Lexington's Weather Observations Part One

I have heard about Lexington's Bluegrass Airport (an official reporting station) temperature readings and how the sensor has been blamed for inflated temperatures for some time now.

Well, I decided to test data values over a 5-year period and found some rather interesting revelations.

Participating subjects include:
Lexington Bluegrass Airport - official
Frankfort Capital City Airport - official
Lexington Mesonet site
Harrodsburg Mesonet site
Frankfort Mesonet site

Since the primary blame for Lexington BG temperatures was an inflationary issue related to a faulty sensor, I chose to collect data that reflected the month of August, typically a hot month, and used values for incoming solar radiation that was among the highest of the month with zero or near-zero precipitation, then compared the different reporting stations. I was looking for any unusual spikes in temperatures coming from the Lexington BG airport compared to nearby surrounding observation sites.

Although I have yet to test the overnight low temperatures nor have I tested values during overcast and rainy conditions, I was able to reach some partial conclusions about the months of August 2011-2015. I am looking forward to seeing how additional data may support or negate the observations and conclusions so far.

For the months of August 2011-2015, Lexington BG vs Frankfort CC...

1	92
2	92
11	80
12	84
23	85
29	83
30	86
4	88
LEX0811	86.3

1	93
2	92
11	81
12	83
23	85
29	84
30	85
4	89
FFT0811	86.5

------------------------

2	93
7	89
8	91
19	83
20	81
22	83
23	86
24	90
25	93
26	90
29	87
30	91
LEX0812	88.1

2	92
7	90
8	92
19	83
20	81
22	85
23	89
24	93
25	92
26	91
29	87
30	92
FFT0812	88.9

------------------------

Considering August 2011 and 2012, I noticed a rather dramatic shift in the Lexington NWS readings. Believe it or not, the data showed Lexington's temperatures actually 'cooled' against the other reporting stations that are limited to this study.

The August years of 2011 and 2012 showed Frankfort to be warmer or at least equal to Lexington in terms of daytime high temperatures, which should be a loss for Lexington since the overall August months of 2011-2015 were in favor of Lexington...except 2012.

Was this 'cooling effect' supported by the Lexington and Harrodsburg Mesonet sites for August 2012?

In August 2011, using the same format as above, the mostly clear day with little or no precipitation, Harrodsburg Mesonet averaged -0.4 degrees difference compared to the official reporting site at Lexington BG airport. For 2012, the Mesonet averaged 1.4 degrees warmer than the official site.

Similarly, Lexington Mesonet averaged nearly 2 degrees cooler than the official site in 2011 while only reporting a 1 degree cooler difference in 2012.

Also, I included the Frankfort Mesonet site as a participant in this section,which a similar pattern showed a 2011 average reading of  -0.8 degrees against Lexington BG while 2012 showed 0.15 warmer.

Something had to happen to the sensor in 2012. But, the following years of 2013 and 2014 would provide ever more mysteries between the official site versus the surrounding locations. A dramatic reversal began to take place....

Against the Frankfort NWS, the Lexington NWS at BG airport reasserted itself as the warmer location in 2013 for August.

2	83
15	76
16	80
24	88
25	87
26	88
30	90
LEX0813	84.6

2	82
15	76
16	80
24	87
25	87
26	88
30	90
FFT0813	84.3

-------------------------------

Then, in 2014, we reached a crescendo in the readings that brought about numerous complaints from within the weather circle and caused a media buzz. Consider the data below....

1	86
3	84
7	86
15	82
25	91
26	89
29	92
LEX0814	87.1

1	86
3	85
7	84
15	81
25	90
26	90
29	90
FFT0814	86.6

----------------------

Harrodsburg Mesonet in 2013...showed a dramatic shift, now about 2 degrees cooler than Lexington BG airport. However, August 2014, the results worsened, at 2.85 degrees cooler.

Frankfort Mesonet in 2013 also showed a huge shift from 1.37 degrees cooler to 2.71 degrees cooler in 2014.

But, the Lexington Mesonet showed the greatest shift. In 2013, the Mesonet reading for this stretch of August showed 2.87 degrees cooler then climaxing at just over 4 degrees cooler in 2014!

During 2014, the sensor at Lexington BG airport had been replaced. Yet, many were still doubtful about the readings obtained as we headed into the 2015 season. Would there be enough improvement?

For the dataset below, the gap between Lexington and Frankfort continued to widen in August 2015, again using the same format as above, hoping to determine if the sensor is 'too sensitive' to a sunny August sky with little or no precipitation....

1	86
2	87
8	84
12	81
13	82
14	85
15	88
16	90
21	81
22	85
24	79
28	84
31	88
LEX0815	84.6

1	85
2	87
8	84
12	81
13	82
14	84
15	87
16	89
21	79
22	83
24	78
28	83
31	87
FFT0815	83.8

------------------------

Although the gap continues to widen, the overall average discrepancy between the two official reporting sites for a sunny sky in August still remains tolerable.

Also, the nearby Mesonet sites showed some improvement against the Lexington BG sensor, which should have led me to expect the same at the Frankfort official site. For example, Harrodsburg Mesonet showed about a 1 degree improvement while Lexington Mesonet reported about a 1.3 degree improvement. Then, Frankfort's Mesonet reading showed a 1.5 degree improvement.

Therefore, the sensor issue at Lexington Bluegrass airport, the official NWS site, has performed better than the prior years, at least for August and a sunny sky. Still, I do not believe that the sensor issue is fully resolved. However, for now, if the sensor can maintain these current levels, the temperature contrasts between the surrounding observation sites can be considered at the extreme range of tolerance.

But, this was just one month selected from each of the years 2011-2015 for only one or two parameters, a sunny sky and zero to near-zero precipitation.

In another post coming soon, I will choose another dataset that will look at overnight low temperatures between these observation sites. The results may surprise you when you find out what I have discovered.

MS