Category Archives: Climatology

April 2011 ends as 7th warmest on record for the globe; Denver warmer and drier than normal

Global surface temperature Anomalies - April 2011. (NOAA)
Not only did Denver and Thornton see warmer than normal temperatures in April, so did the rest of the globe. Click the image for a larger version. (NOAA)

With the effects of La Nina still in full force the globe’s temperatures performed as forecasted during April 2011.  According to NOAA the month ranked as the seventh warmest April on record while Denver saw warmer and drier than normal conditions as well.

Denver saw an average temperature during the month of 48.4 degrees – 0.8 degree above normal.  Temperatures ranged from a record high of 84 degrees on the 2nd down to a low of 19 on the 4th of the month.  Fifteen days saw temperatures dip below the freezing mark which is four more than normal.

Here in Thornton we were slightly cooler with an average of 48.1 degrees for April.  Our high ranged from 86.3 degrees down to a low of 20.6 degrees.

The lack of precipitation and snowfall was one of the biggest stories of the month for the Mile High City.  A mere 1.07 inch of precipitation was recorded in Denver’s rain bucket which was 0.86 inch below the normal of 1.93 inches.

Snowfall was similarly dismal as only 1.2 inches of snow was recorded at Denver International Airport.  This was far below the normal of 9.1 inches for April which is historically our fourth snowiest month.  Through April 30, a mere 21.8 inches of snow has been recorded at Denver’s official monitoring site at Denver International Airport – the second worst snow season to date.

Thornton was a bit wetter than Denver as we recorded 1.54 inches of liquid precipitation.  In terms of snowfall we received only 1.5 inches, most of which (1.3”) fell on the 3rd of the month.

Overall the globe saw warm temperatures as well.  The combined land and ocean temperature average for the month was 57.76° F which was 1.06° above the 20th century average.  Taken separately the land surface temperature was 2.02° above normal and sea temperatures were 0.70° above normal.

April 2011 global climate summary – From NOAA:

The Earth experienced the seventh warmest April since record keeping began in 1880, as the climate phenomenon La Niña continued to be a significant factor. April’s annual Arctic sea ice extent was the fifth smallest since record keeping began in 1979, while the Antarctic sea ice extent was the fourth smallest.

The monthly analysis from NOAA’s National Climatic Data Center in Asheville, N.C., is part of the suite of climate services NOAA provides government, business and community leaders so they can make informed decisions.

Global Temperature Highlights – April

  • The combined global land and ocean average surface temperature for April 2011 was the seventh warmest on record at 57.76 F (14.29 C), which is 1.06 F (0.59 C) above the 20th century average of 56.7 F (13.7 C). The margin of error associated with this temperature is +/- 0.13 F (0.07 C).
  • Separately, the global land surface temperature was 2.02 F (1.12 C) above the 20th century average of 46.5 F (8.1 C), which was the sixth warmest April on record. The margin of error is +/- 0.20 F (0.11 C). Warmer-than-average conditions occurred across most of the southern United States and northern Mexico, much of central South America, Europe and Siberia. Cooler-than-average regions included most of Alaska, western Canada, the northwestern United States, southwestern Greenland and most of Australia.
  • The April global ocean surface temperature was 0.70 F (0.39 C) above the 20th century average of 60.9 F (16.0 C), making it the 11th warmest April on record. The margin of error is +/- 0.07 F (0.04 C). The warmth was most pronounced in the eastern Atlantic Ocean, the northwestern Pacific and across the Southern Hemisphere mid-latitudes.
  • The average temperature was the warmest on record for April across the United Kingdom. Germany reported its second warmest April since records began in 1881.

Global Temperature Highlights – Year-to-date

  • The combined global land and ocean average surface temperature for the year to date (January – April 2011) was 0.86 F (0.48 C) above the 20th century average of 54.8 F (12.6 C), making it the 14th warmest on record. The margin of error is +/- 0.16 F (0.09 C).
  • The year-to-date worldwide land surface temperature was 1.33 F (0.74 C) above the 20th century average — the 17th warmest such period on record. The margin of error is +/- 0.36 F (0.20 C). Warmer-than-average conditions were particularly felt across the southern half of Greenland, Siberia, northern Mexico, the southern United States and across Africa. Cooler-than-average regions included central Canada, the northern United States, western Russia, Kazakhstan, Mongolia, extreme southeast Asia and most of Australia.
  • The global ocean surface temperature for the year-to-date was 0.68 F (0.38 C) above the 20th century average and was the 11th warmest such period on record. The margin of error is +/-0.07 F (0.04 C). The warmth was most pronounced across parts of the most of the western Pacific Ocean, the tropical Atlantic Ocean, the North Atlantic near Greenland and Canada, and the southern mid-latitude oceans.
  • La Niña conditions continued to weaken in April for the fourth consecutive month, although sea-surface temperatures remained below normal across the central and eastern equatorial Pacific Ocean. According to NOAA’s Climate Prediction Center, La Niña will continue to have global impacts as the event continues to decline, but by late spring neither La Niña nor El Niño conditions are expected to prevail in the region.
  • Effective May 2, 2011, NOAA updated its monthly mean temperature dataset, which is used to calculate global land surface temperature anomalies and trends. The Global Historical Climate Network-Monthly (GHCN-M) version 3 dataset replaced GHCN-M version 2. Beginning with this month’s Global State of the Climate Report, GHCN-M version 3 is used for National Climatic Data Center climate monitoring products.  More information on this transition can be found at:http://www.ncdc.noaa.gov/ghcnm.

Polar Sea Ice and Precipitation Highlights

  • The average Arctic sea ice extent during April was 5.7 percent below average, ranking as the fifth smallest April since satellite records began in 1979.
  • The April 2011 Antarctic sea ice extent was 7.7 percent below average and was fourth lowest April extent since records began in 1979.
  • Northern Hemisphere snow cover extent during April ranked as the 15th smallest on record, while the snow cover extent over North America was the 10th largest and Eurasian snow cover was the fifth smallest April snow cover on record.
  • Average rainfall across Australia was 18 percent above average during April. However, for the first month since June 2010, below-average rainfall was reported in the states of Queensland, South Australia and New South Wales. This broke a streak of nine consecutive months with above-normal rainfall in those states.

Denver’s snow season – or rather the lack thereof – reaches near record-setting levels

Denver's snow season through April 30, 2010.
Denver's snow season thus far is the second worst in the past 122 years. Click the image for a larger view. (Denver Weather Examiner)

Conditions have been tinder dry across the Colorado Front Range in recent months and certainly one of the biggest factors has been the lack of snowfall.  Denver is in fact seeing its second least snowiest snow season on record likely setting the stage for a dangerous fire season ahead.

Through April 30, a mere 21.8 inches of snow has been recorded at Denver’s official monitoring site at Denver International Airport.  This is an astonishing 38.6 inches below normal to this point in the season.  At the end of March the season ranked as the third worst but after receiving only 1.2 inches of snow in April, the situation looks even more dismal.

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Here in Thornton we have fared slightly poorer.  ThorntonWeather.com has recorded 21.2 inches, by far the lowest we have seen at this point in the season since we came into operation nearly five years ago.

Only one other season has seen lower snow totals through the end of April.  That occurred 122 years ago during the 1888 to 1889 season when 21.3 inches was recorded.  That also ended up being that season’s final total as only a trace was recorded for the rest of the season.

While the plains of Colorado have seen little snow, that hasn’t been the case in the high country.  The Colorado Rocky Mountains have been inundated with six of the eight basins reporting from 112 to 165 percent of normal snow water equivalent.

Severe drought conditions have settled in on the eastern half of Colorado with the far southeastern corner of the state event reaching extreme drought levels.  NOAA’s drought outlook for the period through July predicts that the drought will continue or intensify.

This situation is cause for alarm for anyone on the plains or in the Colorado mountains east of the Continental Divide.  There have already been several significant fires in the foothills and on the far eastern plains.  Without some significant precipitation, Colorado may find itself seeing a very dangerous and damaging fire season ahead.

Denver’s May weather can bring just about any type of weather

Denver's May weather previewColorado natives and those that have lived here long enough know that Denver and Colorado weather changes considerably throughout the year. The month of May almost seems to pack four seasons of weather conditions into 31 days. You name it, it can happen.

This being the latter half of spring, May does mean warm temperatures. Temperatures in the 80’s are common and reaching into the 90’s is not unheard of. The normal highs start out at 65 on the first but by the end of the month that climbs to 76. The record high for the month was recorded on May 26, 1942 of 95 degrees.

From the warm temperatures to cold, from snow and rain to severe thunderstorms, May can bring just about any type of weather.  Get all of the details in our May weather preview here.

Denver smashes record high temperature for April 2nd

Denver easily broke the record high temperature for April 2nd.
Denver easily broke the record high temperature for April 2nd.

We knew Saturday was going to be a warm one that would likely break the high temperature record for April 2nd but it far exceeded the forecast.

The record high temperature for today’s date was 76 degrees, last set in 1996.  At 1:22pm today the temperature at Denver International Airport hit 84 degrees thus easily eclipsing the old record.  Warm winds and plenty of sun helped the Mile High City reach the mark.

Thornton fared even warmer as we hit a high temperature of 86.4 degrees at 3:14pm.  Some cloud cover has moved in as of this writing and the temperature has dropped a bit so that may be tops for the day.

Highlighting the contrasting conditions that Denver weather can exhibit at any time, we will follow the record setting warmth today with a blast of winter-like conditions arriving tomorrow.  We are expecting a quick shot of snow that will bring some much needed precipitation to the Denver metro area.

Click here for the latest forecast.

Denver suffering through worst snow season in more than 125 years

Denver is having a pitiful snow season - the third worst in the city's history. (Denver Weather Examiner)
Denver is having a pitiful snow season - the third worst in the city's history. (Denver Weather Examiner)

March 31 was the last day of what is historically Denver’s snowiest month but like every other month this season, it fell dismally short in terms of the amount of snowfall.  In fact, as it stands now, the Mile High City and Thornton area experiencing their third worst season of snow since record keeping began.

In a normal snow season, through the end of March, Denver historically averages 51.3 inches of snow – a healthy total needed for water supplies, irrigation and to help keep the wildfire danger down.

For the 2010 to 2011 season we are far behind that mark.  As of yesterday Denver has recorded a paltry 20.6 inches of snow this season at DIA; a total more than 30 inches below normal.  Only two other seasons have seen lower snow totals at this point in the season since record keeping began in 1882 – and those were more than 125 years ago.

For the season Thornton has fared worse than the official Denver totals as we have recorded a mere 19.7 inches (click here for the latest totals).  Stapleton has recorded 22.8 and Denver City Park has fared the best with 26.8.

Only one month in this snow season has Denver seen at or above normal snowfall.  That occurred in January when we recorded 8.0 inches of snow versus the average for the month of 7.7 inches.

By comparison, the Mile High City’s two snowiest months – March and November respectively – saw very little snowfall.  In March a mere 2.5 inches fell in contrast to 11.7 inches on average.  November 2010 saw only 1.5 inches of snow versus the November average of 10.7 inches.

The long range climate forecasts from the National Weather Service predict continued drier and warmer than normal weather for the month.  April is however historically our third snowiest month so there may be hope, especially given the history of the two seasons on record that were worse than this one.

During the 1883 to 1884 season, April brought 18 inches of snow and the 1884 to 1885 season saw an astounding 32 inches of snowfall in the month.  While both snow seasons finished below average, they made up a lot of ground in 30 days.

We can only hope that this season follows suit or we will be in for a very dry – and dangerous – summer.

For more information:

Thornton’s February weather wrap – Cooler and drier than normal

Denver's February 2011 weather reviewFebruary 2011 in the Mile High City was a relatively uneventful one.  Temperatures were below normal and we received less snow and precipitation than what is typical for the month.

In terms of temperature, Denver officially recorded an average of 29.1 degrees during February as measured at Denver International Airport.  While this is 4.1 degrees below normal, it was not cold enough to make ‘top 10’ status.  Temperatures ranged from a high of 67 degrees on the 16th all the way down to a low of -17 on the 2nd.  Neither of these was a record.

Here in Thornton we were slightly warmer with an average temperature of 29.6 degrees.  We recorded a high of 69.3 degrees on the 16th and a low of -14.7 degrees on the 2nd.

One temperature record was set during the month and one tied.  A new record low maximum was set on the 1st when the high temperature only climbed to -1 degrees.  This broke the previous record of 2 degrees set in 1985.  On the 8th the low maximum temperature of 8 degrees tied the mark last set in 1933.

In terms of snowfall, the month saw us record 5.3 inches – 1 inch below normal for February.  This continued the trend for the snow season of below normal snowfalls and by the end of the month we were more than 20 inches below normal.  Nearly half of that snow, 2.6 inches, fell during one storm on the 7th and 8th of the month.  In all, only five days had snow and all of those were before the 9th of the month.

Precipitation was similarly below normal.  A total of 0.42 inch was recorded which was 0.07 inch below the normal 0f 0.49 inch.  Most of that was recorded during the same event that we received the biggest snow of the month mentioned above.  Precipitation was recorded on five days with two of those recording 0.10 inch or more.

Thornton matched the Denver snowfall total of 5.3 inches.  However we received much less precipitation from those snows and recorded only 0.29 inch of liquid moisture.

Below is the official Denver climate summary for February 2011.  Click here to view Thornton’s February climate report.

CLIMATE REPORT
NATIONAL WEATHER SERVICE BOULDER, CO
830 PM MST TUE MAR 1 2011

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

CLIMATE NORMAL PERIOD 1971 TO 2000
CLIMATE RECORD PERIOD 1872 TO 2011

WEATHER         OBSERVED          NORMAL  DEPART  LAST YEAR'S
                 VALUE   DATE(S)  VALUE   FROM    VALUE  DATE(S)
                                          NORMAL
................................................................
TEMPERATURE (F)
RECORD
 HIGH              77   02/28/2006
                        02/04/1890
 LOW              -25   02/01/1951
                        02/08/1936
HIGHEST            67   02/16        77     -10       52  02/27
LOWEST            -17   02/02       -25       8       -1  02/09
AVG. MAXIMUM     43.4              47.2    -3.8     39.7
AVG. MINIMUM     14.7              19.1    -4.4     18.5
MEAN             29.0              33.2    -4.2     29.1
DAYS MAX >= 90      0               0.0     0.0        0
DAYS MAX <= 32      7               4.3     2.7        8
DAYS MIN <= 32     25              26.0    -1.0       28
DAYS MIN <= 0       6               0.3     5.7        1
PRECIPITATION (INCHES)
 RECORD
  MAXIMUM         2.01   1934                                          
  MINIMUM         0.01   1970  
TOTALS           0.42              0.49   -0.07     0.30               
DAILY AVG.       0.01              0.02   -0.01     0.01               
DAYS >= .01         5               5.9    -0.9        9
DAYS >= .10         2                MM      MM        0
DAYS >= .50         0                MM      MM        0
DAYS >= 1.00        0                MM      MM        0
GREATEST
 24 HR. TOTAL    0.19   02/07 TO 02/08     0.10  02/07/10 TO 02/08/10
SNOWFALL (INCHES)
RECORDS
 TOTAL           22.1  1912
TOTALS            5.3               6.3     -1.0      5.8
SINCE 7/1        18.1              39.6    -21.5     46.0

DEGREE_DAYS
HEATING TOTAL     999               892     107      999
 SINCE 7/1       4151              4489    -338     4807
COOLING TOTAL       0                 0       0        0
 SINCE 1/1          0                 0       0        0              

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

WIND (MPH)
AVERAGE WIND SPEED              10.6                     7.6
RESULTANT WIND SPEED/DIRECTION   3/206                   MM
HIGHEST WIND SPEED/DIRECTION    38/250  DATE  02/20    25/360 2/18
HIGHEST GUST SPEED/DIRECTION    46/010  DATE  02/07    35/210 2/01

SKY COVER
POSSIBLE SUNSHINE (PERCENT)   MM    * SUNSHINE DATA DISCONTINUED 10/2009

NUMBER OF DAYS FAIR            6
NUMBER OF DAYS PC             19
NUMBER OF DAYS CLOUDY          3

AVERAGE RH (PERCENT)     52

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

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

Thornton’s March 2011 weather preview – Ch-ch-changes

Thornton's March weather previewColorado’s weather is notoriously fickle capable of dispensing an entire gamut of weather in a very short period of time.  The month of March typifies this as we can see everything  from major snowstorms and bitter cold to summer-like temperatures and tornadoes.

These changes are due to Marches “in between” status – elements during the month have much in common with winter and spring. In addition to arctic fronts, Pacific storms frequently move across Colorado from the west and warm moist air streams up from the Gulf of Mexico northeastward into the state. When these cold fronts collide with the warmer air masses the result can be some crazy weather.

What kind of weather have we seen in March and what can we expect this year? Get the details in our complete March 2011 preview here.

NOAA: 2010 ties as second warmest year on record

NOAA temperature anomaly map showing warmer than average temperatures across much of the globe in 2010. (NOAA)
NOAA temperature anomaly map showing warmer than average temperatures across much of the globe in 2010. View more images in the slideshow below. (NOAA)

Data released by NOAA puts 2010 into the history books as tying with 2005 as the warmest year globally since 1880.  The newly released report is sure to fuel the ongoing climate change and global warming debate for the year to come. 

The National Climatic Data Center’s information shows that the combined global land and ocean temperatures in 2010 were 1.12° F (0.62° C) above the 20th century average.  This ties the year with 2005 as the warmest on record. 

Land surface temperatures globally were the warmest on record as a temperature anomaly of 1.8° F (1.0° C) was recorded.  The oceans fared better according to the NCDC with temperatures 0.88° F (0.49° C) above the 20th century average putting it in the books typing with as the third warmest on record. 

The United States separately was warm as well although not in record-setting form.  Warmer than average temperatures were recorded across much of the nation with the south being the exception.  NOAA said that temperatures are increasing at a rate of 0.12° F per decade. 

Continue reading NOAA: 2010 ties as second warmest year on record

The snow deficit – Denver sees least amount of snow in 122 years

Where's the Snow?
Not since the 1888 to 1889 snow season has Denver seen less snow this far into the snow season than this year.

Amid record-setting snowfall in northern Europe this winter and blizzards on the U.S. East Coast, one place that normally sees its fair share of snow has been left high and dry.  The Mile High City is facing a snow drought of near record proportions having thus far experienced its worst snow season in 122 years.

Denver’s snow season is from July through June and through the end of December Denver has recorded a mere 4.8 inches of snow.  The majority of that (3.3 inches) was received from a pre-New Year’s storm on December 30th.   Here in Thornton we have fared a mere 0.1 inch more snow for a total of 4.9 inches.

On average the city sees 25.6 inches from July through December and the pitiful show so far gives the 2010 to 2011 season a 20.8 inch snow deficit to date.  Only one other time in the 128 years that snow records have been kept in Denver has so little snow been recorded to this point in the season. 

One has to look back to the 1888 to 1889 season to find a more dismal snow season.   It was that season 122 years ago that 3.8 inches of snow had been recorded by the end of December.  The next worst season up to December was two seasons later when 5.5 inches was recorded.

Continue reading The snow deficit – Denver sees least amount of snow in 122 years

Thornton’s 2010 weather year in review

2010 was a relatively uneventful year for weather in Thornton.
2010 was a relatively uneventful year for weather in Thornton.

Many years in Colorado are marked by significant weather events.  The Christmas Blizzards of 2006, the severe thunderstorms that dominated June of 2009 or reaching even further back the Thornton Tornado of 1981.  The same can’t entirely be said about 2010 as we experienced a relatively quiet year without any truly major events. 

Temperatures

In terms of temperatures the year was slightly warmer than the historical average of 50.1 degrees.  In 2010 Denver officially recorded an annual average of 51.2 degrees at Denver International Airport.  Thornton was actually spot on Denver’s historical average at 50.1 degrees.

Denver temperatures ranged from a high of 102 degrees on July 17th down to -16 on January 7th.  The July high was a record for the date but the January low didn’t fall far enough to set a record.  Thornton’s high temperature for the year was 101.6 degrees and our low was -9.7 degrees – both occurring on the same dates as Denver’s.

The average high temperature for the year was 65.3 degrees – 1.1 degrees above normal.  The average low was 37.0 degrees, 1.2 degrees above normal.  Thornton’s average highs and lows were very close to Denver’s at 65.7 degrees and 36.8 degrees respectively. 

DIA reported 47 days with temperatures at or above 90 degrees – 16 above normal.  Thornton stayed cooler recording only 38 days.  Low temperatures dipped below freezing on 158 days in Denver (2 above normal) while Thornton had one more with 159 days. 

Snowfall

The first half of the 2010 to 2011 snowfall season was dismal as Denver recorded a mere 4.8 inches and Thornton recorded 4.9 inches.  This is the second lowest total on record for the period with the only year with less snow being 1888 when 3.8 inches was recorded. 

Continue reading Thornton’s 2010 weather year in review