Back in May, we watched one of the most powerful tornadoes on record buzzsaw across the plains near El Reno, Oklahoma. This week, Super Typhoon Haiyan, one of the most powerful tropical cyclones on record (it may be the most powerful) slammed into the Philippines. At landfall yesterday, its estimated sustained winds were 195 mph with gusts to 235 mph. To help put that in perspective, the EF-5 tornado that struck Moore, OK back on May 20th had estimated winds of 210 mph.

Haiyan is an absolutely perfect example of what a well-organized tropical cyclone looks like. The symmetry is perfect. The eye is razor sharp and is perfectly circular. Even the storm’s anticyclonic outflow aloft is perfect. It is literally a saw blade cutting across the southwest Pacific and the South China Sea.

Haiyan Satellite on Thurs, Nov. 7, 2013 

Models are indicating that Haiyan will continue to push northwest across the South China Sea and slam into the east coast of Vietnam. Due to the orientation of the Vietnamese coastline, the storm may move close to parallel to the coast, which could lead to a larger damage swath. Flooding could become a major problem if the storm moves far enough north, as there is nowhere for the water to go if it gets up in the area near the China-Vietnam border. The good news is that the storm is expected to move over an area of both lower sea surface temperatures and higher shear, which will continue to weaken the storm. That being said, however, the storm is so strong it will not weaken very quickly and is expected to make landfall in Vietnam as a Category 3 storm, with sustained winds around 120 mph.

Now let’s change gears completely and talk about more extreme weather at the opposite end of the spectrum. From Haiyan, let’s shift about 2300 miles northwest to eastern Nepal and talk about some extreme mountain weather. During the fall, the polar jet stream shifts south as the transition from summer to winter occurs. The world’s tallest mountain range sits in a prime location to interact with the jet stream as it shifts south, which brings incredibly extreme conditions to the higher elevations.

Currently, a powerful upper-level storm system has been centered over the far western part of China, with the main branch of the 500 mb jet streaming across China, Nepal, and Tibet. That storm will reach its peak intensity sometime this weekend, with the southwesterly flow of the jet stream reachings peak strength from the northern plains of India across Nepal and into Tibet and China. One small wrench that gets thrown into forecasting for this region is that the 500 mb jet is usually found around 17,000 feet, and many of the Himalayan peaks are much higher than that, so we need to look higher in the atmosphere.

GFS 500 mb forecast for Saturday at 0600 UTC 

Conveniently, many of these powerful upper-level storm systems feature a much more powerful jet at 300 mb (it blows harder due to lower air pressure). This 300 mb jet is typically found around 30,000 feet, which matches up nearly perfectly with the highest peaks of the Himalayas. One peak that aligns nearly perfectly with the strongest area of the jet stream is Mt. Kangchenjunga, which at 28,171 feet is the third highest mountain in the world. The peak is located in the far northeastern corner of Nepal and sits right on the border with India.

If we look at the GFS forecast at 300 mb (the red x marks the location of Mt. Kangchenjunga), we can see a clear jet streak centered over Mt. Kangchenjunga. The ferocious winds of this jet streak, combined with the cold air being brought down by the upper-level low, will lead to bone crushing wind chills and incredibly extreme conditions this weekend. At the summit of Mt. Kangchenjunga, sustained winds will be out of the southwest at 140 mph, with actual temperature in the -20’s Farenheit. This combination will result in wind chills between -70 and -75°F. Thankfully, nobody lives at these extreme elevations, but you can sure see why climbers need to pick their days carefully when they attempt to summit the Himalayan Peaks.

GFS 300 mb wind forecast for Saturday at 0000 UTC 

These conditions are somewhat common on the peaks of the Himalayas as upper-level storm systems pass through. They just don’t get a lot of coverage because they are not impacting any forms of life. The only other place in the world that sees conditions similar to this are the highest mountain peaks in Alaska and the Yukon Territories. While the Rocky Mountains see plenty of their own extreme weather, they are not tall enough to pierce the main branch of the jet stream. Mountain meteorology is pretty fascinating this time of year, and I will definitely be posting more on this topic as we get into winter.

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