Weather Around The World, 6/9: Temperatures Soaring And Weather Systems Spinning

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Tropical cyclone Ashobaa is headed for Oman. Forecast courtesy of US Navy.

Tropical cyclone Ashobaa is headed for Oman. Forecast courtesy of US Navy.

It’s summer in the northern hemisphere, so it’s time to talk about heat waves.

But this week features a wide array of meteorological happenings: heat in the northwest; cold in Boston; tornadoes in China and Colorado — one of which even spun the wrong way; tropical systems in the Indian and eastern Pacific Oceans; wettest May ever in the lower 48; and talk (which is cheap) at the G-7 economic summit of combating climate change.

Let’s go Around The World.

The Heat: Record High Temperatures In The Pacific Northwest

Increasingly common folds in the jet stream are forcing cold air south and warm air north on a regular basis. This week a ridge over the northwest has produced record high temperatures in several states.

Some records set on Monday:

  • Medford, OR, 105, beating the old record by four degrees.
  • Seattle, WA, 83, beating the old record by six degrees.
  • Lewiston, ID, 100, beating the old record by four degrees.
  • Burbank, CA, 102, beating the old record by four degrees.

The heat will moderate in the west during the week, as the jet stream flattens out. But with the jet stream now taking a northerly route, parts of the southern plains and the southeast could see temperatures approaching record levels.

The Cold: New June Record In Boston

For the first time since anyone began to ‘officially’ record the temperature in Boston (since 1880), the maximum failed to reach 50 degrees for two consecutive days in June, topping out at 49 on the first and second.

This is a residual effect of the extremely cold winter; water temperatures are still about five degrees below normal — in the upper 40s. A stiff wind off the water limited the temperatures on the two record-setting days.

Anticyclonic Tornado In Colorado On Saturday

Tornadoes are so narrow that occasionally one can ignore the Coriolis force and spin the wrong way. Photo courtesy of NOAA.

Tornadoes are so narrow that occasionally one can ignore the Coriolis force and spin the wrong way. Photo courtesy of NOAA.

A rare, but not unprecedented, anticyclonic tornado was reported Saturday in Colorado. We’ve all learned that in the northern hemisphere air moves with low pressure on its left, and that cyclones rotate counterclockwise.

The balance of pressure against centrifugal force causes air parcels to move between isobars (lines of equal pressure) and the Coriolis force, arising from the rotation of the earth, requires the movement to be with high pressure on the right.

Occasionally a small system, such as a tornado, spins the wrong way because on a small scale the Coriolis force is small and the air parcels ignore it in comparison to the strength of the other two forces.

Except for the direction of rotation, cyclonic and anticyclonic tornadoes are identical.

Tornado Implicated In Sinking Of Chinese Cruise Ship

The Chinese cruise ship Eastern Star capsized in the Yangtze River last Wednesday when it was apparently hit by an EF-1 tornado with winds up to 100 miles per hour.

The storm struck so suddenly that the crew had no time to issue warnings, get passengers into lifeboats, or even distribute life jackets.

Tornadoes are not as common in China as in the American heartland, but the same general conditions exist: Warm, humid air flows inland from the China Sea, while a drier flow from the west blows over the top. The result is a conditionally unstable atmosphere which is subject to violent overturning when a lifting mechanism is present.

A frontal boundary set off a wide swath of severe weather in the vicinity of the cruise ship. Why the captain was unaware of the danger is unknown, but he is one of the few survivors and is in police custody.

Tropical Cyclone Ashobaa In The Arabian Sea

The Indian subcontinent can be a troublemaker, crashing into Asia to build the Himalayas and cause the faulting responsible for the recent earthquakes in Nepal.

But there is a benign side to this tongue of land sticking out into the Indian Ocean: It has a mitigating effect on tropical cyclone formation by splitting the North Indian Ocean into the Bay of Bengal to the east and the Arabian Sea to the west, interrupting the development of tropical waves.

Nevertheless, cyclones do form in situ — normally one or two per season -and newly-named Cyclone Ashobaa is now threatening the area around the Gulf of Oman.

Ashobaa will reach minimal hurricane strength before feeling the effects of the dry air over the Saudi Arabian peninsula and winding down before reaching land.

Cabo San Lucas Dodges A Bullet As Hurricane Blanca Passes Offshore

Last year Cabo San Lucas on the southern tip of Baja California was devastated by category three Hurricane Odile.

Hurricne Blanca took a scarily similar path this week, with minor but hugely significant differences.

  • Blanca’s path was about 90 miles west of Odile’s.
  • The water temperatures at this time of year are several degrees cooler than they were in September when Odile struck.

The result was just a glancing blow to Cabo, with winds barely touching tropical storm strength, though Blanca was still a hurricane at its closest approach. Blanca made landfall at San Carlos on Monday, with top winds of around 50 miles per hour, and has now dissipated over Baja.

Though the winds connected with Blanca are no longer a concern, the moisture from the system is expected to bring heavy rain to northern Mexico and Arizona today, moving to Colorado and Utah on Wednesday.

Surprise (just kidding): New May Record For Rainfall In Contiguous US

If you live in northern Texas or southern Oklahoma, you know you experienced the wettest May ever. But did you know that your contributions carried the entire lower 48 to a new May record?  Way to go!

The new record was an average of 4.36 inches of melted precipitation, which amounts to over 200 trillion gallons of water.

G-7 Leaders Reach Vague Agreement On Climate

The leaders of seven top economic powers met this week to discuss such matters as Ukraine, Greece, world poverty, and refugees. Since the meeting was in Germany, the host, Angela Merkel, was able to press for discussion of climate change.

In the end, the leaders agreed, with no binding commitment, to try to reduce greenhouse gases to 40 to 70 percent below the levels of 2010 by the year 2050.

With global temperatures continuing to climb and possibly accelerating upwards, the meeting in December of the Conference of the Parties to the United Nations Framework Convention on Climate Change looms as a potential milestone — or possibly just another failure.

Summer Is Here

Do you notice the climate changing where you live? Let Decoded Science know what you see.

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