This week I returned to St. Louis after being out of town for some time. I was greeted by a chorus of moans and groans about the horrible winter. Such kvetching! Of course, it is easy for somebody who has been in warmer climes to pooh-pooh the harshness of the winter back home. So, I decided to look and see what the statistics say, and since that is the focus of this blog, to do a post on what I found. I’m going to look at the winter in St. Louis and in Kansas City. For weather statistics, winter begins December 1st and ends February 28th (or 29th in leap years). I’m writing on February 21, so the data for this winter extends only through 2/20/2019. One final note: for grammatical reasons, in what follows, “normal” means historical average (mean).
The weather service office in each location keeps its data in slightly different formats, so I will do one, then the other.
Winter 2018-2019 in St. Louis
First, let’s ask if it has been excessively cold in St. Louis this winter. According to the National Weather Service, the record low temperature in St. Louis is -22°F, which occurred 1/5/1884. The observed low this winter was -6°F, on 1/20/19: cold, but nowhere near the record. For the 82 days from 12/1/18 through 2/20/19, on 57 of the days the record cold for that date has been -5°F or colder. This year, the low temperature has been nothing like that.
Well, you may say, perhaps the low temperature has not set records, but on most days it has been lower than normal. Figure 1 shows the daily observed low temperature compared to the normal low temperature for that date. The blue line shows the observed temperature for 2018-19, and the red line shows the normal low temperature for that date. The chart suggests that for much of the winter, the low temperature in St. Louis has actually been above normal. There have been a few cold outbreaks, but not record cold. The observed low temperatures over the period this winter have averaged 27°F. The normal low temperatures over the period have averaged 26°F. So guess what? The average low temperature this year has been about a degree above normal.
Well, you may say, perhaps the low temperature has not been excessively low, but the daily high temperature has been colder than usual. It’s not the deep lows of the night that has gotten to us, it’s the fact that it hasn’t warmed during the day. Figure 2 shows the daily observed high temperatures for 2018-19 (blue line), and the normal high temperature for those dates (red line). The chart shows that during the cold outbreaks noted above, the high temperature has, indeed, been cooler than normal. But much of the winter has also had highs above normal. Over the period, the observed highs this winter have averaged 43°F, while over the period, normal highs averaged 42°F.
Winter 2018-19 in Kansas City
The National Weather Service Office in Kansas City does not seem to publish a data series that contains information similar to the one published by the office in St. Louis. I have used, instead, data from the Climate-at-a-Glance data portal. This data does not include daily values, only monthly averages. Plus, it only extends through the end of January. January 19 was the coldest day of this winter, however, so it is included. Data collection began in 1972-73.
Figure 3 shows the data, with the blue line representing the observed values, and the gray line representing the average. The average temperature in Kansas City this winter was 2.5°F above normal.
The month of February to date can be included by using heating degree days instead of temperatures. Heating degree days are a measure designed to indicate to what degree the interior of buildings will require heating. To calculate it, average a day’s high and low temperature, then subtract the result from 65. This is how many heating degree days there were on that day. Now, to measure a period of time, simply sum the heating degree days for each day in the period.
The problem here is that the data in the climate summaries, where the heating degree data is published, use a different period to determine normal than does the data above. The data above uses values that run from when record keeping started to the current date. The climate summaries use data from 1981-2010. It was around 1980 that the effects of climate change really kicked in. This results in different estimates of “normal,” with the climate summary referencing only recent (warmer) history, and the other data referencing much longer (cooler) periods of time.
That said, it is the only way I can think of to include February for Kansas City in this discussion, so this is what the data shows:
|Observed Heating Degree Days||Normal Heating Degree Days||Difference|
|February 1-20 2019||731||657||
Looked at this way, it would appear that December created about 11% fewer degree days than normal, but January and February (to date) have created about 2% and 11% more, respectively. If you sum the differences for the 3 months together, then the winter to date has created 17 more heating degree days than normal, a trivial amount: in terms of heating degree days, Kansas City’s winter in 2018-19 should be understood to be roughly normal.
Now, none of this speaks to snow or blizzards. I understand that the winter storm at the end of January was a terrible event. In a similar fashion, I was in Hawaii when the winter cyclone came ashore in early February. I saw whole fields of banana trees leveled, just snapped off mid-trunk. On the top of Mauna Kea, the wind was recorded at 190+ mph. None of that changes the fact, however, that Hawaii has a lovely climate, and it was a wonderful place to visit (although too crowded these days, I’d say). Same in St. Louis. This blog is more concerned with statistical trends than individual events, and none of the statistics suggest that this has been, on average, a freakishly cold winter.
I read that people who believe in climate change are being peppered with the question “If the Earth is warming so much, how come it is so cold?” Nobody ever said that climate change would banish all cold, and the predictions are for more intense storms, just like the ones referenced above. But the real answer seems to be that it isn’t actually so cold, at least not here in Missouri. The whole question is nothing but phony baloney, at least here in Missouri.
NOAA National Centers for Environmental information, Climate at a Glance: U.S. Time Series, retrieved on February 21, 2018 from http://www.ncdc.noaa.gov/cag.
NOAA, National Weather Service, Kansas City/Pleasant Hill Forecast Office. 2/21/2019. Daily Climate Report. For this post, I used reports for 12/31/2018, 1/31/2019, and 2/20/2019. Viewed online 2/21/2019 https://w2.weather.gov/climate/index.php?wfo=eax.
NOAA, National Weather Service, St. Louis Forecast Office. 2/21/2019. Climate Graphs. Data retrieved on 2/21/2019 from https://www.weather.gov/lsx/cliplot.