The tropics are eerily quiet for late August, but there’s plenty going on elsewhere.
The American monsoon is encroaching westward, even to the southern California coast; Nepal and India are experiencing killer landslides in connection with the Asian monsoon; Europe’s cooling down; and there’s a heat wave in the US heartland. Let’s go around the world.
Weather in the Tropics: Atlantic Basin
No news is good news, even as Americans along the east and Gulf coasts keep a wary eye on tropical waves coming off Africa. The peak of hurricane season in the Atlantic Ocean, Gulf of Mexico, and Caribbean Sea is only three weeks away; yet, conditions remain hostile for tropical cyclone development over most of the area.
A tropical wave in the middle of the ocean showed some signs of life a few days ago, but it is now all but defunct. Still, Bertha fought the odds and eventually formed into a hurricane after nearly succumbing to dry air and vertical wind shear (change of wind with height) as it made its way towards the Caribbean islands.
Tropical Weather: Eastern/Western Pacific Ocean
The western Pacific ocean has already produced four Super-Typhoons (winds over 150 miles per hour) this year, but has now gone very quiet. You can believe in the calm before the storm — or you can believe that anomalously warm water will produce more typhoons; either way, the lull is not likely to last.
The eastern Pacific is the only place in the tropics that shows any signs of life. Tropical Storm Karina is slowly swirling westward, on a path that resembles that of Iselle. It’s too early for Hawaiians to become alarmed, but Mother Nature just seems to have it in for the island chain, so vigilance is advised.
Another system, designated 12-E yesterday, has now been promoted to Tropical Storm Lowell by the National Hurricane Center. Lowell’s likely path will take it parallel to the coast of Mexico, and then towards California.
The water is much too cold where Lowell is going to support anything more than a moderate to strong tropical storm for a while, but some of the moisture could make its way to California where it might interact with a dip in the jet stream to produce some worthwhile rain. It won’t cure the drought.
The waters south and southwest of Mexico are still very warm, and more action can be anticipated.
Monsoons, American And Asian Style
The monsoon in the American southwest is small potatoes when compared with the Asian monsoon. Nevertheless, it brings some useful rain, and cooler temperatures, to the desert and adjoining areas. This year, the rain reached the coast of southern California once this summer, and appears ready to do so again.
In Asia, the monsoon has turned deadly, which it does with exasperating frequency. Nepal has been the center of the deluge and ensuing landslides, with 65 confirmed dead and many still missing this week near the border of India, after tens of lives were lost in the first week of August near the border of China.
These monsoons are just the latest of what now seems an unending series of record-breaking rains and floods. It is relevant to ask if this is related to global warming. Warmer temperatures will allow the atmosphere to hold more moisture — the water vapor capacity of air is directly proportional to temperature. In the range of 60 to 70 degrees, air can hold approximately 3% more water vapor with each one degree rise in temperature.
More water vapor, more rain.
A Half-Hearted Heat Wave In The American Heartland
This has been a hot summer over most of the globe, but not in the United States – particularly not in the midwest, central plains, and northeast. At last, the jet stream, which has sagged south all summer, has retreated to the Canadian border. The center of the United States will be hot.
However, there’s hot and there’s unbearably hot, and this will be the former. By this date, the hours of sunlight have diminished, and heat waves simply don’t have that much oomph.
In New York, for example, there is an hour and a half less sun on August 21 than on June 21, and the sun at its zenith is at a lower angle. We’ll call it a heat wave, but not with any real conviction.
A Cooldown In Europe
After a warm winter and a hot summer, Europe’s weather pattern is changing. The low pressure center that spent most of the summer in the middle of the Atlantic Ocean has moved to the continent. Temperatures will be below normal for the next week from London to Berlin. Moscow will have to wait a few days for below normal temperatures.
What’s Next For The Weather?
As the calendar advances to fall, the jet stream normally becomes more active. This summer, it has been active over the US and is only now relaxing, while the action shifts to Europe. Whatever happens, the weather will be interesting — and, as the earth warms, perhaps unprecedented. What’s going on where you are?.