A Statistical Preview of Denver's July Weather

            ...A STATISTICAL PREVIEW OF DENVER'S JULY WEATHER...
 
AFTER THE RECORD HOT MONTH OF JUNE 2012, DENVER'S WEATHER HISTORY SHOWS THAT JULY CAN GO EVEN HOTTER. JULY IS DENVER'S CLIMATOLOGICAL WARMEST MONTH AND LIKE MOST LOCATIONS IN THE UNITED STATES, THE DAILY AVERAGE TEMPERATURES PEAK APPROXIMATELY 4 WEEKS AFTER THE SUMMER SOLSTICE.
 
DENVER, ALONG WITH THE ENTIRE SPAN OF THE U.S. ROCKIES, EXPERIENCE THE ONSET OF THE NORTH AMERICAN MONSOON DURING JULY. EVERY YEAR A DOMINANT RIDGE OF HIGH PRESSURE TYPICALLY DEVELOPS OVER THE CENTRAL UNITED STATES WITH COLORADO LOCATED ON THE WESTERN EDGE. THIS ALLOWS FOR SUBTROPICAL MOISTURE TO DRAW NORTHWARD, AT ALL LEVELS OF THE ATMOSPHERE, INTO THE ROCKY MOUNTAIN REGION.
 
LIKE JUNE, LOW LEVEL GULF MOISTURE OFTEN FINDS IT'S WAY INTO EASTERN COLORADO ON THE WESTERN EDGE OF THE CENTRAL UNITED STATES LOW-LEVEL JET. THE WEAKEST OF UPPER LEVEL DISTURBANCES IN WEST TO NORTHWESTERLY FLOW ALOFT, RIDING OVER THE MOISTURE AT THE LOW LEVELS, CAN IGNITE AN AFTERNOON AND EVENING OF SEVERE WEATHER RANGING FROM HEAVY RAIN TO TENNIS BALL SIZED HAIL TO TORNADOES.
 
WITH DENVER'S DAILY NORMAL TEMPERATURES PEAKING IN LATE JULY, TEMPERATURE VARIATION BECOMES FAIRLY LOW FROM THE BEGINNING THROUGH THE END OF THE MONTH. DENVER'S MONTHLY MEAN TEMPERATURE FOR JULY IS 74.2 DEGREES (1981-2010 AVERAGES) AND IS DENVER'S WARMEST MONTH OF THE YEAR. JULY STARTS THE MONTH WITH A NORMAL HIGH OF 87 DEGREES AND ENDS WITH A NORMAL HIGH OF 90 DEGREES. FOR LOW TEMPERATURES, THE MONTH BEGINS WITH A NORMAL OF 57 DEGREES AND FINISHES WITH A NORMAL OF 60.
 
THE WARMEST TEMPERATURE EVER RECORDED DURING THE MONTH OF JULY, SINCE RECORDS BEGAN IN 1872, WAS 105 DEGREES ON THE 20TH DAY OF 2005. JULY'S COLDEST TEMPERATURE EVER RECORDED IN DENVER WAS 42 DEGREES AND OCCURRED ON THE 31ST DAY OF 1873.
 
JULY: DENVER`S TOP 5 WARMEST (MEAN TEMPERATURES):
 
77.8 DEGREES 1934 *WARMEST MONTH IN DENVER HISTORY FROM 1872-2011
77.7         2005
77.6         2008
77.3         1936
77.1         1939
 
JULY: DENVER`S TOP 5 COLDEST (MEAN TEMPERATURES):
 
67.4 DEGREES 1895
68.2         1906
68.7         1915
68.8         1904
68.9         1891 & 1950
 
ALONG WITH JUNE, THE POSSIBILITY OF SEVERE WEATHER IN FULL FORCE DURING THE MONTH OF JULY. RAINFALL TOTALS FROM STRONG, RAIN DUMPING THUNDERSTORMS ARE STILL THE MEASURE OF INTEREST. DENVER'S THE 3RD AND 5TH WETTEST MONTHS IN DENVER HISTORY OCCURRED IN JULY, 1965 AND JULY 1998, RESPECTIVELY. THE 8TH HIGHEST 24 HOUR PRECIPITATION TOTAL IN DENVER HISTORY OCCURRED ON JULY 30TH, 1997 AS 2.17 INCHES OF RAIN FELL.
 
JULY: DENVER`S WETTEST
 
6.41 INCHES 1965
5.92        1998
5.60        1997
5.24        1919
4.75        2001
 
JULY: DENVER`S DRIEST
 
0.01 INCHES 1901
0.08        1916
0.24        2008
0.27        2005
0.31        1920
 
                    ...THE OUTLOOK FOR JULY 2012...
 
AFTER RECORD BREAKING HEAT IN JUNE ALONG WITH THE 4TH CONSECUTIVE MONTH OF BELOW NORMAL PRECIPITATION IN DENVER, THE MID TO LONG RANGE FORECAST MODELS INDICATE THE STABLE RIDGE OF HIGH PRESSURE TO CONTINUE TO DOMINATE THE CENTRAL UNITED STATES THROUGH THE MIDDLE OF JULY, 2012. THIS WILL LIKELY ALLOW FOR THE CONTINUATION OF ABOVE NORMAL TEMPERATURES ALONG WITH A BIAS TOWARD BELOW NORMAL PRECIPITATION. FOR THE REMAINDER OF JULY 2012, DESPITE THE CLIMATOLOGICAL PEAK OF THE NORTH AMERICAN MONSOON, THE CLIMATE PREDICTION CENTER'S LONG RANGE OUTLOOK INDICATES A BIAS TOWARD ABOVE NORMAL TEMPERATURES WITH PRECIPITATION PROBABILITIES HOLDING NEAR SEASONAL NORMALS.
 
                       ...JULY STATISTICS...
 
...TEMPERATURES (1981-2010 NORMALS)...
 
AVERAGE HIGH........................... 89.4
AVERAGE LOW............................ 58.9
MONTHLY MEAN........................... 74.2
DAYS WITH HIGH 90 OR ABOVE............. 16 (16.0)
DAYS WITH HIGH 32 OR BELOW.............   0 (0.0)
DAYS WITH LOW 32 OR BELOW..............   0 (0.0)
DAYS WITH LOWS ZERO OR BELOW...........   0 (0.0)
 
...PRECIPITATION...
 
MONTHLY MEAN...........................   2.16 INCHES
DAYS WITH MEASURABLE PRECIPITATION.....   8 (8.3)
AVERAGE SNOWFALL.......................   0.0 INCHES
 
...MISCELLANEOUS JULY AVERAGES...
 
HEATING DEGREE DAYS....................   6
COOLING DEGREE DAYS.................... 289
WIND SPEED (MPH).......................   8.3*
WIND DIRECTION......................... SOUTH*
DAYS WITH THUNDERSTORMS................ 11* (11.1)
DAYS WITH DENSE FOG....................   0* (<0.4)
PERCENT OF SUNSHINE.................... 71*
(NOTE: SUNSHINE DATA ARE NO LONGER COLLECTED AS OF OCTOBER 1, 2009)
 
* = 1971-2002 NORMALS
 
...JULY EXTREMES...
 
RECORD HIGH............................ 105 DEGREES ON 7/20/2005
RECORD LOW............................. 42 DEGREES ON 7/4/1903
                                                      7/31/1873
WARMEST JULY........................... 77.8* DEGREES IN 1934
                                               *WARMEST MONTH IN
                                                DENVER HISTORY
MAXIMUM COOLING DEGREE DAYS............ 405 IN 2005
MINIMUM COOLING DEGREE DAYS............ 181 IN 2009
COLDEST................................ 67.4 DEGREES IN 1895
MAXIMUM HEATING DEGREE DAYS............ 42 IN 1951
MINIMUM HEATING DEGREE DAYS............   0 NUMEROUS YEARS
WETTEST................................   6.41 INCHES IN 1965
DRIEST.................................   0.01 IN 1901
 
FREDIN


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