A Most Unusual Winter

In standard meteorological terms, the Northern Hemisphere winter season is defined as December through February, and now that it's in the books it is worth looking at how Fairbanks fared for various aspects of the climate.

First, and obviously, it was very warm and very dry.  The mean temperature of +3.0°F was the 6th highest on record (1930-present), with January and February being somewhat warmer than December; but none of the 3 months was in the top 5 for mean temperature.  More remarkable was the near complete absence of unusual cold; only 3 days (December 5, 6, and 25) had a daily mean temperature more than 10°F below normal.  In contrast, 34 days were more than 10°F warmer than normal.  The lowest daily high temperature (including November) was a mere -9°F, so there was not a single day that remained at or below -10°F from midnight to midnight; this is unprecedented for a whole winter season.  The last such day was February 9 of last year.

Snowfall and liquid-equivalent precipitation were incredibly meager and both were easily the lowest on record.  The totals (0.13" and 2.5" respectively) were less than 10% of normal, which is astounding for a three-month season.  The snow depth remained nearly constant at either 12 or 13" since December 1, which is the least amount of variation ever seen in Fairbanks for the winter season.

Looking at some other variables that are reported by the airport's ASOS platform, the average visibility was the highest on record since the ASOS was introduced in 1997.  That's not a surprise because it hardly snowed at all; there were only 4 days on which visibility of 1 mile or less was observed, and this is a record for 1950-present.  However, cloud cover was only modestly below normal (7th lowest of 19 years).  As Brian showed in a blog post yesterday, the sea-level pressure for December-February was at record low levels across most of the Bering Sea and western Alaska, so ironically it was a very stormy pattern farther to the west and southwest; it was the persistent southerly flow and downsloping that kept Fairbanks so warm and dry.

Speaking of wind speed, the average daily wind speed in Fairbanks was well above normal and appears to be a record for the ASOS era (excluding 2010-2011, which seems to have a lot of missing data).  Only 53% of the ASOS observations reported calm winds in December through February, compared to about 65% in a normal winter and as high as 81% in 1998-1999.

I've discussed previously the low variance of temperature since the beginning of this year, and it's worth noting again here that the December-February variance of daily temperature anomalies was extremely low.  Only 1997-98 had a lower variance - and that was the last big El Niño winter.  This winter's standard deviation of 10.6°F compares to a long-term normal of 16°F.

Of course with the astonishing lack of snowfall the variance in snow depth was also extremely low (all-time record), as noted above; so one might be tempted to say this was the most boring winter on record.  It's interesting to look at the long-term trend in winter variance of temperature and snow depth - see the chart below.  Both have decreased in the past few decades, and the decrease in snow depth variance is particularly notable.  In fact the snow depth variance seems to be in a well-established long-term downward trend; every one of the past 16 winters has seen snow depth vary by less than what was normal in the 1930-1970 period.  There might be some influence here from changing measuring practices, but I doubt that would explain the bulk of the change.  It's certainly a topic for further investigation.

For the sake of completeness, here's the NWS summary for February.

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
1053 AM AKST TUE MAR 1 2016

...MONTHLY WEATHER SUMMARY FOR FEBRUARY FOR FAIRBANKS ALASKA...

THE REMARKABLY WARM AND DRY WEATHER PATTERN FOR FAIRBANKS CONTINUES.
FEBRUARY 2016 MUCH LIKE JANUARY 2016 AND DECEMBER 2015 WAS WARMER
THAN NORMAL AND EXCEPTIONALLY DRY. ONLY 0.6 INCHES OF SNOW FELL
DURING THE MONTH OF FEBRUARY AT THE FAIRBANKS AIRPORT WHICH
RANKED AS THE 99TH SNOWIEST OF 105 YEARS OF RECORD. NORMAL SNOWFALL
AT THE FAIRBANKS AIRPORT DURING THE MONTH OF FEBRUARY IS 8.1
INCHES. ALL OF THE 0.6 INCHES OF SNOW FELL ON THE 6TH WHICH WAS
THE HEAVIEST 24 HOUR SNOWFALL FOR THE MONTH. TRACE AMOUNTS OF SNOW
FELL ON 3 OTHER DAYS.

ONLY 0.05 INCHES OF PRECIPITATION FELL AT THE FAIRBANKS AIRPORT IN
FEBRUARY WHICH WAS 0.37 INCHES BELOW THE NORMAL PRECIPITATION OF
0.42 INCHES. THIS RANKS AS THE 8TH DRIEST FEBRUARY OF 105 YEARS OF
RECORD.

THE VERY DRY MONTH OF DECEMBER 2015 COMBINED WITH THE EXCEPTIONALLY
DRY MONTHS OF JANUARY AND FEBRUARY 2016 RANKED AS THE LEAST SNOWY
DECEMBER...JANUARY...FEBRUARY PERIOD ON RECORD WITH ONLY 2.5
INCHES OF SNOW FALLING DURING THOSE THREE MONTHS AT FAIRBANKS.
THE SECOND LEAST SNOWY DECEMBER TO FEBRUARY PERIOD OCCURRED DURING
THE WINTER OF 1918 TO 1919 WHERE 4.9 INCHES OF SNOW FELL...NEARLY
DOUBLE WHAT FELL DURING DECEMBER 2015 TO FEBRUARY 2016. DURING THE
DECEMBER 2015 TO FEBRUARY 2016 PERIOD ONLY 0.13 INCHES OF
PRECIPITATION FELL AT THE FAIRBANKS AIRPORT WHICH ALSO RANKS AS
THE DRIEST DECEMBER TO FEBRUARY PERIOD ON RECORD. THIS IS ONLY ONE
THIRD OF THE PRECIPITATION THAT FELL DURING THE SECOND DRIEST
DECEMBER TO FEBRUARY PERIOD DURING THE WINTER OF 1935 TO 1936 WHEN
0.35 INCHES OF PRECIPITATION FELL. DESPITE NEAR RECORD SNOWFALL
IN BOTH SEPTEMBER AND NOVEMBER OF THIS WINTER SEASON...SEASON TO
DATE SNOWFALL CURRENTLY 52.6 INCHES IS NOW 3.7 INCHES BELOW THE
NORMAL SEASON TO DATE SNOWFALL ON THE 1ST OF MARCH OF 56.3 INCHES.

FEBRUARY 2016 WAS ALSO VERY WARM WITH NO SEVERE COLD PERIODS. THE
AVERAGE MAXIMUM TEMPERATURE WAS 20.0 DEGREES ABOVE WHICH WAS 10.0
DEGREES ABOVE THE NORMAL MAXIMUM TEMPERATURE OF 10 ABOVE. THIS
RANKED AS THE 11TH WARMEST OF 108 YEARS OR RECORD. THE AVERAGE
MINIMUM TEMPERATURE WAS 4.2 BELOW WHICH WAS 8.5 DEGREES ABOVE THE
NORMAL MINIMUM TEMPERATURE OF 12.7 BELOW. THIS RANKED AS THE 19TH
WARMEST OF 109 YEARS OF RECORD. THE MEAN TEMPERATURE WAS 7.9 ABOVE
WHICH WAS 9.2 DEGREES ABOVE THE NORMAL MEAN TEMPERATURE OF 1.3
DEGREES BELOW. THIS RANKS AS THE 14TH WARMEST OF 108 YEARS OF
RECORD. THE WARMEST TEMPERATURE DURING THE MONTH OF FEBRUARY WAS
42 DEGREES WHICH OCCURRED ON THE 25TH. THE COLDEST TEMPERATURE WAS
21 BELOW WHICH OCCURRED ON THE 19TH.

THE AVERAGE TEMPERATURE FOR THE DECEMBER 2015 TO FEBRUARY 2016 WAS
3.0 DEGREES WHICH RANKS AS THE 8TH WARMEST DECEMBER TO FEBRUARY
PERIOD ON RECORD. 

THE COLDEST TEMPERATURE OF THIS WINTER SEASON REMAINS 29 BELOW
WHICH OCCURRED ON CHRISTMAS 2015. THERE HAS NOT BEEN A 30 BELOW OR
COLDER DAY TO DATE THIS COLD SEASON. THERE HAS ONLY BEEN ONE COLD
SEASON 1976 TO 1977 IN THE CLIMATIC RECORD THAT THE TEMPERATURE
DID NOT REACH 30 BELOW OR COLDER AT FAIRBANKS. THE LATEST FIRST
OCCURRENCE OF 30 BELOW OR COLDER OCCURRED ON THE 27TH OF FEBRUARY
IN 1986 HOWEVER THE LATEST 30 BELOW OR COLDER IN FAIRBANKS OCCURRED
ON THE 3RD OF APRIL IN 1944. THE AVERAGE COLDEST MINIMUM TEMPERATURE
FOR THE MONTH OF MARCH IS 28 BELOW. ON AVERAGE THE TEMPERATURE
FALLS TO 30 BELOW OR COLDER ON TWO DAYS IN MARCH. THE AVERAGE
NUMBER OF 30 BELOW DAYS OR COLDER IN FAIRBANKS FOR A COLD SEASON
IS 25.

LOOKING FORWARD TO MARCH THE TEMPERATURES CLIMB SHARPLY AS THE
SUN ANGLE AND LENGTH OF DAY INCREASES. THE AVERAGE DAILY HIGH
TEMPERATURE INCREASES FROM 18 DEGREES ABOVE ON THE 1ST TO 34
DEGREES ON THE 31ST. THE AVERAGE DAILY LOW TEMPERATURE INCREASES
FROM 9 BELOW ON THE 1ST TO 8 ABOVE ON THE 31ST. OVER THE PAST 108
YEARS THE TEMPERATURES HAVE RANGED FROM 56 ABOVE IN 1994 TO 56
BELOW IN 1911. MARCH IS ON AVERAGE THE DRIEST MONTH IN FAIRBANKS.
NORMAL PRECIPITATION IS 0.25 INCHES WHILE NORMAL SNOW FALL IS 4.9
INCHES. IN SOME YEARS THE SNOW PACK BEGINS TO MELT BY LATE MARCH
ESPECIALLY IN THE URBAN AREAS.

POSSIBLE SUNSHINE INCREASES BY NEARLY 7 MINUTES PER DAY DURING
MARCH INCREASING FROM 10 HOURS AND 12 MINUTES ON THE 1ST TO 13
HOURS AND 35 MINUTES ON THE 31ST.

THE FORECAST FOR MARCH FROM THE CLIMATE PREDICTION CENTER CALLS
FOR INCREASED CHANCES FOR ABOVE NORMAL TEMPERATURES AND INCREASED
CHANCES OF BELOW NORMAL PRECIPITATION. 


OBSERVED LAST MONTH...02/2016

                         OBSERVED   RANK
AVG MAX TEMP (F)             20.0   11TH WARMEST OF 108 YEARS
AVG MIN TEMP (F)             -4.2   19TH WARMEST OF 109 YEARS
AVG TEMP (F)                  7.9   14TH WARMEST OF 108 YEARS
TOTAL PRECIP (IN)            0.05   8TH DRIEST OF 105 YEARS
TOTAL SNOW (IN)              0.60   99TH SNOWIEST OF 105 YEARS