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 the May Climate can be found at the respective Web Pages of the Southern Regional Climate Center, Western Regional Climate Center, Midwest Regional Climate Center or the Southeast Regional Climate Center.

Additional information concerning drought conditions in portions of Georgia can be found at the University of Georgia's Cooperative Extension Service Web Page.

Additional 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.

Table 1 shows precipitation and temperature ranks for each of the 9 regions and the nation for May 1999, the two-month period of April-May 1999, the six months of December 1998-May 1999, and the past 12 months, June 1998-May 1999.

                          MAY    APR-MAY   DEC 1998-  JUN 1998-
      REGION              1999     1999    MAY 1999   MAY 1999
      ------              ----  ---------  ---------  ---------

                PRECIPITATION:

     NORTHEAST             17        8         38         33
     EAST NORTH CENTRAL    86       99         91         83
     CENTRAL               29       42         56         74

     SOUTHEAST             20       11         20         10
     WEST NORTH CENTRAL    76       88         74        102
     SOUTH                 41       37         56         67

     SOUTHWEST             38       86         21         56
     NORTHWEST             52       18         95         95
     WEST                  24       51         28         50

     NATIONAL              30       43         44         74

                TEMPERATURE:

     NORTHEAST             85       87         97         97
     EAST NORTH CENTRAL    84       91        101        102
     CENTRAL               63       87         98        100

     SOUTHEAST             34       78         88        101
     WEST NORTH CENTRAL    55       44         98        100
     SOUTH                 62       80        101        104

     SOUTHWEST             42       24         98        101
     NORTHWEST             26       20         59         92
     WEST                  56       33         48         51

     NATIONAL              57       61        101        103

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 May, the 1961-1990 normal, and the May 1999 value for each of the 9 regions and the contiguous U.S. for precipitation and temperature.

                               PRECIPITATION (INCHES)
                             DRIEST     WETTEST   NORMAL  1999
         REGION            VALUE YEAR VALUE YEAR   PCPN   PCPN
         ------            ---------- ----------  ------ ------

        NORTHEAST           0.98 1903  7.25 1984   3.79   2.39
        EAST NORTH CENTRAL  1.15 1934  6.23 1908   3.29   4.48
        CENTRAL             1.65 1934  8.03 1995   4.47   3.45

        SOUTHEAST           0.97 1941  7.61 1976   4.21   2.74
        WEST NORTH CENTRAL  0.65 1934  4.63 1962   2.57   2.82
        SOUTH               1.53 1998  7.33 1935   4.17   3.62

        SOUTHWEST           0.19 1974  2.31 1992   1.01   0.87
        NORTHWEST           0.30 1924  4.19 1998   1.79   1.79
        WEST                0.07 1924  2.75 1915   0.73   0.41

        NATIONAL            1.78 1934  4.15 1957   2.91   2.57*

                            * PRELIMINARY VALUE, CONFIDENCE
                              INTERVAL + OR - 0.32 INCHES

                               TEMPERATURE (DEGREES F)
                             COLDEST    WARMEST   NORMAL  1999
         REGION            VALUE YEAR VALUE YEAR   TEMP   TEMP
         ------            ---------- ----------  ------ ------

        NORTHEAST           48.7 1917  61.7 1911   55.5   58.0
        EAST NORTH CENTRAL  46.8 1907  63.7 1977   56.0   58.6
        CENTRAL             56.7 1917  69.8 1962   62.8   63.9

        SOUTHEAST           65.9 1917  74.4 1896   69.3   69.0
        WEST NORTH CENTRAL  47.2 1907  62.6 1934   53.7   53.2
        SOUTH               65.1 1907  75.3 1896   70.2   70.6

        SOUTHWEST           51.7 1917  64.3 1934   58.8   58.5
        NORTHWEST           47.7 1896  58.5 1958   52.3   50.6
        WEST                53.5 1977  65.6 1992   59.6   59.7

        NATIONAL            55.7 1917  65.1 1934   60.7   60.9*

                            * PRELIMINARY VALUE, CONFIDENCE
                              INTERVAL + OR - 0.3 DEG. F.

Table 3 shows statistics for selected river basins: Precipitation rankings are for the hydrologic year-to-date, October-May 1998-1999, where 1 = driest, and 104 = wettest, based on the period 1895 to 1999. 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.

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

    MISSOURI BASIN                    103          0.0%   44.5%
    PACIFIC NORTHWEST BASIN            99          0.0%   18.3%
    CALIFORNIA RIVER BASIN             44          0.0%    6.7%

    GREAT BASIN                        38          0.8%    6.7%
    UPPER COLORADO BASIN               49          0.0%    0.0%
    LOWER COLORADO BASIN               22         38.8%    0.0%
    RIO GRANDE BASIN                   64         18.4%    0.0%

    ARKANSAS-WHITE-RED BASIN          101          0.0%   29.5%
    TEXAS GULF COAST BASIN             73          0.0%    0.0%
    SOURIS-RED-RAINY BASIN            103          0.0%   73.8%
    UPPER MISSISSIPPI BASIN            93          0.0%   16.0%

    LOWER MISSISSIPPI BASIN            44          7.7%    0.0%
    GREAT LAKES BASIN                  44          0.0%    0.0%
    OHIO RIVER BASIN                   37          0.0%    0.0%
    TENNESSEE RIVER BASIN              51          0.0%    0.0%

    NEW ENGLAND BASIN                  37          1.2%    0.0%
    MID-ATLANTIC BASIN                 15         25.7%    0.0%
    SOUTH ATLANTIC-GULF BASIN          13         24.4%    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 the year-to-date, January-May 1999, based on the period 1895-1999. 1 = DRIEST/COLDEST, 105 = WETTEST/HOTTEST.

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

        NORTHEAST                   60             94
        EAST NORTH CENTRAL          97             99
        CENTRAL                     57             82

        SOUTHEAST                   21             74
        WEST NORTH CENTRAL          77             98
        SOUTH                       58            100

        SOUTHWEST                   32            100
        NORTHWEST                   87             70
        WEST                        46             59

        NATIONAL                    54             97

Table 5 shows historical extremes for January-May, the 1961-1990 normal, and the January-May 1999 value for each of the 9 regions and the contiguous U.S. for precipitation and temperature.

                               PRECIPITATION (INCHES)
                             DRIEST     WETTEST   NORMAL  1999
         REGION            VALUE YEAR VALUE YEAR   PCPN   PCPN
         ------            ---------- ----------  ------ ------

        NORTHEAST          10.16 1941 22.11 1979  15.84  16.44
        EAST NORTH CENTRAL  5.06 1934 13.41 1938   9.87  12.08
        CENTRAL            10.36 1941 24.67 1927  17.50  18.48

        SOUTHEAST          12.34 1898 28.00 1998  20.76  16.18
        WEST NORTH CENTRAL  3.06 1934  8.80 1927   6.37   6.91
        SOUTH               8.85 1963 21.44 1957  14.37  14.64

        SOUTHWEST           1.71 1972 10.16 1905   4.48   3.89
        NORTHWEST           7.37 1924 18.07 1953  13.14  15.21
        WEST                4.32 1972 19.31 1998   9.03   8.95

        NATIONAL            9.04 1934 14.59 1983  11.81  11.91

                               TEMPERATURE (DEGREES F)
                             COLDEST    WARMEST   NORMAL  1999
         REGION            VALUE YEAR VALUE YEAR   TEMP   TEMP
         ------            ---------- ----------  ------ ------

        NORTHEAST           32.3 1904  40.9 1998   35.5   37.6
        EAST NORTH CENTRAL  26.5 1979  39.0 1987   32.1   35.6
        CENTRAL             38.8 1978  49.0 1921   43.9   46.1

        SOUTHEAST           52.3 1940  59.3 1974   55.5   57.3
        WEST NORTH CENTRAL  27.4 1899  39.4 1992   33.3   36.4
        SOUTH               51.3 1978  58.2 1911   54.5   57.4

        SOUTHWEST           38.6 1917  48.3 1934   43.5   46.0
        NORTHWEST           35.0 1922  46.2 1934   39.6   40.0
        WEST                43.5 1933  53.1 1934   47.8   47.8

        NATIONAL            40.8 1979  46.9 1986   43.8   46.0

May 1999 Precipitation

Based upon preliminary data, May 1999 was the 30th wettest such month since 1895 for the West-North Central Region. This region includes Montana, Nebraska, North Dakota, South Dakota, and Wyoming.

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January-May 1999 Temperature and Precipitation

The year-to-date, January-May 1999, was the 6th warmest January-May period on record for the Southwest Region. January-May 1999 was the 11th consecutive such five-month period of above-normal temperatures.

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Preliminary data for the West Region ranked January-May 1999 near the long-term mean.

January-May 1999 was the 9th wettest January-May on record for the East-North Central Region. The same five-month period during 1998 was equally as wet.

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Preliminary data ranked January-May 1999 as the 21st driest January-May on record for the Southeast Region. The same five-month period during 1998 was the wettest on record.

Preliminary data indicate that precipitation averaged across the Primary Corn and Soybean agricultural belt was near the long term mean for the first three months of the six-month growing season.

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May 1999 Statewide Temperature and Precipitation

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Based upon preliminary data, May 1999 was the sixth warmest May since 1895 for Maine, the only state in the top ten warm portion of the distribution. Fourteen other states ranked within the warm third of the distribution including the fourteenth warmest May on record for Rhode Island and the sixteenth warmest May since 1895 for Vermont. No state ranked within the top ten cool portion of the historical distribution and only six states ranked within the cool third.

Three states ranked within the top ten dry portion of the historical distribution for May 1999. Maryland - 5th driest Ohio - 9th driest South Carolina - 9th driest May 1999 was the eighth wettest May on record for North Dakota, the only state within the top ten wet portion of the distribution.

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January-May 1999 Statewide Temperature and Precipitation

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Thirteen states were within the top ten warm portion of the distribution for temperature for the year-to-date. Some January-May 1999 ranks include: Texas - 5th warmest Wisconsin - 5th warmest Colorado - 6th warmest Minnesota - 6th warmest Rhode Island - 6th warmest Only California (29th coolest) ranked within the cool-third portion of the historical distribution.

There were two states within the top ten dry portion of the distribution and three states within the top ten wet portion of the historical distribution. Arizona - 8th driest Georgia - 10th driest Wisconsin - 5th wettest Rhode Island - 10th wettest Washington - 10th wettest

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It should be emphasized that all of the temperature and precipitation ranks on these maps are based on preliminary data. The ranks will change when the final data are processed.

DROUGHT WATCH:

Eastern U.S. Precipitation Deficit

Severe drought intensified in the Southeastern U.S. during the spring months. Precipitation over the South Atlantic river basin (which covers the area from eastern Mississippi to North Carolina and Florida) was below normal for 10 of the last 13 months, with February through May being persistently dry. Based on preliminary data, Feb-May 1999 ranked as the fourth driest such 4-month period since 1895.

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The mid-Atlantic region experienced rapidly deteriorating conditions this spring. Based on preliminary data, the three states in the Chesapeake Bay area (Maryland, Virginia, and Delaware) had the 12th driest April-May on record in 1999. A wet winter brought temporary relief, and resulted in the year-to-date (January-May) ranking only 39th driest since 1895. But in the broader picture, this region has been suffering from drought since last summer. Eight of the last 11 months have been drier than normal, with July 1998-May 1999 ranking as the second driest July-May on record. This follows the wettest July-May (1997-98) in this region.

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Northern California Precipitation Deficit

Northern California experienced progressively drier conditions this spring. Preliminary data averaged across the northern third of California indicate that March-May 1999 was the 39th driest spring in the 105-year record, April-May 1999 was the 28th driest such two-month period, and May 1999 was the 16th driest May on record. May 1999 had only a third of the normal May precipitation, resulting in an early start to the normally dry summer season.

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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 at: http://nic.fb4.noaa.gov/products/analysis_monitoring/regional_monitoring/usa.html.

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 on the Internet at: http://nic.fb4.noaa.gov.

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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