Tuesday, September 14, 2010

Some more recent storms

Tuesday, September 14, 2010
3:21 P.M.

After the Columbus Day Storm, we would be without a major storm for some
time. But we had a major windstorm on November 13, 1981. This storm was actually similar to the Columbus Day Storm in depth and track, but its track took it a lit
tle further offshore, preventing the gradients around the area from getting too bad and keeping the strongest ones out at sea. It also moved northward at a slower pace, resulting in lower wind speeds. It was still a major storm though, as the above diagram shows. Pressure is in millibars. This diagram is from the Storm King website. Thanks to Wolf Read.

Another big storm struck in 1993, and on Inauguration Day of that year. He
nce, it is called the Inauguration Day Storm. While everybody was paying attention to ole' Williams induction to the presidency, few noticed the stellar forecasts by the National Weather Service forecasters. This storm was very important because it ma
rked the first major windstorm that we forecasted correctly. We didn't even forecast anything before the Columbus Day Storm, and before the 1/20/1993 storm forecasts were mediocre at best. But this was a successful forecast. And 700,000 people lost power, that too. Seattle's third most devastating storm since 1962 (with the Columbus Day Storm being #1 and the Hanukkah Eve Storm being #2)
1995 saw an absolute monster storm. It followed pretty much a perfect path for intense wind in Seattle and was extremely deep - 953 millibars. However, the Inauguration Day Storm generated stronger wind for us. Why? Because it was more compact. This stor
m was bigger, so the gradient was spread out over a wider area. Of course, that means a ton of areas got clobbered. Alaska to California, to be exact.

We got our 2nd most destructive storm on December 14-15 2006. It had roughly the same winds as the Inauguration Day Storm, but it caused far greater devastation. Why? Because of suburban development, sure, but mainly because the soil was so saturate
d from the previous November (15.63 inches of rain at Sea-Tac!). We also had some extremely heavy short-term rainfall, as this radar image shows. My house actually got pretty much bulls-eyed by it, and a woman who lived a couple miles away died when water flooded her house and she could not get out, sparking a complete re-do of the drainage system in Madison Valley. Se
a-Tac recorded its fastest gust ever at 69 mph, faster than the Columbus Day Storm. Of course, Renton gusted to 100 in the Columbus Day Storm and a little over 50 here, so the Columbus Day Storm was much stronger.

Recently, we had a very unusual storm. Well, ok, it was freshman year, but that's still pretty recent. Over December 1-3 2007, the coast got pounded with tons and tons of wind, and over the last 2 days, torrential rain resulted. Some places got 15 inches of rain in a day as the last storm came through. This main storm was very very deep at 953 millibars and was fed from multiple tropical sources. These events gave the strongest wind gusts on record for some locations, like Astoria. Even stronger than the Columbus Day Storm. Holy Cross in Pacific County reached 137 mph, Naselle ridge reached over 140. But what really made this storm devastating was the duration of the wind. I forget the details, but some place had high winds (gusts over 58) for something like 50 hours. Most locations on the coast have an 8 hour window of these winds. Inland, it is usually like 3 hours. 50 is just off the charts, and that, coupled with the extremely strong wind and extremely heavy rain, made this storm truly spectacular. I forget where I saw it, but I've seen publications saying that this combination of rain and wind is a 1000-year-event. The picture above? All those trees were standing before the event.

That just about wraps it up. I don't think we will have any big windstorms this year, as it is La Nina and we generally get then on ENSO-neutral years. But we certainly could have one.

No comments:

Post a Comment