Including Warm Season (April-September)

National Climatic Data Center, 17 October 2001

Contents of This Report:

• Statewide Temperature Ranks
• Statewide Precipitation Ranks
• Regional Temperature Highlights
• Regional Precipitation Highlights
• Regional Temperature and Precipitation Time Series
• Agricultural Precipitation
• Precipitation and Temperature Ranks, Extremes and Normals
• Water-year River Basin Statistics
• Warm Season Temperatures
• Warm Season Precipitation

Statewide Temperature Ranks

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September 2001 temperatures were warmer than average in the western half of the country. Nevada experienced its record warmest September in the 1895 to present record. This is the second month in a row of record heat for Nevada. Other states that ranked in the top ten warmest for September: Utah - fourth warmest Idaho - sixth warmest Arizona - seventh warmest Montana - eighth warmest Wyoming - ninth warmest Twelve additional states fell into the warm third portion of the historical distribution.

In contrast, much of the eastern half of the country, except the northeast, experienced below normal temperatures. Alabama, Georgia, Florida, South Carolina and North Carolina had temperatures that ranked September 2001 among the top ten coolest Septembers in the 1895 to present record. The graph to the right shows the 1918-2001 temperature time series for Alaska. In September, temperatures averaged across the state were above the long-term mean. Temperatures have been near to above normal for ten of the last thirteen Septembers.

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Statewide Precipitation Ranks

September precipitation was generally characterized by near normal to below normal precipitation over much of the country. Notable exceptions were Nebraska and Kansas which experienced their fifth wettest and eighth wettest September, respectively, in the 1895 to present record. Rains associated with Tropical Storm Gabrielle left Florida with much above normal precipitation for September. Gabrielle moved inland across the west coast of central Florida on the 14th as a 70 mph tropical storm, later developing into a hurricane over the Gulf Stream. Over 10 inches of rain caused major river flooding in west-central Florida.

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Regional Temperature Highlights

September 2001 was the fifth coolest such month in the 1895 to present record for the Southeast region. Temperatures in seven of the last eight Septembers have been cooler than average.

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It was the third warmest September in the1895 to present record for the West region. Average September temperatures in each of the last fifteen years were near to or above the long-term mean. It is interesting to note that while the West region had the warmest ranking in the county, other western regions also experienced much above normal temperatures.

Temperature time series for all regions can be found in the table below.

Regional Precipitation Highlights

September 2001 was the twenty-first driest such month in the 1895 to present record for the Southwest region. This was the second consecutive September where precipitation has been below normal.

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The Northwest region also experienced below normal precipitation. Elsewhere, regional precipitation was near normal.

Precipitation time series for all regions can be found in the table below.

Regional Temperature and Precipitation Time Series

Historical precipitation and temperature ranking maps are also available on the Internet courtesy of the Climate Prediction Center.

Additional information about current climate anomalies can be found at the respective Web Pages of the Southern Regional Climate Center, Western Regional Climate Center, Midwest Regional Climate Center, Southeast Regional Climate Center, High Plains Regional Climate Center, and the Northeast Regional Climate Center.

Agricultural Precipitation

March through September 2001 precipitation averaged near normal over the Primary Corn and Soybean agricultural belt. This makes three consecutive years where precipitation in the period March through September averaged near normal. The growing season for the Primary Corn and Soybean Belt runs from March through September. For further agricultural information visit the Weekly Weather and Crop Bulletin.

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Data Tables

Table 2 shows historical extremes for September, the 1961-1990 normal, and the September 2001 value for each of the 9 regions and the contiguous U.S. for precipitation and temperature.

Table 3 shows statistics for selected river basins: Precipitation rankings are for October 2000-September 2001, where 1 = driest, and 106 = wettest, based on the period 1895 to 2001. Also shown is the areal percent of the basin experiencing severe or extreme long-term (Palmer) drought, and areal percent of the basin experiencing severe or extreme long-term (Palmer) wet conditions, as of September 2001. The river basin regions are defined by the U.S. Water Resources Council.

It should be emphasized that all of the temperature and precipitation ranks and values in Tables 1 through 3 are based on preliminary data. The ranks will change when the final data are processed. National ranks and values are based on a combination of USHCN and divisional data.

Warm Season (April-September) 2001 Temperatures

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Warm Season 2001 temperatures were warmer than average in much of the country except in portions of the east, central and southeast.Nevada had its record warmest April-September in the 1895 to present record. Other states where temperatures ranked in the top ten warmest for April-September 2001: Rhode Island, Montana, Idaho, Wyoming, California, Utah, Colorado, Arizona and New Mexico.

The regional temperature map to the right shows the West, Southwest and West North Central regions having warm seasons that ranked in the top ten warmest in the 1895 to present record. Only the Southeast region had a cooler than average April-September.

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Warm Season (April-September) 2001 Precipitation

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Warm Season 2001 precipitation was generally less than average in most areas of the country except in some north central states and in Gulf Coast states that were affected by tropical systems. Maine was record driest and both Vermont and New Hampshire finished second driest in the 1895 to present record. South Carolina also received much below normal precipitation.

The map to the right displays regional rankings for April-September 2001. The three western regions and the Northeast received below normal precipitation while the West North Central and East North Central regions were wetter than average.

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References

Thomas R. Karl and Albert J. Koscielny, 1982: "Drought in the United States: 1895-1981." Journal of Climatology, vol. 2, pp. 313-329.

Thomas R. Karl and Walter James Koss, 1984: "Regional and National Monthly, Seasonal, and Annual Temperature Weighted by Area, 1895-1983." Historical Climatology Series 4-3, National Climatic Data Center, Asheville, NC, 38 pp.

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