will not be much of
a contrast to the day prior, as better mixing and 850 mb temps to
around +5C will result in highs in the upper 40s in the North
Country to the low 60s in the Genesee Valley and northern Finger
Lakes.

Monday afternoon through much of Monday will remain dry in the wake
of the initial trough passage, but then by Tuesday morning a
trailing open wave will cross the region. Global models remain
conflicted in the exact track of the wave and where the best forcing
will coalesce. Overall there has been a bit of a southward trend,
which increased the northeasterly flow and push of cooler air into
the region for Tuesday. Thus have lower temperatures some for
Tuesday with highs in the 40s to low 50s. Showers will accompany
this wave, but their coverage across the region will be guided by
the track of the wave, with a more southerly track favoring a drier
forecast.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
The lengthy unsettled period will last into Tuesday as the stalled
complex frontal zone remains nearby. Both the GFS and ECMWF based
guidance suggest one more wave moving along the frontal zone and
passing to our north on Tuesday, producing another round of showers.
Temperatures will remain mild given the northerly low track, with
highs at least into the 50s and possibly into the 60s for the
southern half of the area.

Tuesday night and Wednesday a mid level trough will amplify across
Quebec and finally drive the frontal zone well south of our area,
with moisture and showers diminishing from northwest to southeast.
Cold advection associated with the trough will knock temperatures
back a few notches, with highs in the 40s Tuesday.

A slow warming trend should then ensue for the second half of next
week as the trough over Quebec moves offshore of the Canadian
Maritimes and height rises/weak warm advection overspread the
eastern Great Lakes. Model guidance diverges by next Friday with
respect to the track of the next system. The GFS keeps most of the
energy and deeper moisture suppressed well to the south across the
Ohio Valley and southeast States, while the ECMWF takes a much more
northerly track through the Great Lakes and would be a warmer and
wetter solution. Given the time range and inherent uncertainty, have
just included chance POPS for now.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
Frontal boundary has shifted just south of the state this afternoon.
A northeasterly flow north of this boundary will advect cooler air
which will mix with the moist air in place resulting in low cigs.
This pattern is climatologically favorable for IFR or lower cigs at
BUF/IAG/ROC/ART and conditions. Expect IFR/LIFR conditions to last
through mid afternoon before improving a bit. There will also be
periods of precipitation and patchy fog.

Drier air will first build into ART as the boundary pushes further
south, with conditions improving later this afternoon and evening.
Elsewhere, expect a prolonged period of mainly IFR conditions as the
northeasterly flow persists.

Later tonight, expect IFR/MVFR conditions will continue south of
Lake Ontario, with VFR conditions at ART.

Outlook...
Sunday through Tuesday...MVFR/IFR cigs with rain likely at times.
Wednesday and Thursday...VFR.

&&

.MARINE...
A frontal boundary will push further south of Lake Ontario this
afternoon, briefly pushing south of eastern portions of Lake Erie.
A northeasterly flow will develop on the cool side of the front
requiring small craft headlines along the south shores of Lake
Ontario through Sunday evening. Winds and waves will also
briefly build on Lake Erie southwest of Dunkirk. Conditions will
be marginal, but expect there will be a shorter period which
meets small craft criteria into tonight.

After this, expect a benign pattern for the first half of next week
resulting in modest winds with any headlines unlikely.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 2 AM EDT Sunday for LEZ040.
         Small Craft Advisory until 11 PM EDT Sunday for
         LOZ042-043.

&&

$$

SYNOPSIS...TMA
NEAR TERM...TMA
SHORT TERM...CHURCH
LONG TERM...HITCHCOCK
AVIATION...TMA
MARINE...TMA


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