Special Weather Statement, NWS Buffalo, NY

Area Forecast Discussion
National Weather Service Buffalo NY
1201 PM EDT Wed Jul 29 2020

.SYNOPSIS...
An unsettled pattern through Thursday as an upper level low pressure
system to the north tracks away from the region. Dry weather for
Friday through Saturday evening before the next chance for rain
moves into the area Saturday night into Sunday.

&&

.NEAR TERM /THROUGH THURSDAY/...
Scattered showers with a few thunderstorms continue across
especially western NY to the Genesee Valley late this morning. A few
storms have been strong at times but thus far, despite stronger deep
layer shear, MLCAPES only 500-1000j/kg is keeping strength of storms
in check. Main issue thus far from the storms is small hail and
brief, but very heavy downpours.

Additional showers and thunderstorms will continue to develop during
the afternoon and evening as a shortwave trough and associated cold
front begin to approach and eventually cross the region. A few
strong to severe thunderstorms still can't be ruled out as
instability increases through the day. Effective instability will be
dependent on where/when cloud cover can clear out over an area after
showers and thunderstorms move through. Model guidance is suggesting
CAPE values of around 1000 to as much as 1500 j/kg. Increasing shear
through the afternoon will also help with the potential for a few
strong to severe thunderstorms. Lapse rates are the primary factor
limiting the severe potential, with fairly weak rates from 3-6 km.
Temperatures today will be in the upper 70s to mid 80s.

Shower activity will continue tonight as the cold front crosses the
region and low level moisture, combined with cooling 850Ts to around
12C help to initiate a weak lake response. Temperatures tonight will
be in the low to mid 60s.

Thursday, the potential for scattered showers will continue as the
trough axis moves through the area. With 850Ts still around 12C for
the day, a lake response will still be possible downwind of both
lakes as well. Temperatures on Thursday will be in the mid 70s to
low 80s.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
Weak cold front passage Thursday evening. Possibly cold enough in
its wake for lake clouds/sprinkles south shore of Lk Ontario late.

High pressure and confluent flow favors fair dry weather Friday and
Saturday. Shortwave approaches late Saturday night.

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
A positively tilted trough spanning southward across the Northern
Great Lakes to the southeastern Plains will slowly lift
northeastward across the eastern third of the CONUS during the later
half of the weekend and into the first part of the work week. As
such, an associated surface low will track northeast across Lake
Erie and Lake Ontario Sunday, increasing chances for showers and
thunderstorms across the forecast region. With the departing surface
low and passage of the upper level trough axis will continue the
chances for showers/storms on Monday. A large area of surface high
pressure will dominate across the Great Lakes, spanning into the
region Tuesday which will promote dry weather for at least the
latter half of the day.

Temperatures for the later half of the weekend and the first couple
of days of the work week will range in the mid 70s to low 80s.

&&

.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
Showers and isolated thunderstorms will affect ROC in the next
couple hours. Otherwise, expect additional scattered showers and
thunderstorms to develop during the afternoon as a shortwave trough
approaches from the west. Conditions will be primarily VFR today,
but brief periods of MVFR to IFR will occur during heavier showers.

Mainly VFR tonight with a few showers possible through the night.

Outlook...

Thursday through Friday...Mainly VFR. Scattered showers especially
Thursday afternoon. River valley fog possible across the Western
Southern Tier early each morning. Saturday...VFR.
Sunday...MVFR/VFR with a chance of showers and thunderstorms.

&&

.MARINE...
A cold front will push across the Lower Great Lakes today.
Increasing southwest winds on Lake Erie for a few hours this
afternoon will approach Small Craft Advisory levels. Winds are
expected to be a but lighter on Lake Ontario.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 5 PM EDT this afternoon for LEZ020-
         040-041.

&&

SYNOPSIS...JLA/SW
NEAR TERM...JLA/SW
SHORT TERM...RSH
LONG TERM...EAJ/RSH
AVIATION...JLA/SW
MARINE...SW

Special Weather Statement
National Weather Service Buffalo NY
1051 AM EDT Wed Jul 29 2020

NYZ001-002-010>012-291545-
Wyoming-Orleans-Genesee-Niagara-Northern Erie-
1051 AM EDT Wed Jul 29 2020

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN WYOMING...NORTHEASTERN
ERIE...SOUTHEASTERN NIAGARA...SOUTHERN ORLEANS AND GENESEE
COUNTIES...

At 1050 AM EDT, a strong thunderstorm was located near Alden, or near
Clarence, moving east at 35 mph.

Winds in excess of 30 mph are possible with this storm.

Locations impacted include...
Cheektowaga, Clarence, Batavia, Depew, Lancaster, Darien Lakes State
Park, Le Roy, Pembroke, Akron, Alden, Attica, Pavilion, Byron,
Oakfield, Stafford, Alabama, Covington, Corfu, Elba and Alexander.

This includes Interstate 90 between exits 48A and 48.

Torrential rainfall is also occurring with this storm, and may cause
localized flooding especially in low-lying and poor drainage areas.
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 4287 7871 4313 7866 4314 7800 4281 7800
TIME...MOT...LOC 1450Z 268DEG 28KT 4294 7853

JLA

Special Weather Statement
National Weather Service Buffalo NY
1135 AM EDT Wed Jul 29 2020

NYZ003-011>014-291630-
Ontario-Livingston-Wyoming-Genesee-Monroe-
1135 AM EDT Wed Jul 29 2020

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN WYOMING...NORTHERN
LIVINGSTON...SOUTH CENTRAL MONROE...SOUTHEASTERN GENESEE AND WEST
CENTRAL ONTARIO COUNTIES...

At 1134 AM EDT, a strong thunderstorm was located over Pavilion, or
11 miles northwest of Geneseo, moving east at 35 mph.

Winds in excess of 30 mph and pea size hail are possible with this
storm.

Locations impacted include...
Geneseo, Avon, Honeoye Falls, Pavilion, Lima, Honeoye, Hemlock, York,
West Bloomfield, Canadice, Livonia, Covington, Wyoming, Lakeville,
East Bethany, Bethany Center and South Lima.

This includes Interstate 390 between exits 8 and 10.

Torrential rainfall is also occurring with this storm, and may cause
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 4281 7815 4295 7813 4297 7748 4272 7748
TIME...MOT...LOC 1534Z 275DEG 30KT 4287 7803

JLA

Special Weather Statement
National Weather Service Buffalo NY
1151 AM EDT Wed Jul 29 2020

NYZ012-085-291645-
Southern Erie-Wyoming-
1151 AM EDT Wed Jul 29 2020

...STRONG THUNDERSTORMS WILL AFFECT SOUTHWESTERN WYOMING AND
SOUTHERN ERIE COUNTIES...

At 1148 AM EDT, a strong thunderstorm was located over Colden, or 7
miles southeast of Hamburg, moving east at 35 mph. Another
thunderstorm was developing near Derby and Eden, also moving east at
35 mph.

Winds in excess of 30 mph and half inch hail are possible with these
storms.

Locations impacted include...
Hamburg, Evans, Boston, Eden, Springville, Colden, Silver Creek,
Angola, Arcade, North Collins, Chaffee, Derby, East Concord, Evangola
State Park, Angola on the Lake, North Boston, Concord, Yorkshire,
Holland and Sardinia.

This includes Interstate 90 between exits 57A and 57.

Torrential rainfall is also occurring with these storms, and may
cause 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 4273 7906 4275 7901 4275 7816 4252 7817
      4252 7846 4254 7847 4251 7860 4252 7899
      4254 7903 4254 7908 4257 7911 4257 7913
      4255 7915 4255 7917
TIME...MOT...LOC 1548Z 275DEG 30KT 4268 7871

JLA

Special Weather Statement
National Weather Service Buffalo NY
1221 PM EDT Wed Jul 29 2020

NYZ012-013-021-085-291700-
Allegany-Livingston-Southern Erie-Wyoming-
1221 PM EDT Wed Jul 29 2020

...A STRONG THUNDERSTORM WILL AFFECT WYOMING...SOUTHEASTERN ERIE...
SOUTHWESTERN LIVINGSTON AND NORTH CENTRAL ALLEGANY COUNTIES...

At 1221 PM EDT, a strong thunderstorm was located 7 miles northeast
of Chaffee, or 12 miles southeast of East Aurora, moving east at 35
mph.

Winds in excess of 40 mph and half inch hail are possible with this
storm.

Locations impacted include...
Letchworth State Park, Perry, Warsaw, Mount Morris, Chaffee,
Portageville, Varysburg, Holland, Sheldon, Nunda, Eagle, Pike,
Castile, Silver Springs, Leicester, Gainesville, Hermitage, Bliss,
Hunt and Dalton.

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

LAT...LON 4259 7864 4275 7852 4279 7787 4249 7796
TIME...MOT...LOC 1621Z 267DEG 31KT 4267 7842

Fries

Special Weather Statement
National Weather Service Buffalo NY
1226 PM EDT Wed Jul 29 2020

NYZ013-014-291700-
Ontario-Livingston-
1226 PM EDT Wed Jul 29 2020

...A STRONG THUNDERSTORM WILL AFFECT EAST CENTRAL LIVINGSTON AND
CENTRAL ONTARIO COUNTIES...

At 1225 PM EDT, a strong thunderstorm was located over Honeoye, or 14
miles east of Geneseo, moving east at 45 mph.

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

Locations impacted include...
Conesus, Bristol, Rushville, Honeoye, Hemlock, Gorham, Canadice,
Cheshire, Cottage City, Bristol Mountain and Hall.

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

LAT...LON 4272 7774 4288 7757 4285 7698 4284 7697
      4276 7698 4276 7731 4271 7735 4265 7737
TIME...MOT...LOC 1625Z 274DEG 38KT 4275 7753

Fries

Special Weather Statement
National Weather Service Buffalo NY
109 PM EDT Wed Jul 29 2020

NYZ012-013-021-291745-
Allegany-Livingston-Wyoming-
109 PM EDT Wed Jul 29 2020

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT SOUTHEASTERN WYOMING...
SOUTHERN LIVINGSTON AND NORTHEASTERN ALLEGANY COUNTIES...

At 109 PM EDT, radar indicated strong thunderstorms were located
along a line extending from 6 miles southeast of Letchworth State
Park to near Portageville. Movement was east at 35 mph.

Winds in excess of 40 mph and pea size hail are possible with these
storms.

Locations impacted include...
Dansville, Letchworth State Park, Portageville, Nunda, Pike, Ossian,
Canaseraga, Rossburg, Hunt, Dalton, Ossian Center and Swain.

This includes Interstate 390 between exits 4 and 5.

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

LAT...LON 4248 7812 4256 7822 4265 7786 4260 7749
      4258 7749 4258 7766 4253 7766 4253 7772
      4246 7772 4244 7773
TIME...MOT...LOC 1709Z 278DEG 32KT 4258 7787 4255 7807

Fries