Weather Around The World, 11/25: Give Thanks; It Could Be Worse

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The forecast for Wednesday morning, courtesy of NOAA

Extreme Travel Weather Event Broccoli. The forecast for Wednesday morning, courtesy of NOAA

The big news last week was the monster snowfall in Buffalo, New York, followed by a melting rain which produced flooding.

This week, Extreme Travel Weather Event Broccoli (That’s Decoded Science’s name for what’s coming — The Weather Channel calls it winter storm Cato) will affect the mid-Atlantic coast and New England on Wednesday.

Fetch Me Some Snow, Please

Everybody knows that Buffalo is in the Great Lakes’ Lake-Effect Snow Belt. But accumulations depend critically on the distance the wind blows over the water: the fetch.

Lakes Superior and Huron are wide enough so that wind from almost any direction can create a significant snowfall.

But Lakes Michigan, Erie, and Ontario are thinner; only a wind blowing down the length of these lakes can produce snow depths measured in feet.

The Lake-Effect Snow that accompanied Extreme Weather Event Artichoke was a perfect storm for Buffalo. The city gets a lot of snow. In a normal season, Buffalo records 94 inches of snow, more than any other city of population over 200,000 in the lower 48 States. But Artichoke was something special.

There were two primary reasons for the massive accumulation of snow in and around Buffalo:

  • The storm came early in the season, when the contrast between the water, which holds some of its summer warmth well into winter, is at its warmest of the cold season. The greater the contrast between water and air temperature, the greater the snowfall potential.
  • For the wind to have maximum fetch approaching Buffalo, it has to be west-southwest. Normally cold air comes from the northwest, and Buffalo gets a glancing blow. Not this time. Hours turned into days as the wind howled across the entire expanse of Lake Erie from the west-southwest and dumped snow on the nearest shoreline.

Artichoke Departed With The Retreat Of The Polar Vortex

Extreme Weather Event Artichoke is now officially over. Temperatures have rebounded to normal or above in most of the eastern US, Lake-Effect snow has subsided, and the polar vortex has moved north into central Canada.

Potential Holiday Travel Nightmare For The East Coast

Decoded Science has named Significant Travel Weather Event Broccoli. As a wave in the jet stream, accompanied by a low pressure center at the surface, ripples up the east coast Wednesday and Thursday, holiday travel is likely to be disrupted in the major cities of the northeast.

Most of the precipitation will fall as rain along the coast, sparing the airports in Washington and New York from major snow accumulations, but planes and autos will both be slowed by heavy rain and some slushy snow along the coast. Inland locations can expect significant snow accumulations. The position of the rain/snow line depends critically on the exact path of the storm. Central Virginia, Pennsylvania, and New York could measure up to six inches of snow, while there could be as much as a foot from central Connecticut and Massachusetts through northern New England.

On Wednesday morning, Decoded Science will report fully on Significant Travel Weather Event Broccoli, including a detailed forecast for major cities.

Europe May Not Have A Holiday, But It Still Has Weather

The continent continues to be influenced by a ridge of high pressure in the upper atmosphere that is resilient to change, and which has brought an extended spell of warmer than average weather from London to Moscow.

Fierce cold from Siberia is spreading westward, and could reach much of Europe by early next week, but Paris, Berlin, and Edinburgh should remain mild through the weekend.

El Niño Now More Likely

The sea surface temperatures have increased across the Pacific. Graphic courtesy of NOAA

The sea surface temperatures have increased across the Pacific. Graphic courtesy of NOAA

Recent observations of water temperatures in the tropical Pacific Ocean indicate that an El Niño may be about to reach critical mass. As of November 24, NOAA is keeping its estimate of the probability of an El Niño developing by January at 58%. Decoded Science is revising its estimate to 50% from 35%.

Not only have the sea surface temperatures warmed, but the passing of a Kelvin wave, a wave that propagates along the equator in response to the rotation of the earth, is creating more hospitable conditions for the El Niño.

Atlantic And Eastern Pacific Hurricane Seasons Come To A Close

The eastern Pacific will conclude its official hurricane season on November 30. It has been an active summer, with unprecedented action near Hawaii and a constant flow of storms from south of Mexico along the coast. One hurricane broke records in southern Baja California and the remnants of several others caused record rains in the southwestern US.

The Atlantic hurricane season also ends on November 30. It seemed very quiet, but though the number of named systems was well below normal, there were average numbers of both hurricanes and major hurricanes (category three or higher).

Considering the hostile conditions that prevailed across the Atlantic most of the summer — dry air and strong vertical wind shear — it is surprising that any hurricanes at all were able to form. Warm water was the enabling factor, and increasing water temperatures due to global warming don’t bode well for future seasons.

Big Warmup In The Eastern US

The warm weather of the last few days, including record highs in the New York snow belt, will be interrupted by one more shot of polar air through Friday. After that a pronounced warmup is in store. All of the eastern United States will reach high temperatures as much as 20 degrees above normal next week.

This change in the overall pattern has occurred from time to time in the last year, but each time the general jet stream flow of high pressure over the eastern Pacific and a lobe of the polar vortex dipping into the midwest has returned. Maybe this time will be different.

The weather is always changing. What’s it doing where you live?

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