Friday, September 23, 2011

Blast Furnace from the Past

With temperatures headed back toward something like normal over Interior Alaska this upcoming weekend, this seems a good time to look back at one of the greatest autumn chinooks of record.

It was mid-September back in '95, when sustained strong southerly flow brought six straight days with highs of 70F or higher to Fairbanks. Here is the NCAR reanalysis for 4am ADT Sep 20th:

Remarkable in itself, but this was topped off by one of the most anomalous temperature records in the 100+ years of weather observations here. On September 20th, a very mild airmass and strong southeast winds that remained up all kept the daily low temperature to an unbelievable 65F. Here's a plot of the upper air observations from Fairbanks for 4am ADT Sep 20th, courtesy of the Plymouth State Weather Center. Note that the near surface is well mixed thanks to the winds:

The low of 65F is not only, by far, the highest daily minimum temperature of record in September, its higher than any daily min temperature in August. This is a stunning 4.6 standard deviations above the long term mean daily minimum temperature for the three days centered on September 20th. This "standardized departure" is the largest daily positive anomaly in the Weather Bureau/NWS era of observations (1930-present) in Fairbanks.

No comments:

Post a Comment