The recent heat wave in the Midwest and the eastern United States has been characterized by all sorts of exaggerated claims. One even made it into Wikipedia as an “official” all time high record. From http://en.wikipedia.org/wiki/U.S._state_temperature_extremes
Dr. Roy Spencer alerted me to a problem on Monday, and I did some preliminary investigation, confirming that yes indeed, not only was that 113°F value not an official new high temperature record, it doesn’t even appear to be air temperature, but so far out of line could it be the heat index value for July 22nd? Either that, or a careless typo by the volunteer Wikipedian conflating 103F to 113F.
I wanted to wait a few days to see if Wikipedia’s claim that it is “self-correcting” would actually work as advertised, and I’m happy to report that the table has in fact been corrected.
It is back to the previous value of 106°F / 41°C July 15, 1995 in Danbury, CT, which is well documented. But doing further research on the high for July 22nd that was erroneously cited, even that value seems to be inconsistent with published records.
So what was the actual record and the previous one for Hartford? Well, that’s the thing, depending on where you look, you get different answers. Curious, I found myself getting sucked down another climate science rabbit hole, which took my entire Saturday morning and part of Saturday afternoon to compile for you below.
First, I checked the record event report (RER) for Windsor locks (Now an ASOS station at Hartford’s Bradley International Airport) from the NWS WSFO in Boston:
000 SXUS71 KBOX 222019 RERBDL RECORD EVENT REPORT NATIONAL WEATHER SERVICE TAUNTON MA 419 PM EDT FRI JUL 22 2011 ...RECORD DAILY MAXIMUM TEMPERATURE AND AN ALL TIME RECORD TEMPERATURE SET AT HARTFORD CT... AT 406 PM THE TEMPERATURE REACHED 103 DEGREES AT BRADLEY INTERNATIONAL AIRPORT. THIS SETS A NEW RECORD HIGH TEMPERATURE FOR TODAYS DATE FOR HARTFORD CT. THE PREVIOUS RECORD WAS 101 DEGREES IN 1926.THE TEMPERATURE OF 103 DEGREES ALSO SETS AN ALL TIME RECORD HIGH TEMPERATURE FOR HARTFORD. THE PREVIOUS RECORD OF 102 DEGREES WAS SET ON MULTIPLE DATES OF JULY 6 2010...AUGUST 9 OF 2001 AND JULY 3 OF 1996.
And that was dutifully reported in the Norwich Bulletin, which erroneously conflated in the title the new Windsor Locks (Bradley Airport) record for the date, and all time high for that station, with the all time high state record of 106°F on July 15th, 1995 in Danbury, CT:
Clearly, it wasn’t the hottest day in the state history. The headline is wrong.
But here’s the thing, when you go check the official records at the National Climatic Data Center’s interactive records plotting tool, you don’t get the same as what was reported in the RER:
The RER from WSFO Boston says for the date of July 22nd:
THE PREVIOUS RECORD WAS 101 DEGREES IN 1926.
The NCDC Records lookup says:
Previous 97.0°F on 1955-07-22
Let’s check some other sources, the HamWeather interactive records generator says:
They report yet a third previous record value:
Old record 97° in 1926
Bizarre. Three different sources say the previous record was three different values and dates in the past.
So what was the previous high temperature record for Hartford Bradley Airport/Windsor Locks? I have no idea, and apparently nobody is sure either, including NWS/NOAA/NCDC.
But I started to wonder about the station itself. This was an ASOS station, and as we know, they tend to have technical problems associated with reporting false high temperatures due to a design flaw, and sometimes due to placement. So I decided to have a look at the station itself. First stop, NCDC MMS station meta-database to get the exact lat/lon for the ASOS station with the COOP ID NUMBER of 063456 as reported by NCDC.
Oddly though, when I went to look up the lat/lon, I found this station had two COOP NUMBERs assigned to it, 063456 and 069704:
Looking at the history, that appears related to a station move in 1954:
By NOAA COOP station rules (as I understand them), new COOP numbers are assigned when the new environment is appreciably different, such as by distance, elevation, and/or environment. This may explain why we have different references to past record high temperature. The databases presenting the record comparisons may be using different COOP ID numbers.
But what about the temperature record of 103°F itself? I wanted to see how it compared to nearby stations, because as I’ve demonstrated in the past, ASOS stations can produce false high temperature records where a nearby station might be degrees cooler. For example the ASOS station in Honolulu that created a whole string of false temperature records that the NWS admits to, but leaves the records intact anyway. In that episode I demonstrated that two NOAA stations, only 3.9 miles apart had vastly different high temperatures. One station (ASOS at the airport) set records, the other, at the NOAA Pacific Tsunami Warning Center did not.
So how would this one in Hartford hold up? Well at first glance, we see the Google Earth image for the Hartford Bradley ASOS station at 41.9381 -72.6825 shows a significantly different environment than the surrounding countryside:
The “A” marks the location of the ASOS weather station. Note how the airport is a patch of brown in a sea of green, likely due to the change in vegetation. That’s quite a stark contrast and certainly does not seem representative of the area.
In the National Weather Service Observing Handbook No. 2 (NWS, 1989), it talks about “representivity” stating:
“The equipment site should be fairly level, sodded, and free from obstructions (exhibit 5.1). It should be typical of the principal natural agricultural soils and conditions of the area…Neither the pan nor instrument shelter should be placed over heat-absorbing surfaces such as asphalt, crushed rock, concrete slabs or pedestals. The equipment should be in full sunlight during as much of the daylight hours as possible, and be generally free of obstructions to wind flow.”
Here’s the closeup view of the ASOS station at Bradley AP:
While certainly fine placement for monitoring the runways, it is not the best for climate monitoring. Note the mower lines. The character of the grass changes with the season no doubt.
So I decided to have a look at the data that day, Weather Underground helpfully archives the data, and they report the record high:
I found the temperature graph WU plotted very interesting:
It appears that from 1:30PM to 5PM, the temperature plateaued and did not change. To me, that suggests some sort of saturation related equipment failure. But, since I don’t have maintenance records for that station, I can only speculate.
But, there are other sources of data. Weather Underground also helpfully logs private weather stations in the area. Here’s one located on Poquonock / Hawthorne Ln, Windsor, CT at lat/lon 41.885 -72.692, just 3.6 miles to the SSW:
And the high temperature WU reported by that station KCTWINDS6, is 99.9°F, which is 3 degrees cooler than the nearby airport record high of 103°F:
Here’s the temperature graph:
Note the duration of the plateau is shorter, from about 2:15PM to 4:30PM. Note also the time at which the 99.9 F high occurred:
15:53 99.9 °F
3:53PM was Tmax for this private weather station.
Remember the RER from WSFO Boston said:
AT 406 PM THE TEMPERATURE REACHED 103 DEGREES AT BRADLEY INTERNATIONAL AIRPORT.
So why the 3 degree difference in Tmax at about the same time? One possibility is that the airport environment is more efficient at converting solar radiation to heat, and kept accumulating heat faster than the environment of the KCTWINDS6, or as I posited earlier, it may have something to do with the ASOS equipment itself.
OK, well maybe that’s a fluke, let’s look at another station. I found another one logged by WU about 12 miles SE, called KCTMANCH2.
The high at KCTMANCH2 is also 99.9°F, which is 3 degrees cooler than the nearby airport record high of 103°F:
The graph is consistent with the other private weather station:
As is the time of the high temperature:
15:45 99.9 °F
While the other private station KCTWINDS6 had no metadata on the station type, I tend to trust the data from this particular station, because it is a quality weather station , one of the best available, The Davis Vantage Pro2 with fan aspiration:
So we have two stations at 6 and 12 miles from the airport that show identical highs (99.9°F) in a similar time frame. But, lest I be accused of cherry picking, lets look at another nearby station, one that does not agree with my premise, one even closer, just under 3 miles away at 41.920 -72.735:
This station, KCTEASTG2 had a high temperature that hit 103.6°F, and in fact it would be rounded up to 104°F by NWS rules if it were an official station. At first glance it would tend to confirm the airport record high temperature as being valid.
But when you look at the data log, you discover an odd discontinuity, the high temperature was set around 11AM:
From the KCTEASTG2 data arhcive, that high was:
11:13 103.6 °F
That Tmax doesn’t make any sense meteorologically. It is before peak insolation, and very short lived. According to this solar calculator provide by NASA, solar noon for that location is at 13:57 (GMT-6, DST enabled).
I’d tend to discount this station data as it looks to me as some sort of local exposure effect, like the station being influenced by direct sun or reflection of sun off a window or some other similar bias which can happen in backyard. Note the data settles down afterwards. This could simply be a case of direct or reflected sun hitting the sensor.
The metadata published by WU on KCTEASTG2 also doesn’t support a good case for this station’s measurement quality:
The WS-2308CH is a cheap weather station made in China, sold by LaCrosse. One of the big design flaws is the thermometer shelter, seen below, which bizarrely has no slots or louvers for air flow in the plastic cover, which would tend to create a trapped air hotspot when exposed to direct sunlight. That makes this station temperature exposure suspect if it gets the direct sun.
Back to the data. After that first peak at around 11AM, it cools rapidly, then starts a slow plateau upwards, peaking again over 90 minutes earlier than the time of the record high set at the airport
14:25 100.9 °F
That’s still two degrees cooler than the airport, and around the time of all the other measurements, a window of 15:45-16:15, we find:
So given the later afternoon temperatures are in the settled period after the first 11AM peak, they might be valid. The temperature data for that period are in agreement with the other two private weather stations I cite above.
Finally one more station, this one 7.4 miles to the NNE at 42.009 -72.576 in a residential area:
The temperature peaked at 102.0F
The timing of Tmax was also a bit earlier than the other stations, but has that similar ramp up right about 11AM:
According the KCTENFIE5 data archive, the Tmax was just before 1 PM:
12:55 102.0 °F
That peak temperature is an hour before solar noon in the area at 13:57, and very brief, 20 minutes later it is down a whole degree again:
13:15 101.0 °F
It never comes close to that peak again at solar noon or thereafter, so again there may be some sort of local exposure effect going on. This station while a good one, is not fan aspirated:
Without looking at the site and equipment placement, I can’t tell if that early Tmax is related to some sort of exposure issue (like a sunlight reflection) or not. But it is suspect giving the time prior to solar noon and briefness of it. Even so it didn’t reach the 103°F recorded at the airport.
At the time of the new record high at the airport, 4:06 PM, 7.3 miles to the SW, the temperature at is once again in agreement KCTENFIE5 with all the other private weather stations nearby:
16:05 99.0 °F
- The Norwich Bulletin reporter didn’t check the data, and erroneously conflated all time station record with an all time state record.
- The previous record dates/values for Windsor locks cited by three different sources doesn’t match the Record Event Report issued by WSFO Boston, possibly due to the station move not being recorded in the databases properly or old databases being used.
- There was no new all time state record for Connecticut set. The old one of 106°F on July 15th, 1995 in Danbury, CT stands.
- The land use/albedo of the Windsor Locks/Bradley AP ASOS is significantly different than the surrounding area, and by NOAA’s own COOP handbook, would not likely be representative.
- Other weather stations around the airport within a radius of 3-12 miles don’t show a Tmax equal to the new record high of 103°F for Windsor Locks/Bradley AP ASOS. The one that does is highly suspect due to timing and equipment. A second station that comes close has a Tmax before solar noon.
- All four stations around the airport are within a degree of each other, between 99.0 and 99.9F around 4PM, when the new record high was recorded.
- As demonstrated previously in Honolulu, ASOS airport stations are known to create new record highs erroneously. This was also demonstrated by an episode of record high temperatures in Tuczon related to ASOS equipment documented by professor Ben Herman.
- Now, as documented on WUWT a few days ago, even internal NOAA staff are beginning to doubt the accuracy of these ASOS stations.
So what is my point of all this and why did I spend so much time on it?
It is easy to claim new records, and to report them. Just look at how easy it was for some dimwit to turn 103°F into 113°F on Wikipedia and how easy it was for the reporter to make a false claim of confusion about the all time Connecticut state record. It took just a few minutes for the reporter to write the story and headline claiming “hottest day in state history”, but it took half a day of solid work to debunk it and present it here.
When one goes looking at the data in context, a different story emerges. That story shows that there’s far more to the temperature data than the peaks and valleys. Often, they don’t make sense in the context of the measurement environment, yet they are widely used, often without question as demonstrated in this episode. Worse, sloppy or confused old records don’t seem to be adequate for determining what the previous record high for the date actually is, as demonstrated by the wide disagreement in reporting it.
To fully understand what we are measuring in surface temperature, taking the single peak high temperature without understanding the context of it can be a risky business. As I’ve said many times before, the dynamically changing land use environment at airports is inconsistent with the need for stability in long term climate measurement. Even if the station never moved, comparing highs of the past (when the airport was smaller) can lead to inflated highs today.
I would hope that NOAA takes a hard look at the new record high at Windsor Locks/Bradley AP, to see if it is valid, and that the Norwich Bulletin corrects their erroneous story about the state all-time high.