It’s an ongoing problem in the weather world…bad data…and it has taken its toll on the Cincinnati Northern-Kentucky International Airport (CVG). This is something I have been seeing more and more in our area (and nationally) and unfortunately it will have impacts for years to come. The problem? Poor siting of the official weather station which is being subjected to the Urban Heat Island (UHI) of Cincinnati. As the suburbs continue to grow, the airport is being surrounded more and more by subdivisions and roads and industry. On a day with steady winds over 10 mph that’s not a problem, but when you have light winds crossing the hot asphalt and concrete and then blowing over the airport, the instrument shelter there will report readings that are artificially higher than the surrounding regions.
We saw that today as temperatures slowly rose to the mid 80s by 1 pm at CVG, but then jumped 4 degrees in one hour as winds became light and variable, hitting 90 degrees at 2 pm. Moving up four degrees in the middle of the afternoon on a day with mixed clouds and light winds is highly unusual, and doing it before the peak heating hours (3 to 5 pm in the summer) is even more unlikely.
CVG is now dealing with artificial heating on its north-northwest, north, northeast and east side leaving only south, southwest and west winds untainted by the urban heating. This is not as big an issue when you have stronger winds that can overcome the heating, or overcast skies so the sun isn’t baking the pavement, or rain falling across the area keeping things cool. However, when winds are 10 mph or less on a sunny or partly sunny day (or at night) we’re seeing more and more impacts from the city, and when you consider that a north wind often means cooler air, it’s frustrating to see temperatures rise at CVG while areas north of the city stay cooler.
The temperature at CVG is reflecting the temperature of that area, which makes it accurate, but just for that area and only because of artificial heating. What happens is that we get tainted data for our official records and when comparing CVG 20 or more years ago to CVG today we’re not comparing the same surroundings. Therefore we can’t properly compare weather patterns of today to back then because it seems hotter in the same weather pattern that years ago would have produced daytime highs or nighttime lows that were 3 to 5 degrees cooler, sometimes more.
In the case of Saturday, July 30th, the streak of 90s that started 13 days ago continues and for the record books it will appear as if the summer of 2011 had some extended heat wave that lasted into August when that’s simply not true. Saturday was warm and humid, but not hot or oppressive and certainly not a day in the 90s across the region. Since World Meteorological Organization standards are quite clear on the proper siting of weather instruments, and since we’re not supposed to be recording urban temperatures at these official reporting stations, we’re now getting bad data with little way to clean it up.
The bottom line is that Saturday was officially another day in the 90s, but not for most reading this, and it certainly not like days in the 90s just a few decades ago when CVG was surrounded by trees and open meadows. Watch for this to have a huge impact on cold winter mornings when some areas are shivering but the airport shows readings 5 to 10 degrees warmer anytime the winds are right.
We need some rain and stronger winds so we can finally end the current 90-degree streak, but for now it should continue through Wednesday, August 3rd and then finally end with rain showers and cooler air arriving for Thursday. So much for reliable weather and climate data…
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