From The Cliff Mass Climate Weblog
Cliff Mass
A tragedy happen yesterday (Sunday, September 4) with the crash of a float aircraft over Mutiny Bay of southern Whidbey Island simply after 3 PM (see map under, the star signifies the accident web site).
The plane was en route from Friday Harbor to Renton. Like all plane accidents, will probably be examined comprehensively by the Nationwide Visitors Security Board (NTSB), which could be very precious. Flying is very secure as a result of the causes of previous accidents are painstakingly investigated and the system is improved in consequence.
A number of people have requested me whether or not there was a meteorological contributor to this horrible prevalence, and after analyzing the information, I did discover one thing vital.
Let me present you now.
In the course of the precise time of the accident a entrance was transferring by means of the regon, and this passage, interacting with native terrain, produced a really sharp low-level wind shift within the lee of the Olympics.
Listed below are the floor observations at 3 PM. To the south of the accident web site the winds had been from the south (the barbs face the course from which the wind is coming) whereas to the north the winds had been from the northwest.
Temperatures had been a lot hotter within the southerly circulation in comparison with the northerly circulation.
Such convergence of low-level airflow typically accompanies frontal passage over Puget Sound and sometimes produces a band of clouds and precipitation: the notorious Puget Sound Convergence Zone.
This transition could be very sharp, as a cool wedge of chilly, northerly air undercuts and pushes apart hotter southerly circulation (see schematic vertical cross part under).
To see how sharp the transition was, let me present you the observations from a floor observing location (Bush Level), simply north of Mutiny Bay (courtesy of the WeatherUnderground).
The underside panel is wind course. Wow… a VERY sharp, virtually instantaneous wind shift from southerly to northerly at 3 PM. The highest panel (crimson line) reveals temperature, which plummeted after the windshift. Different close by observations confirmed the identical factor.
The seen satellite tv for pc picture 3 PM reveals a band of clouds related to the windshift line.
Actually not that spectacular and the climate radar confirmed no lively precipitation with the windshift line (see under).
3 PM climate radar
The vertical construction of the forefront of the wind shift line (illustrated by the determine above) can be a slim wedge of northerly winds at low ranges, with the southerly winds proper above. Excessive-resolution UW WRF mannequin simulations indicated such a construction (see simulated sounding with top at 2 PM for the purpose in query). The Camano Island radar famous the identical factor.
With all this meteorology in thoughts, let’s get again to the float aircraft accident. Based on flightradar24 (under), the aircraft was flying round 600 ft AGL, climbed to round 1000 ft, after which quickly misplaced altitude at 3:09 PM (2209 UTC). Plane pace was round 125 knots earlier after which misplaced pace simply after 3:08 PM.
Flying south they’d the northerly winds behind them. Then they hit the convergence zone line. Shifting from northerly to southerly winds might clarify their speedy lack of pace. Though their floor pace would decline, their airspeed might enhance, inflicting extra raise. Did that contribute to their rising elevation on the finish?
Not solely did the wind reverse abruptly, however there would have been appreciable turbulence as a result of robust vertical wind shear related to the convergence/windshift line.
Did this have something to do with this accident?
I have no idea. All I can say is that the accident occurred in an space of an lively wind shift and potential low-level turbulence. Is it a coincidence that the accident occurred concurrently with their traversal of the large wind shift?
