Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 271339
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
939 AM EDT SAT AUG 27 2016

.SYNOPSIS...
Expansive high pressure over the Great Lakes will drift east to New
England today. A weak cold front will then produce a few showers and
thunderstorms on Sunday, before high pressure returns for early next
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
It will be absolutely gorgeous across all of Western and North
Central New York today...as high pressure over Quebec will serve up
sun filled skies and comfortable humidity levels. It will be warmer
than Friday though...as this mornings KBUF sounding depicted an
airmass featuring H85 temps arnd 17c. Fully mixed...this will easily
support afternoon temps in the mid to upper 80s inland from the
lakes.

A shortwave over the Lower Ohio Valley this morning was already
generating some showers and thunderstorm...and as we push through
tonight...this feature will ride up and over the persistent H5
ridge to cross the Lower Great Lakes. This will offer the chance
for some showers and thunderstorms for the bulk of our region
after midnight. This opportunity for rainfall will be accompanied
by thickening mid and high level moisture...while the return flow
around the Canadian surface high will advect warmer and notably
more humid air into the region. The combination of these two
factors will hold temperatures roughly 10 deg higher than those of
this morning...as mins will generally range from 65 to 70. It will
be a bit cooler east of Lake Ontario.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Sunday will turn more unsettled as a shortwave trough moves into the
Great Lakes. This will slowly force a weak frontal boundary across
the forecast area on Sunday with a warm, humid and unstable airmass
in place. Frontal forcing and moisture advection don`t look very
impressive at the moment, and thus expect fairly scattered
convective coverage across the region that perhaps becomes slightly
more focused ahead of the frontal passage Sunday evening.
Sunday will be another fairly warm and sticky summer day, with
highs in the mid to upper 80s and dew points returning to the mid
to upper 60s. This will produce CAPE values around 1000 to 1500
J/k inland from the lake breeze boundaries, combined with deep
layer shear increasing to around 30 knots and storm motions of 25
to 30 knots could produce a few stronger storms with some gusty
winds.

By Monday, a shortwave trough will track overhead and into New
England by the afternoon. Morning cloud cover will dissipate from
northwest to southeast as drier air and subsidence move into the
region through the afternoon. Temperatures will take a step back on
Monday, as 850 mb temperatures fall to +12 to +14C, thus highs will
be in the upper 70s to low 80s. Drier air will mix down in the
afternoon, allowing dew points to fall in the comfortable 50s. High
pressure will build across the region Monday night and Tuesday
leaving dry conditions and mostly clear skies. Monday night will
feature optimal radiational cooling with a dry airmass, and light
winds allowing temperatures to fall into the 50s for most locations,
except near the lake shores and urban locations. Tuesday will see a
warming trend as high pressure slights to slide east and the airmass
modifies with 850 mb temps to +17C, resulting in high temperatures
back into the mid 80s.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
The longwave pattern will change, at least temporarily, during the
second half of next week and potentially allow for a brief push of
cooler air to enter the Great Lakes and New England. The North
Pacific wave train will amplify early next week, with a trough
moving into the Pacific Northwest. This will in turn force
downstream amplification across North America, with a ridge
centering on the high plains and a fairly deep downstream trough
developing across Quebec, forcing at least a temporary departure of
the strong, hot ridge dominating the east.

Looking at the details, a cold front associated with the deepening
Quebec trough will push southeast across the area Tuesday night and
early Wednesday. This frontal boundary will not have much moisture
to work with, as the Gulf of Mexico moisture will be largely cut off
from reaching this far north. The best large scale ascent will
remain north of the Canadian border in closer proximity to the
deepening trough. Given the relatively poor moisture and dynamics,
expect the cold front to only produce isolated to widely scattered
showers and thunderstorms.

High pressure will then build back into the Great Lakes Thursday and
Friday, bringing a return to mainly dry weather. Temperatures will
be notably cooler, with highs only in the lower to mid 70s by late
in the week with lows in the 50s.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
High pressure over Quebec will provide the region with fine flying
weather today...as VFR conditions will be accompanied by light winds.

VFR weather will continue through at least the first half of
tonight. As we push deeper into the overnight though...a mid level
disturbance will pass by to our north and present the risk for some
thunderstorms. Outside of any convection...cigs and vsbys should
remain at VFR levels.

Outlook...
Sunday...VFR/MVFR with scattered to numerous showers and
thunderstorms.
Sunday night and Monday...Mainly VFR with a chance of showers and
thunderstorms.
Tuesday...VFR.
Wednesday...VFR with a chance of showers and thunderstorms.

&&

.MARINE...
High pressure centered over Quebec this morning will drift east
across the Lower St Lawrence Valley this afternoon. This will keep a
weak sfc pressure gradient over the Lower Great Lakes...and while
winds may be too light for preferred sailing conditions...it will be
nearly ideal for other recreational boating.

Conditions will deteriorate somewhat tonight as a mid level
disturbance will push across the region. While light winds and
negligible waves will persist...there will be the risk for some
thunderstorms after midnight.

This risk will increase on Sunday as a cold front will slowly push
across the Lower Great Lakes.

Fine weather for boating will return on Monday as the next Canadian
sfc high will build across the region.

&&

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

&&

$$

SYNOPSIS...TMA
NEAR TERM...RSH
SHORT TERM...CHURCH/WCH
LONG TERM...HITCHCOCK
AVIATION...RSH
MARINE...RSH



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