Weather Around The World, 11/17: Climate Talks A week Away; Northern Hemisphere Slides Towards Winter

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Home / Weather Around The World, 11/17: Climate Talks A week Away; Northern Hemisphere Slides Towards Winter
Today's forecast calls for widespread snow, some heavy, in the Rockies. Forecast courtesy of NOAA.

Today’s forecast calls for widespread snow, some heavy, in the Rockies. Forecast courtesy of NOAA.

In less than two weeks, COP21 (the twenty-first Conference of the Parties to the United Nations Framework Convention on Climate Change) will convene in Paris to try to put a lid on global warming.

The President of France assured everyone that the conference will be held, despite the recent violence in Paris.

Meanwhile, weather is increasingly winter-like over the US and Europe — and correspondingly summer-like Down Under.

Let’s go Around The World.

Climate Talks To Draw Increased Security

When Francois Hollande, President of France, was asked if COP21 would be postponed or canceled, he answered “No, no, no, no, no.” Pretty emphatic, I would say.

Of course there will be stepped up security there, as elsewhere, in the wake of the terrorist attacks. Some have asked whether Isis perpetrated these crimes with the intent of interfering with the climate conference. The weather is hard enough to explain, so Decoded Science declines to try to go inside the head of a terrorist.

Approximately 4,000 delegates are expected for the conference, including 127 heads of state. US President Obama and Secretary of State Kerry are planning to go. Though it’s always good to be optimistic, the question arises whether this is too large a number of conferees to produce anything effective. On the other hand, what other way is there if greenhouse gas emissions are to be curbed worldwide?

All countries were supposed to submit emissions goals, known as Intended Nationally Determined Contributions (INDC), by October 1, but about 30 have not yet done so. The cooperation of all major emitters, and probably virtually all emitters, is necessary in order for the conferees to be able to promulgate emissions standards that can be enforced. That much cooperation has not been in evidence in the previous 20 Conferences of the Parties. Will the 21st be any different?

Snow, Wind, Cold In The Northern Hemisphere

As the sun’s heat wanes in the northern hemisphere, cold air advances southward and the jet stream, which essentially is a reflection of the temperature gradient on the ground, moves south and strengthens. Incursions of cold air into the southern Rockies and central Europe are bringing snow and wind.

This week’s weather in the US will mirror last week’s, with an active storm early and mid-week, as a strong trough (dip) in the jet stream allows low pressure to form at the surface. Later in the week, the jet stream relaxes , pressure gradients (change of pressure with distance) at the surface relax, and conditions return to normal for the season.

Thunderstorms And Hail In Australia

Just as thunderstorm frequency increases during northern hemisphere spring, the same thing happens in the southern hemisphere — where spring is now. On Thursday, severe thunderstorms hit Melbourne with hail reported. The storms moved northeast to Sydney on Friday.

As the sun rises higher in the sky in the spring, it heats the ground, which in turn heats the lower atmosphere relative to the mid-levels. The whole column of air becomes more unstable (simply put, warm air rises and if it’s warm enough it keeps rising). In the spring, when cold fronts still make equatorward incursions into the temperate latitudes, the fronts provide a lifting mechanism. Spring storms generally occur in clusters or lines; as summer advances and fronts are not so active, severe weather tends to be more isolated.

Weather Channel Names A Winter Storm: Ajax

The storm in the central US is a reflection of a pronounced dip in the jet stream. Analysis courtesy of NOAA.

The storm in the central US is a reflection of a pronounced dip in the jet stream. Analysis courtesy of NOAA.

The variety of bad weather associated with a strong jet stream trough has been named winter storm Ajax by the Weather Channel (WC).

Decoded Science has agonized over what to do with winter storms and their names. At first, we went along with the WC.

We recognize the usefulness of being able to refer to a weather event with a single designation. But the nature of winter storms makes using that category unwieldy.

Last year we began to name weather events and patterns by using names that carried some meaning, such as last year’s weather pattern Yeti, which brought so much snow to the northeast.

Here’s the problem: Winter storms create all kinds of weather, not necessarily connected with any particular meteorological metric.

The analogy to tropical cyclones is tempting, but leads us astray. Cyclones are defined by central pressure and maximum wind; no such objective criteria are available for winter storms.

The Weather Channel has promulgated confusing criteria for naming storms. They have something to do with area covered and population affected. But winter storms can produce snow, rain, wind, hail, lightning, cold, and ice in various combinations.

Decoded Science will unapologetically continue to name non-tropical weather events on a purely subjective basis, whenever we feel such an event is meteorologically noteworthy or will affect people in a significant way. We will choose names that in some way convey the type of event.

The Weather Channel’s Ajax does not live up to our criteria at this time. It is simply a common late fall reflection of the re-energized jet stream; those experiencing snow and cold are accustomed to such weather at this time of year.

This is not to say that up to two feet of snow in the Rockies won’t cause some inconvenience for travelers — and glee for skiers.

Atlantic And Eastern Pacific Tropical Cyclone Seasons Ready To Wrap Up

November 30 marks a beginning (of COP21) and an end (of the hurricane season). The Atlantic season, as per most forecasts, was quiet due to El Niño. The western Pacific was active — again the expected result of El Niño. There is currently no activity in the Atlantic, but an area of disturbed weather in the Pacific well west of the Mexican coast has a 20% chance of developing according to the National Hurricane Center.

The 27th tropical storm of the western Pacific season will very likely become a typhoon as it passes Guam, and could threaten Asia. Forecast courtesy of US Navy.

The 27th tropical storm of the western Pacific season will very likely become a typhoon as it passes Guam, and could threaten Asia. Forecast courtesy of US Navy.

In the western Pacific, there are disturbed areas in both the northern and southern hemispheres, one of which is forecast to become a typhoon.

There is also a potentially developing system in the Indian Ocean.

The peak of worldwide tropical cyclone activity has passed, but with oceans warming, there is the possibility of a tropical cyclone somewhere in the world year round.

Weather Around The World Looks Ahead

NOAA is scheduled to issue its October global land and sea temperature report on Thursday. This will be the last such report before COP21, so it could have outsized importance to the conferees. Decoded Science will have an in-depth report on the report as soon as it hits the wires.

Meanwhile, how’s the onset of winter (or summer, depending on your hemisphere) progressing in your neighborhood?

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