Monday, December 31, 2012

December 31, 2012 U.S. Snow Cover

What a stunning change in snow cover in one month. 

As of December 31, 2012 , 61.9% of the lower 48 states is snow covered compared to only 13.3% as of November 30, 2012.

The color shading on the map shows the area with a snow cover and the shades of Blue indicates the current depth of snow (see the scale on the bottom of the map.

Here is a listing of the measured snow depths across Nebraska as of 6am December 31, 2012.
Grand Island, 5 inches; Hastings, 4 inches.; Norfolk 3 inches.; Valley (NWS), 3 inches; Offutt AFB, 2 inches.; Eppley airport, 2 inches.; North Platte, 1 inch.; Valentine 1 inch.; Lincoln, 1 inch.

Sunday, December 30, 2012

Dec. 2012 HDD in Big 10 country

Winter temperatures have arrived across much of the Midwest in the last third of this month, but most locations will still have average temperatures well above normal for December. One simple method of measuring how "cold" it has been in a location is to use heating degree days (HDD). The warm season equivalent is known as cooling degree days (CDD). HDD's and CDD's are calculated by taking the difference in a mean daily temperature (mean of daily maximum temperature and daily minimum temperature) from a base temperature of 65°F. For example, yesterday in Lincoln the daily max. was 28°F and the daily min. was 2°F, giving a daily mean temperature of 15°F. Thus, 65-15 = 50 HDD. The daily record for HDD's in Lincoln was set way back on February 11, 1899 when the daily average temperature was -20°F, yielding 85 HDD's. As mentioned earlier, temperatures have been mild this month (especially in the first week), and most locations are running behind average on mean temperature and accumulated HDD's for December. Without further adieu, here are the accumulated HDD's for December 2012 (through yesterday, 12/29) from most to least in Big 10 cities. The numbers in parentheses represent the total CDD's in July 2012.

Minneapolis, MN 1167 (475)
Lincoln, NE 1060 (570)
Madison, WI 988 (455)
Iowa City, IA 950 (537)
East Lansing, MI 891 (403)
Ann Arbor, MI 884 (439)
Evanston, IL 809 (506)
State College, PA 803 (340)
Champaign, IL 784 (488)
West Lafayette, IN 782 (466)
Bloomington,IN 717 (513)
Columbus, OH 705 (488)

 This will be updated at the end of the next two months to see how this list shapes up as we get deeper into the winter. The Twin Cities are almost a lock to finish first but would expect Madison to surpass Lincoln by the end of January. It is also likely that Champaign and West Lafayette will surpass State College within the next few weeks and remain ahead the remainder of the climatological winter. No word on what the prize is for finishing in a certain position but it does seem apparent that the Legends football division is the colder of the two!

Tuesday, December 25, 2012

Lincoln's White Christmas Climatology

A "White Christmas" is traditionally defined as having "one or more inches of snow on the ground on the morning of December 25".  This year, December 25, 2012, there was officially 2 inches of snow on the ground, so Lincoln officially had a "White Christmas" in 2012.

Although monthly snowfall data exists back to 1900, daily data only exist from 1948 to present.

Looking at the 65 years of data (1948-2012) for December 25, Lincoln had one or more inches of snow on the ground 20 times or 30.8% of the 65 years.

Here are the December 25 snow cover rankings with "Value" = the amount of snow on the ground in inches on December 25.

Rank  Value  Year

  1      14   1983
  2      11   2000
  3      10   2009
  4       8   1973, 1952, 1948
  7       7   1968
  8       5   1961
  9       3   2008
 10       2   2012, 1997, 1981, 1980, 1969, 1962
 16       1   2007, 2001, 1974, 1957, 1949
Another interesting Christmas Day snow climatology is the number of Christmases that had measurable snowfall.  Measurable means 0.1 inches or larger.  Lincoln has only had 5 Christmas Days with measurable snowfall in last 65 years (1948-2012) which is only 7.7% of the time!  

Here are the rankings of measured snowfall on Christmas Day:

Rank    Value  Year

  1      9.5   2009
  2      1.3   1962 
  3      1.0   2000
  4      0.8   1957
  5      0.2   1997


 for the e climateHere are the December 25 sno

The photo below was taken on Christmas morning 2012 in Lincoln, NE.

Sunday, December 23, 2012

December 2012 U.S. Snowcover

After a very mild start to December 2012, cold Arctic air has plunged into the lower 48 states and snow cover has dramatically increased. The two maps show the snow cover as of December 1, 2012 and December 22, 2012.  The snow cover on December 1, 2012 was only 10.0% of the lower 48 states.  By December 22, 2012 the snow cover had increased to 46.8% of the conterminous U.S.  With this much snow snow cover it will be difficult for temperatures to warm above normal in Nebraska for the next few weeks.

Wednesday, December 19, 2012

November 2012 Global Temperature Anomalies

NOAA: November global temperatures fifth highest on record

Link to previous monthly global temperature Anomaly Maps:   Archived Maps

According to NOAA scientists, the globally-averaged temperature for November 2012 marked the fifth warmest November since record keeping began in 1880. It also marked the 36thconsecutive November and 333rd consecutive month with a global temperature above the 20th century average. The last below-average November temperature was November 1976 and the last below-average temperature for any month was February 1985.. Most areas of the world experienced higher-than-average monthly temperatures, including far eastern Russia, Australia, the central and western United States, northern Africa, and most of Europe and western Asia. Meanwhile, central Asia, Alaska, much of western and central Canada, and the eastern United States were most notably cooler than average.

November 2012 Global Highlights

  • The average combined global land and ocean surface temperature for November 2012 was 0.67°C (1.21°F) above the 20th century average of 12.9°C (60.4°F). This is the fifth warmest November since records began in 1880. Including this November, the 10 warmest Novembers have occurred in the past 12 years.

  • The globally-averaged land surface temperature for November 2012 was the sixth warmest November on record, at 1.13°C (2.03°F) above average. The globally-averaged ocean surface temperature was also sixth warmest on record, at 0.50°C (0.90°F) above average.

  • ENSO-neutral conditions continued in the eastern equatorial Pacific Ocean during November 2012. Neutral conditions are expected to last through the Northern Hemisphere winter 2012/13 and into spring 2013.

  • The average combined global land and ocean surface temperature for September–November 2012 was 0.67°C (1.21°F) above the 20th century average of 14.0°C (57.1°F), marking the second warmest September–November on record, behind 2005.

  • The globally-averaged land surface temperature for September–November 2012 was the third warmest September–November on record, at 1.03°C (1.85°F) above average. The Southern Hemisphere land temperature was record warm for the period.

  • The combined global land and ocean average surface temperature for January–November 2012 was the eighth warmest such period on record, at 0.59°C (1.06°F) above the 20th century average.

Tuesday, December 11, 2012

Record Long Snow-Free Streak in Lincoln, NE

Record Longest Streak of Snow-Free Days in Lincoln, NE!

Photo (December 11, 2012)  looking out from Hardin Hall, East Campus, UNL toward
the city center and City Campus of UNL.  Note the green lawns as we approach
mid-December with no measurable snowfall yet this Autumn.

 The "snow-free streak" is defined as the length of time between the last measurable snowfall in the Winter/Spring until the first measurable snowfall in the following Autumn/Winter.

The previous record of 295 days was set in 2004 with the snow-free season extending from February 6 to November 28, 2004.

The last measurable snowfall in Lincoln this year was on February 13, 2012, with 1.1 inches. The period of snow-free days this year reached 295 days as of December 4, 2012, tying the record.   Lincoln remained snow-free as of December 5 setting a new record of 296 snow-free days.  This record has continued  to increase. As of December 11, 2012 the snow-free streak has been extended to 302 days. 

We are not alone with this weather anomaly since Omaha and Norfolk are also experiencing their longest observed streak of snow-free days

Here is a listing of the top ten longest snow-free periods in Lincoln's snowfall data archive:

Columns 2 and 3 = last snowfall in the Winter/Spring;
Columns 7 and 8 = first snowfall in the following Autumn/Winter;
CD = Calendar Day Number
snow free = number of days between the last and the first snowfalls

snow free












The Lincoln Snowfall Climatology is at this link:  Lincoln, NE, Snowfall Climatology
The Snow-Free climatology is at this link: Lincoln, NE, Snow-Free

The long streak without measurable snowfall is due to a combination of ongoing drought conditions and record warmth.

Monday, December 10, 2012

January-November, 2012 U.S. Climate Update

January 1 through November 30, 2012 is the driest on record for the state of Nebraska (118 years of data).  And, for the same time period, it was the warmest on Record for the state of Nebraska.

Colorado and Wyoming join Nebraska in also having their driest year on record through November 30.  And, 17 states also join Nebraska for having their warmest year on record though November 30.

Note that none of the conterminous 48 states are averaging below normal temperature for the year to date as of November 30, 2012.  Three states are having a near normal year in temperatures and the remaining 45 states are all experiencing a warmer than normal year for temperatures to date as of November 30. 

Note the summary below the two maps.

  • Climate Highlights — Year-to-Date (January-November)
  • The January-November period was the warmest first 11 months of any year on record for the contiguous United States. The national temperature of 57.1°F was 3.3°F above the 20th century average, and 1.0°F above the previous record warm January-November of 1934. During the 11-month period, 18 states were record warm and an additional 24 states were top ten warm.
  • It appears virtually certain that 2012 will surpass the current record (1998, 54.3°F) as the warmest year for the nation. December 2012 temperatures would need to be more than 1.0°F colder than the coldest December (1983) for 2012 to not break the record.
  • January-November 2012 was the 12th driest such period on record for the contiguous U.S., with a precipitation total 3.08 inches below the long-term average of 26.91 inches.
  • Drier-than-average conditions stretched across the central part of the country, from the Rocky Mountains to the East Coast. Colorado, Nebraska, and Wyoming each had their driest year-to-date on record and eight additional states had 11-month precipitation totals among their ten driest.
  • Wetter-than-average conditions were present for the Pacific Northwest, the central Gulf Coast, and New England. Washington State experienced its ninth wettest year-to-date.

Friday, December 7, 2012

November 2012 Statewide Climate Summary

November 2012 Statewide Climate Summary

The western half of the U.S. (lower 48 states) had above normal to much above normal temperatures in November 2012.  In contrast the Eastern third of the U.S. had below to much below normal temperatures for November 2012.  The Nebraska statewide average temperature in November 201was the 93rd coldest or 24th warmest on record (118 years of data).

There are two maps included below to illustrate the November 2012 temperature departures from normal.  The first map is a state by state ranking (ranking relative to each specific state's climate record) and a shaded map illustrating the temperature departures form normal on a "climate division" basis.  The number of climate divisions  ranges from only 3 in Maine to as many as 10 in several states.Nebraska has climate divisions numbered from 1 to 9 but only has 8 climate division since a climate division number 4 is not shown (and we have no idea why there isn't a climate division number 4 for Nebraska!)

  • Climate Highlights — November from NCDC
  • The average temperature for the contiguous U.S. during November was 44.1°F, 2.1°F above the 20th century average, tying 2004 as the 20th warmest November on record.
  • November brought warmer-than-average conditions to the western half of the country. The largest temperature departures from average were centered near the Rockies where Arizona, Colorado, New Mexico, Utah, and Wyoming had November temperatures among their ten warmest.
  • The Eastern Seaboard, Ohio Valley, and Southeast were cooler than average during November. North Carolina tied its 10th coolest November on record, with a statewide-averaged temperature 3.5°F below average.
  • The November nationally-averaged precipitation total of 1.19 inches was 0.93 inch below the long-term average and the 8th driest November on record. A large area of the country experienced below-average precipitation in November. Drier-than-average conditions stretched from the Intermountain West, through the Plains, into the Midwest, and along the entire East Coast. Twenty-two states had monthly precipitation totals ranking among their ten driest.
  • According to the November 27th, 2012 U.S. Drought Monitor report, 62.7 percent of the contiguous U.S. was experiencing moderate-to-exceptional drought, larger than the 60.2 percent at the end of October. Drought conditions improved for parts of the Northern Rockies, which were wetter than average during November, while they worsened for parts of the Southwest, Southeast, and Mid-Atlantic.

Tuesday, December 4, 2012

January -November 2012 Climate Update

January 1-November 30, 2012 Update: data tables and maps

Lincoln, NE:
total precipitation = 17.64 inches (7th driest on record)
normal precipitation = 28.00 inches

Departure = - 10.36 inches

Driest January 1-November time periods (1887-2012)
Rank  Value  Ending Date
  1   13.06   11/30/1936 
  2   14.81   11/30/1890
  3   15.78   11/30/1894
  4   15.89   11/30/1895
  5   16.52   11/30/1953
  6   16.79   11/30/1934
  7   17.64   11/30/2012  8   17.72   11/30/1887
  9   17.75   11/30/1955
 10   17.80   11/30/1988

Average temperature January 1-November 30, 2012 = 58.4F (5th warmest on record) 
Rank  Value  Ending Date
  1    58.4   11/30/1934
  2    57.7   11/30/1921
  3    57.4   11/30/1931
  4    57.3   11/30/1938
  5    57.2   11/30/2012
  6    56.9   11/30/1939
  7    56.6   11/30/1963
  8    56.3   11/30/1990
  9    56.2   11/30/1933, 11/30/1987

Omaha, NE:
total precipitation = 20.76 inches (21st driest on record)
normal precipitation = 29.58 inches

Departure = - 8.82 inches
Driest January 1-November 30 time periods (1871-2012)
Rank  Value  Ending Date
  1   14.57   11/30/1934
  2   15.12   11/30/1910
  3   15.87   11/30/1911
  4   16.88   11/30/1894
  5   17.17   11/30/1927
  6   17.24   11/30/1953 
  7   17.91   11/30/1933
  8   18.14   11/30/1976
  9   18.48   11/30/1916
 10   18.58   11/30/1939
 11   18.81   11/30/1887
 12   19.40   11/30/1974
 13   19.50   11/30/1936
 14   19.51   11/30/1897
 15   19.70   11/30/1925
 16   20.20   11/30/1930
 17   20.36   11/30/1937
 18   20.47   11/30/1889
 19   20.56   11/30/1988
 20   20.73   11/30/1918
 21   20.76   11/30/2012
Average temperature January 1-November 30, 2012 = 58.4F (warmest on record)
Rank  Value  Ending Date
  1    58.4   11/30/2012
  2    57.9   11/30/1934
  3    57.7   11/30/1931, 11/30/1921
  5    56.3   11/30/1938, 11/30/1933
  7    55.9   11/30/1954, 11/30/1987, 11/30/1946
 10    55.8   11/30/1939