Mark Johnson, Chief Meteorologist of WEWS in Cleveland writes:
A friend of mine, Justin Berk, a local TV Met in Baltimore, MD had this story to tell today:
“There’s something fishy going on at BWI (Baltimore International Airport),” he says. Hourly obs at BWI airport (April 12, 2012) never went higher than 59 degrees.
(See the obs from BWI below – Anthony)
But, he noticed the official high temperature was listed as 62 degrees.
“There’s no way a jump of 3-4 degrees occurred and then fell back down between obs,” he added. Why the discrepancy? Justin called the local NWS office.
For a brief 10 minutes, the steady NW wind that persisted all day at BWI shifted to a westerly direction. That allowed the HEAT from the nearby runway to provide a quick 3 degree warm-up between hourly obs. Once the winds shifted back to a NW direction, the temperature fell back to 59 degrees.
The NWS employee concurred that the extra warmth came from the runway.
Global Warming is real (thanks to poorly-sighted thermometers)! This is the second time Justin observed a false high temperature reading this week at BWI.
I followed up on this, and his story checks out.
First the table of high/low for the day from BWI:
And here are the hourly observations for the day from the BWI airport ASOS station:
Source: http://www.nws.noaa.gov/obhistory/KBWI.html (downloaded at 2AM EST 4/13)
Here in what the BWI ASOS station looks like along with compass points added:
And here is a view looking to the west:
Seems an open and shut case. This is not the first issue with weather observations at BWI, they also have issues with measuring snow, and I reported here:
UPDATE: 3PM PST 4/13/12 The Capital Weather Gang tries to avoid the siting issue with an alternate explanation. This from comments.
I’ve posted a different perspective on this at washingtonpost.com: The case of the curious temperature spike at BWI airport: asphalt or the sun?
REPLY: Anything to avoid UHI it seems with you guys. As for sun/wind debate. It could very well be both. Asphalt absorbs sunlight pretty well. More sun coupled with a shift of wind to the asphalt area can easily make a quick 3 degree jump. Sunlight by itself on grass, not so much. You didn’t mention albedo in your article so I’ll assume you don’t understand it.
Bottom line – airports are a poor place for temperature observations used for climate purposes, as they aren’t representative and are very dynamic with land use changes, and, see this detailed analysis.
Airports are part of USHCN.