March 29, 2022

A Super Jet Stream Will Cross the Pacific this Weekend.

If you want to take a very fast flight across the Pacific from Tokyo to Seattle, book your ticket on Sunday.

Normally, such flights take about 8.5 hr.   But Sunday you will do it in well under 8 hours..perhaps as short as 7.5 hr--and I suspect the route will be more direct than normal.

The reason: a nearly continuous, strong jet stream across the Pacific.

As a reminder, a jet stream is a relatively narrow current of strong winds in the upper troposphere and lower stratosphere, typically found between 25,000 and 40,000 feet above sea level.

To illustrate, here are the predicted winds (in knots) at around 38,000 ft (200 hPa pressure) at 5 PM PDT Sunday..  Reds and browns are the strongest winds-- with the most energetic winds of 150-175 knots (175-200 mph)

A balloon released from Japan could make it across the Pacific (roughly 4700 miles) in roughly a day in a half.  

The jet stream is the locus of clouds and storms and a map of predicted cloudiness (simulated satellite image) for 5 PM PDT Sunday shows the continuous ribbon of clouds across the Pacific.

To have some fun, I used the NOAA Hysplit system to calculate three-dimensional air trajectories, tracing the previous path of air reaching over Seattle at 3 PM Sunday at 8000 meters and 10,000 meters above sea level (see figure).  I plotted the air trajectories over the past 60 hours.  

The over Seattle on Sunday will have come from Japan!

From Mount Fuji to Mount Rainier in about 50 hours. And before that North Korea and Russia.

The airspace of our planet is very interconnected..... something we should never forget.


  1. Will this also bring another round of "tropical" walls of rain?

  2. Perfect Fu-Go balloon weather

  3. To germinate my grass seed, I wish we could forecast a stream of warm air, my seed is going to get 'trench root'.

  4. The most direct route is the great circle which is farther north than where the wind chart shows the jet stream. But the airlines will take whichever one produces the shortest estimated time enroute, even if it's farther.

    1. The airlines coming from Asia to North America usually take a slightly southern route compared to the great circle to take advantage of the jet stream. Going the other way (North America to Asia) they'll take the more northern route.

  5. I thought the more common routes from Asia to North America (and back) usually involved routes over the Arctic, regardless of the jet stream conditions at the time. Interesting that it took inaccurate Super Fortress bombing runs over Japan during WWII in order to discover the jetstream phenomenon.

  6. The great circle should actually be called the great straight

  7. So...if tactical nukes are employed in the Ukraine now, in 50 hours, we could have fallout here in the West Coast?

  8. I've taken that flight many many times and don't appreciate the tail wind. When you arrive at 7 a.m., customs makes you wait on the plane until 8 a.m. when they are done with coffee and donuts.


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