A Statistical Preview of Denver's January Weather

       ...A STATISTICAL PREVIEW OF DENVER`S JANUARY WEATHER...
 
ALONG WITH MOST LOCATIONS OF THE HIGH PLAINS OF THE UNITED STATES, JANUARY IN DENVER RESTS IN THE MIDDLE OF THE COLDEST AND DRIEST PORTION OF THE YEAR. SIMILAR TO DECEMBER AND FEBRUARY, UNSEASONABLY MILD TEMPERATURES CAN OCCUR ALONG WITH EXTENDED PERIODS OF EXTREME COLD WHERE THE MERCURY CAN DROP INTO THE MINUS DOUBLE DIGITS. ARCTIC COLD FRONTS ARE MOST COMMON IN JANUARY, AND WINTER STORM SYSTEMS ARE TYPICALLY DRYER COMPARED THOSE OF LATE FALL AND LATE WINTER.
 
DENVER'S MONTHLY MEAN TEMPERATURE FOR JANUARY IS 30.7 DEGREES (1981-2010 AVERAGES) AND IS DENVER'S 2ND COLDEST MONTH OF THE YEAR BEHIND DECEMBER'S MONTHLY MEAN TEMPERATURE OF 30.0 (1981-2010 AVERAGES).
JANUARY'S DAILY NORMAL HIGH TEMPERATURES HOLD VERY CONSTANT THROUGH THE MONTH STARTING WITH A HIGH OF 43 DEGREES AND ENDING WITH A NORMAL HIGH OF 44 DEGREES. FOR LOW TEMPERATURES, THE MONTH BEGINS WITH A NORMAL LOW OF 17 DEGREES AND FINISHES WITH A LOW OF 17 DEGREES.
 
THE WARMEST TEMPERATURE EVER RECORDED DURING THE MONTH OF JANUARY, SINCE RECORDS BEGAN IN 1872, WAS 76 DEGREES ON THE 28TH DAY OF THE MONTH, 1888. JANUARY'S COLDEST TEMPERATURE EVER IN DENVER WAS -29 DEGREES ON 9TH OF 1875. THIS IS ALSO THE COLDEST TEMPERATURE EVER RECORDED IN DENVER'S HISTORY.
 
DENVER'S TOP 5 COLDEST JANUARYS (MEAN TEMPERATURES):
 
16.9 DEGREES 1930 ***COLDEST MONTH IN DENVER HISTORY
18.0         1979
18.1         1875
18.2         1937
19.1         1963
 
DENVER'S TOP 5 WARMEST JANUARYS (MEAN TEMPERATURES):
 
40.3 DEGREES 1986
40.0         1934
39.6         1953
39.4         1935
38.3         1893
 
FOR DENVER'S NINE MONTH SNOW PERIOD OF SEPTEMBER THROUGH MAY, JANUARY RANKS 4TH BEHIND MARCH, NOVEMBER AND DECEMBER. DENVER NORMALLY COLLECTS 7.0 INCHES IN JANUARY BASED ON AVERAGES FROM OLD STAPLETON INTL AIRPORT (1981-2010 AVERAGES). SIMILAR TO FEBRUARY, THE SNOWSTORMS WHICH REACH THE FRONT RANGE ARE TYPICALLY LESS POTENT COMPARED TO THOSE OF DECEMBER AND MARCH AND ARE OFTEN DRIVEN BY CANADIAN AND ARCTIC SURFACE COLD FRONTS WITH LOWER MOISTURE CONTENT.
 
DENVER'S SNOWIEST JANUARYS:
 
24.3 INCHES 1992
22.2        1949
20.5        1883
19.2        1948
17.4        1959
 
THE WINTER PERIOD OF DECEMBER THROUGH MARCH OVER THE HIGH PLAINS STATES OCCASIONALLY RECEIVES EXTENDED DROUGHT-LIKE CONDITIONS. THESE DRY PERIODS ARE OFTEN ASSOCIATED WITH LA NINA PHASES OF THE PACIFIC OCEANIC REGION AND CAN TAKE MONTHLY TEMPERATURES TO ABOVE SEASONAL NORMALS MAINLY DUE TO WARMER NIGHT-TIME LOW TEMPERATURES FROM LACK OF SNOW COVER. LA NINA PATTERNS ARE ALSO ASSOCIATED WITH CONTINUOUS WINDY DOWNSLOPE PERIODS ALONG THE EASTERN PLAINS REGION, INCLUDING THE FRONT RANGE FOOTHILLS AND THE ENTIRE I-25 CORRIDOR, INCLUDING DENVER. THIS DOWNSLOPE WEATHER FEATURE ALSO PROVIDES A WARM BIAS TO TEMPERATURES EAST OF THE CONTINENTAL DIVIDE.
 
DENVER'S LEAST SNOWIEST JANUARYS:
 
 T   INCHES 1934, 2003
0.1         1931
0.2         1933
0.3         1952
0.4         1914
 
                    ...THE OUTLOOK FOR JANUARY 2013...
 
WINTER FINALLY ARRIVED TO COLORADO AND THE FRONT RANGE OVER THE CHRISTMAS HOLIDAY. THIS BROUGHT FRESH SNOW TO THE REGION ALONG WITH TEMPERATURES WHICH WERE WELL BELOW SEASONAL NORMALS. UNSETTLED WEATHER CROSSED INTO THE NEW YEAR AS A MINOR STORM SYSTEM BRUSHED ACROSS THE STATE AND REINFORCED THE COLD AIR OVER THE REGION DUE TO CONTINUED NORTHWESTERLY FLOW ALOFT.
 
LOOKING TOWARD THE FIRST 10 DAYS OF JANUARY 2013, THE SHORT TO MID-RANGE MODELS INDICATE THAT A SERIES OF WINTER STORM SYSTEMS WILL BRING THE POSSIBILITY OF MORE LIGHT SNOW AND CONTINUED COLD AIR TO THE CENTRAL ROCKIES. PAST THIS PERIOD, THE MID TO LONG TERM INDICATIONS POINT TO A PERSISTENT COLD MEAN TROUGH OF LOW PRESSURE HOLDING OVER VARIOUS POINTS OF NORTH AMERICA THROUGH THE FIRST TWO THIRDS OF JANUARY 2013. THIS WOULD INDICATE A BIAS TOWARD TEMPERATURES HOLDING BELOW SEASONAL NORMAL AND PRECIPITATION POSSIBILITIES BEING ABOVE NORMAL. AS WE LOOK TOWARD THE LAST 10 DAYS OF JANUARY, THE LONG RANGE MODELS INDICATE A TREND BACK TOWARD NORMAL SEASONAL TEMPERATURE AND PRECIPITATION LEVELS.
 
WITH THE CURRENT EL NINO SOUTHERN OSCILLATION CONDITIONS HOLDING IN A NEUTRAL PHASE OVER THE PACIFIC REGION, WIDE VARIATIONS FROM THE TEMPERATURE AND PRECIPITATION MEANS ARE NOT EXPECTED,
MOST NOTABLY AS THE YEAR MOVES TOWARD SPRING.
 
                       ...JANUARY STATISTICS...
 
...TEMPERATURES (1981-2010 NORMALS)...
 
AVERAGE HIGH........................... 44.0
AVERAGE LOW............................ 17.4
MONTHLY MEAN........................... 30.7
DAYS WITH HIGH 90 OR ABOVE.............   0
DAYS WITH HIGH 32 OR BELOW.............   6 (5.5)
DAYS WITH LOW 32 OR BELOW.............. 29 (29.4)
DAYS WITH LOWS ZERO OR BELOW...........   2 (1.7)
 
...PRECIPITATION...
 
MONTHLY MEAN...........................   0.41 INCH
DAYS WITH MEASURABLE PRECIPITATION.....   4 (4.1)
AVERAGE SNOWFALL.......................   7.0 INCHES (4TH SNOWIEST
                                                      MONTH)
DAYS WITH ANY SNOWFALL.................   5.0
DAYS WITH SNOWFALL GREATER THAN 1.0"...   2 (2.2)
 
...MISCELLANEOUS JANUARY AVERAGES...
 
HEATING DEGREE DAYS.................... 1063
COOLING DEGREE DAYS....................    0 (0.0)
WIND SPEED (MPH).......................    8.6*
WIND DIRECTION......................... SOUTH*
DAYS WITH THUNDERSTORMS................    0* (<0.5)
DAYS WITH DENSE FOG....................    1* (1.1)
PERCENT OF SUNSHINE....................   71*
(NOTE: SUNSHINE DATA ARE NO LONGER REPORTED AS OF OCTOBER 1, 2009)
 
* = 1971-2002 NORMALS
 
...JANUARY EXTREMES...
 
RECORD HIGH............................ 76 DEGREES ON 1/27/1888
RECORD LOW............................. -29 DEGREES ON 1/9/1875
                               (LOWEST TEMPERATURE IN DENVER HISTORY)
WARMEST................................ 40.3 DEGREES IN 1986
MAXIMUM/MINIMUM COOLING DEGREES DAYS... NONE EVER RECORDED
COLDEST................................ 16.9 DEGREES IN 1930
                                  (COLDEST MONTH IN DENVER HISTORY)
MAXIMUM HEATING DEGREE DAYS............ 1492 IN 1930
MINIMUM HEATING DEGREE DAYS............   758 IN 1986
WETTEST................................   2.35 INCHES IN 1883
DRIEST.................................   0.01 INCHES IN 1933
 
FREDIN


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