Warmth Aloft Persists

Valley locations in the Fairbanks area continue to see cold and stagnant conditions under high pressure, but temperatures aloft are much warmer, resulting in a strong inversion.  Yesterday evening saw a temperature of -31 °F at Goldstream Creek and +9 °F on Keystone Ridge, a difference of 40 °F in a short distance.  Farther aloft, the temperature measured by balloon sounding yesterday afternoon was as high as +18 °F at 869 mb or 3766 feet above ground level; and other soundings have been even warmer in recent days.

The persistent absence of cold conditions aloft has been a very prominent feature of the winter in Fairbanks so far, and in fact it's record-breaking by quite a large margin.  The chart below shows the lowest observed value of the column maximum temperature in the early winter, i.e. prior to the turn of the year, for each year since 1948.  Remarkably, this winter's balloon soundings from Fairbanks have not yet observed a column colder than -11.1 °C (+12 °F) throughout the troposphere; there has always been air at least this warm at some level.  The previous record in this respect was -18.5 °C (-1 °F) in 1953.  The chart shows an interesting pattern of rising minima in recent decades, indicating that this year's outcome is a continuation of a long-term trend.

Another way of expressing the extreme persistence of warmth this winter is that only two soundings so far have observed a column colder than -10 °C throughout (back in November).  The next closest winter in this regard is 2000-2001, with 13 soundings colder than -10 °C by the turn of the year, and even the exceptionally warm early winter of 2002 had 22 soundings meeting this threshold of cold.