Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 230803
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
403 AM EDT Sun Apr 23 2017

.SYNOPSIS...
High pressure stretched across the forecast area will produce a fine
Spring day to end the weekend...as temperatures will climb into the
60s away from the lakes. While a weak cool front will settle south
and wash out across our area tonight...the fair weather will
continue into the start of the new work week. Canadian high pressure
will nose southeast across the Lower Great Lakes...and this will
produce another sun filled day on Monday. Some unsettled weather
will return later Monday night and Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
It will be a fine day across the region today...as high pressure
stretching across the Lower Great Lakes will combine with a dry
airmass to guarantee sun filled skies. It will also be warmer...as
H85 temperatures in the vcnty of 6 C this afternoon will support max
temps in the 60s away from the cool lakes. The weak surface pressure
gradient and strengthening mid spring insolation will lend to the
development of some localized lake breezes...and this will keep the
mercury from climbing out of the mid 50s along a large percentage of
the lake shore areas.

Tonight...a stronger...more expansive area of high pressure over
northern Manitoba will nose southeast and push a weak cool front
into our forecast area. The front will essentially wash out over our
region during the overnight...while the bulk of the limited moisture
associated with the front will remain to the north of Lake Ontario.
This will allow for another fair uneventful night of weather...with
nothing more than some cirrus over the western counties and some
alto-cu for areas north of the Tug Hill. Temperatures tonight will
drop to within a couple degrees of 40 for most of the region...with
mins in the mid 30s across most of the Southern Tier and North
Country.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
On Monday our region will be firmly under the influence of strong
Canadian high pressure drifting from northern Ontario Province to
western Quebec. This will result in another fine late April day...with
mostly sunny skies and 850 mb temps of +3C to +7C again supportive of
highs ranging through the 60s across the bulk of the area. The above
stated...a prevailing northeasterly low level flow will keep areas
along and a bit inland from the south shores of both lakes noticeably
cooler...with readings along the immediate south shore of Lake Ontario
likely struggling to top 50 degrees. Meanwhile the warmest temps will
be found across the interior valleys of the Southern Tier and Finger
Lakes...where highs should again be in the mid to upper 60s.

Monday night and Tuesday a cutoff low and its associated surface
reflection will meander its way northeastward along the southeastern
U.S. coastline. An influx of Atlantic moisture around the northern
flank of this system will bring increasing clouds back into our
region...as well as the potential for some showers later Monday night
and Tuesday. Over the past 24 hours the model guidance suite has
continued to trend toward a slightly further west and wetter solution
for our region...with enough confidence in measurable rainfall now in
place to justify bumping PoPs up into the likely range along our
southeastern periphery and further up into the chance range elsewhere...
with the best overall shower potential still looking to come during the
first half of Tuesday. As this system lifts further northeast and off
the Atlantic coastline Tuesday night...its associated moisture field
and attendant synoptic forcing should then recede off to our east...
resulting in a return to mainly dry and quiet weather areawide by later
Tuesday night. Meanwhile our temperatures will remain at pleasantly
above average levels...with lows in the lower to mid 40s Monday night
followed by highs ranging between the upper 50s and 60s on Tuesday...
with lows then dipping into the upper 40s to lower 50s Tuesday night.

On Wednesday a sharpening upper level ridge will be found across our
region...in between the weakening cutoff low lifting just offshore of
the New England coastline...and the next mid and upper level trough
developing into the Great Lakes and Upper Midwest. The combination of
strong subsidence under this ridge...increasing amounts of sunshine...
and warm advection attendant to a southeasterly downslope flow will
help drive 850 mb temps up to between +9C and +12C across our region...
which should in turn allow for a pretty nice day with highs warming
into the 70s areawide...with the warmest overall readings (mid-upper
70s) found south of Lake Ontario.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
Wednesday night and Thursday the medium range guidance remains
in reasonable agreement that the next modest surface low will
lift from the Great Lakes into northwestern Quebec...while
eventually pivoting its trailing modest cold front across our
region. This said...the timing of this front also continues to
trend markedly slower...with a guidance consensus now holding
this boundary off until mid-late Thursday afternoon and Thursday
evening. Consequently...it is appearing more and more likely
that our region will remain mainly dry through at least the
first half of Thursday...while also experiencing temperatures
more typical of early summer than mid spring. With respect to
the latter... continued warm air advection and a more southerly
downslope flow should result in lows failing to drop below the
mid 50s to lower 60s Wednesday night...with continued
warming/downsloping then allowing daytime highs to climb to at
least the 75-80 degree range areawide Thursday...with widespread
highs in the 80s more likely if current consensus 850 mb temps
of around +15C actually verify.

As the cold front passes through our region later Thursday and
Thursday night...it should be accompanied by at least some
scattered showers and thunderstorms...for which high chance PoPs
remain in play from our existing continuity. Following its
passage...high pressure and cooler/drier air should then build
across our region later Thursday night and Friday and provide
return to mainly dry and cooler weather... though temperatures
will still remain well above normal with daytime highs still
expected to range through the 60s on Friday.

Moving on into the last third of this period...the medium range
guidance packages also continue to trend progressively slower
with the arrival of the next system late in the week/next
weekend. As a result...the next warm frontal boundary now does
not look to arrive until Saturday at the earliest...which should
result in our region remaining on the cooler side of the
boundary through the end of the week...and the next round of
shower/thunderstorm chances largely holding off until Saturday
afternoon and night.

Looking out just beyond the end of this period...it still
appears that another round of summerlike warmth (with highs
potentially reaching into the 80s again) will be possible
following the passage of the aforementioned warm front...with
this potentially occurring sometime between Sunday and Monday of
the following week.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
VFR conditions will be found across the vast majority of western and
north central New York through daybreak...with the possible exception
being east of lake Ontario where some patchy fog could result in
MVFR vsbys for sites such as KART and KGTB.

The nearly cloud free skies and light winds will remain in place
across the region though the upcoming day...as high pressure will
remain in control of our region. This fair weather will continue
through tonight as well.

Outlook...

Monday...VFR.
Tuesday and Wednesday...Mainly VFR with a chance of showers.
Thursday...VFR/MVFR with a chance of showers and thunderstorms.

&&

.MARINE...
High pressure stretching across the Lower Great Lakes today and
early tonight will keep light winds and negligible waves in place to
end the weekend.

In the wake of a weak cool front...a stronger more expansive area of
high pressure over northern Manitoba will nose across Lake Ontario
on Monday. This will establish freshening northeast winds that...at
the very least...will generate choppy conditions on Lake Ontario
west of Irondequoit Bay. Waves could very well build to between 4
and 5 feet for these areas...which would support small craft
advisories. Otherwise...fair weather will continue.

As the surface high moves across Quebec and an inverted trough
becomes established over the Upper Mississippi Valley Monday night
and Tuesday...winds across the Lower Great Lakes will veer to the
southeast. This will encourage waves to subside within the New York
nearshore waters while the higher waves will be pushed into Canadian
waters.

&&

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

&&

$$

SYNOPSIS...RSH
NEAR TERM...RSH
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...RSH
MARINE...RSH



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