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State of the Climate
National Overview
June 2011

National Oceanic and Atmospheric Administration

National Climatic Data Center


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Did You Know?

U.S. Climate Normals
U.S. Climate Normals
1971-2000 Normals: approximately 8000 stations

Beginning August 1, 2011, the U.S. ASOS maps and the monthly mean maximum and minimum temperature anomaly maps will be using the newly updated 1981-2010 Normals to calculate anomalies. Other 30-year Normals anomaly-based monitoring products will not be affected by the Normals transition until early 2012.

Climate Normals are three-decade averages of climatological variables. The most widely-used Normals are those for daily and monthly station-based temperature, precipitation, snowfall and heating and cooling degree days. These come from NOAA's Cooperative and First-Order station networks. Meteorologists and climatologists regularly use Normals for placing recent climate conditions into historical context; such as comparisons with the day's weather conditions on local television. Normals are also utilized in many applications across a variety of sectors. These include regulation of power companies, energy load forecasting, crop selection and planting times, construction planning, building design, and many others.

Several changes and additions will be incorporated into the 1981-2010 Normals. Monthly temperature and precipitation Normals will utilize underlying data values that have undergone additional quality control to account for things such as stations having been moved. Unlike the 1971-2000 Normals, daily (rather than monthly) data will be used extensively in daily temperature Normals as well as heating and cooling degree day Normals, providing greater precision of intra-seasonal features. More details can be found in Arguez et al. 2011.

When the new Normals are released, relevant comparisons between the new version and previous versions will be highlighted. Observational evidence shows that the 2000-2009 timeframe was the warmest decade on record in the U.S. Therefore, we expect that the new Normals will generally be warmer on average for most stations, but not uniformly warmer for all stations and all seasons. In fact, some station Normals in certain seasons will become cooler.

Information on the current Normals, as well as the history of the Normals, can be found on NCDC's U.S. Climate Normals webpage. For general questions about Normals or help accessing the 1971-2000 product, please contact NCDC's Customer Services Branch.

More about climate monitoring…


National Overview:

The weather pattern over the contiguous United States during June 2011 was a continuation of an upper-level high pressure ridge over the southern to eastern U.S. and an upper low pressure trough over the Northwest, with the storm track mostly keeping to the northern states. Occasional weather systems moved across the middle of the country toward the east, dragging weak fronts into the Southeast. Hot and dry weather was associated with the upper high, while cooler-than-normal weather dominated the Northwest.

More than 4000 daily high temperature records were tied or broken in June, mostly east of the Rockies, and there were 159 reports of the record hottest temperature for June and 42 reports of all-time record hottest temperature ever. Drought intensified across parts of the Southwest to Southeast. While the southern Plains' 1950s drought of record is unsurpassed in terms of duration, the current drought in parts of Texas is more intense than the 1950s drought when measured by the Palmer Hydrological Drought Index. While blanketing the southern U.S. with hot and dry weather, a upper level high pressure system effectively blocked any Gulf of Mexico moisture from feeding into the area. Meanwhile, the upper-level low pressure trough in the Northwest attributed to the cool, wet anomalies in the region.

Cold fronts and low pressure systems moving in the storm track flow are influenced by the broadscale atmospheric circulation. Two such large-scale atmospheric circulation drivers were essentially neutral during June. The equatorial Pacific was in an ENSO-neutral state, which means the La Niña has officially ended even though atmospheric circulation anomalies still reflected some aspects of La Niña. The Pacific/North American (PNA) pattern was also neutral and thus not a significant player in the nation's weather this month. But two other large-scale atmospheric circulation drivers were influential during June 2011. The first was the North Atlantic Oscillation (NAO) pattern, which was negative for most of the month. A negative NAO this time of year (summer, represented by July on the NAO teleconnection maps) is typically associated with warmer-than-normal temperatures and drier-than-normal conditions in the southern Plains and Southeast, cooler-than-normal weather in the Northwest and northern Plains, and wetter-than-normal conditions in the northern Plains and Midwest. The second atmospheric circulation index was the Arctic Oscillation (AO) pattern, which was slightly negative for most of the month. A negative AO this time of year (April-June) is typically associated with coolness in the northern Plains and Great Lakes to Northeast, dryness in the Southeast to Northeast and coastal Northwest, and anomalous wetness in northern California and the northern Plains.

The pattern of observed temperature anomalies for June 2011 and the last three months (April-June) is a very good match for the NAO pattern for July (summer). The June and April-June 2011 precipitation patterns are a reasonable match for the NAO and AO patterns in the southern Plains and Southeast.



Alaska Temperature and Precipitation:

For additional details about recent temperatures and precipitation across the U.S., see the Regional Highlights section below and visit the Climate Summary page. For information on local temperature and precipitation records during the month, please visit NCDC's Records page. For details and graphics on weather events across the U.S. and the globe please visit NCDC's Global Hazards page.


Regional Highlights:

These regional summaries were provided by the six Regional Climate Centers and reflect conditions in their respective regions. These six regions differ spatially from the nine climatic regions of the National Climatic Data Center.

See NCDC's Monthly Records web-page for weather and climate records for the most recent month. For additional national, regional, and statewide data and graphics from 1895-present, for any period, please visit the Climate at a Glance page.


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 provided on the Temperature and Precipitation Maps page and the Climate at a Glance page as they become available.


Citing This Report

NOAA National Climatic Data Center, State of the Climate: National Overview for June 2011, published online July 2011, retrieved on May 29, 2012 from http://www.ncdc.noaa.gov/sotc/national/2011/6.

Questions?

For questions on technical or scientific content of this report, please contact:

Jake Crouch:
Jake.Crouch@noaa.gov

For general climate monitoring questions, please contact:

CMB.Contact@noaa.gov

For climate data orders, please contact the National Climatic Data Center's Climate Services and Monitoring Division:

NCDC.Orders@noaa.gov

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