Special Weather Statement, NWS Buffalo, NY

Area Forecast Discussion
National Weather Service Buffalo NY
311 PM EDT Tue May 30 2017

.SYNOPSIS...
A broad upper level low will meander across the region through the
rest of the week...bringing periodic opportunities for showers and
thunderstorms along with near to slightly below average temperatures.
Some of the storms could produce strong gusty winds and hail both
this afternoon and Wednesday afternoon...with the greatest potential
for the stronger storms found from interior portions of the Southern
Tier northeastward across the Finger Lakes and North Country.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Satellite imagery late this morning showing a leading shortwave
pushing across Lake Ontario with an area of showers set to move
through the North Country through midday. Meanwhile subsidence in
the wake of this wave is leading to clearing across western NY.
However, a secondary robust shortwave seen on WV imagery is pushing
into northern Indiana. This wave will quickly track across Lake Erie
and into western NY early this afternoon. Forcing ahead of this
trough, combined with steepening lapse rates, diurnal destabilization
and increasing speed shear ahead of the wave will result in strong
to severe thunderstorms developing around midday. Satellite imagery
and BUF/DTX morning soundings suggest an elevated mixed layer
pushing across Lake Erie ahead of the main wave, with steep mid-
level lapse rates. This combined with fairly low freezing levels
under 10kft will support large hail growth given the deep layer
shear profile of 50 to 60 knots supporting strong rotating updrafts.
Expect thunderstorms will initiate across the western Southern Tier
by about 1pm, with initially some discrete cells, which will upscale
into a line with bowing segments possible as the cluster of storms
tracks through the Finger Lakes and into central NY. The greatest
severe threat will be from the western Southern Tier, across the
Finger Lakes and across the southern Tug Hill region of Oswego and
Lewis counties. Large hail will be the primary threat, but as storms
upscale into a line expect wind damage reports will increase into
central NY.

Meanwhile across the Niagara Frontier to just west of Rochester,
expect a fairly pleasant day in store. The synoptically aided lake
breeze will keep convection in check across the Niagara Frontier,
with mostly sunny skies, but breezy conditions with gusts up to 35
mph. The Saint Lawrence valley in northern Jefferson county will see
very similar conditions with mostly sunny skies, although a tad less
windy.

On Wednesday, a very similar setup will be in place as a large scale
upper-level low drifts slowly eastward across northern Ontario.
Overall thermodynamic profiles carbon copies of Tuesday, expect that
everything is about 3C cooler as the upper level low is slightly
closer. Cyclonic flow aloft with weak waves rotating around the
parent low will maintain synoptically favorable conditions for
convection, while the robust southwesterly lake breeze in place will
again provide focus for convective initiation. CAPE/shear values
will be slightly less than Tuesday, although the lower freezing
heights will support hail easily surviving to the surface.
Thunderstorms will again focus across the western Southern Tier, the
Finger Lakes and into the Southern Tug Hill (southeast of the lake
breeze), while mostly dry and mostly sunny conditions will be found
across the Niagara Frontier and Saint Lawrence Valley. The only
difference for Wednesday will be that the flow turns a bit more west-
southwesterly by late afternoon, which may allow for some lake breeze
convection along the Niagara Peninsula in Ontario to survive into
Niagara and Orleans counties by late afternoon and early evening
after the main convection southeast of the lake breeze departs into
central NY.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
Showers and thunderstorms will taper off from west to east Wednesday
evening with the passage of an upper level trough and surface cold
front. The northern extension of an expansive high over the southern
U.S. will pass across the forecast area behind the cold front,
resulting in fair skies, but cool temperatures on Thursday, with
highs in the low to mid 60s.

Another potent shortwave rotating through the base of the upper
level low centered over north-central Quebec will bring a chance for
a few showers late Thursday night, mainly to the North Country. A
follow-on shortwave will punch across the forecast area Friday
afternoon or evening, bringing another round of showers and
thunderstorms. At this point, it appears that the greatest
precipitation potential will be across the North Country,
closest to the track of the shortwave. Another round of
convection will likely be ongoing along a warm frontal boundary
just to our southwest. The final track of the shortwave will
affect the position of this front - should it track a little
farther north, some of this frontal precipitation may creep into
the Southern Tier, or should the shortwave drop a little
farther south, convection associated with that system may dip
farther south into the forecast area. Given these uncertainties,
will stick with broadbrushed chance pops from Friday afternoon
into Friday night for the time being.

Regarding temperatures, as mentioned above, advection of colder and
drier air behind Wednesday evenign's cold frontal passage will allow
temperatures to drop into the 40s inland of the lakes, with low 50s
along the lakeshore. After a cool day Thursday, we will see 50s
Thursday night, as the coolest air associated with the upper level
trough passes off to the east, and warmer air advecting ahead of the
next system pushes temperatures slightly warmer - into the mid to
upper 60s, on Friday. We should see mid 50s once again Friday night,
with lower 50s in the North Country, fairly normal values for early
June, as the area will be caught in between cool air to the north
over Canada, and much warmer air to the south over the Ohio and
Mississippi valleys.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Unfortunately...the forecast for the weekend into early next week
has turned decidedly more pessimistic. The operational ECMWF and a
fair number of GFS ensembles are now strongly suggesting that the
front from Friday/Friday night will stall across Pennsylvania...as
energy crossing the Canadian prairies will develop a fairly strong
wave along the frontal boundary back across the Upper Mississippi
Valley. This wave will then consolidate into a compact storm system
over the Great lakes region later in the weekend as the upper level
support likely evolves into yet another closed low.

The result of this updated scenario...
There will be some leftover showers across the Southern Tier counties
on Saturday with limited clearing elsewhere. Temperatures will top out
in the 60s for most areas.

Showers...or possibly even a period of steadier rain...will push north
across the region late Saturday night and Sunday as the aforementioned
surface low tracks east across Lake Erie.

As the stacked low drifts across our region Sunday night and MOnday...
the rain will become more showery.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
VFR conditions will prevail through the TAF period. The only
exceptions will be localized MVFR/IFR conditions with thunderstorms
that develop this afternoon across the western Southern Tier, and
track through the Finger Lakes to southern Tug Hill region through
late afternoon. A few stronger storms may produce large hail and
damaging wind gusts. However, most of the stronger storms should
remain south and east of the TAF sites.

Showers and thunderstorms end tonight with VFR conditions
prevailing, then more showers and thunderstorms will develop along
the lake breeze boundaries on Wednesday. Again large hail and
damaging wind gusts are possible with the stronger storms Wednesday,
however these will again remain mostly south and east of the TAF
sites. A few storms may track from the Niagara Peninsula in Ontario
to near IAG along the lake breeze boundary by late Wednesday
afternoon.

Outlook...
Wednesday night through Sunday...Mainly VFR...with
localized IFR/MVFR possible in scattered to numerous showers and
thunderstorms at times.

&&

.MARINE...
A cold front will cross the region today...with another round of
showers and thunderstorms marking its passage...some of which could
be capable of strong wind gusts and hail across central and eastern
portions of Lake Ontario. In the wake of the front...southwest winds
will again freshen a bit across the Lower Lakes region this
afternoon...though at this point both winds and waves are expected
to remain below advisory levels.

During the middle and latter portions of the week a broad upper level
trough will continue to meander its way eastward across the region...while
maintaining a persistent general southwesterly to westerly flow across
Lakes Erie and Ontario. This said...at this point it appears that both
winds and waves will remain below advisory criteria.

&&

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

&&

SYNOPSIS...CHURCH
NEAR TERM...CHURCH
SHORT TERM...WOOD
LONG TERM...RSH
AVIATION...CHURCH
MARINE...CHURCH

Hazardous Weather Outlook
National Weather Service Buffalo NY
421 PM EDT Tue May 30 2017

NYZ004-006-008-012>014-019>021-085-312030-
Wayne-Oswego-Lewis-Wyoming-Livingston-Ontario-Chautauqua-Cattaraugus-
Allegany-Southern Erie-
421 PM EDT Tue May 30 2017

This Hazardous Weather Outlook is for portions of western and north
central New York.

.DAY ONE...Tonight.

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Showers and thunderstorms will redevelop Wednesday...with some
storms expected to be strong to severe with another round of gusty
winds and hail possible.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

This product, along with other watches, warnings, advisories, and
statements issued by the National Weather Service office in Buffalo
can be found on the internet at http://www.weather.gov/buf

NYZ005-312030-
Northern Cayuga-
421 PM EDT Tue May 30 2017

...SEVERE THUNDERSTORM WATCH 299 IN EFFECT UNTIL 8 PM EDT THIS
EVENING...

This Hazardous Weather Outlook is for portions of central New York.

.DAY ONE...Tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Severe Thunderstorm Watch.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Showers and thunderstorms will redevelop Wednesday...with some
storms expected to be strong to severe with another round of gusty
winds and hail possible.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

This product, along with other watches, warnings, advisories, and
statements issued by the National Weather Service office in Buffalo
can be found on the internet at http://www.weather.gov/buf

LEZ020-040-041-LOZ030-042>045-062>065-SLZ022-024-312030-
Upper Niagara River and Buffalo Harbor-
Lake Erie nearshore waters from Ripley to Dunkirk-
Lake Erie nearshore waters from Dunkirk to Buffalo-
Lower Niagara River-
Lake Ontario nearshore waters from the Niagara River to Hamlin Beach-
Lake Ontario nearshore waters from Hamlin Beach to Sodus Bay-
Lake Ontario nearshore waters from Sodus Bay to Mexico Bay-
Lake Ontario nearshore waters from Mexico Bay to the Saint Lawrence
River-
Lake Ontario open waters from the Niagara River to Hamlin Beach-
Lake Ontario open waters from Hamlin Beach to Sodus Bay-
Lake Ontario open waters from Sodus Bay to Mexico Bay-
Lake Ontario open waters from Mexico Bay to the Saint Lawrence River-
Saint Lawrence River from Cape Vincent to Ogdensburg-
Saint Lawrence River from Ogdensburg to Saint Regis-
421 PM EDT Tue May 30 2017

This Hazardous Weather Outlook is for the New York waters of Lake
Erie, Lake Ontario, and the Saint Lawrence River.

.DAY ONE...Tonight.

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

The chance for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

This product, along with other watches, warnings, advisories, and
statements issued by the National Weather Service office in Buffalo
can be found on the internet at http://www.weather.gov/buf

NYZ001>003-007-010-011-312030-
Niagara-Orleans-Monroe-Jefferson-Northern Erie-Genesee-
421 PM EDT Tue May 30 2017

This Hazardous Weather Outlook is for portions of western and north
central New York.

.DAY ONE...Tonight.

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

The probability for widespread hazardous weather is low.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

This product, along with other watches, warnings, advisories, and
statements issued by the National Weather Service office in Buffalo
can be found on the internet at http://www.weather.gov/buf

Special Weather Statement
National Weather Service Buffalo NY
313 PM EDT TUE MAY 30 2017

NYZ014-301945-
Ontario-
313 PM EDT TUE MAY 30 2017

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN ONTARIO COUNTY...

At 313 PM EDT, a strong thunderstorm was located over Rushville, or
10 miles south of Canandaigua, moving northeast at 50 mph.

Winds in excess of 40 mph and dime size hail are possible with this
storm.

Locations impacted include...
Geneva, Phelps, Rushville, Gorham, Seneca Castle, Seneca Lake State
Park, Cottage City, Hall and West Junius.

This includes Interstate 90 near exit 42.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 4301 7706 4301 7696 4287 7696 4286 7698
      4277 7697 4276 7698 4276 7731 4277 7731
TIME...MOT...LOC 1913Z 224DEG 41KT 4275 7722

HITCHCOCK

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BUFFALO NY
328 PM EDT TUE MAY 30 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0208 PM     HAIL             1 ENE HURON             43.24N  76.86W
05/30/2017  E0.75 INCH       WAYNE              NY   PUBLIC

&&

EVENT NUMBER BUF1701149

WOOD

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BUFFALO NY
401 PM EDT TUE MAY 30 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0225 PM     HAIL             FAIR HAVEN              43.33N  76.70W
05/30/2017  E0.75 INCH       CAYUGA             NY   PUBLIC

            DIME-SIZED HAIL AT FAIR HAVEN STATE PARK

&&

EVENT NUMBER BUF1701150

WOOD

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BUFFALO NY
422 PM EDT TUE MAY 30 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0225 PM     MARINE HAIL      2 N FAIR HAVEN          43.35N  76.70W
05/30/2017  E0.75 INCH       LOZ044             NY   PUBLIC

&&

EVENT NUMBER BUF1701151

SJW

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BUFFALO NY
423 PM EDT TUE MAY 30 2017

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0205 PM     MARINE HAIL      1 W NORTH POND          43.65N  76.20W
05/30/2017  M0.75 INCH       LOZ045             NY   PUBLIC

&&

EVENT NUMBER BUF1701152

SJW

Special Weather Statement
National Weather Service Buffalo NY
423 PM EDT TUE MAY 30 2017

NYZ006-302045-
Oswego-
423 PM EDT TUE MAY 30 2017

...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN OSWEGO COUNTY...

At 422 PM EDT, a strong thunderstorm was located over Cicero, or 8
miles north of Syracuse, moving east at 35 mph.

Winds in excess of 40 mph are possible with this storm.

Locations impacted include...
Oneida Lake, Constantia, Cleveland, Bernhards Bay, Lower South Bay
and Lakeport.

This storm will cross Oneida Lake, boaters on the lake should seek
safe harbor immediately.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 4315 7588 4316 7592 4317 7593 4317 7595
      4318 7596 4318 7600 4320 7604 4320 7608
      4322 7609 4329 7587
TIME...MOT...LOC 2022Z 249DEG 31KT 4316 7609

HITCHCOCK