Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 221352
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
952 AM EDT SUN MAY 22 2016

.SYNOPSIS...
A persistent upper level storm system along the Pennsylvania
border will slowly settle south later today and tonight. Clouds
and leftover light showers will gradually give way to partial
clearing in the process. High pressure over the Upper Great Lakes
will then offer beautiful sun filled skies for Monday and Tuesday.
A period of summer warmth will arrive for the second half of the
week along with higher humidity and a few scattered showers and
thunderstorms.

&&

.NEAR TERM /THROUGH TONIGHT/...
A nearly stationary upper level storm system along the Pennsylvania
border will very slowly drift south this afternoon and evening. This
will allow for drier air to gradually move south which will
encourage improving conditions. The nicest weather today should be
found across parts of the North Country...specifically the Thousand
Islands Region...along with the Niagara Frontier where the most
abundant sunshine is anticipated. Inland across the Finger Lakes and
the Western Southern Tier...a weak northerly flow will retard the
clearing. There will also be some leftover light showers in these
areas.

In terms of temperatures...we can expect afternoon highs to range
from the lower 70s across the North Country and parts of the IAG
Frontier to the low 60s near the Pennsylvania border and 50s along
the immediate lake shores.

Any remaining diurnal showers across the higher terrain will taper
off by mid to late evening as the boundary layer stabilizes. The mid
level low will continue to move south across the Mid Atlantic
states...allowing deeper moisture to slowly pull away from our
region. This will allow for a slow clearing trend from north to
south overnight with the lake plains clearing first, and higher
terrain last. Expect lows in the lower 50s on the lake plains with
some mid 40s in the cooler Southern Tier Valleys and Tug Hill region.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Early next week will feature pleasant spring weather with fair
weather and above normal temperatures. A closed upper level low
across the Mid-Atlantic states on Monday will gradually lift into
the Gulf of Maine by Tuesday night which will promote a surface
ridge to the west of this which will build across our region. An
ensemble of model guidance is in good agreement on this pattern
which provides above average forecast confidence during the period.

The majority of model guidance keeps our area dry throughout the
entire short term period, however the 00Z GFS/12Z ECMWF forecast
some light and diurnally driven QPF across far Eastern portions.
Model guidance is often too high with afternoon dew points. With
BUFKIT soundings showing very small values of `thin` CAPE lower dew
points would effectively suppress any showers so will leave out any
mention at this time. Near lakes an afternoon lake breeze should
suppress most diurnal cloud cover resulting in sunny skies and
virtually no chance for any precipitation through Tuesday. A weak
vorticity ripple from upstream convection will cross the ridge late
Tuesday night with a slight chance for showers late.

Temperatures will be above normal during the period with daytime
highs mainly in the 70s on Monday and Tuesday. The exception will be
the immediate lakeshores which will only reach the 60s. A
Northwesterly gradient flow on Monday will help suppress the typical
Southwest lake breeze at Buffalo and Watertown. On Tuesday there
will be minimal gradient flow with typical afternoon lake breezes
expected. In general expect slightly greater diurnal temperature
ranges than consensus temperature guidance due to the dry regime.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
An upper level ridge will remain across the region resulting in a
summer-like pattern with a prolonged period of above normal
temperatures. As the upper ridge axis approaches the region during
midweek, so will the opportunity for late day and evening
convection. There will be an opportunity for late day through
evening thunderstorms on Wednesday and Wednesday night as a couple
ripples of vorticity move across the upper ridge, from southern
Ontario to the North Country and spreading into western NY during
Wednesday evening and night.

Subtle shortwaves will continue to encounter the ridge axis with
periodic chances for mainly diurnally driven showers and
thunderstorms. These shortwaves will be hard to time with POPs
reflecting a diurnal trend. Otherwise a consensus of 00Z runs of the
GFS/GGEM/ECMWF suggests the best chance for showers or thunderstorms
is Thursday even though they cannot be ruled out any day. These
would tend to develop along and inland of the lake breeze.

The ridge will strengthen with consensus 850 hPa temperatures
gradually warming from from +14C to +17C during the period. Highs on
Wednesday will range from the mid 70s to lower 80s. These will
gradually warm to the upper 70s to mid 80s by Saturday corresponding
to the warmest air aloft. A weak flow will result in typical
afternoon lake breeze development which will cool areas near the
lakeshores, including the cities of Buffalo and Watertown.

The weak southerly flow will also build the humidity through this
period with uncomfortable levels reached by the end of the week. Dew
points will climb into the lower 60s which will also provide a
rough proxy for overnight lows.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
A persistent upper level storm along the Pennsylvania border will
help to keep a fair amount of cloud cover over much of the region
today...but VFR cigs can be expected with light winds. These clouds
could produce a few light showers across parts of the Finger Lakes
and Southern Tier.

High pressure centered over the Upper Great Lakes will slowly press
east tonight and Monday. This will support continued fair VFR
weather with decreasing amounts of cloud cover.

Outlook...
Tuesday and Wednesday...VFR.
Thursday...Mainly VFR with a chance of showers and thunderstorms.

&&

.MARINE...
A weak cold front will cross the lower lakes this morning with winds
becoming northerly at around 10 knots behind the front today. High
pressure will then build into the central and eastern Great Lakes
Monday and Tuesday with light winds and flat wave action. Relatively
light winds will continue for the second half of the week, although
there will be a few scattered thunderstorms as summer warmth and
humidity build into the region.

&&

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

&&

$$

SYNOPSIS...RSH
NEAR TERM...RSH
SHORT TERM...APFFEL
LONG TERM...APFFEL/THOMAS
AVIATION...HITCHCOCK/RSH
MARINE...HITCHCOCK


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