Tuesday, October 12, 2010

Powerful storm in southeast Alaska

Southeast Alaska is no stranger to "crappy" weather.  If you want to know what it's like to visit Ketchikan, where the average annual rainfall exceeds 375 cm (150 inches), go stand in a carwash for a couple of hours and you'll have a pretty good idea.

Over the weekend, a powerful storm with sustained winds of 40 m/s (hurricane force) and an estimated gust of 50 m/s) struck the Ketchikan area.  A tree fell on a power substation, causing all the residents in Alaska's 5th largest city to lose power for 12 hours.

As damage cleanup continues, the area is about to be rocked again by another landfalling cyclone.  The GFS and satellite analysis below shows the low-center to be just upstream of SE Alaska this morning.

With the large-scale pressure gradient still not aligned along the coast, winds in SE Alaska remain tolerable.

That will change, however, once the surface occluded front, evident as a tongue of warm air in the GFS analysis (red contours), makes landfall and the large-scale pressure gradient aligns aligned along the coastal orography.  This is a classic scenario for widespread strong winds in SE Alaska (localized strong winds occur in a variety of patterns depending on local topography).

1 comment:

  1. While not the strongest in SE AK, did have several 60+ mph gusts and a peak of 68 at the Juneau Airport which was very impressive. There were some very wet, but fun trips to the precip can!