Entire Report - February 2007


National Overview

NCDC transitioned to the nClimDiv dataset on Thursday, March 13, 2014. This was coincident with the release of the February 2014 monthly monitoring report. For details on this transition, please visit our public FTP site and our U.S. Climate Divisional Database site.

Maps and Graphics:


February Most Recent 3 Months Most Recent 6 Months
Most Recent 12 Months Year-to-Date US Percent Area Very Wet/Dry/Warm/Cold
Annual Summary for 2006

PLEASE NOTE: All temperature and precipitation ranks and values are based on preliminary data.  The ranks will change when the final data are processed, but will not be replaced on these pages.  Once available, graphics based on final data will be provided on the Climate Monitoring Products page.


For graphics covering periods other than those mentioned above or for tables of national, regional, and statewide data from 1895-present, for February, last 3 months or other periods, please go to the Climate At A Glance page.
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National Overview:


February and Winter
  • The December 2006-February 2007 winter season was marked by periods of unusually warm and cold conditions in the U.S., but the overall seasonal temperature was near average.

  • The winter season got off to a late start in much of the country. December was the 11th warmest such month on record (based on revised data), and spring-like temperatures covered much of the eastern half of the nation during the first half of January.

  • The warmer-than-average seasonal temperatures in the more heavily populated regions of the Midwest and East helped reduce residential energy needs for the nation as a whole for the winter season. Using NOAA's Residential Energy Demand Temperature Index (REDTI), it was determined that the nation's residential energy demand was approximately 3 percent lower than what would have occurred under average climate conditions for the season.

  • Seasonal energy demand would have been lower if not for February's colder temperatures. For the month, temperature-related residential energy demand was approximately 6 percent higher than what would have occurred under average climate conditions for February.

  • February was among the third coldest in the 113-year record for the contiguous U.S. Thirty-six states in the eastern two-thirds of the nation were cooler than average, while Texas and the eleven states of the West were near average to warmer than average.

  • Winter season precipitation was above average in the central U.S. from the Upper Midwest to New Mexico, Texas and Louisiana. Drier-than-average conditions stretched from the Deep South to Kentucky, the Mid-Atlantic, and along the Northeast Seaboard states. Much of the West was also drier than average.

  • Through early March, water-year precipitation in Los Angeles was the lowest on record, less than 25% of normal.

  • Several snow storms hit the Plains, Midwest, and Northeast in February. A complex, wide-reaching winter storm moved from the Mid-Mississippi Valley into the Mid-Atlantic and New England February 14 and 15. This storm ranked as a Category 3 event on the Northeast Snowfall Impact Scale (NESIS). The heaviest snow fell in interior regions of the Northeast where amounts over 20 inches were widespread.

  • This event was preceded by a 10-day lake effect storm that dumped more than 100 inches of snow on New York's Tug Hill Plateau. A total of 141 inches was reported at Redfield in Oswego County. Additional information on snowfall during the 2006-2007 winter season is available

  • For February, precipitation was below average in the Southeast, Northeast, and Midwest regions. For the Southern Region, the 9th driest February on record followed two wetter-than-average months.

For information on local temperature and precipitation records during the month of February, please visit NCDC's Extremes page.

  • Across the United States, extreme drought conditions were observed in areas of Wyoming and Nebraska, as well as northern Minnesota and parts of Texas. Exceptional drought was limited to areas of south Texas. For more information on drought during February, please visit the U.S. Drought page.

  • El Niño-Southern Oscillation (ENSO) conditions have transitioned from ENSO-warm phase to ENSO-neutral by the end of February. Current forecasts indicate that a transition from ENSO-neutral conditions to La Niña could occur over the next 3 months. For additional information on ENSO conditions, please visit the NCDC ENSO Monitoring page and the latest NOAA ENSO Advisory.
For additional details, see the Monthly and Seasonal Highlights section below and visit the February Climate Summary page. For details and graphics on weather events across the U.S. and the globe please visit NCDC's Global Hazards page.
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Monthly and Seasonal Highlights:


Contiguous U.S.:

For additional national, regional, and statewide data and graphics from 1895-present, for February, the last 3 months or other periods, please visit the Climate At A Glance page.
  • February Temperature: 34th coldest February in the 1895-2007 record.  The preliminary nationally averaged temperature was 32.86°F (0.48°C), which was 1.84°F (1.02°C) below the 1901-2000 (20th century) mean.

  • February Precipitation: 16th driest nationally in the 1895-2007 record. An average of 1.56 inches (40 mm) fell over the contiguous U.S. in February, 0.46 inches (12 mm) below the 20th century mean for the month.

  • December - February (winter) Temperature: 45th warmest in the 1895-to-present record, 0.63°F (0.35°C) above the 20th century mean. The preliminary nationally averaged December - February temperature was 33.63°F (0.91°C).

  • December - February (winter) Precipitation: A total of 6.24 inches (159 mm) of precipitation fell during this 3-month period, which corresponds to a ranking of 47th driest.

  • September - February (6-month): The national average temperature was the 57th coldest for this 6-month period. The nationally-averaged temperature was 43.71°F (6.51°C), which was 0.09°F (0.05°C) above the 20th century mean. At 14.25 inches (362 mm), September - February precipitation was above average and ranked as the 30th wettest such period in the 1895-2007 record.

  • January to February (Year-to-date): The 42nd coldest January-February on record. The nationally averaged year-to-date temperature was 32.13°F (0.07°C), or 0.65°F (0.36°C) below the mean. The year-to-date period was the 21st driest January-February in the 113-year record, receiving a national average of 3.70 inches (94 mm) of precipitation during the period, or 0.54 inches (14 mm) below the 20th century mean.

  • March 2006 - February 2007: The 13th warmest such period in the 1895-2007 record.  The preliminary nationally-averaged annual temperature was 53.94°F (12.19°C), which was 1.14°F (0.64°C) above the mean. Precipitation was near the mean for the March 2006 - February 2007 period, ranking it as the 50th driest March - February in the 112-year record.  The nationally-averaged annual precipitation accumulation was 29.17 inches (741 mm), or 0.03 inches (1 mm) above the 20th century mean.

Alaska:
  • February Temperature: 42nd warmest on record (1918-2007) for February with temperatures 1.4°F (0.8°C) above the 1971-2000 mean.

  • December-February Temperature: 28th warmest on record (1918-2007) for the 3-month period (December - February) with temperatures 1.4°F (0.8°C) above the 1971-2000 mean.

Other Statewide and Regional Highlights:
  • February precipitation across Montana was 6th wettest on record. Mississippi, Louisiana, and Tennessee were the 6th, 7th, and 8th driest on record, respectively.

  • December - February temperatures across Delaware and New Jersey ranked 13th warmest on record. Four states, including Texas and New Mexico were below average for the period. Nebraska and Kansas tied for second wettest, while Tennessee was 6th driest.

  • In the South and Southwest regions, December - February temperatures were below average.

  • Temperatures over the past 6-months (September - February) were above average in the Northeast and the East North Central regions. Precipitation for the period was near to above average in all regions except the West .

  • September - February temperatures were much above average for three states, Rhode Island, New Jersey and Connecticut. Seven states were below average for the period, including Colorado and New Mexico. Colorado and Indiana ranked 3rd wettest for September - February. California experienced its 11th driest such period on record.

  • During the Year-to-Date period (January-February), temperatures were below average across 16 states in the central U.S. Only two states (Delaware and New Jersey) had temperatures above average during this period. All other states reported near-average temperatures. Alabama, Tennessee and Rhode Island each had their 10th driest such period on record. Eleven additional states, from the Southwest to the Great Lakes and into parts of the Northeast experienced above average precipitation during this period.

  • January-February temperatures across the Southwest, South and Central regions were below average. Every other region was near average during this period. The Northwest, West and Southeast regions experienced below average precipitation during the year-to-date period.

  • March 2006 - February 2007 was warmer or much-warmer-than-average for 37 states, including New Jersey. Indiana was record wettest for the period.

See NCDC's Monthly Extremes web-page for weather and climate records for the month of February.

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PLEASE NOTE: All of the temperature and precipitation ranks and values are based on preliminary data.  The ranks will change when the final data are processed, but will not be replaced on these pages.  Graphics based on final data are available on the Climate Monitoring Products page.

Global Analysis

Global Highlights:

  • Based on preliminary data, globally averaged combined land and sea surface temperature was the warmest on record for boreal winter (December 2006 - February 2007) and sixth warmest for February.
  • December 2006 - February 2007 temperatures were above average in Europe, Asia, western Africa, southeastern Brazil, and the northeast half of the United States. Cooler-than-average conditions occurred in parts of Saudi Arabia and central U.S.
  • Precipitation during December 2006 - February 2007 was above average in Scandinavia, England, northern Europe, southern Brazil, and the southern Plains to the eastern Great Lakes of the contiguous U.S. Drier than average conditions were observed in southern India, southern Europe, eastern and western U.S., and the eastern coast of Australia.
  • ENSO conditions transitioned to a neutral phase during February.

Contents of this Section:

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The data presented in this report are preliminary. Ranks and anomalies may change as more complete data are received and processed. The most current data may be accessed via the Global Surface Temperature Anomalies page.
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Top of PageIntroduction

Temperature anomalies for December 2006 - February 2007 and February 2007 are shown on the dot maps below. The dot maps, below left, provides a spatial representation of anomalies calculated from the Global Historical Climatology Network (GHCN) data set of land surface stations using a 1961-1990 base period. The dot maps, below right, are a product of a merged land surface and sea surface temperature anomaly analysis developed by Smith and Reynolds (2005). Temperature anomalies with respect to the 1961-1990 mean for land and ocean are analyzed separately and then merged to form the global analysis. Additional information on this product is available.

Anomalously warm temperatures covered much of the globe during the first two months of the year. The January-February 2007 year-to-date map of temperature anomalies shows the presence of warmer than average temperatures across almost all land areas. Warmer than average Sea Surface Temperatures (SSTs) occured in the equatorial Pacific, North and South Atlantic, and the South Indian Ocean. Cooler than average conditions were observed in the northeastern Pacific and some areas in the South Pacific.

During boreal winter, temperatures were above average across the entire globe, with the exception of Saudi Arabia, Iraq, and areas in the central U.S. Warmer than average SSTs were observed across all oceans, with the exception of parts of the northeastern Pacific and South Pacific where cooler than average SSTs were observed.
Current season's Land Surface Temperature Dot map
larger image of Dec-Feb land surface temperature anomalies
Current season's blended Land and sea surface Temperature Dot map
larger image of Dec-Feb blended surface temperature anomalies


During February, there were above average temperatures across central and southern Europe, south Asia, most of Central America, parts of South America, and western sections of Africa, the U.S., and Alaska. Cooler than average temperatures were observed in Scandinavia, Siberia, and the northeastern half of the United States. Warmer than average SSTs occurred in the North and South Atlantic, Indian Ocean, and the Niño regions. SSTs decreased in the Niño regions during the month of February, transitioning from a warm phase to neutral ENSO conditions. Please see the latest ENSO discussion for additional information.

Current month's Land SurfaceTemperature Dot map
larger image of February land surface temperature anomalies
Current month's blended Land and sea surface Temperature Dot map
larger image of February blended surface temperature anomalies

The mean position of upper level ridges of high pressure and troughs of low pressure (depicted by positive and negative 500-millibar height anomalies on the December 2006 - February 2007 and the February map) are generally reflected by areas of positive and negative temperature anomalies at the surface, respectively. For other Global products see the Climate Monitoring Global Products page.

Images of sea surface temperature conditions are available for all weeks during 2007 at the weekly SST page.

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Top of Page Temperature Rankings and Graphics

Effective with the February 2006 report, NCDC transitioned from the use of the Operational Global Surface Temperature Index (Quayle et al. 1999) to the blended land and ocean dataset developed by Smith and Reynolds (2005). The differences between the two methods are discussed in Smith et al. (2005).

The global land and ocean surface temperatures were sixth warmest on record in February, but a record warm January helped push the Boreal winter to its highest values since records began in 1880. The global December 2006 - February 2007 land surface temperature was the warmest on record, while the ocean-surface temperature tied for second warmest in the 128-year period of record, approximately 0.06°C (0.1°F) cooler than the record established during the very strong El Niño episode of 1997-1998.

Current Month / Seasonal / Year-to-date
February Anomaly Rank Warmest Year on Record

Global

Land
Ocean
Land and Ocean

+0.93°C (+1.67°F)
+0.47°C (+0.85°F)
+0.60°C (+1.08°F)

9th warmest
3rd warmest
6th warmest

2002 (+1.62°C/2.92°F)
1998 (+0.55°C/0.99°F)
1998 (+0.82°C/1.48°F)

Northern Hemisphere

Land
Ocean
Land and Ocean


+1.08°C (+1.94°F)
+0.47°C (+0.85°F)
+0.70°C (+1.26°F)


10th warmest
2nd warmest
6th warmest


2002 (+2.11°C/3.80°F)
1998 (+0.53°C/0.95°F)
2002 (+1.03°C/1.85°F)

Southern Hemisphere

Land
Ocean
Land and Ocean


+0.49°C (+0.88°F)
+0.49°C (+0.88°F)
+0.49°C (+0.88°F)


13th warmest
4th warmest
5th warmest


1986 (+1.23°C/2.21°F)
1998 (+0.57°C/1.03°F)
1998 (+0.62°C/1.12°F)

Global Land and Ocean Triad plot
larger image of global, land and ocean February temperatures
Global Hemisphere Triad plot
larger image of global and hemispheric February temperatures

December-February Anomaly Rank Warmest Year on Record

Global

Land
Ocean
Land and Ocean

+1.35°C (+2.43°F)
+0.48°C (+0.86°F)
+0.72°C (+1.30°F)

warmest
2nd warmest
warmest

2002 (+1.20°C/2.16°F)
1998 (+0.55°C/0.99°F)
2004 (+0.65°C/1.17°F)

Northern Hemisphere

Land
Ocean
Land and Ocean

+1.59°C (+2.86°F)
+0.50°C (+0.90°F)
+0.91°C (+1.64°F)

warmest
2nd warmest
warmest

2002 (+1.55°C/2.79°F)
1998 (+0.52°C/0.94°F)
2002 (+0.82°C/1.48°F)

Southern Hemisphere

Land
Ocean
Land and Ocean

+0.59°C (+1.06°F)
+0.48°C (+0.86°F)
+0.49°C (+0.88°F)

7th warmest
3rd warmest
4th warmest

1998 (+0.81°C/1.46°F)
1998 (+0.57°C/1.03°F)
1998 (+0.61°C/1.10°F)

Global Land and Ocean Triad plot
larger image of global, land and ocean Dec-Feb temperatures
Global Hemisphere Triad plot
larger image of global and hemispheric Dec-Feb temperatures

January-February Anomaly Rank Warmest Year on Record

Global

Land
Ocean
Land and Ocean

+1.40°C (+2.52°F)
+0.47°C (+0.85°F)
+0.72°C (+1.30°F)

2nd warmest
3rd warmest
2nd warmest

2002 (+1.53°C/2.75°F)
1998 (+0.54°C/0.97°F)
2002 (+0.73°C/1.31°F)

Northern Hemisphere

Land
Ocean
Land and Ocean


+1.67°C (+3.01°F)
+0.48°C (+0.86°F)
+0.93°C (+1.67°F)


2nd warmest
2nd warmest
2nd warmest


2002 (+1.99°C/3.58°F)
1998 (+0.52°C/0.94°F)
2002 (+0.98°C/1.76°F)

Southern Hemisphere

Land
Ocean
Land and Ocean


+0.58°C (+1.04°F)
+0.47°C (+0.85°F)
+0.49°C (+0.88°F)


8th warmest
6th warmest
4th warmest


2003 (+0.81°C/1.46°F)
1998 (+0.56°C/1.01°F)
1998 (+0.60°C/1.08°F)

Global Land and Ocean Triad plot
larger image of global, land and ocean year-to-date temperatures
Global Hemisphere Triad plot
larger image of global and hemispheric year-to-date temperatures
The most current data may be accessed via the Global Surface Temperature Anomalies page.

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Top of Page Precipitation

The maps below represent anomaly values based on the GHCN data set of land surface stations using a base period of 1961-1990. During boreal winter, above average precipitation fell over areas that include Scandinavia, England, northern Europe, southern Brazil, and the southern Plains to the eastern Great Lakes of the contiguous U.S. Drier than average conditions were observed in southern India, southern Europe, eastern and western U.S., and the eastern coast of Australia.

During February 2007, above average precipitation fell over areas that include England, northern India, eastern Brazil, and parts of Europe. Below average precipitation was observed in eastern U.S., northwestern Brazil, and most of Australia. Additional details on flooding and drought can also be found on the February Global Hazards page.

Precipitation Dot map in Millimeters for December-February
larger image of Dec-Feb global land surface precipitation anomalies
Precipitation Dot map in Millimeters for February
larger imageof February global land surface precipitation anomalies

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Top of Page ENSO SST Analysis




Last week of the month's ENSO condtions Map
Click here for animated loop



  • Sea Surface Temperatures decreased across the equatorial Pacific Ocean during February, as the El Niño episode weakened to a neutral phase (shown in the adjacent animation of weekly sea surface temperature anomalies). A comprehensive summary of February 2007 ENSO conditions can be found on the ENSO monitoring page. For the latest advisory on ENSO conditions go to NOAA's Climate Prediction Center (CPC) and the CPC ENSO Diagnostic Discussion.


  • Images of sea surface temperature conditions are available for all weeks since 2003 at the weekly SST page.

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Top of Page References


Peterson, T.C. and R.S. Vose, 1997: An Overview of the Global Historical Climatology Network Database. Bull. Amer. Meteorol. Soc., 78, 2837-2849.

Quayle, R. G., T. C. Peterson, A. N. Basist, and C. S. Godfrey, 1999: An operational near-real-time global temperature index. Geophys. Res. Lett., 26, 333-335.

Smith, T. M., and R. W. Reynolds (2005), A global merged land air and sea surface temperature reconstruction based on historical observations (1880-1997), J. Clim., 18, 2021-2036.

Global Hazards

Please note: Material provided in this report is chosen subjectively and included at the discretion of the National Climatic Data Center (NCDC). The ability to report on a given event is limited by the amount of information available to NCDC at the time of publication. Inclusion of a particular event does not constitute a greater importance in comparison with an event that has not been incorporated into the discussion. Data included in this report are preliminary unless otherwise stated. Links to supporting information are valid at the time of publication, but they are not maintained or changed after publication.


Global Focus

Satellite animation of Tropical Cylcones Favio and Gamede on February 22, 2007
Indian Ocean Tropical Cyclones
Global Hazards And Significant Events
February 2007
Tropical Cyclone Favio brushed the southern tip of Madagascar and made landfall in Mozambique on February 22. Additional information can be found below.
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Drought & Heat | Flooding | Storms | Tropical Cyclones | Extratropical Cyclones | Severe Winter Weather
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Drought conditions
Across the United States, extreme drought conditions were observed in areas of Wyoming and Nebraska, as well as northern Minnesota and parts of Texas. Exceptional drought was limited to areas of south Texas.
Drought Monitor depiction as of February 27, 2007
U.S. Drought Monitor

National Snow & Ice

NCDC transitioned to the nClimDiv dataset on Thursday, March 13, 2014. This was coincident with the release of the February 2014 monthly monitoring report. For details on this transition, please visit our public FTP site and our U.S. Climate Divisional Database site.

The two satellite-derived animations above show the daily snow cover across the Northern Hemisphere (left map) and North America (right map) throughout February 2007. By clicking on the images, the change in sea-ice extent across parts of the Arctic can be seen through the month as well as several significant snowfall events across the U.S.

  • Several snow storms hit the Plains, Midwest, and Northeast in February. A complex, wide-reaching winter storm moved from the Mid-Mississippi Valley into the Mid-Atlantic and New England February 14 and 15. This storm ranked as a Category 3 event on the Northeast Snowfall Impact Scale (NESIS). The heaviest snow fell in interior regions of the Northeast where amounts over 20 inches were widespread. Additional information on this event is available from the National Weather Service State College PA Forecast office.
  • This event was preceded by a 10-day lake effect storm that dumped more than 100 inches of snow on New York's Tug Hill Plateau. A total of 141 inches was reported at Redfield in Oswego County. Additional information on lake effect snow events is available.
  • Two winter storms coming within a week struck the Upper Midwest in late February and early March. Heavy snowfall with record-breaking amounts in some locations occurred from February 23 through March 2.
  • Beneficial snows fell in the Sierras of California and the Great Basin Ranges in late February and early March, but the winter as a whole remained much drier than average.

More information on significant winter weather and other hazards can be found on NCDC's Hazards page.

The map to the left depicts percent of average snowpack in the West and Alaska as of March 1st. Regions showing a surplus in snow water equivalent (SWE) totals are over the Northern Cascades and the Front Range of the Rockies in Colorado and New Mexico. During the last week of February, snowfall was significant over the Sierra Nevada and Great Basin ranges. Snowfall amount increases ranged from over three feet in parts of the Sierras and Cascades to less than one foot over the eastern slope of the Rockies. Snow cover actually decreased over Arizona and most of New Mexico. Extreme variations in snowpack levels exist across Alaska, with the highest values occuring in the southeast portion of the state.

Drought

NCDC transitioned to the nClimDiv dataset on Thursday, March 13, 2014. This was coincident with the release of the February 2014 monthly monitoring report. For details on this transition, please visit our public FTP site and our U.S. Climate Divisional Database site.

Contents Of This Report:
Map showing Palmer Z Index

Top of Page National Overview

  • A file containing the national monthly percent area severely dry and wet from 1900 to present is available for the severe to extreme and moderate to extreme categories.
  • Historical temperature, precipitation, and Palmer drought data from 1895 to present for climate divisions, states, and regions in the contiguous U.S. are available at the Climate Division: Temperature-Precipitation-Drought Data page in files having names that start with "drd964x" and ending with "txt" (without the quotes).


Top of Page Detailed Drought Discussion


At the end of February extreme hydrologic drought was concentrated in Texas, Wyoming, and northern Minnesota. Drought and abnormal dryness covered a broad swath from central and southern California through the northwestern Plains into the upper Midwest (February 27 Drought Monitor). Drought and abnormal dryness continued in Florida and increased in the central and southern Appalachians. In southern California and the upper Midwest, soil moisture was low. Vegetative health had become more stressed in the West. Streamflow was low in the East, especially in Tennessee, in parts of the Plains, and in Wyoming.

Map showing Standardized Precipitation Index

In Texas and Florida mandatory or voluntary water restrictions were in place in several municipalities. Private water wells were becoming dry in Texas. Burning bans were common in drought-stricken areas, and wildfires reduced forage in western Nebraska and increased in number in Florida. The hay supply in the central part of the country was 20 percent of average, leading to increased prices and abnormal selling of livestock at auctions. The killing of livestock and pets by wild animals in southcentral Texas increased as the wildlife searched for new food and water sources during the continuing drought. Dryness has increased the salinity of Virginia's James River and the Chesapeake Bay permitting the growth of parasites that are harmful to oysters; in some areas the oyster death rate was 90 percent. Impacts in drought-stricken areas have been collected and summarized by county at the National Drought Mitigation Center's Drought Impact Reporter.




Top of Page State/Regional/National Moisture Status


A detailed review of drought and moisture conditions is available for all contiguous U.S. states, the nine standard regions, and the nation (contiguous U.S.):

STATES:
Alabama Arizona Arkansas California Colorado Connecticut
Delaware Florida Georgia Idaho Illinois Indiana
Iowa Kansas Kentucky Louisiana Maine Maryland
Massachusetts Michigan Minnesota Mississippi Missouri Montana
Nebraska Nevada New Hampshire New Jersey New Mexico New York
North Carolina North Dakota Ohio Oklahoma Oregon Pennsylvania
Rhode Island South Carolina South Dakota Tennessee Texas Utah
Vermont Virginia Washington West Virginia Wisconsin Wyoming


REGIONS:
Northeast Region East North Central Region Central Region
Southeast Region West North Central Region South Region
Southwest Region Northwest Region West Region
Map showing the nine U.S. standard regions
NATIONAL:
Contiguous U.S.




Top of Page Pre-Instrumental Perspective


There is no Febuary 2007 Paleoclimatic Perspective

Global Snow & Ice

Contents of this Section:


Top of Page Northern Hemisphere Snow Cover Extent

As shown in the time series to the right, mean Northern Hemisphere snow cover extent during winter 2006/2007 was below average. Much of this was due to anomalously warm conditions across Asia, Europe, Canada, and the northeast half of the U.S. Winter 2006/2007 snow cover extent over the Northern Hemisphere was the 8th lowest extent in the historical record. Mean Northern Hemisphere winter snow cover extent for the 1967-2007 period of record is 45.4 million square kilometers.
Current season's Northern Hemisphere Snow Cover extent
larger image of Northern Hemisphere winter snow cover
Current season's North America Snow Cover extent
larger image of North America winter snow cover
Snow cover for winter 2006/2007 across North America was above average, and was the 13th largest extent over the 41-year historical record. This was in part due to a series of snow and ice storms that struck the U.S. during the month of February. Average North America winter snow cover extent is 17.0 million square kilometers for the 1967-2007 period of record.

Upper Air

Top of Page Troposphere

Temperatures above the Earth's surface are measured using in-situ balloon-borne instruments (radiosondes) and polar-orbiting satellites (NOAA's TIROS-N). The radiosonde and the satellite records have been adjusted to remove time-dependent biases (artificialities caused by changes in radiosonde instruments and measurement practices as well as changes in satellite instruments and orbital features through time).

Lower Troposphere
Current Month / Seasonal / Year-to-date

February Anomaly Rank Warmest Year on Record Trend
UAH low-trop +0.41°C/0.74°F 2nd warmest 1998 (+0.69°C/1.24°F) +0.17°C/decade
*RSS low-trop +0.33°C/0.59°F 8th warmest 1998 (+0.76°C/1.37°F) +0.23°C/decade
*Version 03_0


December-
February
Anomaly Rank Warmest Year on Record Trend
UAH low-trop +0.41°C/0.74°F 2nd warmest 1998 (+0.51°C/0.92°F) +0.16°C/decade
*RSS low-trop +0.39°C/0.70°F 5th warmest 1998 (+0.58°C/1.04°F) +0.22°C/decade
*Version 03_0


January-
February
Anomaly Rank Warmest Year on Record Trend
UAH low-trop +0.47°C/0.85°F 2nd warmest 1998 (+0.62°C/1.12°F) +0.17°C/decade
*RSS low-trop +0.40°C/0.72°F 7th warmest 1998 (+0.70°C/1.26°F) +0.23°C/decade
*Version 03_0


Mid-Troposphere
Current Month / Seasonal / Year-to-date
These temperatures are for the atmospheric layer centered in the mid-troposphere (approximately 2-6 miles above the Earth's surface) which also includes a portion of the lower stratosphere. (The MSU channel used to measure mid-tropospheric temperatures receives about 25 percent of its signal above 6 miles). Because the stratosphere has cooled due to increasing greenhouse gases in the troposphere and losses of ozone in the stratosphere, the stratospheric contribution to the tropospheric average, as measured from satellites, may create an artificial component of cooling to the mid-troposphere temperatures. The University of Washington (UW) versions of the UAH and RSS analyses attempt to remove the stratospheric influence from the mid-troposphere measurements, and as a result the UW versions tend to have a larger warming trend than either the UAH or RSS versions. For additional information, please see NCDC's Microwave Sounding Unit page.

The radiosonde data used in this global analysis were developed using the Lanzante, Klein, Seidel (2003) ("LKS") bias-adjusted dataset and the First Difference Method (Free et al. 2004). Additional details are available. Satellite data have been adjusted by the Global Hydrology and Climate Center at the University of Alabama in Huntsville (UAH). An independent analysis is also performed by Remote Sensing Systems (RSS) and a third analysis has been performed by Dr. Qiang Fu of the the University of Washington (UW) (Fu et al. 2004)** to remove the influence of the stratosphere on the mid-troposphere value. Global averages from radiosonde data are available from 1958 to present, while satellite measurements began in 1979.


YTD Ratpac image
Larger Image of year-to-date RATPAC mid-tropospheric temperatures

Winter 2007 Ratpac image
Larger Image of boreal winter RATPAC mid-tropospheric temperatures

Radiosonde measurements indicate that for the January-February year-to-date period, temperatures in the mid-troposphere were 0.68°C (1.22°F) above average; the 3rd warmest January-February since global measurements began in 1958, slightly cooler than January-February 1998 and the record warm January-February 2005. As shown in the table below, satellite measurements of the January-February 2007 year-to-date period for the middle troposphere varied from 2nd to 3rd warmest on record, depending on the analysis method.

During the boreal winter, radiosonde measurements indicate that temperatures in the mid-troposphere were 0.56°C (1.01°F) above average, the 4th warmest boreal winter on record. There is little difference between the 5 warmest boreal winter seasons on record for the globe (1998, 2004, 2005, 2007, 2006). The table below displays that satellite measurements for the boreal winter varied from 3rd to 5th warmest on record, depending on the analysis method.

The global mid-troposphere temperatures were warmer than average in February 2007, as shown in the table below. Satellite measurements for February 2007 varied from 5th to 7th warmest on record, depending on the analysis method.

February Anomaly Rank Warmest Year on Record Trend
UAH mid-trop +0.20°C/0.36°F 5th warmest 1998 (+0.63°C/1.13°F) +0.07°C/decade
*RSS mid-trop +0.24°C/0.43°F 6th warmest 1998 (+0.71°C/1.28°F) +0.14°C/decade
**UW-UAH mid-trop +0.31°C/0.56°F 5th warmest 1998 (+0.80°C/1.44°F) +0.15°C/decade
**UW-*RSS mid-trop +0.32°C/0.58°F 7th warmest 1998 (+0.83°C/1.49°F) +0.20°C/decade
*Version 03_0


December-
February
Anomaly Rank Warmest Year on Record Trend
UAH mid-trop +0.20°C/+0.36°F 4th warmest 1998 (+0.43°C/0.77°F) +0.05°C/decade
*RSS mid-trop +0.27°C/0.49°F 5th warmest 1998 (+0.49°C/0.88°F) +0.12°C/decade
**UW-UAH mid-trop +0.31°C/+0.56°F 3rd warmest 1998 (+0.57°C/1.03°F) +0.12°C/decade
**UW-*RSS mid-trop +0.36°C/+0.65°F 5th warmest 1998 (+0.60°C/1.08°F) +0.18°C/decade
RATPAC +0.56°C/1.01°F 4th warmest 1998 (+0.59°C/1.06°F) +0.16°C/decade
*Version 03_0


January-
February
Anomaly Rank Warmest Year on Record Trend
UAH mid-trop +0.27°C/+0.49°F 2nd warmest 1998 (+0.56°C/1.01°F) +0.07°C/decade
*RSS mid-trop +0.34°C/0.61°F 3rd warmest 1998 (+0.62°C/1.12°F) +0.13°C/decade
**UW-UAH mid-trop +0.38°C/+0.68°F 2nd warmest 1998 (+0.71°C/1.28°F) +0.14°C/decade
**UW-*RSS mid-trop +0.43°C/+0.77°F 3rd warmest 1998 (+0.75°C/1.35°F) +0.20°C/decade
RATPAC +0.68°C/1.22°F 3rd warmest 2005 (+0.75°C/1.35°F) +0.15°C/decade
*Version 03_0

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Top of Page Stratosphere

Current Month / Seasonal
The table below summarizes stratospheric conditions for February 2007. On average, the stratosphere is located approximately between 10-14 miles above the Earth's surface. Over the last decade, stratospheric temperatures have been below average in part due to the depletion of ozone and the increase in greenhouse gases in the Earth's atmosphere. The large positive anomaly in 1982 was caused by the volcanic eruption of El Chichon in Mexico, and the sharp jump in temperature in 1991 was a result of the eruption of Mt. Pinatubo in the Philippines. In both cases the temperatures returned to pre-eruption levels within two years.

February Anomaly Rank Coolest Year on Record
UAH stratosphere -0.51°C (-0.92°F) 6th coolest 2006 (-0.79°C/-1.42°F)
*RSS stratosphere -0.38°C (-0.68°F) 9th coolest 2006 (-0.70°C/-1.26°F)
*Version 03_0

December-
February
Anomaly Rank Coolest Year on Record
UAH stratosphere -0.57°C (-1.03°F) 8th coolest 2006 (-0.77°C/-1.39°F)
*RSS stratosphere -0.43°C (-0.77°F) 9th coolest 2006 (-0.66°C/-1.19°F)
*Version 03_0

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For additional details on precipitation and temperatures in February, see the Global Hazards page.
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Top of Page References

Christy, John R., R.W. Spencer, and W.D. Braswell, 2000: MSU Tropospheric Temperatures: Dataset Construction and Radiosonde Comparisons. J. of Atmos. and Oceanic Technology 17 1153-1170.

Free M., D.J. Seidel, J.K. Angell, J. Lanzante, I. Durre and T.C. Peterson (2005) Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC): A new dataset of large-area anomaly time series, J. Geophys. Res., 10.1029/2005JD006169.

Free, M., J.K. Angell, I. Durre, J. Lanzante, T.C. Peterson and D.J. Seidel(2004), Using first differences to reduce inhomogeneity in radiosonde temperature datasets, J. Climate, 21, 4171-4179.

Fu, Q., C.M. Johanson, S.G. Warren, and D.J. Seidel, 2004: Contribution of stratospheric cooling to satellite-inferred tropospheric temperature trends. Nature, 429, 55-58.

Lanzante, J.R., S.A. Klein, and D.J. Seidel (2003a), Temporal homogenization of monthly radiosonde temperature data. Part I: Methodology, J. Climate, 16, 224 240.

Lanzante, J.R., S.A. Klein, and D.J. Seidel (2003b), Temporal homogenization of monthly radiosonde temperature data. Part II: Trends, sensitivities, and MSU comparison, J. Climate, 16, 241 262.

Mears, Carl A., M.C. Schabel, F.J. Wentz, 2003: A Reanalysis of the MSU Channel 2 Tropospheric Temperature Record. J. Clim 16, 3650-3664.

El Niño/Southern Oscillation

EL NIÑO EVENT DISSIPATES RAPIDLY:
COOLER SSTs DEVELOP ACROSS THE CENTRAL EQUATORIAL PACIFIC






Sea-Surface Temperatures (SSTs) and Mixed-Layer Conditions:
The above average Sea-Surface Temperature (SST) anomalies associated with the 2006/2007 El Niño diminshed over the past month, signaling the end of the warm event. However, warmer than average SSTs persisted in the far western equatorial Pacific from approximately 160°E to 170°W in February. Water temperatures in the equatorial mixed-layer also declined in February, with a large area of -3.0°C (+3.6°F) and cooler temperature anomalies between 50-150 meters depth in the eastern equatorial Pacific. This layer of cooler water continued to develop and slowly propagated eastward in February.

For the month, the SST anomaly in the Niño 3.4 Index region was +0.06°C (+0.11°F), which was a decrease of -0.64°C (-1.15°F) compared to the January anomaly. The SSTs in the Niño 4 Index region of the western equatorial Pacific also cooled during February to a monthly anomaly of +0.42°C (+0.76°F) above the mean (map of Niño regions). For the most recent global ocean surface temperatures, please see the loop of satellite-derived weekly SST anomalies for February 2007.

Despite the rapid decrease in the SST anomalies in the Niño 3.4 index region, at the end of February the 3-month running mean remained above +0.5°C (+0.9°F). (NOTE: For NOAA's official ENSO classification scheme, please see NOAA's El Niño/La Niña Index Definition).

The Climate Prediction Center's most recent ENSO Diagnostic Discussion indicated that the 2006/2007 warm event (El Niño) had dissipated by the end of February. The latest ENSO forecast from the Australian Bureau of Meteorology (BoM) also reflected the transition from a warm event to neutral ENSO conditions in the equatorial Pacific basin over the past month (see the Australian BoM ENSO Wrap-Up).





Equatorial Zonal Winds (U-Component Winds) and Sea-Level Topography:
The easterly Trade winds were above normal across the central and eastern equatorial Pacific during February.

Significant week-to-week variability in the near-surface winds has been observed along the equatorial region of the Pacific over the past month, as shown in the loop of February zonal winds. A period of anomalous westerly flow occurred in the far western equatorial Pacific region during early February, as easterly Trade winds were stronger-than-average across most of the central and eastern equatorial Pacific basin during the past month.

Pacific sea levels measured by the NASA/JPL Jason-1 satellite were below average across the central equatorial Pacific in February, reflecting the cooler-than-average ocean surface temperatures that have developed in this region (see the most recent image of 27 February 2007 sea level anomalies).



Outgoing Longwave Radiation (OLR):
The map to the left shows the spatial pattern of global OLR (in W m-2) measured by satellite during February. A region of negative OLR anomalies was measured in the far western equatorial Pacific near Indonesia, west of the Date Line, illustrating the enhanced tropical convection observed in this region over the past month.

The monthly OLR index for February was +0.1 W m-2 averaged across an area in the western Pacific near the Date Line between 160° E and 160° W. Therefore, the February value was near-neutral, and was also the first month with a positive index value following six consecutive months with negative OLR indices.

Note that high frequency variability in OLR is typically associated with the Madden-Julian Oscillation (MJO), which is convective activity that propagates west to east in the near-equatorial region from the Indian Ocean into the Pacific Ocean approximately every 30-60 days). The latest MJO activity can be seen in CPC's graphs of Daily MJO Indices.


Southern Oscillation Index (SOI):
The standardized SOI was -0.5 in February. The SOI has shown considerable variablity during the 2006/2007 El Niño event, although it was negative for the first three months of 2007. Before this, the SOI was negative for six consecutive months during the formative phase of the most recent El Niño [note that consistently negative (positive) values of the SOI are typical of El Niño (La Niña) conditions].

A transition to near-neutral SOI values, and potentially postive monthly values, is possible over the next several months as NOAA's Climate Prediction Center (CPC) has forecasted a transition from neutral to La Niña conditions during April-June 2007.

Citing This Report

NOAA National Climatic Data Center, State of the Climate for February 2007, published online March 2007, retrieved on November 25, 2014 from http://www.ncdc.noaa.gov/sotc/2007/2.