Through climate analysis, National Climatic Data Center scientists have identified nine climatically consistent regions within the contiguous United States which are useful for putting current climate anomalies into an historical perspective.

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.

Table 1 shows precipitation and temperature ranks for each of the 9 regions and the nation for April 2000, the two-month period of March-April 2000, the six months of November 1999-April 2000, and the past 12 months, May 1999-April 2000.

            PRECIPITATION AND TEMPERATURE RANKS, BASED
            ON THE PERIOD 1895-2000.  1 = DRIEST/COLDEST,
            106 = WETTEST/WARMEST FOR APRIL 2000,
            106 = WETTEST/WARMEST FOR MAR-APR 2000,
            105 = WETTEST/WARMEST FOR NOV 1999-APRIL 2000,
            105 = WETTEST/WARMEST FOR MAY 1999-APRIL 2000.

                       APR    MAR-APR   NOV 1999-  MAY 1999-
   REGION              2000     2000    APR 2000   APR 2000
   ------              ----  ---------  ---------  ---------

             PRECIPITATION:

  NORTHEAST             97       91         59         69
  EAST NORTH CENTRAL    31       19         12         44
  CENTRAL               44       18         23          6

  SOUTHEAST             58       41         16         29
  WEST NORTH CENTRAL    69       87         60         70
  SOUTH                 43       68         21         16

  SOUTHWEST             22       79         23         61
  NORTHWEST             37       39         62         45
  WEST                  67       40         51         41

  NATIONAL              47       50         11         20

             TEMPERATURE:

  NORTHEAST             49       93         96        104
  EAST NORTH CENTRAL    62      101        105        104
  CENTRAL               49       85        104         99

  SOUTHEAST             24       74         82         72
  WEST NORTH CENTRAL    79      100        105        103
  SOUTH                 69       91        105        102

  SOUTHWEST             99       97        104        104
  NORTHWEST             97       91        101         93
  WEST                 100       95        103        101

  NATIONAL              87      102        105        104

It should be emphasized that all of the temperature and precipitation ranks in Tables 1 through 5 are based on preliminary data. The ranks will change when the final data are processed.

Table 2 shows historical extremes for April, the 1961-1990 normal, and the April 2000 value for each of the 9 regions and the contiguous U.S. for precipitation and temperature. It should be noted that the 2000 values will change when the final data are processed.

                             PRECIPITATION (INCHES)
                          DRIEST     WETTEST   NORMAL  2000
      REGION            VALUE YEAR VALUE YEAR   PCPN   PCPN
      ------            ---------- ----------  ------ ------

     NORTHEAST           1.40 1896  6.81 1983   3.42   4.80
     EAST NORTH CENTRAL  1.04 1946  4.84 1896   2.63   2.02
     CENTRAL             1.55 1915  6.82 1927   3.95   3.44

     SOUTHEAST           0.85 1986  7.06 1928   3.52   3.60
     WEST NORTH CENTRAL  0.48 1926  2.83 1984   1.62   1.75
     SOUTH               1.08 1987  6.92 1957   2.98   2.90

     SOUTHWEST           0.26 1989  2.58 1900   0.83   0.55
     NORTHWEST           0.61 1977  3.81 1937   1.97   1.69
     WEST                0.14 1909  3.25 1967   1.22   1.30

     NATIONAL            1.41 1987  3.56 1957   2.38   2.31*

                         * PRELIMINARY VALUE, CONFIDENCE
                           INTERVAL + OR - 0.23 INCHES

                            TEMPERATURE (DEGREES F)
                          COLDEST    WARMEST   NORMAL  2000
      REGION            VALUE YEAR VALUE YEAR   TEMP   TEMP
      ------            ---------- ----------  ------ ------

     NORTHEAST           38.8 1943  50.4 1921   44.4   44.3
     EAST NORTH CENTRAL  35.7 1950  51.8 1915   44.0   44.5
     CENTRAL             45.4 1907  59.5 1896   53.4   52.9

     SOUTHEAST           56.6 1901  66.6 1954   62.1   60.6
     WEST NORTH CENTRAL  34.5 1920  49.5 1915   43.0   44.8
     SOUTH               57.2 1983  67.4 1925   62.7   63.1

     SOUTHWEST           44.4 1920  55.6 1989   49.9   54.4
     NORTHWEST           39.7 1975  52.6 1934   44.9   49.0
     WEST                43.3 1967  58.5 1934   51.9   57.0

     NATIONAL*           48.2 1920  56.2 1981   52.3   54.3

                         * National Temperature Values based
                           on USHCN
 

Table 3 shows statistics for selected river basins: Precipitation rankings are for October 1999-April 2000, where 1 = driest, and 105 = wettest, based on the period 1895 to 2000. 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 April 2000.

                                PRECIPITATION  % AREA  % AREA
  RIVER BASIN                       RANK        DRY     WET
  -----------                   -------------  ------  ------

  MISSOURI BASIN                     20          5.0%   16.3%
  PACIFIC NORTHWEST BASIN            60          0.0%    0.0%
  CALIFORNIA RIVER BASIN             49         28.8%    0.0%

  GREAT BASIN                        30          0.0%    0.0%
  UPPER COLORADO BASIN                8          0.0%    0.0%
  LOWER COLORADO BASIN                4         70.0%    0.0%
  RIO GRANDE BASIN                    7         50.7%    3.9%

  ARKANSAS-WHITE-RED BASIN           48          0.0%   21.3%
  TEXAS GULF COAST BASIN             14          9.3%    0.0%
  SOURIS-RED-RAINY BASIN              7          0.0%   25.0%
  UPPER MISSISSIPPI BASIN             3         28.8%    0.0%

  LOWER MISSISSIPPI BASIN             7         50.4%    0.0%
  GREAT LAKES BASIN                  14         14.5%    0.0%
  OHIO RIVER BASIN                   27         20.2%    0.0%
  TENNESSEE RIVER BASIN              21          0.0%    0.0%

  NEW ENGLAND BASIN                  68          0.0%    7.7%
  MID-ATLANTIC BASIN                 55          0.0%    0.0%
  SOUTH ATLANTIC-GULF BASIN          20         17.6%    0.0%

The river basin regions are defined by the U.S. Water Resources Council.

Table 4 shows precipitation and temperature ranks for each of the 9 regions and the nation for January-April 2000. Based on the period 1895-2000.

         1 = DRIEST/COLDEST, 106 = WETTEST/HOTTEST.

      REGION                PRECIPITATION  TEMPERATURE
       ------                -------------  -----------

      NORTHEAST                   85             90
      EAST NORTH CENTRAL          22            101
      CENTRAL                     37             98

      SOUTHEAST                   26             69
      WEST NORTH CENTRAL          93            103
      SOUTH                       32            105

      SOUTHWEST                   54            104
      NORTHWEST                   64             97
      WEST                        83            104

      NATIONAL                    42            106

Table 5 shows historical extremes for January-April, the 1961-1990 normal, and the January-April 2000 value for each of the 9 regions and the contiguous U.S. for precipitation and temperature. It should be noted that the 2000 values will change when the final data are processed.

                            PRECIPITATION (INCHES)
                          DRIEST     WETTEST   NORMAL  2000
      REGION            VALUE YEAR VALUE YEAR   PCPN   PCPN
      ------            ---------- ----------  ------ ------

     NORTHEAST           7.92 1941 17.31 1936  12.05  14.19
     EAST NORTH CENTRAL  3.66 1958  9.30 1951   6.58   5.48
     CENTRAL             8.13 1941 19.95 1950  13.03  11.97

     SOUTHEAST           9.59 1916 24.75 1998  16.55  13.37
     WEST NORTH CENTRAL  2.14 1926  5.11 1896   3.80   4.43
     SOUTH               5.91 1936 16.78 1973  10.20   9.20

     SOUTHWEST           1.12 1972  9.14 1905   3.47   3.61
     NORTHWEST           5.95 1977 16.43 1904  11.35  11.79
     WEST                3.44 1977 17.01 1995   8.30  10.99

     NATIONAL            7.03 1910 12.02 1998   8.90   8.72

                            TEMPERATURE (DEGREES F)
                          COLDEST    WARMEST   NORMAL  2000
      REGION            VALUE YEAR VALUE YEAR   TEMP   TEMP
      ------            ---------- ----------  ------ ------

     NORTHEAST           25.6 1904  36.0 1998   30.6   33.0
     EAST NORTH CENTRAL  19.0 1936  33.7 1987   26.1   31.5
     CENTRAL             33.2 1978  45.2 1921   39.2   42.8

     SOUTHEAST           48.2 1978  56.5 1974   52.0   53.8
     WEST NORTH CENTRAL  21.0 1936  35.1 1992   28.2   33.1
     SOUTH               46.4 1978  54.9 1911   50.5   54.8

     SOUTHWEST           35.3 1917  44.7 1986   39.7   44.2
     NORTHWEST           30.8 1922  43.4 1934   36.4   39.0
     WEST                39.7 1937  50.4 1934   44.8   48.2

     NATIONAL*           37.2 1912  44.3 2000   40.6   44.3

                         * National Temperature Values based
                           on USHCN

 

Regional Temperature - April 2000

Based upon preliminary data, April 2000 was the seventh warmest such month since 1895 for the West Region.

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Preliminary data suggest that April 2000 was the 24th coolest such month since 1895 for the Southeast Region. Extreme temperature variability during April has been a characteristic in the Southeast Region for the last twenty years.

Regional Precipitation - April 2000

It was the tenth wettest April on record for the Northeast Region. Three of the last eight such months have been much wetter than the long-term mean.

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Preliminary data suggest that April 2000 was the 22nd driest such month since 1895 for the Southwest Region. Seven of the last fourteen such months have been much below the long-term mean.

Regional Temperature - January-April 2000

Preliminary data indicate that the year-to-date, January-April 2000, was the second warmest such period on record for the South Region. The last two such periods have been much above the long-term mean.

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Regional Precipitation - January-April 2000

January-April 2000 was the 14th wettest such period since 1895 for the West-North Central Region. Only three of the last fourteen such periods have been much above the long-term mean.

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January-April 2000 was the 22nd driest such period on record for the East-North Central Region. This was the first such period of much below normal precipitation since January-April 1989.

April 2000 Statewide Ranks

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Fifteen states ranked within the warm-third portion of the historical distribution for April 2000 while seven states ranked within the top ten warm. Specific rankings include: Nevada - 2nd warmest Arizona - 3rd warmest New Mexico - 6th warmest Utah - 6th warmest Six states, all in the southeast, ranked within the cool-third of the historical distribution.

It was the driest April on record for Missouri. Seven other states ranked within the dry-third portion of the distribution. It was the sixth wettest April on record for Vermont and the seventh wettest April since 1895 for New York. Thirteen other states ranked within the wet third portion of the distribution.

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January-April 2000 Statewide Ranks

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Forty-five states ranked within the warm-third portion of the historical distribution for January-April 2000 while twenty-two states ranked within the top ten warm. It was the second warmest such year-to-date on record for New Mexico and Texas. Other rankings include: Idaho - 3rd warmest Iowa - 3rd warmest Nevada - 3rd warmest Oklahoma - 3rd warmest Utah - 3rd warmest No state ranked within the cool-third of the historical distribution.

January-April 2000 was the eighth driest such period on record for Louisiana. Eleven other states ranked within the dry-third portion of the distribution. It was the ninth wettest January-April on record for Wyoming and the tenth wettest January-April on record for New York. Sixteen other states ranked within the wet-third portion of the distribution.

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Palmer Drought Indices

The Palmer Z Index shows how monthly moisture conditions depart from normal (short-term drought and wetness). The April 2000 pattern shows areas of extremely dry conditions centered over Missouri and Iowa, and over the Desert Southwest and Great Basin. Other areas with moisture deficits in April include parts of the Southeast, Gulf Coast, and parts of southern Texas to the Northern Rockies. Unusually wet conditions were centered over western South Dakota and stretched from the Northeast through the Tennessee Valley to parts of the Lower Mississippi Valley.

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The animated maps show the geographical pattern of the moisture anomalies for the last 12 months. On these maps, the red shading denotes dry conditions while the green shading indicates wet conditions.

The Palmer Drought Index maps show long-term (cumulative) drought and wet spell conditions. By the end of April 2000, long-term drought continued across the southern tier states from southern California to the Southeast, then northward up the Mississippi Valley to the Ohio Valley, Great Lakes, and central Plains. Patchy long-term wet conditions were found in the Northeast and across parts of the central and northern Plains into the Rockies.

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The animated maps show how the geographical pattern of the long-term moisture conditions has changed over the last 12 months. On these maps, the red shading denotes drought conditions while the green shading indicates wet conditions.

The Primary Corn and Soybean Belt Precipitation Deficit

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Nine of the last ten months have averaged drier than normal over much of the Primary Corn and Soybean agricultural belt. March-April 2000, the growing season to-date, was the 20th driest such period since 1895. Enough precipitation fell during March and April, and the wetter-than-normal February, to moisten the top layers of the soil, but persistently dry conditions from summer 1999 into winter 1999-2000 (see graph) have depleted the moisture in lower soil layers. August 1999-April 2000 ranked as the sixth driest August-April on record, and July 1999-April 2000 ranked as the seventh driest such ten-month period since 1895.

This recent persistent dryness has brought a shift in long-term Palmer drought conditions from moderate wet spell as recently as July 1999 to severe drought beginning in January 2000 for the agricultural belt as a whole. The severity of the April 2000 Palmer index rivals that of the 1970's and 1980's droughts, although those earlier droughts were of longer duration. The growing season for the Primary Corn and Soybean Belt runs from March through September.

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Preliminary streamflow measurements by the United States Geological Survey can be found at the United States Geological Survey's web page.

Current and historical drought information can be found at the Web Page for the National Drought Mitigation Center. The Center monitors current droughts both in the United States and worldwide. Damage due to the drought has been summarized by NOAA and the Office of Global Programs in the Climatological Impacts section of the Climate Information Project. Crop impact information can be found at the USDA NASS (National Agricultural Statistics Service) and Weekly Weather and Crop Bulletin pages. Drought statements by local National Weather Service Offices can be found at the NWS Hydrologic Information Center. Drought threat assessments and other information can be found at NOAA's Drought Information Center.

For more information, refer to ...

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.

NOAA's National Climatic Data Center is the world's largest active archive of weather data. The preliminary temperature and precipitation rankings are available from the center by calling: 828-271-4800.

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

NOAA works closely with the academic and science communities on climate-related research projects to increase the understanding of El Niño and improve forecasting techniques. NOAA's Climate Prediction Center monitors, analyzes and predicts climate events ranging from weeks to seasons for the nation. NOAA also operates the network of data buoys and satellites that provide vital information about the ocean waters, and initiates research projects to improve future climate forecasts. The long lead climate outlooks are available from the Climate Prediction Center.

For all climate questions other than questions concerning this report, please contact the National Climatic Data Center's Climate Services Division:

Climate Services Division
NOAA/National Climatic Data Center
151 Patton Avenue
Asheville, NC 28801-5001
fax: 828-271-4876
phone: 828-271-4800
email: ncdc.orders@noaa.gov

William Brown
NOAA/National Climatic Data Center
151 Patton Avenue
Asheville, NC 28801-5001
fax: 828-271-4328
email: william.brown@noaa.gov

Mike Changery
NOAA/National Climatic Data Center
151 Patton Avenue
Asheville, NC 28801-5001
fax: 828-271-4328
email: mchangry@ncdc.noaa.gov

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