Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 250558
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
158 AM EDT WED MAY 25 2016

.SYNOPSIS...
Summertime weather is on its way with highs climbing through the 70s
and into the 80s by this weekend.  Along with the warmer
temperatures, an increase in humidity will also bring back
increasing chances of showers and thunderstorms each day leading up
to and into the Memorial Day weekend.

&&

.NEAR TERM /THROUGH TODAY/...
A narrow ridge of high pressure will build east across our region
through tonight. This will continue to bring fair weather as the mid-
level ridge tracks east across the forecast area. Expect increasing
high clouds from northwest to southeast as there will be an increase
in upper level moisture ahead of a weak shortwave and surface front
tracking into the central Great Lakes. Low temperatures will be a
little cooler tonight as winds decouple and become nearly calm and
surface dewpoints fall to the mid 30s to mid 40s. Overnight lows now
expected to dip into the upper 40s in the cooler spots of the
Southern Tier and North Country with temperatures warmest along the
Lake Erie shoreline, where southerly flow will promote downsloping
and keeping lows in the upper 50s.

On Wednesday the mid-level ridge will be temporarily flattened as
the subtle shortwave trough moves across the eastern Great Lakes.
This will be mirrored by a surface trough/windshift which would be
the focus for a chance of thunderstorm development Wednesday mainly
toward the afternoon hours. General subsidence across Western NY
should inhibit most, if not all, convection south of Lake Ontario
this afternoon, but there could still be widely scattered convection
across the Saint Lawrence Valley closer to the upper trough and
farther from the subsidence across WNY.

Temperature-wise expect again to climb into the U70s/L80s with a
gusty west to southwest flow boosting highs potentially into the mid-
80s in the warmer valley locations. A Lake Erie lake breeze will
keep locations along the shoreline including downtown Buffalo about
10-15 degrees cooler.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
Any lingering showers east of Lake Ontario will end Wednesday
evening. This will leave a mainly dry night as a ridge of high
pressure builds from New England to the Mid Atlantic.
Temperatures will remain quite mild with lows in the lower 60s on
the lake plains of western NY, and mid to upper 50s in the cooler
Southern Tier valleys and North Country.

Thursday will bring the best chance for more widespread showers and
thunderstorms as more coherent forcing crosses the region. Model
consensus continues to track a mid level trough across the region
but some 12Z runs are a bit weaker than previous runs. Even though
this may limit areal coverage somewhat, increasing boundary layer
moisture will result in surface based instability to support some
showers and thunderstorms.  These may produce locally heavy
downpours, but otherwise a lack of deep layer shear will limit
thunderstorm intensity.

Showers and scattered thunderstorms will slowly diminish in coverage
Thursday night with the loss of diurnal instability and as better
forcing and warm advection exit to the east. However the environment
will be very moist with ample elevated instability that it would
only take a weak upper level disturbance to spark a thunderstorm.

On Friday there is little indication from model guidance that there
will be any significant upper level waves, however surface based
instability is likely to result in some showers and thunderstorms.
These are most likely form along or just inland of lake breeze
boundaries. More organized activity should taper off Friday night,
but similar to Thursday night it is difficult to rule out a stray
shower or thunderstorm.

Temperatures will be above normal throughout the period with highs
mainly in the lower to mid 80s on Thursday, and the mid to upper 80s
on Friday. It will be a bit cooler along the immediate lakeshores
due to the lake breeze. Also, dew points will rise to near 70 on
Friday, resulting in quite muggy conditions considering for May.
Overnight lows will also be on the warm side, with lows in the 60s
on Thursday and Friday nights.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
The first extended period of summer`s warmth will be upon us this
time period as a ridge of high pressure sets up over the eastern
United States. Southerly flow around this area of high pressure will
bring warmth and moisture of which both will bring unstable
conditions such that mainly afternoon showers and thunderstorm will
be possible each day. Greatest chances for showers and thunderstorms
will come along lake breeze boundaries...to the east and south of
the Great Lakes...and also over the higher terrain east of both
lakes. Lowest chances will be over the cooler lake waters...and
northeast of the lakes as the southwest flow spreads this
stabilizing cooler air inland.

The upper level ridge will peak in the Saturday/Sunday time
period...which will be the same time that 850 hPa temperatures also
peak. These two days will likely be the warmest of the period...and
afternoon temperature readings could near daily record highs. A
listing of record highs will be found in the climate section below.
It is possible that a few 90F degree readings will be measured
either weekend day in the Genesee Valley.

Monday and Tuesday will remain warm...though likely a few degrees
cooler than the weekend as the upper level ridge breaks down.
Overnight lows will be similar each of the four night, generally in
the low to mid 60s.

The first wave of moisture will pass us Saturday and Sunday...this
moisture of Gulf of Mexico origin. After this passes...a second wave
of moisture...this stemming from possible tropical development off
the Southeast States...will be Atlantic based with the moisture
nearing us from the southeast.

This moisture will also contribute to building dewpoints/humidity
levels. As dewpoints rise into the mid to even upper 60s, the
comfort level to the airmass will quickly diminish. Sticky days
and muggy nights will accompany the first period of summer
warmth.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
Widespread VFR conditions will continue to prevail tonight as a
narrow ridge of high pressure moves overhead. An upper trough will
pass north of the forecast area and a weak surface trough will cross
the area, but dry air and general subsidence across Western NY
should preclude the development of showers or thunderstorms this
afternoon. There may be widely scattered convection this afternoon
across the Saint Lawrence Valley, closer to the upper trough and
farther from the center of subsidence over WNY.

Outlook...
Wednesday night...VFR with a slight chance of showers.
Thursday through Sunday...Mainly VFR with a chance of showers and
thunderstorms.

&&

.MARINE...
A ridge of high pressure will build across the lakes tonight
continuing fair weather with breezy westerly winds. Winds and waves
will remain fairly negligible through the next few days. The
tranquil pattern will continue through the end of the week, although
a few thunderstorms may produce locally higher winds and waves at
times each day from Wednesday through next weekend.

&&

.CLIMATE...
The first extended period of summer`s warmth will be upon us this
weekend. Temperatures will climb well into the 80s, of which some
of these daily readings may near record levels. Listed below are
the records for our three climate stations.

BUFFALO...

Friday.....May 27th...Record High Maximum...89F...1978
......................Record High Minimum...69F...1991

Saturday...May 28th...Record High Maximum...86F...2012
......................Record High Minimum...69F...1911

Sunday.....May 29th...Record High Maximum...87F...1987
......................Record High Minimum...68F...1987


ROCHESTER...

Friday.....May 27th...Record High Maximum...92F...1978
......................Record High Minimum...70F...1918

Saturday...May 28th...Record High Maximum...93F...1911
......................Record High Minimum...68F...1939

Sunday.....May 29th...Record High Maximum...92F...2006
......................Record High Minimum...69F...1908


WATERTOWN...

Friday.....May 27th...Record High Maximum...87F...1960
......................Record High Minimum...67F...1991

Saturday...May 28th...Record High Maximum...85F...2012
......................Record High Minimum...64F...1987

Sunday.....May 29th...Record High Maximum...87F...2012
......................Record High Minimum...63F...2006


A climatic day is between 1 AM EDT to 1 AM EDT.

Temperature records for Buffalo and Rochester date back to 1871,
while records for Watertown start in 1949.

&&

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

&&

$$

SYNOPSIS...SMITH/WOOD
NEAR TERM...WCH/WOOD
SHORT TERM...APFFEL
LONG TERM...THOMAS
AVIATION...WCH
MARINE...SMITH
CLIMATE...THOMAS



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