Special Marine Warning 69, NWS Buffalo, NY

Area Forecast Discussion
National Weather Service Buffalo NY
427 PM EDT Tue Aug 6 2019

.SYNOPSIS...
An upper level trough moving across the Great Lakes region will
maintain chances for showers and thunderstorms through Thursday.
A few of these storms will bring a soaking rainfall along with
gusty winds. A cool front will cross the area Thursday, ending the
period of showers and thunderstorms, while bringing much cooler
and less humid air into our region for Friday.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Visible and Water Vapor imagery this afternoon displays several key
features that will influence our weather the next 24-hours. The
first are several N-S boundaries formed from prior convection that
are passing across the eastern end of Lake Ontario. These features
will bring storms into the Finger Lakes and Eastern Lake Ontario
region through the early evening.

The second feature is an outflow boundary dropping southward across
WNY...mainly west of the Genesee Valley. This feature is likely to
interact with storms blossoming over the Southern Tier...to produce
a few stronger storms with gusty winds. Instability is not the
greatest...with ML CAPE values around 500 to 1000 J/KG across the
Southern Tier this mid afternoon and shear values are low with winds
up through 600 hPa generally less than 30 knots. Thus, the severe
threat will remain low with perhaps an isolated strong to severe
storm here. If any of these storms begin to train over the same
area, ponding of water in low lying areas is likely.

The third feature is an MCV across western OH. This feature will
slowly rotate eastward through the evening hours towards WNY. While
daytime storms will begin to wane through the evening with the loss
of daytime instability...this feature is likely to bring an uptick
in showers and isolated thunder for the second half of tonight
across WNY. This feature will bring morning showers with isolated
thunder through the first half of Wednesday.

A fourth feature...this a subtle shortwave moving across IA/MO will
dip into the lower Ohio River Valley tonight. This feature will
maintain an upper level trough across our region tomorrow...which
will continue the threat for showers and thunderstorms through the
day.

Temperatures tonight will remain mild with lows in the 60s.
Dewpoints will not be much lower and some pockets of fog and or low
clouds are possible across the hills of SW NYS and also SE and E of
Lake Ontario tonight. The presence of an upper level trough,
combined with morning cloudiness will make tomorrow cooler than
today...with highs in the mid to upper 70s.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
The main upper level low that will bring the first shot of cooler
weather to the region late this week is clearly identifiable over
northern Saskatchewan and Manitoba via GOES water vapor channels.
this system will move into Northern Ontario by Wednesday night with
a surface cold front extending from the midwest northeast through
the SOO. Downstream over WNY, there should be a break in convection
as daytime heating and associated convection along and east of lake
breezes move east and wane with the loss of heating.

The next focus will be with the cold front itself and/or a subtle
prefrontal trough that will bring a high likelihood for more showers
and thunderstorms across the region.  Compared to earlier in the
week, shear will be a little higher, with a corresponding higher
severe weather threat, at least for WNY which will be closer to the
upper level jet that will be moving SE toward the Ohio Valley.

With the cold front passage, expect notable drying and abundant low
level mixing, enough for breezy conditions over WNY late Thursday
and further east into the evening (and over the Eastern Lake Ontario
region) Thursday night.  Temperatures aloft drop enough for for a
lake response overnight, but there will probably be some subsidence
behind the front.  Latest model soundings seem to indicate some dry
air below the inversion, so will back off overnight from possible
lake effect showers overnight.

Friday, the coldest air aloft will move toward the region, while a
shortwave trough rounds the base of the low to the north and moves
across the region.  But by this time, the lower portions of model
profiles appear to be rather dry aloft with trapped mid level
moisture. This should result in an abundant cumulostratus (aka self
destruct sunshine resulting in mostly cloudy skies) with a hybrid
lake effect and upslope cloud field with evolving lake shadows in a
WNW-->W flow during the day. There may be a slight chance for brief
showers or sprinkles, but otherwise it should be notably cooler and
breezy day.

This trend will continue Friday night, with improved chances for
some lake effect banding ESE of Lake Ontario as the coldest air
aloft grazes the region from the north.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Breezy northwest winds will diminish but continuing sufficient over-
water instability should result in more lake effect showers Friday
night into Saturday morning. Only have chance pops where low-level
convergence should be strongest to the southeast of Lake Ontario.
Similar to what occurs Friday, may see showers expand somewhat on
Saturday during peak heating downwind of the lakes. At the least
will see partly to mostly cloudy skies. Temps again will struggle
into the lower 70s which is 5-10F below normal for this time of
year.

A mid-level ridge will begin to build into the Great Lakes region
Saturday and last through Sunday. Surface high pressure will track
off the Mid-Atlantic coast by Sunday. Warm air advection will occur
during this time and winds will back to the southwest. The increase
to subsidence and warming aloft will put an end to any lake effect
rain showers making Saturday night fairly dry.

High pressure will move off the east coast Sunday through Monday and
southwest flow and warmer temperatures will continue to move into
the region. Another cold front will move through the region into the
next work week.

Temperatures will begin to rebound, reaching the the upper 70's
Sunday and Monday. With the high pressure the main weather feature,
low temperatures will average the low to mid 50's during the weekend
and into early next week, though readings in the 40s will be
possible at typical colder inland spots any one of those nights
along with some patchy fog.

&&

.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
For the 21Z TAFS showers and thunderstorms will be scattered to
numerous across the TAF region through 23Z...diminishing
during the evening with the loss of daytime heating.

An MCV will bring additional showers and isolated thunder back into
our region for the second half of tonight. This feature will bring a
reduction to flight conditions across WNY...with IFR possible across
KJHW/KBUF. Elsewhere MVFR flight conditions are likely with this
feature.

An upper level trough will continue across the region tomorrow with
showers and chances for thunderstorms continuing through the
afternoon hours. Any storm could bring brief flight reduction to
IFR/MVFR.

Outlook...

Wednesday night...Shower and thunder ending through the evening.
Mainly VFR.

Thursday...Mainly VFR, with likely showers and thunderstorms
producing local/brief MVFR to IFR.

Friday through Sunday...Mainly VFR.

&&

.MARINE...
An upper level trough will slowly pass across the Eastern Great
Lakes region tonight though Thursday. This feature will bring
showers and thunderstorms...with surface winds generally 10 to 15
knots. Waves will range from a foot up to three feet through
Thursday.

Looking further out towards the end of the week, a strong cold front
by summer standards will cross the eastern Great Lakes Thursday
evening. West to northwest winds will increase in the wake of the
front with Small Craft Advisory conditions looking likely later
Thursday night through Friday evening. In addition, a very cool
airmass making its way across the Lower Great Lakes may favor the
development of waterspouts late Thursday night into Friday morning
and again late Friday night into Saturday morning. At this time,
only included chance of waterspouts Friday night into Saturday
morning since winds in the lowest 5kft will lighten by that time
which favors low-level convergence/waterspout formation and also
helps not disrupt/rip apart any waterspouts that do try to form.
Stay tuned.

&&

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

&&

SYNOPSIS...Thomas
NEAR TERM...Apffel/Thomas
SHORT TERM...JLA/Zaff
LONG TERM...HSK/JLA
AVIATION...Apffel/Thomas
MARINE...Hitchcock/JLA/Thomas

Hazardous Weather Outlook
National Weather Service Buffalo NY
356 AM EDT Tue Aug 6 2019

NYZ004>007-070800-
Wayne-Northern Cayuga-Oswego-Jefferson-
356 AM EDT Tue Aug 6 2019

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

.DAY ONE...Today and tonight.

A few thunderstorms today could produce gusty winds and heavy
downpours. There is a marginal risk of an isolated severe storm.
Localized flooding could occur, especially if thunderstorms move
repeatedly over the same area.

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

A few thunderstorms on Wednesday could produce gusty winds and heavy
downpours. There is a marginal risk of an isolated severe storm.
Localized flooding could occur, especially if thunderstorms move
repeatedly over the same area.

Moderate to strong northwest winds will result in shoreline erosion,
and increase the potential for lakeshore flooding Thursday night into
Friday.

.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>003-008-010>014-019>021-085-070800-
Niagara-Orleans-Monroe-Lewis-Northern Erie-Genesee-Wyoming-
Livingston-Ontario-Chautauqua-Cattaraugus-Allegany-Southern Erie-
356 AM EDT Tue Aug 6 2019

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

.DAY ONE...Today and tonight.

A few thunderstorms today could produce gusty winds and heavy
downpours. There is a marginal risk of an isolated severe storm.
Localized flooding could occur, especially if thunderstorms move
repeatedly over the same area.

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

A few thunderstorms on Wednesday could produce gusty winds and heavy
downpours. There is a marginal risk of an isolated severe storm.
Localized flooding could occur, especially if thunderstorms move
repeatedly over the same area.

.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-SLZ022-024-070800-
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-
356 AM EDT Tue Aug 6 2019

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.

No hazardous weather is expected at this time.

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

There is a chance of waterspouts Friday night into Saturday morning.

.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

JLA

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Special Weather Statement
National Weather Service Buffalo NY
536 PM EDT Tue Aug 6 2019

NYZ001-010-012-020-085-062215-
Cattaraugus-Southern Erie-Wyoming-Niagara-Northern Erie-
536 PM EDT Tue Aug 6 2019

...A GUST FRONT WILL AFFECT WESTERN WYOMING...NORTH CENTRAL
CATTARAUGUS...ERIE AND SOUTH CENTRAL NIAGARA COUNTIES...

At 534 PM EDT, radar indicated a gust front located along a line
extending from 10 miles southwest of Niagara Falls to 7 miles
southeast of Springville. Movement was northeast at 45 mph.

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

Locations impacted include...
Buffalo, Cheektowaga, West Seneca, North Tonawanda, Clarence,
Lackawanna, Kenmore, Depew, Amherst, Tonawanda, Lancaster, Hamburg,
East Aurora, Williamsville, Grand Island, Elma, Boston, Eden,
Pendleton and Marilla.

This includes Interstate 90 between exits 57A and 49.

LAT...LON 4273 7906 4276 7898 4280 7892 4284 7893
      4291 7890 4293 7891 4296 7893 4296 7896
      4299 7901 4314 7865 4290 7846 4287 7846
      4287 7841 4266 7817 4246 7871
TIME...MOT...LOC 2134Z 259DEG 39KT 4305 7935 4245 7856

HSK

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Special Weather Statement
National Weather Service Buffalo NY
544 PM EDT Tue Aug 6 2019

NYZ001-002-062245-
Orleans-Niagara-
544 PM EDT Tue Aug 6 2019

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT NIAGARA AND WESTERN
ORLEANS COUNTIES...

At 542 PM EDT, radar indicated strong thunderstorms were located
along a line extending from 6 miles northeast of Sanborn to 24 miles
west of Fort Niagara State Park. Movement was east at 15 mph.

Winds in excess of 30 mph are possible with these storms. Very heavy
rain is also occurring.

Locations impacted include...
Lockport, Medina, Newfane, Lewiston, Youngstown, Middleport, Fort
Niagara State Park, Ridgeway, Shelby, Wilson, Lyndonville, Barker,
Cambria Center, Olcott, Ransomville, Gasport, Model City and
Appleton.

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

LAT...LON 4330 7909 4336 7883 4341 7835 4315 7837
      4314 7904 4317 7905 4325 7906 4328 7908
      4329 7909
TIME...MOT...LOC 2142Z 264DEG 20KT 4322 7881 4321 7954

HSK

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