Does A Warmer Than Average Spring Mean A Hotter Summer?
We went without much of a winter this year with temperatures above average and below average snow. Spring has brought above average temperatures to most of the area. So far for the month of March the average high temperature in Fort Smith has been 73 and the average is 65. In Fayetteville the average so far this month has been 68 compared to the average of 60. So the average high temperature so far this spring has been running about 8 degrees above average.
First of all let’s take a look at why we are seeing the warmer than average highs. A big area of high pressure to our east has set up a little further east than normal and big systems have been “cut-off” from the jet-stream out west. This has allowed southerly winds to be pumped in from the south across not only our area but much of the central United States. Record high temperatures have been recorded as far north as Michigan during this unseasonable warmth.
This has left many of us wondering what summer has in store (especially after the record-breaking heat we saw last summer). There is plenty of time left for this spring to even out temperature wise and it’s much too early to know where the spring of 2012 will rank as far as the warmest springs on record.
To better understand to relationship between warmer than average springs and the hottest summers we take a look back at history. We will use observations from Fort Smith because it is a more expansive data set…129 years of climatology from 1883 to 2011.
I looked at the hottest 10, 20 and 25 springs and then looked at the hottest 10, 20 and 25 summers for Fort Smith. What I found was a very low correlation between the hottest springs and hottest summers. For the 10 hottest springs, and 2 of those years (1918 and 1936) were in the 10 hottest summers. That is only 20% of hottest spring turning into the hottest summers…very low statistically and that tells me there is little to no correlation between the warmer than average springs turning into hotter than average summers.
If we expand that data out to the 25 hottest springs and summer, only 5 of the 25 springs turned into the hottest summers on record…again 20%. So that data are consistent even when looking at more years.
We are in the middle of a global pattern shift with a weakening La Nina pattern which could gradually switch to a El Nina pattern by latter in the summer. The Climate Prediction Center’s 3 month outlook for our area for the months May, June and July show an equal chance of below average and above average temperatures during the early the middle part of summer. This mean that temperatures should be about average for those months.
Looking at the months of June, July and August (which we consider to be meteorological summer) the temperature outlook shows just a slight chance of above average temperatures for our area.
Summers are typically hot in our area with the hottest months being in July and August with average monthly highs in the low to mid 90′s. No doubt we will see temperatures climb to near 100 as we do every summer, but this warmer weather this spring is no indication of above average summer temperatures.