Tuesday, July 30, 2013

Record Warm Spell for Anchorage

* Updated 7/31

Much as already been made regarding the breaking of the record for consecutive 70-degree days for Anchorage. Today is day number 14 in a row and the forecast for the next several days indicates that the record will be extended. What has not been noted anywhere is that the last two weeks has been the warmest two week period ever measured in Anchorage when looking at the average daily temperature. Here is the list:

14-Day Ave Temp            Date Range              Rank
          64.96             7/17/2013 - 7/30/2013      1 * (minor edit on 7/31)
          64.89             7/7/2003 - 7/20/2003        2
          64.82             6/20/1953 - 7/3/1953        3
          64.75             7/18/1936 - 7/31/1936      4

In addition, Anchorage (and Fairbanks) are closing in on their warmest summer-to-date records. Here is an update of the chart uploaded a few days ago.

Note: Each of the thin lines represents the cumulative average temperature for the summer season at a specific point in the season for the 10 warmest summers on record. Here is an example of how it works.

Date            Temperature       Season-to-Date Temp.     Calculation
June 1               66                              66.0                       66 / 1
June 2               62                              64.0                       (66+62) / 2
June 3               71                              66.3                       (66+62+71) / 3
June 4               67                              66.5                       (66+62+71+67) / 4
June 5               65                              66.2                       (66+62+71+67+65) / 5

At the beginning of the summer there is a lot of variation since the value in the denominator is small. Over the course of the summer the lines tend to converge.


  1. A minor suggestion, Brian: when I first saw this chart a few days ago, I didn't pay attention and I thought it was showing the daily temperatures compared to normal and in previous warm summers. Then after a while I wondered how the temperature could be above normal every day in Fairbanks, and I realized it was showing the summer-to-date average every day. You've made this clear in the chart inset text, but it might be worth clarifying in future posts, just to avoid any confusion. It's a useful and clever way of looking at the data, but new to some people (including myself).

    1. Thanks Richard. Those plots are definitely confusing but I like them so much I have a hard time leaving them out. I added a better description to yesterday's post that will hopefully make it a little more readable. Let me know what you think.

  2. Excellent Brian, that is crystal clear and I think will help some people. Nice work.

  3. I keep referring to this animation to see a rough reason as to why the recent warmth:


    Maybe there's a better explanation or pic? If so, how about sharing it?