An extraordinary weather event has been occurring above our heads on July 18, 2019.
A new totally unusual record has been broken: The strongest summer jet stream ever observed over the Pacific Northwest.
The jet stream is a narrow current of strong winds in the upper troposphere (roughly 25,000 ft to 35,000 ft above sea level). It is often the conduit for storms and is associated with a large temperature gradient in the middle and lower troposphere. Winds in the jet stream are westerly (from the west) and aircraft like to fly in the jet stream going east, while avoiding it going west. You are now Jet Steam certified!
The jet stream typically reaches its highest speeds during the wintertime, when temperature and pressure differences across the mid-latitudes are at their greatest. In the summer, there is also a greater amount of rising air (convection, which leads to thunderstorms) which can disrupt the jet. In the cold months, the jet stream usually maxes out around 160 knots (184 mph).
In February 2019, the New York National Weather Service recorded something that it never had before in our parts: a jet-level wind speed over 200 knots – approximately 231 mph!
Now on July 18, 2019, scientists at the radiosonde site at Quillayute (UIL) have measured the strongest summer jet stream ever observed over the Pacific Northwest with wind speeds of 140 knots (161 mph). This is amazingly fast for this time of the year.
Amazing and unusual record
Vertical soundings at Quillayute go back to the late 1960s… So we are talking about a half-century of observations here. As shown in the first diagram, the previous record was around 110 knots between April 1st and Octorber 15th (summer).
So the 140 knots observed on July 18, 2019, absolutely shattered the half-century-old record. In fact, the wind over us right now is greater then the records for any date from April 1 to mid-October.
Interestingly, a July-August record was set on the same day at the next upper air station to the south at Salem, Oregon, as shown in the diagram below:
Those jet stream wind speeds look like January, not July. That’s another truly unusual weather event.