Creating county climate summaries for Oklahoma

In Oklahoma, county-level offices of the Natural Resources Conservation Service (NRCS) are required to prepare five-year plans. One element of the plans is a section on weather and climate in their county. In 1994, several NRCS offices approached the Oklahoma Climatological Survey (OCS) for general information on normal and extreme conditions, to be included as part of their plan. This opened a dialogue that sparked generation of new products, and ultimately a complete set of county climate summaries for Oklahoma.

In 1999, those offices again contacted OCS for updates of the information provided. Rather than replicating what was provided in 1999, OCS developed more detailed analyses for the particular counties. The Oklahoma Mesonet, which was not available in 1994, was incorporated to provide analyses of wind, humidity and soil temperatures –information that had not been previously considered but is essential to planning agricultural practices. Through word-of-mouth, other counties contacted OCS for similar county reports.

The 2004 cycle represented an even greater opportunity. Based upon an understanding of the needs and applications of the information, OCS had prepared a detailed set of tables that not only provided normal and extreme conditions, but some measures of probabilities on a monthly or seasonal basis. During the 2004 cycle, detailed analyses were provided to 14 of Oklahoma's 77 counties. Rather than shelving the process until the 2009 update, OCS decided to complete the analyses for all of Oklahoma's counties. The result is a CD-ROM publication that will be provided to each county NRCS and Extension office, as well as posted on the OCS website.

The county climate summaries consist of three major elements:(1) Detailed assessments that include: a written overview of the climate; charts of annual temperature and precipitation; a table of monthly normals and extremes; 20% ‘exceedence values' for monthly temperature and precipitation; probability-based freeze and frost dates and growing season lengths for 24, 28 and 32 degrees; wind rose and frequency distribution table; mean monthly humidity, dewpoint, vapor pressure and soil temperatures; and a listing of historically significant tornadoes in the county; (2) A ‘quickfacts' summary of average and extreme temperatures and precipitation, average wind speed, sunshine, humidity, and severe weather occurrences, and winter weather; and (3) Detailed summaries of averages, extremes and probabilities for long-term cooperative observer stations and Oklahoma Mesonet stations in the county. In addition, an overview of Oklahoma's climate is provided. These elements are combined through a web-based interface on the CD-ROM that allows individuals to select information by county or by observing station.

Development of the products was iterative, both with the NRCS offices and internally to OCS. The quickfacts summaries are designed to provide general information in a way appealing to a diverse audience. The detailed summaries provide a greater depth of information for those who are more significantly affected by climate variability. The station tables provide localized information for quality observing sites. Because some counties did not have adequate long-term records, an objective analysis was performed to determine the county averages used in the quickfacts summaries. Extremes were based on all observing stations, even those with short records, obtained from the TD-3206 and TD-3200 datasets from NCDC.

The process of developing these county climate summaries will be presented, along with examples of the final products and some feedback from those who have begun using the summaries.