Weather Grinch steals Christmas...

What a storm! When teaching weather, I frequently take the Socratic approach by asking questions. The most profound question I ask…if the surface winds are from the east, which way is the low-pressure system moving? Most of the time, I either get silence or the wrong answer. I must admit it is a loaded question, a sort of, which came first, the chicken or the egg question. If this question appeared on a Transport Canada or FAA exam, it might go like this:

If the winds are easterly (blowing from the east), where is the “low” expected to go?

1. It doesn’t matter. Your weather App will figure it out.

2. It will move westward due to the easterly winds.

3. It will move north, southeast or west depending on what Mother Nature says.

4. Surface winds do not dictate the motion nor intensity of the surface low. The upper air pattern, usually derived from the 500 hPa (mb) chart, determines the motion and whether it will intensify or decay. Hint, pick the longest answer.

I've attached the surface analysis that captured the Grinch Storm and the upper air 500 hPA chart. There is an upper low directly above, thus steering the surface low. The surface low will not move until the upper low moves. It’s why it’s been blowing a gale in most of Ontario for days. With a low stacked like that, it means imminent meteorological death.

Update. Days later, while undulating over Hudson Bay and rapidly weakening, this weather Grinch’s aftermath still wreaks havoc with the airlines.