When we are lucky enough that a hurricane doesn’t hit us, we seldom ask where it went. We are usually just grateful that it missed us.
Certainly the East Coast had enough recent problems with floods from Hurricane Irene that most of us were grateful when Hurricane Katia wandered around in the Atlantic and died out. But here is the follow-up—the remnant of Katia, the post-tropical storm, is heading for Ireland and Scotland! After all, who doesn’t want to visit the Emerald Isle?
Post-tropical storm Katia heading for Ireland. Source: NOAA
When hurricanes die out, it is usually because they have no more hot water energizing their storm. This is because they drifted over land (bad) or colder water (good). However, they don’t just disappear. They turn from a tropical storm to an extratropical storm. This means they are still stormy. They may have as much wind as a tropical storm and they have lots and lots of rain.
Extratropical merely means that a storm is no longer in the tropics. It no longer has a warm core. It can be shaped like a cyclone or a long front. A post-tropical storm is when a hurricane, typhoon or other tropical storm has lost its hurricane-like characteristics while still remaining wet and stormy. Tropical Storm Lee, for example, weakened after it hit land. It became a less windy tropical depression, then a post-tropical or extratropical rain storm. It has caused a lot of really wet weather all along the East Coast. Hopefully you, gentle reader, were not affected by it.
Even when they are no longer tropical, tropical storms can cause a lot of rain – Hurricane Katia and post-tropical storm Lee Source: NOAA
Hurricane Katia, roared through the Atlantic as giant Category 4 hurricane. Fortunately it didn’t hit anything. It weakened. It finally cooled into an extratropical storm. It is now going to rain on Ireland and there are some concerns about how strong the winds will be. They may be up to 70 miles per hour and Ireland is really not used to these types of storms.
What has happened is that the Atlantic has grown much warmer over the past 15 years. This has allowed storms that once died out in the middle of the ocean to cross over to Europe. Indeed, in 2005, a tropical storm hit sunny Spain! Rainstorms from hurricanes have reached as far north as Norway.
If there is a lesson to be learned from this, it is that hurricanes can be a nuisance even after they are gone. Just ask Ireland.
Evelyn Browning Garriss, historical climatologist, is a longtime writer for The Old Farmer's Almanac. She is also editor of The Browning World Climate Bulletin  and has advised farmers, businesses, and investors worldwide on upcoming climate events and their economic and social impact for the past 21 years.