Saturday, May 3, 2014

First 70°F Day in Fairbanks

Yesterday was the first 70°F day of the year in Fairbanks (and Anchorage). This is the 8th earliest occurrence of the first 70°F day for Fairbanks (and the second earliest for Anchorage). The earliest occurrence for Fairbanks was April 27, 2005. Figure 1 shows the date of the first 70°F day for Fairbanks since 1920. There is a gentle trend toward earlier dates. So what does it mean for the rest of the summer? Well, the short answer is: not much. Figure 2 shows the total number of 70°F days versus the date of the first occurrence and Figure 3 shows the date of the first occurrence versus the average June/July high temperature. It is plain to see that there is a low correlation. There are slightly more 70°F days in years that it gets off to an early start but that is a little misleading. If you break out the Top 10 years with the earliest 70°F occurrences (average date is May 2), the June/July average high temperature was 71.1°F. If you look at the Bottom 10 years with the earliest 70°F occurrences (average date is June 6), the June/July average high temperature was 71.3°F.

So will it be a warm summer? Perhaps. But not because of when the first "warm" day occurred.

Figure 1. Date of the first 70°F day of the year in Fairbanks (1920-2014).

Figure 2. Scatter plot showing the (lack of) correlation between the first 70°F day of the year in Fairbanks and the total number of 70°F days for the season.

Figure 3. Scatter plot showing the (lack of) correlation between the first 70°F day of the year in Fairbanks and the average high temperature in June and July.

4 comments:

1. CPC's info looks warm to me, especially with the predicted demise of La Nina:

http://www.cpc.ncep.noaa.gov/products/predictions/long_range/fxus05.html

http://www.cpc.ncep.noaa.gov/products/predictions/long_range/two_class.php

Bring on the sun, mosquitoes, and forest fires?

Gary

1. Thanks for the links Gary. My gut feeling is that it will be a warm, dry summer. Hopefully the mosquitoes will be better this year.

2. It looks like there is actually something of a correlation with the number of 70-degree days (Figure 2). I wonder if this is reflecting a lagged correlation with summer precipitation or cloudiness, so that the diurnal range is larger (but mean temperature not much different) in summers that start early. Or it could just be that Figure 2 includes 70-degree days in May.

1. Richard, the small correlation you noted in Figure 2 is indeed a reflection of the 70°F days captured in May. Those seasons with early tallies are indistinguishable from other seasons if you strip out the May data.