Saturday, May 16, 2015

Temperature Extremes

The heat is on in the interior, with the temperature reaching 76 °F in Fairbanks and Nenana yesterday, and 77 °F in Northway.  It probably won't be many days before 80 °F is reached in Fairbanks, as forecasts show the strong ridge over northwestern Canada persisting and perhaps intensifying next week.

Bettles recorded a daily minimum temperature of 53 °F on Thursday, which is the warmest low temperature for this early in the season except for the extreme early heat wave of May 1995.  The 1995 heat wave brought a high temperature of 81 °F to Bettles on May 11 (the earliest 80+ reading by nearly two weeks), and raised the mercury to a remarkable 88 °F in Fairbanks on the same day (the earliest 85+ reading by 13 days).  Without a doubt, the 1995 event is the gold standard for early extreme heat in Fairbanks; a few other years have reached 80 °F by mid-May, but never much above that level.

I thought it would be interesting to view a graphical representation of the earliest and latest extremes of temperature in Fairbanks - see the chart below.  The left side of the chart shows the extremes for earliest warmth (high Tmax, high Tmin) or latest cold (low Tmax, low Tmin) from January 1 through June 30; so for example, the 88 °F on May 11 shows up as a jump in the "highest Tmax" line.  It's interesting that the cold extremes also show a jump at about the same time - that would be the extreme cold of May 8-9, 1964.  The right side of the chart shows the earliest cold and latest warm extremes, from July 1 through December 31.

The chart is quite a handy tool for seeing the periods of the year during which any particular extreme has been observed, for example 80 °F has never been observed earlier than May 9 or later than September 5.  It's interesting to see how late in the year minimum temperatures above 60 °F have been observed; but this is due to one event, the great chinook of late September 1995.  (As an aside, I'm intrigued by a possible connection between May and September weather - early and late extreme warmth in 1995, late and early extreme snowfall in 1992... food for thought!)

Here are corresponding charts for Bettles, McGrath, and Northway.

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