Thornton closed out 2011 with a month that while not necessarily historical, brought significant weather to the area.  Snow was one of the bigger stories as we piled up a good bit of the white stuff and temperatures were below normal for the month.

December 2011 came in like a lion as a cold front and associated upper level storm arrived during the first week of the month.  Denver International Airport recorded 9.2 inches of snow during the period while here in Thornton we saw 10.7 inches.  Temperatures were a bone chilling 17.2 degrees below normal during that time.

The middle of the month saw the weather moderate and return to more seasonal conditions.  Temperatures overall however remained slightly below average.

With the third week of the month we saw another snowstorm arrive on the 21st and 22nd.  Denver recorded 7.3 inches of snow.  Thornton once again saw higher totals as we measured 9.1 inches.

The constant snow cover kept temperatures down through the first few weeks of the month and for a time it looked like the month could make it into the books as one of the coldest on record.  A late month warming trend however changed that situation.

In the end, December 2011’s average temperature was 26.6 degrees.  While this was 3.4 degrees below normal, it pushed the month out of ‘top 10 coldest’ contention.

The snow during the month, while also not record setting, was significant.  Denver wrapped up December with 16.5 inches – nearly double the 8.5 inch December average.  For the season to date we stood at 29.5 inches giving us a good start toward the 53.5 inch seasonal average.

In terms of precipitation, 0.78 inches was recorded in Denver which was 0.47 inch above normal.

At DIA, temperatures ranged from a high of 58 degrees on the 18th down to a low of -5 degrees on the 6th.  Thornton saw similar marks with a high of 59.7 degrees, also on the 18th, and a low of -6.5 degrees on the 6th.

Mother Nature did close out the month and 2011 with a significant windstorm across northeastern Colorado.  The New Year’s Eve event saw DIA record a 59mph wind gust and Thornton saw 45mph.  Many other areas saw much higher speeds – click here for a summary of the event.

Click here to view the Thornton climatological summary for December 2011.  Below is the official Denver summary from the National Weather Service.

CLIMATE REPORT
NATIONAL WEATHER SERVICE BOULDER, CO
335 PM MST TUE JAN 3 2012

...THE DENVER CO CLIMATE SUMMARY FOR THE MONTH OF DECEMBER 2011... 

CLIMATE NORMAL PERIOD 1981 TO 2010
CLIMATE RECORD PERIOD 1872 TO 2012

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR`S
                 VALUE   DATE(S)  VALUE   FROM    VALUE  DATE(S)
                                          NORMAL
................................................................ 
TEMPERATURE (F)
RECORD
 HIGH              79   12/05/1939
 LOW              -25   12/22/1990
                        12/24/1876
HIGHEST            58   12/18        79     -21       70  12/14
LOWEST             -5   12/06       -25      20        0  12/31
AVG. MAXIMUM     38.5              42.8    -4.3     48.9
AVG. MINIMUM     14.8              17.1    -2.3     19.6
MEAN             26.6              30.0    -3.4     34.3
DAYS MAX >= 90      0               0.0     0.0        0
DAYS MAX <= 32      7               5.8     1.2        2
DAYS MIN <= 32     30              29.4     0.6       28
DAYS MIN <= 0       2               2.0     0.0        1

PRECIPITATION (INCHES)
RECORD
 MAXIMUM         5.21   1913
 MINIMUM         0.00   1881
TOTALS           0.78              0.31    0.47     0.22
DAILY AVG.       0.03              0.01    0.02     0.01
DAYS >= .01         6               4.1     1.9        2
DAYS >= .10         3               1.1     1.9        2
DAYS >= .50         0               0.1    -0.1        0
DAYS >= 1.00        0               0.0     0.0        0
GREATEST
 24 HR. TOTAL    0.48   12/21 TO 12/22           12/30 TO 12/31

SNOWFALL (INCHES)
RECORDS
 TOTAL           57.4   1913
TOTALS           16.5               8.5

DEGREE_DAYS
HEATING TOTAL    1182              1086      96      944
 SINCE 7/1       2434              2463     -29     2072
COOLING TOTAL       0                 0       0        0
 SINCE 1/1        964               769     195      870

FREEZE DATES
RECORD
 EARLIEST     09/08/1962
 LATEST       06/08/2007
EARLIEST                        10/07
LATEST                          05/05
.................................................. 

WIND (MPH)
AVERAGE WIND SPEED              9.4
RESULTANT WIND SPEED/DIRECTION   4/224
HIGHEST WIND SPEED/DIRECTION    45/270    DATE  12/31
HIGHEST GUST SPEED/DIRECTION    59/270    DATE  12/31

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM
AVERAGE SKY COVER           0.40
NUMBER OF DAYS FAIR           15
NUMBER OF DAYS PC             12
NUMBER OF DAYS CLOUDY          4

AVERAGE RH (PERCENT)     62

WEATHER CONDITIONS. NUMBER OF DAYS WITH
THUNDERSTORM              0     MIXED PRECIP               0
HEAVY RAIN                0     RAIN                       0
LIGHT RAIN                0     FREEZING RAIN              1
LT FREEZING RAIN          0     HAIL                       0
HEAVY SNOW                1     SNOW                       5
LIGHT SNOW                6     SLEET                      0
FOG                      11     FOG W/VIS <= 1/4 MILE      3
HAZE                      4

-  INDICATES NEGATIVE NUMBERS.
R  INDICATES RECORD WAS SET OR TIED.
MM INDICATES DATA IS MISSING.
T  INDICATES TRACE AMOUNT.