Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 230615

Area Forecast Discussion
National Weather Service Buffalo NY
215 AM EDT SAT JUL 23 2016

Hot and humid conditions will last through the weekend as high
pressure moves across the Lower Great Lakes. Outside of some showers
and thunderstorms across the North Country and Saint Lawrence
Valley today...conditions will be largely rain free. A cool front
will then bring at least a chance of showers and thunderstorms
Monday as it crosses our region...then dry weather and above-
average temperatures return to the area for much of next week.


The remainder of the night will be mainly dry outside of a few
thunderstorms across the Western Southern Tier which should exit
into Pennsylvania in the next hour or so. Overnight temperatures
are on the warm side, with many areas still well into the 70s.
Temperatures will only fall modestly with 5 to 10 mph winds
limiting radiational cooling.

A weak frontal boundary will drop across the region today and
while this will not bring much cooler temperatures it will bring
much drier air. Dew points south of the front are in the upper 60s
to lower 70s, but as this front drops southward across the region
dew points will drop into the upper 50s to lower 60s. High
temperatures today will still be well above normal with most areas
topping out in the mid to upper 80s with some lower 90s across
low-lying areas in the Genesee Valley and Finger Lakes regions.
Even so, it will feel a bit more comfortable than yesterday due to
the lower humidity.

The frontal passage will largely be a dry one, with maybe a few
clouds with otherwise mostly sunny conditions. The one notable
exception is the St. Lawrence Valley and North Country which will
be closest an upper level trough axis which extends into New
England. Model guidance has consistently dropped a vort max across
this region this afternoon which is likely to spark some showers
and thunderstorms. The steadiest of this will probably be to the
north and east, but there is a good chance storms will clip Lewis
and far northern Jefferson counties. Suspect that the lake breeze
will keep Watertown dry despite some model QPF guidance to the
contrary. The dynamic lift from the vort max combined with
favorable diurnal timing may result in a few strong to severe
thunderstorms. SPC has this area in a marginal risk.


The bulk of the short term period will be characterized by continued
heat and humidity into early next week. Spotty shower and
thunderstorm chances increase late Sunday night into Monday before a
subtly less hot and humid airmass returns for Tuesday.

An amplified ridge axis will build across the region Sunday with a
sharp increase in 850 mb temperatures to around +20 to even +22 over
the Southern Tier by the afternoon. This will result in widespread
max temperatures about 90 across western NY and the Genesee Valley.
Low to mid 80s will remain across the North Country where the warmer
airmass is slower to arrive. Humidity will increase again,
especially toward Sunday evening as deep southwesterly flow becomes
established ahead of the next wave tracking through Ontario. Despite
the increasing heat and humidity, Sunday will remain a dry day with
rising heights aloft and large scale subsidence in place under
surface high crossing the region. This will also allow for light,
lake-breeze dominated winds.

Sunday night into Monday, the aforementioned trough will track from
Ontario toward Quebec near the Hudson Bay with a trailing cool front
that will cross the region on Monday. A very warm night is in store
Sunday night ahead of this front as dew points climb to near 70 by
Monday morning, and low temperatures in the low to mid 70s, again
not a comfortable sleeping night. Shower and thunderstorm chances
will increase across the region early Monday morning, with the focus
likely shifting toward our east by Monday afternoon. Despite the
potential for a few stronger storms featuring locally heavy rain and
gusty winds, expect these will again be widely scattered, with may
locations seeing little if any precipitation. Again weakly forced
frontal passage should be rather lackluster and will offer little if
any drought relief.

High pressure builds in on Tuesday with northwesterly winds in place
across the region. This will bring a slightly cooler and drier
airmass into the region as dew points fall into the lower 60s and
850 mb temperatures around +16C promote high temperature in the low
to mid 80s.


Surface high pressure will build slowly east across the Great Lakes
region Tuesday night and Wednesday with another period of dry
weather. Despite the weak cold frontal passage on Monday, There will
be little change in airmass with just slightly less humidity, but
still above normal temperatures. Expect highs on Wednesday to reach
into the mid to upper 80s in most areas, with a few 90 degree
readings possible in the normally warmer spots of the Genesee

Thursday and Thursday night a trough will move east across Ontario
and Quebec. The stronger forcing will remain well north of the
Canadian border, with a trailing weak surface cold front moving east
across the Great Lakes. The frontal passage will provide at least
some chance for scattered showers and thunderstorms, with spotty

The latest 12Z ECMWF and GFS guidance clears the front east of the
area later Thursday night, with weak high pressure allowing dry
weather to return by next Friday. Temperatures will be knocked back
a notch to a little closer to average behind the front by Friday.


High pressure building southeastward from the Upper Great Lakes
will largely provide our region with fair/dry VFR weather through
the TAF period, though there will be a couple of exceptions.

There is a small chance fog will develop tonight, with some
guidance hinting at this. Since winds should not go calm overnight and
the lack of rainfall will only carry a tempo for JHW with VFR
conditions elsewhere.

Showers and thunderstorms will develop this afternoon and may pass
near ART, but probably will stay just east of the terminal

For tonight, high pressure will expand across the area with VFR
conditions outside of a small chance for Southern Tier valley

Sunday night and Monday... Mainly VFR with a chance of showers
and thunderstorms and associated brief MVFR/IFR.
Tuesday and Wednesday...VFR.


Overnight...expect quiet conditions with any convection across the
Saint Lawrence Valley rapidly dying out...and winds and waves
continuing to diminish.

Some scattered showers and thunderstorms will be possible across
the Saint Lawrence Valley this afternoon.

While lake breezes should once again bring a light to moderate chop
to nearshore waters this afternoon...high pressure moving
overhead should keep associated winds lighter...negating the need
for any SCAs or beach hazard statements. In fact...generally quiet
conditions should persist across Lakes Erie and Ontario Saturday
and Sunday... before a weak cold front crosses the region on
Monday and brings the next chance for showers and thunderstorms.





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