It's Freezing in NYC in Middle of Summer
It may be hot in New York City, but there is a place to cool down and get a cold one.
As world leaders gather in Paris for the COP21 conference on climate change, the weather pattern worldwide happens to be entering into a pattern of extremes. Unusual warm spells will affect a large percentage of the world's population over the next two weeks, but a chilly spell is expected to penetrate unusually far south into parts of the tropics.
Here are the five areas of the world we're watching for extreme weather between now and the middle of December.
North America
North American Pattern
This map shows a European ECMWF computer model forecast for temperatures next week (in degrees Celsius), relative to average for the time of year, at about 5,000 feet above sea level. Virtually the entire North American continent is shown with temperatures at or above average on this plot.
Typically when one part of North America is much warmer than normal, another part of the continent is much cooler. That won't be the case next week, the week of Dec. 6-12.
Winter warmth here often comes from large north-south swings in the jet stream, the ribbon of high winds about 30,000 feet above sea level that encircles the Northern Hemisphere. Those north-south swings can help usher tropical air north and pull arctic air south.
Instead, next week will feature a strong west-to-east jet stream over the eastern Pacific Ocean, aiming right at the middle of the U.S. West Coast before splitting into two branches. One will bring mild Pacific air into Canada while the other dips into the southern U.S. and Mexico.
As a result, very mild air will sweep across Canada, bringing extremely warm temperatures (by December standards) across the entire country. Some of that warmth will spill over into the northern U.S. as well.
Meanwhile, the southern U.S. and Mexico probably won't see record-breaking warmth, but the southern branch of the jet stream may dip far enough south to keep a tropical or subtropical influence on the weather pattern over the southern U.S., allowing temperatures to at least hover a little above average for early and mid-December.
Europe
Europe Warmth
A plot from the American GFS computer model shows an unusually warm pattern expected over the European continent on Dec. 11, 2015, as reflected in the altitude above sea level of the 850-millibar atmospheric pressure level.
Most of Europe is already in the grips of exceptionally mild December weather pattern, and that is likely to continue in most areas through next week.
In Europe's case, however, it is an unusually strong northward bulge in the jet stream that's to blame (or credit) for the warm spell. While the orientation of that jet stream will change from time to time over the next 10 days, it will generally tend to snap back to a path over the United Kingdom and Scandinavia.
This will leave most of the European continent in a zone of mild weather. In parts of Scandinavia and the Baltics, cities that normally see sub-freezing high temperatures this time of year may instead have above-freezing low temperatures.
While the position of the jet stream will bring periods of precipitation (mostly rain) to the U.K. and Scandinavia, areas south of there will see next to nothing in terms of rain and snow through Dec. 10 or so. That means no snow for Alpine ski resorts for at least a week – but also no rain for most people living or vacationing in Spain, Italy and Greece.
According to the official French meteorological agency, Meteo-France, mild weather will persist throughout the week of Dec. 7-13, with "calm and rather dry weather in the south of the country, and a few rainy spells in the north." The agency's outlook for Dec. 14-27 calls for temperatures to "remain above seasonal normals nationwide."
Siberia and East Asia
Norilsk, Russia
Norilsk, Russia, seen in this photo from the winter of 2012-13, is the world's coldest city with a population of 100,000 or more. The sun never rises in December, and average daily high temperatures are below zero even on the Fahrenheit scale. (Photo credit: Elena Chernyshova)
A vast zone of unusually mild air is already in place over Siberia, and by next week unusually warm weather is expected to expand farther south into the much more highly populated areas of East Asia, including parts of China, Japan and South Korea.
Siberia, a vast and sparsely populated region of the Russian Federation, is home of some of the world's coldest inhabited places. The current pattern is not so much a warm spell as it is a reprieve from the typically brutal winter cold of the region.
In the Russian city of Norilsk, which is north of the Arctic Circle and never sees the sun rise during the month of December, the temperature surged to 23 degrees above zero Fahrenheit (minus 5 Celsius) on Tuesday, Dec. 1. That's much warmer than the average highs in December, which hover in the single digits below zero Fahrenheit (20s below zero Celsius).
In an outlook issued Monday, the Japan Meteorological Agency said there is at least a 30 percent chance that temperatures during the week beginning Dec. 6 will rank within the warmest 10 percent of all recorded temperatures in history for this time of year across the major industrial cities of Japan from Tokyo westward, including Osaka, Nagoya, Hiroshima and Fukuoka. This region, known as the Taiheiyō Belt, contains the vast majority of Japan's population.
Middle East and North Africa
Middle East Cold Snow
Brightly colored areas indicate locations where The Weather Channel forecasts snowfall accumulations (bright shaded areas) for Dec. 3 through Dec. 9, 2015, across the Middle East. Accumulations exceeding a foot are anticipated in the mountains of Iran, far northern Iraq, Turkey and the Caucasus. Fainter shaded areas with dark outlines indicate locations where The Weather Channel expects low temperatures to fall below freezing on Dec. 9. Lines within those regions indicate colder temperatures in increments of 1 Fahrenheit degree (about 0.6 Celsius degree).
As unusually warm air parks over Europe and Siberia, the large-scale circulation of the atmosphere may drive some of the chilly air typically seen in those regions southward into the Middle East and even parts of North Africa through next week.
Widespread snowfall will accompany this cold surge late this week through early next week across the mountains of the Caucasus (Georgia, Armenia, Azerbaijan) as well as Turkey, Iran and far northern Iraq. It may even be cold enough for a brief period of snow in the Iranian capital, Tehran.
A much larger area will feel the cold air. Lows may drop below freezing in the deserts as far south as northern Saudi Arabia at times by early next week. In Baghdad, readings may drop close to the freezing mark at night – probably not welcome news in a city beset by infrastructure problems and frequent power outages.
In the immediate Persian Gulf region, however, the cooldown may be welcome after a brutally hot summer. Dubai may finally see low temperatures drop below 20 C (68 F) for the first time since April 4.
What remains to be seen is the potential impact of the cold air intruding even farther southwest into North Africa – particularly the Sahel, the region just south of the Sahara Desert stretching from Mauritania and Mali east to Sudan.
Those areas are in the tropics – around the same latitude as southern Mexico – and therefore not accustomed to huge variations in temperature. But computer model forecasts suggest this unusual weather pattern could send temperatures some 4 to 8 Celsius degrees (7 to 14 Fahrenheit degrees) below average in a region already dealing with malnutrition, drought and pockets of armed conflict.
South Africa
South Africa Heat
The Weather Channel forecast highs (in degrees Fahrenheit) for southern Africa, issued Dec. 2, 2015 and valid for highs Monday, Dec. 7, 2015. Highs exceeding 100 F (38 C) are seen in parts of South Africa and Botswana, with highs exceeding 90 F (32 C) extending into parts of Namibia, Zimabwe, Zambia and Mozambique.
The Southern Hemisphere's day-to-day weather patterns are generally not affected in any noticeable way by what goes on in the Northern Hemisphere, but parts of southern Africa will have their own extreme weather to deal with.
This is actually not big news for the region, which is moving toward the end of its spring season and has already seen record-shattering heat several times in the past six weeks.
In fact, Augrabies Falls National Park in South Africa reported a high of 114 degrees (45.3 C) on Tuesday, which appears to have broken the all-time record it just set on Oct. 27, when it hit 110 F (43.5 C). A caveat, however: only 31 years of records are available at this site.
South Africa's capital city, Pretoria, and the nearby financial hub of Johannesburg, both set all-time record highs Nov. 11 and may challenge those records again in the Dec. 6 through Dec. 8 time frame.
Pretoria reached 104 degrees (40 C) in the November heat wave, while Johannesburg topped out at 97 F (36 C); forecast highs this weekend look to be a bit short of that but still exceptionally hot for the region, which sits more than 4,000 feet above sea level.
The hot and dry pattern is not what the region needs; according to the BBC, South Africa is now facing its worst drought in 30 years – and scientists believe the pattern has strong ties to the strong El Niño thousands of miles away over the eastern Pacific Ocean.
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