Weather Blog

Classic rain shadow forms during Dec. 13 storm

Classic rain shadow forms during Dec. 13 storm
(Originally posted Friday, Dec. 13)

There was a classic rain shadow today as the storm's front pushed inland and we got a strong, southwest flow. Here is a visible satellite: 


That was caused by strong southwest flow that squeezes out its moisture when it goes up the southwesern side of the Olympic Mountains. The air then dries out when it sinks down the northeastern side of the Olympics. And note who is in the middle of that clearing hole? Sequim, as usual. There's a reason they only get 18" of rain a year :) Also, pressure was falling quite rapidly as this storm energized offshore. This photo is from my father's weather station in Port Angeles:


Note the pressure going straight down. Port Angeles' pressure dropped 37 millibars -- from 30.17 to 29.12 on the inches of mercury scale -- between midnight and 1pm. Amazing!