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Area Forecast Discussion (AFD)

Issued by Buffalo, NY (BUF)

                            
001 
FXUS61 KBUF 260758
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
358 AM EDT Sat May 26 2018

.SYNOPSIS...
Persistent southwesterly flow will continue to bring very warm 
weather through the Memorial Day holiday. There will be a few widely 
scattered showers and thunderstorms each day, mainly across the 
North Country and areas well inland from the lakes. Even in these 
areas, the vast majority of the time will be rain free.

&&

.NEAR TERM /THROUGH TONIGHT/...
IR satellite imagery shows most of the thicker clouds confined to 
the North Country early this morning, with thin high clouds for the 
rest of the area. A few widely scattered showers will continue in 
the Saint Lawrence Valley through early this morning.

High pressure will remain anchored off the coast of the southeast 
states today and tonight, with persistent southwesterly flow across 
the Ohio Valley and eastern Great Lakes. A shrinking bubble of drier 
air will persist over our region today, keeping most areas dry. The 
presence of this dry air, combined with warm mid level temperatures 
will keep instability anemic for the bulk of the area, with SBCAPE 
only around 500J/kg despite the very warm surface temperatures. An 
isolated shower cannot be ruled out late this afternoon across the 
higher terrain of the western Southern Tier near the PA state line, 
but otherwise the bulk of Western NY and areas southeast of Lake 
Ontario will be rain free. Mid/high clouds will increase across the 
area today, yielding partly sunny skies. 

The one exception to the dry weather will be across the North 
Country. A stalled frontal zone will remain draped from the Ottawa 
Valley to northern NY and act as a conduit for several mid level 
waves to move along. Instability will also be greater in this area 
with better boundary layer moisture and cooler temperatures aloft. 
These waves will produce a few periods of scattered showers today 
and tonight, with the better coverage of showers and scattered 
thunderstorms expected this afternoon and evening with increased 
diurnal instability. Southwest flow off Lake Ontario will maintain a 
stable lake shadow for most of the eastern Lake Ontario region, with 
shower chances mainly relegated to the Thousand Islands region and 
western foothills of the Adirondacks on the fringe of the stable 
lake shadow.

Most of the showers and scattered thunderstorms across the North 
Country will end later this evening with the loss of diurnal 
instability, although a few more widely scattered showers cannot be 
ruled out overnight. A few scattered showers may also develop 
overnight across the western Southern Tier, and eventually the 
western Finger Lakes toward Sunday morning as a weak mid level wave 
and deeper moisture cross PA and the Southern Tier of NY.

Temperatures will continue to be very summer-like, with highs in the 
mid 80s today at lower elevations in Western NY, and upper 70s for 
the North Country. A southwest breeze will keep the Buffalo and 
Watertown areas cooler. Lows tonight will be in the lower 60s for 
most, with some upper 50s in the cooler Southern Tier valleys and 
Lewis County.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Summery warmth and humidity will continue through the second half 
of the holiday weekend, with scattered afternoon shower and 
thunderstorm chances inland from the lakes.

A diffuse shortwave will cross NYS on Sunday, which will help 
trigger some widely scattered showers and thunderstorms developing 
along a convergent boundary near the Genesee Valley and along the 
Lake Erie lake breeze boundary over the western Southern Tier. Dew 
points will continue to rise to into the mid 60s, helping to fuel 
some instability for convective initiation as well as making for a 
more uncomfortablely humid feel to the air. Temperatures will be in 
the mid 80s inland from the lake breezes, with cooler readings in 
the 70s along the lake shores. Light northeast winds south of Lake 
Ontario near the convergent boundary will actually help Buffalo one 
of the warmer spots, with the south shore of Lake Ontario and 
Rochester area slightly cooler. 

Any showers and thunderstorms will move into Central NY by Sunday 
evening, however activity that forms across the Ontario peninsula 
Sunday will venture eastward across Lake Erie and Lake Ontario. 
Expect this will largely be diminishing by the time it reaches the 
forecast area, and have decreased overnight PoPs into the slight 
chance range. Temperatures will stay mild overnight with 
temperatures in the mid 60s. 

Memorial Day will be warm with the potential for temperatures to 
reach the mid-upper 80s in interior valleys. Dewpoints will continue 
to hover in the mid to upper 60s making for a slightly uncomfortable 
day. An upper level trough axis will move across the region during 
the day and winds will become northerly by Monday evening. Shower 
and thunderstorm chances will be mainly confined to interior areas 
of the forecast area and over the higher terrain in closer proximity 
to a front that should be to the south. Locations along the lake 
plains will be both shadowed by the lake breezes and away from the 
better moisture and forcing behind the front. Activity will taper 
off into Monday evening with mostly dry conditions expected 
overnight. Lows will be in the upper 50s to mid 60s again Monday 
night.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Canadian high pressure will build across the northeast CONUS 
Tuesday. This will bring a return to dry weather, as well as 
give us a brief break from the heat and humidity of the holiday 
weekend, with highs in the mid 70s to around 80 and dew points back 
into the 50s.

The high will start to drift east Wednesday bringing back some 
warmer and more humid air. The day should remain dry, but can't 
completely rule out an isolated afternoon shower or storm near the 
Lake Erie Lake Breeze given the returning instability.

As we head into Thursday and Friday, the upper level ridge will be 
ushered off to the east, while a potent shortwave approaches from 
the northern Plains and the remnants of Alberto push into the Ohio 
Valley. This will bring a better chance for scattered showers and 
storms for Thursday and Friday, as well as the potential for locally 
heavy rainfall.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
VFR will prevail today and tonight with a bubble of relatively drier 
air holding strong over the eastern Great Lakes. A few showers and 
thunderstorms will develop across the North Country at times near a 
stalled frontal zone, with the greatest concentration of activity 
this afternoon and evening mainly north and east of KART. A few 
isolated showers are also possible late today and tonight across the 
western Southern Tier. Otherwise the rest of the area will remain 
dry with an increase in mid/high clouds.

Outlook... 

Sunday and Monday...Mainly VFR with widely scattered showers and 
thunderstorms.
Tuesday and Wednesday...VFR.

&&

.MARINE...
High pressure will remain anchored off the coast of the southeast 
states through Memorial Day, with a weak pressure gradient in place 
across the eastern Great Lakes. This will promote light winds and 
flat wave action the majority of the time. High resolution guidance 
suggests a brief period of moderate northeast winds may develop this 
evening on Lake Ontario as a weak backdoor front and composite 
outflow boundary drops southwest across the lake. If this 
materializes, it would produce a few hours of choppy wave action 
along the south shore of Lake Ontario starting this evening.

There may be a few widely scattered thunderstorms at times with 
locally higher winds and waves.

&&

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

&&

$$

SYNOPSIS...Hitchcock
NEAR TERM...Hitchcock
SHORT TERM...Church
LONG TERM...Church
AVIATION...Hitchcock
MARINE...Hitchcock


000
FXUS61 KBUF 260758
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
358 AM EDT Sat May 26 2018

.SYNOPSIS...
Persistent southwesterly flow will continue to bring very warm 
weather through the Memorial Day holiday. There will be a few widely 
scattered showers and thunderstorms each day, mainly across the 
North Country and areas well inland from the lakes. Even in these 
areas, the vast majority of the time will be rain free.

&&

.NEAR TERM /THROUGH TONIGHT/...
IR satellite imagery shows most of the thicker clouds confined to 
the North Country early this morning, with thin high clouds for the 
rest of the area. A few widely scattered showers will continue in 
the Saint Lawrence Valley through early this morning.

High pressure will remain anchored off the coast of the southeast 
states today and tonight, with persistent southwesterly flow across 
the Ohio Valley and eastern Great Lakes. A shrinking bubble of drier 
air will persist over our region today, keeping most areas dry. The 
presence of this dry air, combined with warm mid level temperatures 
will keep instability anemic for the bulk of the area, with SBCAPE 
only around 500J/kg despite the very warm surface temperatures. An 
isolated shower cannot be ruled out late this afternoon across the 
higher terrain of the western Southern Tier near the PA state line, 
but otherwise the bulk of Western NY and areas southeast of Lake 
Ontario will be rain free. Mid/high clouds will increase across the 
area today, yielding partly sunny skies. 

The one exception to the dry weather will be across the North 
Country. A stalled frontal zone will remain draped from the Ottawa 
Valley to northern NY and act as a conduit for several mid level 
waves to move along. Instability will also be greater in this area 
with better boundary layer moisture and cooler temperatures aloft. 
These waves will produce a few periods of scattered showers today 
and tonight, with the better coverage of showers and scattered 
thunderstorms expected this afternoon and evening with increased 
diurnal instability. Southwest flow off Lake Ontario will maintain a 
stable lake shadow for most of the eastern Lake Ontario region, with 
shower chances mainly relegated to the Thousand Islands region and 
western foothills of the Adirondacks on the fringe of the stable 
lake shadow.

Most of the showers and scattered thunderstorms across the North 
Country will end later this evening with the loss of diurnal 
instability, although a few more widely scattered showers cannot be 
ruled out overnight. A few scattered showers may also develop 
overnight across the western Southern Tier, and eventually the 
western Finger Lakes toward Sunday morning as a weak mid level wave 
and deeper moisture cross PA and the Southern Tier of NY.

Temperatures will continue to be very summer-like, with highs in the 
mid 80s today at lower elevations in Western NY, and upper 70s for 
the North Country. A southwest breeze will keep the Buffalo and 
Watertown areas cooler. Lows tonight will be in the lower 60s for 
most, with some upper 50s in the cooler Southern Tier valleys and 
Lewis County.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Summery warmth and humidity will continue through the second half 
of the holiday weekend, with scattered afternoon shower and 
thunderstorm chances inland from the lakes.

A diffuse shortwave will cross NYS on Sunday, which will help 
trigger some widely scattered showers and thunderstorms developing 
along a convergent boundary near the Genesee Valley and along the 
Lake Erie lake breeze boundary over the western Southern Tier. Dew 
points will continue to rise to into the mid 60s, helping to fuel 
some instability for convective initiation as well as making for a 
more uncomfortablely humid feel to the air. Temperatures will be in 
the mid 80s inland from the lake breezes, with cooler readings in 
the 70s along the lake shores. Light northeast winds south of Lake 
Ontario near the convergent boundary will actually help Buffalo one 
of the warmer spots, with the south shore of Lake Ontario and 
Rochester area slightly cooler. 

Any showers and thunderstorms will move into Central NY by Sunday 
evening, however activity that forms across the Ontario peninsula 
Sunday will venture eastward across Lake Erie and Lake Ontario. 
Expect this will largely be diminishing by the time it reaches the 
forecast area, and have decreased overnight PoPs into the slight 
chance range. Temperatures will stay mild overnight with 
temperatures in the mid 60s. 

Memorial Day will be warm with the potential for temperatures to 
reach the mid-upper 80s in interior valleys. Dewpoints will continue 
to hover in the mid to upper 60s making for a slightly uncomfortable 
day. An upper level trough axis will move across the region during 
the day and winds will become northerly by Monday evening. Shower 
and thunderstorm chances will be mainly confined to interior areas 
of the forecast area and over the higher terrain in closer proximity 
to a front that should be to the south. Locations along the lake 
plains will be both shadowed by the lake breezes and away from the 
better moisture and forcing behind the front. Activity will taper 
off into Monday evening with mostly dry conditions expected 
overnight. Lows will be in the upper 50s to mid 60s again Monday 
night.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Canadian high pressure will build across the northeast CONUS 
Tuesday. This will bring a return to dry weather, as well as 
give us a brief break from the heat and humidity of the holiday 
weekend, with highs in the mid 70s to around 80 and dew points back 
into the 50s.

The high will start to drift east Wednesday bringing back some 
warmer and more humid air. The day should remain dry, but can't 
completely rule out an isolated afternoon shower or storm near the 
Lake Erie Lake Breeze given the returning instability.

As we head into Thursday and Friday, the upper level ridge will be 
ushered off to the east, while a potent shortwave approaches from 
the northern Plains and the remnants of Alberto push into the Ohio 
Valley. This will bring a better chance for scattered showers and 
storms for Thursday and Friday, as well as the potential for locally 
heavy rainfall.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
VFR will prevail today and tonight with a bubble of relatively drier 
air holding strong over the eastern Great Lakes. A few showers and 
thunderstorms will develop across the North Country at times near a 
stalled frontal zone, with the greatest concentration of activity 
this afternoon and evening mainly north and east of KART. A few 
isolated showers are also possible late today and tonight across the 
western Southern Tier. Otherwise the rest of the area will remain 
dry with an increase in mid/high clouds.

Outlook... 

Sunday and Monday...Mainly VFR with widely scattered showers and 
thunderstorms.
Tuesday and Wednesday...VFR.

&&

.MARINE...
High pressure will remain anchored off the coast of the southeast 
states through Memorial Day, with a weak pressure gradient in place 
across the eastern Great Lakes. This will promote light winds and 
flat wave action the majority of the time. High resolution guidance 
suggests a brief period of moderate northeast winds may develop this 
evening on Lake Ontario as a weak backdoor front and composite 
outflow boundary drops southwest across the lake. If this 
materializes, it would produce a few hours of choppy wave action 
along the south shore of Lake Ontario starting this evening.

There may be a few widely scattered thunderstorms at times with 
locally higher winds and waves.

&&

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

&&

$$

SYNOPSIS...Hitchcock
NEAR TERM...Hitchcock
SHORT TERM...Church
LONG TERM...Church
AVIATION...Hitchcock
MARINE...Hitchcock