Record highs in Raleigh ... ain't no big deal anymore

In an effort to stave off boredom the other day, I looked at some of the climatological data on the RDU NWS site. It had seemed to me that we had record highs quite often in 2007. The data bore that out.

There were 33 days w/ record highs in 2007. This is considering a record period from 1944 through 2007. So in that 64 year period, all things being equal, one would expect to get (366/64, or 5.7)record highs every year. One oddity though, days in which the record high is a tie (temps are measured to nearest integer) are attributed to the most recent year. So, one would expect the more recent years to have more record highs due to this artifact. I've looked at the 2007 records at RDU and most of them are not ties, but actual records. As you can see the 33 record highs for the year is not only 27 more than usual, but 14 more than we've ever seen before. On average, every 11th day was a record high in Raleigh. Wow.

I've also looked at the record lows at RDU. Same as above ... it's a 64 year record and ties go to the most recent year. Over the last 6 years, in a period in which we should have gotten about 34-35 record lows, we've gotten only 6 (just one in 2007, a chilly 27 deg F on 4/8). Record lows have been very uncommon in this area over the last 6 years. Most record lows at RDU are from the time period 1960-1985. It's supposed to get quite cold here over the next few days, but the forecasts are that we won't get w/in 5 deg F of any records.

So, the odds this year of getting a record high on any given day were 1 in ~11; the odds of getting a record low were 1 in 366.

Why is this happening. Some potential reasons:

1) It's possible that the monitor itself changed or was moved at some time over this 64 year period, perhaps to some place warmer. I don't think that happened, but cannot say for sure.

2) Certainly, the landuse patterns around the airport have changed dramatically over the last 20-30 years. Rapid development in the Triangle has appreciably reduced the amount of forested area in this part of Central NC. Most of this former forest has been replaced by urban devices like asphalt or concrete. This may be leading to a bigger heat island effect around the RDU site (& area as a whole).

3) Maybe it's a symptomatic of global warming. According to NCDC, 2007 was on pace (thru November) of being the 8th warmest year (of the last 100 or so) in the U.S. and the 5th warmest (since 1880) globally.

Oh well, it's a complicated issue and the record highs in Raleigh may not mean anything, other than it was an abnormally warm year here. Interestingly, ozone air pollution was quite low in Raleigh this year. Ozone forms on high temperature days, but it appears as if the control programs that EPA, States, industry, and the population at large have agreed to and implemented have had their intended effect. I suspect that if the same cooperation could be applied to the global climate change subject, we would see the same results.

Hope everyone has a great 2008.