This is a map from wikipedia. It shows the path often taken by commercial airliners to take advantage of the jet stream when it is running from Japan to the United States. This usuallyoccurs during the winter months.
Could this thing bring radiation here? I don’t know.
During the Second World War the Japanese used the jet stream to send bombs by balloon to the United States. That would suggest to me that the wind currents are quite reliable.
From wikipedia -
The balloon campaign was the fourth attack the Japanese had made on the American mainland. The fūsen bakudan campaign was, however, the most earnest of the attacks. The concept was the brainchild of the Imperial Japanese Army’s Ninth Army’s Number Nine Research Laboratory, under Major General Sueyoshi Kusaba, with work performed by Technical Major Teiji Takada and his colleagues. The balloons were intended to make use of a strong current of winter air that the Japanese had discovered flowing at high altitude and speed over their country, which later became known as the jet stream.
The jet stream blew at altitudes above 9.15 km (30,000 ft) and could carry a large balloon across the Pacific in three days, over a distance of more than 8,000 km (5,000 miles). Such balloons could carry incendiary and high-explosive bombs to the United States and drop them there to kill people, destroy buildings, and start forest fires.
From another web site -
The balloon bombs were released from Japan in the winter months when the jet stream is the strongest. They popped up to altitude (20,000 to 40,000 ft.) and if they were lucky into the stream. They traveled along in an easterly direction crossing the Pacific at around 200 mph in the jet stream. In daytime they would ride at the maximum altitude but as time wore on they would sink. At night they would collect dew and become heavy. Below a set height the altimeter would cause a set of blow plugs (charges that released the ballast) to fire releasing the sand bag ballast. The lost of weight would cause the balloon to pop back up to altitude. This continued till all the sand bags were gone. The last ballast was the armament. Thermite bombs were armed and dropped in the last positions on the ring. Anti-personnel bombs were also used. After all the ballast was gone a picric acid block blew up destroying the gondola. A fuse was lit that was connected to a charge on the balloon itself. The hydrogen and air mixture burned the balloon envelope up as a large orange fireball.
I’m couldn’t find any information on the jet stream’s current location.
If radiation were to reach 30,000 feet and enter the jet stream, it will probably go faster than a “bomb balloon.”
I’m just speculating but I haven’t seen anything about this anywhere and I thought I would see if someone who knows more than I will talk about this.