Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 301835

Area Forecast Discussion
National Weather Service Buffalo NY
235 PM EDT MON MAY 30 2016

High pressure centered from the western Great Lakes to the
Mississippi Valley early this afternoon...will move to New England
by Wednesday afternoon. Warm and humid conditions will return
Thursday ahead of the next cold front that will move through the
region by Thursday evening.


Isolated showers have formed along a lake breeze in Niagara and
Orleans counties.  The showers will dissipate by 21Z.

Very dry airmass from H8 to H4 per 12Z regional soundings over the
Great lakes and this airmass will remain in place through Tuesday.
Scattered cumulus clouds will dissipate this evening...and will
reform Tuesday afternoon along and inland from the lake breezes. Low
level moisture in the southern tier valleys will condense into fog


Tuesday evening a weak mid level trough and surface front will swing
east through Quebec, with the trailing weak surface boundary sagging
slowly south across the area. This system will be moisture starved
with nothing more than a few evening clouds across the North
Country, and a subtle wind shift for the remainder of the area. High
pressure will then build into Quebec overnight with clearing skies.
The clear skies and drier airmass will allow for good radiational
cooling with lows in the low to mid 50s in most areas, and upper 40s
in some of the cooler Southern Tier Valleys and Tug Hill region.

On Wednesday high pressure will build east across Quebec and
northern New England, with subsidence and drying extending down into
the lower Great Lakes and providing ample sunshine and low humidity.
High temperatures will reach the upper 70s in most areas, with
northeast flow keeping the south shore of Lake Ontario cooler.

Later Wednesday night and Thursday a mid level trough and surface
low will move into northwest Ontario province just north of Lake
Superior, while a surface cold front moves into the central Great
Lakes Wednesday night and crosses our region on Thursday. The latest
12Z model runs continue to speed up this system by a few hours over
previous runs, with showers possibly reaching far western NY as
early as late Wednesday night. A better chance of rain will arrive
Thursday as the cold front moves from west to east across the area.
The stronger large scale forcing will remain over the western Great
Lakes in closer proximity to the mid level trough, but there is
enough large scale ascent from a weak mid level shortwave and upper
level jet combined with low level convergence along the front to
justify increasing POPS into the likely range for Thursday and
Thursday evening. Instability will increase just ahead of the front
with SBCAPE reaching 1000J/kg, supporting a few scattered
thunderstorms as well.

Thursday night any showers and scattered thunderstorms will end from
west to east following the passage of the cold front as drier air
advects into the lower Great Lakes. Expect the last of the rain to
clear the eastern Lake Ontario region by daybreak Friday.

On Friday humidity will be on the way down again behind the front as
a drier airmass builds into the region. Skies will partially clear,
although diurnal cumulus will likely form along and inland from the
lake breeze boundaries yielding a mix of sun and clouds for the
afternoon. Highs will reach the mid to upper 70s in most areas.


There is high confidence that the first weekend of June will be much
more comfortable than the about to end Memorial Day a
notable pattern change will take place across the continent.

As we push through the first weekend of June...the near zonal flow
along the length of the Canadian border will then buckle as
anomalously strong ridging will blossom across the Inter-Mountain
West. The resulting downstream troughing over the Great Lakes Region
will allow cooler...more comfortable Canadian air to pour south.
With H85 temps averaging in the single digits C...daytime highs will
be in the 70s F...right where they should be for this point in the
warm season.

In terms of precipitation...high pressure situated over the Great
Lakes should supply our region with mainly dry weather.

A look further down the road...
Medium range ensembles strongly suggest that the longwave trough
will not only remain in place over eastern Canada and the Great
Lakes region through the first full week of June...but that a deep
upper level low will close off over Quebec. This would keep any
oppressive heat and humidity well south of our region...with
temperatures likely settling to below normal values. This scenario
is also supported by the 6 to 10 and 8 to 14 day temperature
forecasts from the Climate Prediction Center.


VFR through the 18Z Tuesday for most locations. There is a low
chance for IFR conditions at KJHW between 08Z and 11Z as patchy fog
may form. Surface winds at or below 15 knots.

Tuesday night and Wednesday...VFR.
Thursday and Friday...Mainly VFR with a chance of showers and


Mainly dry conditions expected through Wednesday under high
pressure. Winds will increase to around 15 knots which will produce
choppy wave action but still well below small craft advisory
criteria. A cold front passing through late Thursday may bring
thunderstorms with gusty winds and higher waves. High pressure will
build into the area late Friday and Saturday.





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