Monday, May 03, 2010

14.21" / 361 mm

That is the two-day storm total rainfall at my official CoCoRAHS reporting station in the orchard. There are two things that are remarkable about this number, other than its just being FRIGGIN' HUGE. First, this is a typical number for this storm! Total of of 12-16" are widespread; covering many counties, hundreds of small stream drainages, and the homes of probably close to a million people. Second, this number is so far beyond unprecedented it is hard to believe. Nashville's official NOAA 2-day storm total was 13.53". This is a new record, breaking the old record of 6.68" set in 1979 (records go back to the 1870s). In other words, this is more than twice as much rain in a 48 hour period than has ever before been recorded there in 140 years. In our case, the bulk of that rain fell between noon Saturday and noon Sunday, so if I had measured hourly increments I would probably have a 24 hour period with about 10" of rain in it.

To our north, Hickman County seems to have fallen down a black hole. Radar estimates indicate that they were one of the hardest hit counties. They are very rural and hilly, much like Lewis County where we live. The last report was at noon yesterday, when the county government issued a civil emergency statement declaring a county wide flood emergency and that the entire area was without power and communications. Another report indicated that the drinking water treatment plant had shut down. It is typical in these situations for isolated areas to drop off the media radar, to resurface days or weeks later with harrowing tales. As an indication of how bad things might be there, the automated USGS gauge on the Duck River at Centerville has been transmitting data through the flood. It shows the Duck having crested nearly 10 feet above the previous all-time record crest, with data going back at least 119 years.

I know that you can't infer much from single events, especially in an anecdotal context. But you combine things like this with the snowstorms last winter in the mid-Atlantic, and it does make you begin to seriously wonder about global weirding. We were noting that the last three places we have lived (here, Fort Collins CO, and Georgetown SC) have all experienced "100 year floods" during our time there (the Great May Day Floods of '10, the Spring Creek Flood, and Hurricane Hugo). It isn't just that these events were in the general area; they directly affected our immediate location. Something does not add up about this...

It also appears that the first person who was killed by the flooding in Nashville was a young man whom we actually know.

What a weekend...

ADDENDUM: The Nashville NWS office has prepared a summary of storm total rainfall from CoCoRAHS data. They have us mapped as 14.39" in the western edge of Lewis County; I guess they included my 0.18" from Friday in the total.


Post a Comment

<< Home

Site Meter