UPDATE: Another new record at BWI on July 7th:
RECORD EVENT REPORT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 522 PM EDT WED JUL 07 2010 ...RECORD HIGH TEMPERATURE SET AT BALTIMORE MD... A RECORD HIGH TEMPERATURE OF 101 DEGREES WAS SET AT BALTIMORE MD TODAY. THIS BREAKS THE OLD RECORD OF 99 SET IN 1993.
A new record high temperature was set in Baltimore today…
RECORD EVENT REPORT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 0547 PM EDT TUE JUL 06 2010 ...RECORD HIGH TEMPERATURE SET AT BALTIMORE MD... A RECORD HIGH TEMPERATURE OF 105 DEGREES WAS SET AT BALTIMORE MD TODAY. THIS BREAKS THE OLD RECORD OF 101 SET IN 1999.
The temperature is measured here at the BWI airport at this NOAA ASOS. It doesn’t look bad from this photo provided by NOAA. In fact with the exception of the building, it looks reasonably well sited. More photos here.
But when you look at this BWI ASOS station from the air, an entirely different picture emerges.
From Bing Maps, see interactive view here.
Here’s the East looking view:
Note how close the NOAA ASOS station is to the asphalt accessway, and how it is surrounded on 3 sides by runway and taxiways.
Here’s a ground level view showing the asphalt accessway:
But also notice the vent in the ILS instrumentation building. That’s an exhaust vent. When the wind blows from the NW, it will carry any waste heat from that vent (note it points downward) directly into the ASOS sensor array, as shown in this zoomed aerial view from Bing Maps below:
Interactive view of above here.
Note the direction of the wind when the ASOS recorded 105° F per this screen cap of the NWS hourly observations for BWI:
The ILS waste heat, combined with the asphalt proximity of the accessway, as well as the runway and taxiway on three sides contributed to the new high temperature record, in my opinion.
When you look at other stations high temps (which I plotted) in the area on the same day, the 105° F record high stands alone near Baltimore, though one other airport, Frederick, also with ASOS measured the same 105° F high. The Baltimore downtown Tmax (at the Museum/Science Center) was 103°F.
From the website CCF, who also had an interest in the issue, it was reported that some other private stations nearby also didn’t hit 105.
Nearby Weatherbug stations, which are considered to be fairly accurate, were all lower:
- Columbia hit 102F at Clemens Crossing ES.
- Ellicott City hit 100F at Veterans ES.
- Owings Mills hit 100F at The Harbour School.
This suggests that BWI stands alone in the 105 temperature for this area.
Since the Frederick, MD Airport ASOS (nearly 40 miles away) also hit 105, let’s have a look at it:
Interactive view from Bing maps here. Note that this station while an older style AWOS instead of ASOS, also has it’s sensors sited near/over asphalt and near the waste heat of the ILS building and it’s electronics. Just like BWI. I suppose we shouldn’t be surprised.
And here’s the observations from Frederick:
While the winds at this time weren’t in the direction that would pull waste heat from the ILS building, I’ll point out that the KFDK AWOS sensors are sited directly over the asphalt, where the BWI ASOS has asphalt very close by. This is great for keeping weeds down and mowing, not so great for measuring temperature.
Washington National has similar siting over asphalt (or possibly dark crushed rock, but does not have an ILS electronics building nearby. It does have one feature though, the Potomac river is only 180 meters away.
Of course, the KDCA ASOS station isn’t far from a megaplex of tarmac, terminals, and aircraft.
If you wonder if tarmac/taxiway/runways are capable of generating a lot of heat, this story from Albany, NY yesterday, on the same day the new record high was set at BWI, might be of interest:
Oh, and by the way, Albany’s airport also had a new record that same day:
RECORD EVENT REPORT NATIONAL WEATHER SERVICE ALBANY NY 958 PM EDT TUE JUL 6 2010 ...RECORD HIGH MINIMUM TEMPERATURE TIED AT ALBANY NY... THE LOW TEMPERATURE AT THE ALBANY INTERNATIONAL AIRPORT ONLY DROPPED TO A LOW 76 DEGREES AT 509 AM JULY 6TH. THIS TIES THE OLD RECORD HIGH MINIMUM TEMPERATURE OF 76 DEGREES SET BACK IN 1911.
It takes some time for all that tarmac heat to dissipate. You can bet they didn’t have tarmac there in 1911. The high temp also got pretty warm:
TEMPERATURE (F) YESTERDAY MAXIMUM 96 353 PM 97 1886 82 14 80 MINIMUM 76 509 AM 47 1961 59 17 51
While this certainly isn’t an exhaustive survey, it does illustrate that the two highest reading airport stations today at BWI and FDK have siting issues.The BWI ASOS went in in 1995 according to the NCDC MMS Metadatabase. It set a new record of 101 for this date 4 years later. We can be certain that in the years prior, the station was not sited just like you see it now. Airports are dynamic engines of change.
Also from the CCF website:
Records go back to 1880 for Baltimore, so this is an impressive feat, and it has been done before. A temperature of 105F has been hit four other times in the the area’s, and many long ago. So these numbers should quell the talk of Global Warming with this hot summer.
Here are the four other dates:
- June 29th, 1934
- August 6th 1918
- August 7th 1918
- August 20th 1983
Another mark hit many times in Baltimore was 104F on these days:
- July 3, 1898
- July 16 1988
- August 4th, 1930
- July 6th: 101F in 1999* BROKEN TODAY with 105F
- July 7th: 99F in 1993
- July 8th: 100F in 1993
- July 9th: 103F in 1936
- July 10th: 107F in 1936 * Hottest of all time for Baltimore
The question is, are airport stations like this at BWI climate-worthy? I sincerely doubt it.
I’d like to share a story that I’m proud of. At ICCC4 in Chicago this past May, I gave my presentation on what I’ve learned from the surfacestations.org project and what is about to be published. One member of the audience came up to chat afterwards. I was surprised to see Dr. Harrison Schmitt, Apollo 17 astronaut, and the only geologist to walk on the moon. He said:
Anthony, I want you to know that you are spot on about these airport stations. I’ve seen them read up to 10 degrees warmer than the surroundings. But that’s what they are supposed to read. Pilots need to know the runway conditions, and these stations measure that. Their primary mission is aviation, not climate.
A proud moment for me, having a man who was a hero of mine, whom I watched on Live Lunar TV in high school, giving praise, but also stating the base truth of the matter. Climate monitoring is not part of the mission plan for airports, but they get co-opted for the task.
For example, BWI also has problems with snow records, which I’ve covered before:
Here’s some related reading about Baltimore’s other high reading climate (USHCN) station (now closed):
Full story here: