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National Oceanic and Atmospheric Administration Climate of 1999 - April U.S. Regional and Statewide Analyses National Climatic Data Center, 14 May, 1999

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April 1999: Climate Overview Detailed Climate Perspectives . . . Global Analysis Global Regional Analyses U.S. National Analysis U.S. Regional/Statewide Analyses Extreme Events 1999 Monthly Reports

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 April Climate can be found at the respective Web Pages of the Southern Regional Climate Center and the Western 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 April 1999, the two-month period of March-April 1999, the six months of November 1998-April 1999, and the past 12 months, May 1998-April 1999.

                  PRECIPITATION AND TEMPERATURE RANKS, BASED
                  ON THE PERIOD 1895-1999.  1 = DRIEST/COLDEST,
                  105 = WETTEST/WARMEST FOR APRIL 1999,
                  105 = WETTEST/WARMEST FOR MAR-APR 1999,
                  104 = WETTEST/WARMEST FOR NOV 1998-APR 1999,
                  104 = WETTEST/WARMEST FOR MAY 1998-APR 1999.

                    	     APR    MAR-APR   NOV 1998-  MAY 1998-
         REGION              1999     1999    APR 1999   APR 1999
         ------              ----  ---------  ---------  ---------

                   PRECIPITATION:

        NORTHEAST              7       21         20         43
        EAST NORTH CENTRAL    96       63         65         74
        CENTRAL               69       47         61         81

        SOUTHEAST             17       10         22         12
        WEST NORTH CENTRAL    91       82         93        101
        SOUTH                 56       67         65         46

        SOUTHWEST             98       68         31         51
        NORTHWEST             14       12        101        101
        WEST                  74       45         44         70

        NATIONAL              63       37         60         71

                   TEMPERATURE:

        NORTHEAST             68       65         95        102
        EAST NORTH CENTRAL    83       89        100        104
        CENTRAL               89       61         99        101

        SOUTHEAST             93       54         98        103
        WEST NORTH CENTRAL    48       85        100        101
        SOUTH                 85       72        104        104

        SOUTHWEST             16       62         98        101
        NORTHWEST             25       35         77         93
        WEST                  15       31         49         38

        NATIONAL              60       72        104        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 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           1.40 1896  6.81 1983   3.42   1.99
           EAST NORTH CENTRAL  1.04 1946  4.84 1896   2.63   3.68
           CENTRAL             1.55 1915  6.82 1927   3.95   4.30

           SOUTHEAST           0.85 1986  7.06 1928   3.52   2.32
           WEST NORTH CENTRAL  0.48 1926  2.83 1984   1.62   2.22
           SOUTH               1.08 1987  6.92 1957   2.98   3.15

           SOUTHWEST           0.26 1989  2.58 1900   0.83   1.64
           NORTHWEST           0.61 1977  3.81 1937   1.97   1.06
           WEST                0.14 1909  3.25 1967   1.22   1.47

           NATIONAL            1.41 1987  3.56 1957   2.38   2.49*

                               * PRELIMINARY VALUE, CONFIDENCE
                                 INTERVAL + OR - 0.23 INCHES

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

           NORTHEAST           38.8 1943  50.4 1921   44.4   45.3
           EAST NORTH CENTRAL  35.7 1950  51.8 1915   44.0   46.5
           CENTRAL             45.4 1907  59.5 1896   53.4   56.0

           SOUTHEAST           56.6 1901  66.6 1954   62.1   65.0
           WEST NORTH CENTRAL  34.5 1920  49.5 1915   43.0   42.2
           SOUTH               57.2 1983  67.4 1925   62.7   64.4

           SOUTHWEST           44.4 1920  55.6 1989   49.9   47.2
           NORTHWEST           39.7 1975  52.6 1934   44.9   43.5
           WEST                43.3 1967  58.5 1934   51.9   49.5

           NATIONAL            47.4 1975  55.7 1981   51.7   52.0*

                               * PRELIMINARY VALUE, CONFIDENCE
                                 INTERVAL + OR - 0.2 DEG. F.

Table 3 shows statistics for selected river basins: Precipitation rankings are for the hydrologic year-to-date, October-April 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                    104          0.0%   44.5%
       PACIFIC NORTHWEST BASIN            97          0.0%   14.0%
       CALIFORNIA RIVER BASIN             44          0.0%    6.7%

       GREAT BASIN                        41          0.0%    6.7%
       UPPER COLORADO BASIN               50          0.0%    0.0%
       LOWER COLORADO BASIN               21         28.7%    0.0%
       RIO GRANDE BASIN                   67          0.0%    0.0%

       ARKANSAS-WHITE-RED BASIN          101          0.0%   37.5%
       TEXAS GULF COAST BASIN             78          0.0%    0.0%
       SOURIS-RED-RAINY BASIN            104          0.0%   23.1%
       UPPER MISSISSIPPI BASIN            95          0.0%    7.1%

       LOWER MISSISSIPPI BASIN            53          7.7%    0.0%
       GREAT LAKES BASIN                  40          0.0%    0.0%
       OHIO RIVER BASIN                   49          0.0%    0.0%
       TENNESSEE RIVER BASIN              51          0.0%    0.0%

       NEW ENGLAND BASIN                  35          0.0%    0.0%
       MID-ATLANTIC BASIN                 17         22.8%    0.0%
       SOUTH ATLANTIC-GULF BASIN          16         18.0%    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-April 1999, based on the period 1895-1999. 1 = DRIEST/COLDEST, 105 = WETTEST/HOTTEST.

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

           NORTHEAST                   69             81
           EAST NORTH CENTRAL          81             96
           CENTRAL                     72             85

           SOUTHEAST                   26             77
           WEST NORTH CENTRAL          83             97
           SOUTH                       56             98

           SOUTHWEST                   30            100
           NORTHWEST                   84             78
           WEST                        52             54

           NATIONAL                    59             99

Table 5 shows historical extremes for January-April, the 1961-1990 normal, and the January-April 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           7.92 1941 17.31 1936  12.05  13.29
           EAST NORTH CENTRAL  3.66 1958  9.30 1951   6.58   7.47
           CENTRAL             8.13 1941 19.95 1950  13.03  14.86

           SOUTHEAST           9.59 1916 24.75 1998  16.55  13.38
           WEST NORTH CENTRAL  2.14 1926  5.11 1896   3.80   4.17
           SOUTH               5.91 1936 16.78 1973  10.20  10.68

           SOUTHWEST           1.12 1972  9.14 1905   3.47   2.94
           NORTHWEST           5.95 1977 16.43 1904  11.35  13.14
           WEST                3.44 1977 17.01 1995   8.30   8.49

           NATIONAL            7.03 1910 12.02 1998   8.90   9.17

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

           NORTHEAST           25.6 1904  36.0 1998   30.6   32.5
           EAST NORTH CENTRAL  19.0 1936  33.7 1987   26.1   29.9
           CENTRAL             33.2 1978  45.2 1921   39.2   41.8

           SOUTHEAST           48.2 1978  56.5 1974   52.0   54.3
           WEST NORTH CENTRAL  21.0 1936  35.1 1992   28.2   32.2
           SOUTH               46.4 1978  54.9 1911   50.5   54.2

           SOUTHWEST           35.3 1917  44.7 1986   39.7   42.7
           NORTHWEST           30.8 1922  43.4 1934   36.4   37.3
           WEST                39.7 1937  50.4 1934   44.8   44.8

           NATIONAL            36.1 1979  43.2 1986   39.6   42.3

April 1999 Regional Temperature and Precipitation

Preliminary data ranked April 1999 as the 13th warmest April on record for the Southeast Region. The region was dominated by high pressure during a good portion of the month which allowed for abundant sunshine and above normal temperatures.

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Preliminary data ranked April 1999 as the 15th coolest April on record for the West Region. A predominant onshore flow and several upper-level troughs, which moved through central and southern California, allowed for cooler than normal conditions.

Based upon preliminary data, April 1999 was the 8th wettest April on record for the Southwest Region. Several upper-level closed lows migrated across the region from the Pacific providing some much needed precipitation for the region.

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April 1999 was the 7th driest April since 1895 for the Northeast Region, based upon preliminary data. A predominant east coast ridge kept most precipitation events to the west of the region.

January-April 1999 Temperature and Precipitation

The year-to-date, January-April 1999, was the 8th warmest January-April period on record for the South Region.

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Preliminary data ranked January-April 1999 as the 52nd warmest January-April on record for the West Region. The last two such four-month periods have averaged near normal while the prior four such four-month periods were much warmer than normal.

January-April 1999 was the 22nd wettest January-April on record for the Northwest Region. The last five such four-month periods have averaged much wetter than normal.

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Preliminary data ranked January-April 1999 as the 30th driest January-April on record for the Southwest Region. For the January through March period, most precipitation events moved north of the region. It was during April that the predominant storm track moved far enough south to bring much-need precipitation to the region.

Preliminary data indicate that precipitation averaged across the Primary Corn and Soybean agricultural belt was above normal for the first two months of the six-month growing season and ranked as the 38th wettest such March-April period on record.

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April 1999 Statewide Temperature and Precipitation

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Based upon preliminary data, April 1999 was the fifth warmest such month on record for Louisiana, ninth warmest April on record for Alabama, and the tenth warmest April since 1895 for Florida, Mississippi, and Tennessee. Twenty-two other states ranked within the warm-third portion of the distribution. No state was within the top-ten cool portion of the distribution while ten states ranked within the cool-third.

Based upon preliminary data, April 1999 was the third wettest such month on record for Iowa, Kansas, and Wyoming. It was the fourth wettest April since 1895 for Utah, the sixth wettest for Colorado, the ninth wettest for Wisconsin, and the tenth wettest April on record for Nebraska. Eleven other states ranked within the wet third of the distribution. April 1999 was the driest such month on record for Maine and Massachusetts and the second driest April on record for New Hampshire and Vermont. April was the third driest such month on record for Connecticut, the fifth driest for New York, the eighth driest for Georgia, and the tenth driest April since 1895 for Alabama. Fourteen other states ranked within the dry third of the distribution.

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January-April 1999 Statewide Temperature and Precipitation

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Fourteen states ranked within the top-ten warm portion of the distribution for the year-to-date, January-April 1999. The year-to-date was the third warmest such period on record for New Mexico and the fifth warmest such period on record for Colorado and Texas. Thirty-one other states ranked within the warm-third portion of the distribution. Only California ranked within the cool-third of the distribution.

Kansas, with a rank of ninth wettest, was the only state within the top-ten wet portion of the distribution for the four-month period, January-April 1999. Nineteen other states ranked within the wet-third of the distribution. Arizona, with a rank of eighth driest, was the only state within the top-ten dry portion of the distribution for the same four-month period. Four other states ranked within the dry-third of the distribution.

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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.

Southeast Region Precipitation Deficit

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Moderate to severe long-term drought plagued the Southeast Region during April, a situation which has been developing over the past year. Ten of the last sixteen months have averaged below normal for precipitation and, in fact, precipitation has averaged below normal for ten of the last 12 months. The Southeast Region covers Virginia to Alabama.

Based upon preliminary data, February-April 1999 was the seventh driest such period on record for the Southeast Region. The third wettest such three-month period since 1895 occurred just last year. February-April 1998 had abundant rainfall, a signature of El Niño conditions.

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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 or on the World Wide Web at: http:/www.ncdc.noaa.gov/ol/documentlibrary/cvb.html

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

NCDC / Climate Research / Climate of 1999 / April / U.S. Regional/Statewide / Search / Help