Special Weather Statement, NWS Buffalo, NY

Area Forecast Discussion
National Weather Service Buffalo NY
1208 AM EDT Fri May 19 2017

.SYNOPSIS...
Notably cooler air will work its way across our region behind a cold
front later today. Temperatures will be some 15 to 20 degrees lower
than those from the past two days. Meanwhile...Canadian high
pressure will support mainly fair dry weather through the first half
of the upcoming weekend.

&&

.NEAR TERM /THROUGH TODAY/...
A cold front will gradually work its way across western and central
New York during the overnight. Radars are showing several strong to
severe thunderstorms continuing to track eastward along the edge of
the front near midnight. Mesoanalysis shows limited/weak CAPE but
effective shear of 40+kts continues to support the severe cells.
Damaging winds to 60 mph and quarter-sized hail remain the main
threats within the warned cells along with frequent lightning.

It will be much cooler by daybreak...as the mercury will settle into
the 50s throughout...rather than hold in the 60s and 70s like the
past two nights.

Friday will likewise be starkly different than Thursday as a cool
northerly flow will pass across the region. With lingering moisture
in the lower levels a few showers will remain possible from roughly
the Genesee Valley eastward, with perhaps a sprinkle farther
southward towards the Niagara Frontier. The northerly flow will
maintain a deck of stratus clouds through much of the day before
high pressure brings a drier airmass, eroding the clouds from north
to south through the afternoon hours.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
On Friday night, high pressure centered south of Hudson Bay will
ridge southward into our region. Winds will be on the light side,
but not completely calm resulting in marginal radiational cooling
conditions. Lows will mainly be in the lower 40s, but temperatures
will drop into the mid to upper 30s across the North Country where
patchy frost is possible.

The surface high and mid/upper level ridging should keep the area
dry on Saturday. A warm frontal boundary will sharpen to our south
during the day, which will keep temperatures below normal with highs
in the 60s. Also, mid level clouds from this warm front will start to
spread in the region from SW-NE Saturday afternoon.

On Saturday night, model consensus brings the mid-level thermal
gradient into the region. This may result in some showers Saturday
night, mainly across western portions of the cwa. Clouds from the
mid-level boundary and increasing southeasterly winds will limit
radiational cooling with lows in the 50s in most areas. Only the
North Country which is closest to the departing surface ridge will
have any chance to cool with lows in the mid to upper 40s.

Sunday should be the warmest day of the period, as warm air surges
northwards across the region ahead of the approaching low, with
temperatures climbing back into the mid to upper 70s. Meanwhile,
showers and thunderstorms will become more widespread as the warm
front continues to move northward across the region. Due to the
convective nature of this, Sunday will not be a complete washout
even though there may be a couple rounds of showers due to the
boundary, and then again from diurnally driven instability.

Model consensus continues to suggest the steadiest activity will
move through Sunday night, just ahead of the cold front. A fairly
solid line is expected with a deep SSW flow which will tap into some
moisture from the Gulf of Mexico. Because of this will increase PoPs
to categorical, with rainfall amounts likely to average between a
half an inch and an inch. Overnight temperatures will still be on
the warm side, largely depending on the timing of the front.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
In general there is better than average agreement among long range
model guidance with 00/06Z ECMWF/GFS/GGEM guidance showing the same
general pattern with only minor differences in timing and
temperatures. The ECMWF is about 6 hours faster and slightly warmer
than GFS and GGEM guidance, with a consensus providing the most
likely solution.

A cold front will move to the east of the area on Monday, with some
showers lingering depending on the progression of this front.
Conditions will dry from west to east during the day, with below
normal high temperatures (in the 60s) behind the front.

A ridge of high pressure will build in behind the front, providing
dry weather Monday night and most of Tuesday. Temperatures will warm
a bit with highs in the upper 60s to lower 70s. Tuesday will
probably be the most pleasant day of the week as another slow moving
upper level trough is forecast to cut off across the region mid-week.

Model guidance suggests there will be a sharp trough or cut off low
to our west on Wednesday, and then across New York state on
Thursday. This will lead to a wet pattern, with below normal
temperatures. Given model agreement, the forecast hedges higher than
consensus guidance for the PoPs. This will result in showers for
Wednesday and Thursday, though there should be periods of dry
weather as well. Two-day rainfall amounts from this system are
likely to average around an inch, but will vary by location.

&&

.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
VFR conditions will be in place across the region for much of the
overnight...although scattered strong to severe cells continue to
track mainly south/east of the TAF sites.

In the wake of a cold front...low level moisture will be lifted into
MVFR cigs for much of the region. These lower cigs are forecast to
remain in place for Friday morning before cigs improve to VFR during
the midday and afternoon.

Outlook...
Friday night and Saturday...VFR.
Saturday night...Mainly VFR. A chance of showers and thunderstorms.
Sunday through early Monday morning...VFR/MVFR. Showers and
thunderstorms likely.
Later Monday and Tuesday...Mainly VFR.

&&

.MARINE...
Winds across the Lower Great Lakes will continue to subside during
the course of the night as a weaker sfc pressure gradient will
accompany the passage of a cold front.

High pressure over northern Manitoba will then build across the
Upper Great lakes later today and tonight. While northwest winds
ahead of this fair weather feature will briefly freshen on Lake
Ontario...they will subside again before waves reach small craft
advisory levels.

Northeast winds tonight and Saturday will make for choppy conditions
on the west half of Lake Ontario...and particularly for the
nearshore waters west of Hamlin Beach and for the Lower Niagara
River...although criteria is not expected to reach small craft
advisory levels.

&&

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

&&

SYNOPSIS...RSH/SMITH
NEAR TERM...RSH/SMITH
SHORT TERM...APFFEL
LONG TERM...APFFEL
AVIATION...RSH/SMITH
MARINE...RSH/SMITH

Hazardous Weather Outlook
National Weather Service Buffalo NY
914 PM EDT Thu May 18 2017

NYZ007-008-200115-
Jefferson-Lewis-
914 PM EDT Thu May 18 2017

...SEVERE THUNDERSTORM WATCH 237 IN EFFECT UNTIL 11 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...Friday through Wednesday.

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

NYZ001>006-010>014-019>021-085-200115-
Niagara-Orleans-Monroe-Wayne-Northern Cayuga-Oswego-Northern Erie-
Genesee-Wyoming-Livingston-Ontario-Chautauqua-Cattaraugus-Allegany-
Southern Erie-
914 PM EDT Thu May 18 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...Friday through Wednesday.

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

LEZ020-040-041-LOZ030-042>045-062>065-SLZ022-024-200115-
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-
914 PM EDT Thu May 18 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...Friday through Wednesday.

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
1149 PM EDT THU MAY 18 2017

NYZ012-013-021-190415-
Allegany-Livingston-Wyoming-
1149 PM EDT THU MAY 18 2017

...A STRONG THUNDERSTORM WILL AFFECT SOUTHERN WYOMING...SOUTHWESTERN
LIVINGSTON AND NORTHWESTERN ALLEGANY COUNTIES...

At 1149 PM EDT, a strong thunderstorm was located 7 miles northeast
of Arcade, or 18 miles west of Letchworth State Park, moving east at
45 mph.

Wind gusts up to 50 mph and half inch hail are possible with this
storm.

Locations impacted include...
Letchworth State Park, Perry, Warsaw, Mount Morris, Arcade,
Portageville, Nunda, Eagle, Pike and Castile.

This includes Interstate 390 between exits 6 and 7.

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 4251 7831 4252 7831 4252 7842 4269 7844
      4277 7779 4250 7777
TIME...MOT...LOC 0349Z 265DEG 37KT 4261 7833

Wood

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BUFFALO NY
1159 PM EDT THU MAY 18 2017

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

1146 PM     MARINE TSTM WIND 1 W DUNKIRK             42.49N  79.36W
05/18/2017  M39 MPH          LEZ041             NY   ASOS

&&

EVENT NUMBER BUF1701132

JAM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BUFFALO NY
1200 AM EDT FRI MAY 19 2017

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

1143 PM     HAIL             1 E DUNKIRK             42.49N  79.32W
05/18/2017  M0.75 INCH       CHAUTAUQUA         NY   TRAINED SPOTTER

&&

EVENT NUMBER BUF1701133

CHURCH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BUFFALO NY
1202 AM EDT FRI MAY 19 2017

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

1140 PM     MARINE HAIL      1 W DUNKIRK             42.49N  79.36W
05/18/2017  M0.75 INCH       LEZ041             NY   TRAINED SPOTTER

&&

EVENT NUMBER BUF1701134

CHURCH

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BUFFALO NY
1229 AM EDT FRI MAY 19 2017

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

1155 PM     TSTM WND DMG     SILVER CREEK            42.54N  79.17W
05/18/2017                   CHAUTAUQUA         NY   LAW ENFORCEMENT

            TREES AND WIRES DOWN

&&

EVENT NUMBER BUF1701135

JAM

Special Weather Statement
National Weather Service Buffalo NY
1232 AM EDT FRI MAY 19 2017

NYZ012-013-020-021-085-190515-
Cattaraugus-Allegany-Livingston-Southern Erie-Wyoming-
1232 AM EDT FRI MAY 19 2017

...A STRONG THUNDERSTORM WILL AFFECT SOUTHERN WYOMING...NORTHEASTERN
CATTARAUGUS...SOUTHEASTERN ERIE...SOUTHWESTERN LIVINGSTON AND
NORTHERN ALLEGANY COUNTIES...

At 1232 AM EDT, a strong thunderstorm was located over Ashford
Hollow, or 18 miles north of Salamanca, moving east at 50 mph.

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

Locations impacted include...
Letchworth State Park, Springville, Arcade, Franklinville, Belfast,
Rushford, Ashford Hollow, Houghton, Chaffee and East Concord.

This includes Interstate 86 near exit 32.

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 4235 7877 4260 7871 4257 7779 4230 7779
TIME...MOT...LOC 0432Z 269DEG 45KT 4243 7868

Wood