learned about the Bz tipping south

Visited the Space Weather web site.

Some nice aurora shots, as expected.

Also a STEVE image! Wow.

The text was interesting.

This remarkable and surprising storm began on March 23rd when magnetic fields in the space around Earth suddenly shifted.  In the jargon of space weather forecasting "BsubZ tipped south."  South-pointing magnetic fields can open a crack in Earth's magnetosphere and, indeed, that's what happened.  Earth's "shields were down" for almost 24 hours, allowing solar wind to penetrate and the storm to build to category G4. 

We got lucky.