lake effect weather briefing #8 - lewisfirst · lake effect weather briefing #8 thursday / friday...

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Lake Effect Weather Briefing #8 Thursday / Friday – November 20-21

Significant Lake Effect Snows Flood Potential

Applies to NWS Buffalo Area of Responsibility Only

http://www.weather.gov/buf

http://www.facebook.com/US.NationalWeatherService.Buffalo.gov

National Weather Service - Buffalo NY http://www.facebook.com/US.NationalWeatherService.Buffalo.gov

@NWSBuffalo on Twitter

Recent Radar Image - 500 AM 11/19/2014

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11/20/2014




Current Headlines

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Lake Effect Snow Warning

Lake Effect Snow Advisory

Lake Effect Snow WARNINGS Erie, Genesee, Wyoming Counties through 1 AM Friday Chautauqua and Cattaraugus Counties from 6 AM Thursday through Noon Friday Jefferson and Lewis Counties from through Noon Friday Oswego County from 4 PM Thursday through 6 PM Friday

Lake Effect Snow ADVISORIES Monroe County through 7PM Thursday Livingston county through 4AM Friday




Today through Friday – Off Lake Erie

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At 600 AM, lake effect snow extends across central Erie county northeast through Monroe county Maximum snowfall rates are around 3 inches per hour

The band settles across south Buffalo, the Southtowns and eastern suburbs for the afternoon hours. Snowfall rates increasing to 3 to 4 inches per hour Snow will extend into southwest Monroe and northern Livingston counties

Lake effect snows push into the “Ski Country” – southern Erie, Wyoming, Northern Chautauqua and Cattaraugus counties late afternoon Snowfall rates 2 to 3 inches per hour

Snows continue to drift south through the evening Snows confined to Chautauqua/Cattaraugus counties Friday will weaken as

drier air builds in

While the overall the snow will be drifting south throughout the day, we will likely see some oscillation in the snowband today

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Today through Friday – Off Lake Ontario

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At 600 AM, lake effect snow extended across central Jefferson and northern Lewis counties Maximum snowfall rates 1 to 2 inches an hour

Lake effects continues across Jefferson and Lewis counties through afternoon reaching the Tug Hill Region this evening Snowfall rates increase to around 3 to 4 inches per hour

Further southward drift begins around midnight with snow across northern Oswego and southern Lewis counties

Lake snows reach central Oswego county by daybreak Friday then settle further south during the afternoon

Lake effect snows will transition toward multiband during the afternoon Friday. Lake effect snow showers will continue through Friday night along the south shore of

Lake Ontario from the eastern suburbs of Rochester to Oswego county

While the overall the snow will be drifting south throughout the day, we will likely see some oscillation in the snowband today 11/20/2014




Hourly Snowfall Rate – Threat Areas 8 AM Thursday 2 PM Thursday

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http://www.weather.gov/buf/Snow_Threat Visit this website to see hour-by-hour forecast location of the highest snowfall rates. Click “Step forward one image” located below the graphic.


http://www.weather.gov/buf/Snow_Threat



Hourly Snowfall Rate – Threat Areas 6 PM Thursday 10 PM Thursday

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http://www.weather.gov/buf/Snow_Threat Visit this website to see hour-by-hour forecast location of the highest snowfall rates. Click “Step forward one image” located below the graphic.


http://www.weather.gov/buf/Snow_Threat



Snowfall Forecast

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Today Tonight




Snowfall Forecast

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Friday Friday Night




Storm Total Forecast – Second Lake Effect Storm – through Friday

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Round TWO: Tonight through Friday

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Temperatures Will remain well below

normal through the end of the week More typical of January than

late November

Lightning and Thunder will accompany the lake snows

Winds Westerly winds will again gust to 40 mph

Blowing and drifting resulting in near-blizzard-like conditions North / South roads

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Weather Synopsis – Friday / Friday Night

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Lake effect snow will still be ongoing as we move into Friday Off Lake Erie confined to Chautauqua and western

Cattaraugus Counties Off Lake Ontario lake snows will extend along the

south shore of the lake from Monroe through Oswego counties

As the next weather system approaches lake effect snow off both lakes will sweep north as it weakens and ends

Temperatures in the low to mid 20s Friday and down into the teens Friday Night

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Friday Evening’s (7PM) Forecast Surface Map




Weather Synopsis – Saturday / Saturday Night

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A southerly flow of milder air begins

Temperatures begin to warm Daytime temperatures in the mid 30s to around 40 Overnight temperatures will slowly rise overnight

Showers also overspread the region There is a chance the precipitation may begin as a

short period of a mix of rain/freezing rain at the onset

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Saturday Morning’s (7AM) Forecast Surface Map




Weather Synopsis – Sunday / Monday

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A complex area of low pressure lifts across the Great Lakes Region

Temperatures continue to warm Daytime temperatures Sunday in the upper 40s to

around 50 and upper 50s to around 60 on Monday Temperatures Sunday Night in the mid to upper 40s

Showers are likely with this system

Forecast rainfall will range from a quarter- to three-quarter inch

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Monday Morning’s (7AM) Forecast Surface Map




Flooding Potential

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Warm-up will result in snowmelt Combination of rain and snowmelt results in flooding concerns in areas of maximum lake effect

snow A conservative estimate of 15:1 snow/water ratio could yield four to six inches of water in the snowpack

Areas of concern: Buffalo area creeks Sunday through Monday Southwest Monroe area creeks Sunday through Monday

These are generally “fast risers” Tonawanda creek may be longer term

Headwaters in Wyoming County – already two feet 48 hour lag between Batavia and Rapids Amherst/Tonawanda crest 72-96 hours after rain/snowmelt

Black River Flats of Lewis county through Jefferson County

Core samples will be taken to get a measure of how much water is in the snow. Hydrologic models will be run after that information is received.

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General Reminders

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Emergency managers, government partners and media can log onto to NWSChat Live (http://nwschat.weather.gov/) to get critical warning decision expertise from the forecasters and exchange real-time information

The latest Area Forecast Discussion can be found at: http://forecast.weather.gov/product.php?site=NWS&issuedby=BUF&product=AF

D&format=CI&version=1&glossary=1&highlight=off

Follow us on Facebook and Twitter! https://www.facebook.com/US.NationalWeatherService.Buffalo.gov @NWSBUFFALO or #BUFWX

11/20/2014


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lake effect weather briefing #8 - lewisfirst · lake effect weather briefing #8 thursday / friday...

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