Let’s everyone be careful out there. I have witnessed some strange things in the last month. On the 22nd at JFK with level 5 thunderstorms in the area a KLM flight took off with a 16 knot tailwind on 22R with a huge cell 3 miles N and tower calling a wind shear alert. After a runway switch to 4 a Aero Mexico flight accepted a take off clearance with no available departure path and WS alerts and only cancelled take off when they got a onboard WS alert. 2 minutes later a Ethiopian inbound flight landed on 4R after declaring a fuel emergency. As they touched down we were getting onboard radar windshear alerts for the arrival corridor. The cell over JFK had tops reported at 56,000 feet at that time.

I was in JFK a couple of months ago in the queue for a 22 R departure but facing up towards the ILS arrival path during particularly bad weather, causing >1 hour ground and air delays.
We were surprised when our PWS went off as we were in the queue stationary on the taxiway. Suffice to say, the next couple of arrivals on the approach went around.
One of the times we were glad to be on the ground with loads of excess fuel happy to wait it all out.

Luckily everyone reads PPRuNe! :E

I would say sometimes people are less than careful depending on circumstances. KLM knew that if they did not depart it was going to be a long night. Tower asked if any of the other aircraft in line were willing to depart as KLM rolled. The radio stayed silent so the majority were careful and yes we all had a long night.

The above is correct however Delta had a headwind at the time of departure with no tower wind shear alerts. Both aircraft had a clear departure corridor after getting airborne. Winds and conditions were changing by the minute.

Been a bad year for thunderstorms

We have not had a major windshear accident in a long time. It breeds complacency. This cell had the ability to turn that 16 knot tailwind into 50 knots in the blink of a eye. It’s good to be lucky but luck eventually runs out.