Special Weather Statement, NWS Buffalo, NY

Area Forecast Discussion
National Weather Service Buffalo NY
247 PM EDT Sat Aug 17 2024

.SYNOPSIS...
A large storm system over the Upper Great Lakes will slowly drift
eastward across the area through Monday. This will result in
occasional showers and some thunderstorms, although there will also
be periods of dry weather. Rain could be heavy at times, with a few
strong thunderstorms with gusty winds also possible. Following the
passage of this system, Canadian high pressure will build across our
region and provide us a prolonged period of fair and cooler weather
that will last for most of next week.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
Broad and vertically stacked low pressure will slowly drift east
across Lower Michigan this afternoon to Lake Ontario by Sunday
night. The cyclonic flow aloft associated with this trough and
embedded disturbances will bring an unsettled pattern which will
last for the rest of the weekend.

Subsidence behind a warm front which exited the region earlier today
allowed for some sunshine today. This increased instability with
LAPS soundings showing SB CAPE 1000 to 2000 J/Kg across Western New
York. This will support increasing areal coverage of storms this
afternoon into early evening. Limited agreement among mesoscale
guidance that the steadiest storms will develop along a weak
boundary across far Western NY this afternoon and then will
gradually move eastward across the Genesee Valley before weakening
late this evening. However, scattered showers and thunderstorms
cannot be ruled out anywhere during this time. WPC and SPC each have
all or most of our area in a marginal risk for excessive rainfall
and severe weather.

Wind profiles are modest from a severe weather perspective,
with only about 25 to 30 knots at 850mb and 700 mb winds not
much stronger. As a result there's limited wind shear, but a few
strong to severe pulse storm cannot be ruled out, especially
considering the large scale lift provided by the shortwave. PWAT
values of 1.75 to 2 inches across Western NY also support
locally heavy rainfall, with a risk for flash flooding from
training or slow moving storms. This will have to be monitored,
especially from the Genesee Valley westward through this evening.

After this, showers and storms will taper off some late tonight
as instability wanes, but at least a chance will persist during
the entire overnight period. Lows will range from the mid 60s to
around 70, with a risk of fog across higher terrain in the
Southern Tier late in the night.

On Sunday the trough will push closer to our region, with more cloud
cover and an earlier start for showers. Expecting less diurnal
instability, but more synoptic scale lift due to the trough. Showers
and a few thunderstorms will expand in coverage mid-day, again
bringing the risk for locally heavy rainfall during the day. This is
due to precipitable water values around 1.75 inches and a weak flow
aloft promoting slow storm motion.

Sunday night the trough axis will move across the area, resulting in
a wind shift to the northwest during the night. Chances for showers
and isolated thunderstorms will linger underneath the trough, with
patchy fog also developing across higher terrain following the wind
shift to the northwest.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Unsettled weather will continue into the start of the work week,
with a cold front crossing the region from west to east early
Monday. We will hang onto showers and a few thunderstorms through
the day with still deep moisture, anabatic frontal precipitation,
and convergence along a 25 knot northerly LLJ ahead of the axis of
the mid level trough.

These showers will end through the evening hours towards the east,
with some clearing towards the west.

This northerly flow and steepening low level lapse rates will
encourage cloud reformation Tuesday, with partly to mostly cloudy
skies over the region...until a much drier airmass from the north
diminishes the strato-cu later through the day.

Clearing skies, light winds and mid single digit 850 hPa
temperatures will quickly drop temperatures in the evening...with
overnight lows Tuesday night dropping into the low to mid 40s inland
to mid 50s along the lake shorelines.

Highs Monday and Tuesday will largely remain in the 60s under cloud
cover and within an 850 hPa airmass that will be in the mid single
digits Celsius.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Sprawling surface high pressure will cross the region early this
period, with cool low humid conditions Wednesday through Thursday
morning giving way to day-to-day warming behind the surface high
through Saturday.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
Approaching mid level trough and diurnal instability will
support increasing coverage of showers and thunderstorms this
afternoon into this evening. Greatest coverage will push into
far Western NY through 20Z then spread east to the Genesee River
and KROC late afternoon and evening before weakening.
Thunderstorms driven by subtle features, making exact timing
challenging so handled with tempo groups for most TAF sites.
Mainly VFR flight conditions outside of brief MVFR or lower due
to vsby in heavier rain.

Showers and thunderstorms taper off some after midnight, but
there still will remain a risk throughout the overnight hours.
Increasing low moisture with the approach of the trough will
result in expanding MVFR cigs with most sites MVFR by Sunday
morning. Chances for showers and thunderstorms will again
increase Sunday afternoon, but low confidence in exact timing
and location.

Outlook...

Sunday night...VFR/MVFR lowering to mainly IFR following the
wind shift. Showers and scattered thunderstorms with lowering
cigs with the northwesterly wind shift.

Monday...MVFR/IFR ceilings with showers likely and a
chance of thunderstorms.

Tuesday...Improvement to VFR.

Wednesday and Thursday...VFR.

&&

.MARINE...
A general southerly to southwesterly flow will prevail through most
of Sunday. Winds may briefly touch 15 to 20 knots, but the flow will
push the highest waves into Canadian waters. Of greater concern to
marine interests this weekend will be the potential for scattered
thunderstorms, which could produce locally gusty winds and higher
waves.

Following the passage of a cold front Sunday night into Monday,
northerly flow will bring chopping conditions which may require
small craft headlines for some or all of the waters. In addition,
the cooler air aloft will bring conditions favorable for waterspouts
Sunday night and into Monday.

Conditions should then gradually improve on Tuesday as Canadian
high pressure begins building into the region...with a
slackening pressure gradient allowing for winds and waves to
subside.

&&

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

&&

SYNOPSIS...Apffel/JJR
NEAR TERM...Apffel/JJR
SHORT TERM...Thomas
LONG TERM...Thomas
AVIATION...Apffel
MARINE...Apffel/JJR

Hazardous Weather Outlook
National Weather Service Buffalo NY
447 AM EDT Sat Aug 17 2024

NYZ001>008-010>014-019>021-085-181000-
Niagara-Orleans-Monroe-Wayne-Northern Cayuga-Oswego-Jefferson-Lewis-
Northern Erie-Genesee-Wyoming-Livingston-Ontario-Chautauqua-
Cattaraugus-Allegany-Southern Erie-
447 AM EDT Sat Aug 17 2024

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

.DAY ONE...Today and tonight.

Occasional showers and scattered thunderstorms will cross the region
today through tonight. A few storms may contain isolated strong
winds and localized heavy rainfall this afternoon and evening. There
is a Marginal Risk of severe thunderstorms and excessive rainfall.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Occasional showers and scattered thunderstorms will continue Sunday.
A few storms may contain gusty winds and localized heavy rainfall.
There is a Marginal Risk of excessive rainfall.

.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-SLZ022-024-181000-
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-
447 AM EDT Sat Aug 17 2024

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

.DAY ONE...Today and tonight.

Occasional showers and scattered thunderstorms will cross the region
today through tonight. A few storms may contain isolated strong
winds and locally higher waves this afternoon and evening.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

Occasional showers and scattered thunderstorms will continue through
Sunday. A few storms may contain isolated gusty winds and locally
higher waves.

.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

Hitchcock

Preliminary Local Storm Report
National Weather Service Buffalo NY
356 PM EDT Sat Aug 17 2024

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

0326 PM     Tstm Wnd Dmg     1 ENE Stockton          42.32N 79.34W
08/17/2024                   Chautauqua         NY   911 Call Center

            Tree down on road, cable wire across road.

&&

Special Weather Statement
National Weather Service Buffalo NY
433 PM EDT Sat Aug 17 2024

NYZ019-172130-
Chautauqua NY-
433 PM EDT Sat Aug 17 2024

...A STRONG THUNDERSTORM WILL IMPACT SOUTHERN CHAUTAUQUA COUNTY
THROUGH 530 PM EDT...

At 433 PM EDT, Doppler radar was tracking a strong thunderstorm near
Wattsburg, or 21 miles southeast of Erie, moving east at 35 mph.

HAZARD...Wind gusts up to 50 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Jamestown, Clymer, Jamestown West, Frewsburg, Busti, French Creek,
Panama, Niobe, and Ashville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4209 7976 4210 7906 4200 7906 4200 7976
TIME...MOT...LOC 2033Z 262DEG 29KT 4197 7973

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH

Mitchell

Special Weather Statement
National Weather Service Buffalo NY
530 PM EDT Sat Aug 17 2024

NYZ003-004-013-014-172215-
Ontario NY-Livingston NY-Wayne NY-Monroe NY-
530 PM EDT Sat Aug 17 2024

...A STRONG THUNDERSTORM WILL IMPACT SOUTHWESTERN WAYNE...
NORTHEASTERN LIVINGSTON...SOUTHEASTERN MONROE AND NORTHWESTERN
ONTARIO COUNTIES THROUGH 615 PM EDT...

At 530 PM EDT, Doppler radar was tracking a strong thunderstorm over
Honeoye Falls, or 9 miles south of Brighton, moving east at 25 mph.

HAZARD...Wind gusts up to 40 mph and pea size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Rochester, Canandaigua, East Rochester, Fairport, Brighton,
Henrietta, Penfield, Palmyra, Victor, Honeoye Falls, Bristol, Lima,
Bloomfield, Farmington, Walworth, Mendon, East Bloomfield, Rush, West
Bloomfield, and Manchester.

This includes the following highways...
 Interstate 390 between exits 9 and 12.
 Interstate 90 between exits 43 and 46.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4281 7772 4310 7770 4320 7732 4308 7721
      4286 7725
TIME...MOT...LOC 2130Z 260DEG 21KT 4299 7763

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

Thomas

Preliminary Local Storm Report
National Weather Service Buffalo NY
543 PM EDT Sat Aug 17 2024

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

0503 PM     Tstm Wnd Dmg     1 N Sardinia            42.55N 78.51W
08/17/2024                   Erie               NY   Public

            Large tree down on roadway.

&&

Preliminary Local Storm Report
National Weather Service Buffalo NY
546 PM EDT Sat Aug 17 2024

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

0401 PM     Tstm Wnd Dmg     2 NNW Collins           42.52N 78.93W
08/17/2024                   Erie               NY   Public

            Tree down on Gowanda State Road.

&&

Special Weather Statement
National Weather Service Buffalo NY
552 PM EDT Sat Aug 17 2024

NYZ012-019-020-085-172230-
Chautauqua NY-Cattaraugus NY-Southern Erie NY-Wyoming NY-
552 PM EDT Sat Aug 17 2024

...STRONG THUNDERSTORMS WILL IMPACT SOUTHWESTERN WYOMING...
CATTARAUGUS...SOUTHEASTERN ERIE AND SOUTHEASTERN CHAUTAUQUA COUNTIES
THROUGH 630 PM EDT...

At 549 PM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Springville to near Frewsburg to near
Russell. Movement was east at 25 mph.

HAZARD...Wind gusts up to 40 mph, half inch hail, and torrential
         rainfall.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible. Heavy rainfall may cause localized flash flooding.

Locations impacted include...
Salamanca, Allegany State Park, Springville, Ashford, Arcade,
Franklinville, Ashford Hollow, Chaffee, East Concord, Frewsburg,
Concord, Yorkshire, Sardinia, Great Valley, New Albion, Conewango,
Carrollton, Randolph, Napoli, and Little Valley.

This includes Interstate 86 between exits 14 and 21.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with these storms and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4200 7925 4209 7920 4258 7874 4258 7829
      4200 7871
TIME...MOT...LOC 2149Z 256DEG 20KT 4251 7875 4211 7912 4199 7919

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

Mitchell