Thursday, July 18, 2019
The Strongest Summer Jet Stream to Hit the Pacific Northwest EVER!
An extraordinary weather event has been occurring above our heads during the past 24-hour. A record that was not only broken, but shattered to little pieces.
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 (change in temperature with horizontal distance) 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 ECMWF 12-h forecast for 5 AM this morning for the wind speed at the 250 hPa pressure level (about 35,000 ft) clearly shows the jet stream, with the orange/red colors being the strongest winds.
This is a HUGE and very zonal (east-west oriented) jet stream…as shown by the next map at the same time. This looks like January, not July.
But now I will really impress you.
The wind this morning at the radiosonde site at Quillayute (UIL) was 140 knots (161 mph) at the 250 hPa level (again around 35,000 ft). This is amazingly fast for this time of the year.
The plot below shows the climatology of the winds at this level throughout the year at this location, with the red lines being the all-time record for each date (the black lines are average winds for the date, blue lines, the record low winds). Vertical soundings at Quillayute go back to the late 1960s…so we are talking about a half-century of observations. The previous record was around 110 knots…so the 140 knots observed today absolutely shattered the record. In fact, the wind over us right now is greater then the records for any date from April 1 to mid-October.
Record, but lesser winds, are being observed at the next upper air station to the south: Salem, Oregon (see below)
A truly unusual event. And one that should not be pinned on global warming. In fact, several of the global warming jet stream papers (e.g., by Jennifer Francis and others) suggest that global warming will bring a weak and wavy jet stream. This is just the opposite.