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National Oceanic and Atmospheric Administration

Climate of 1999
U.S. Regional and Statewide Analyses

Includes December Summary
and Drought Update

National Climatic Data Center, 12 January 2000

Standard Regions for Temperature and Precipitation
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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.

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Top of Page Annual 1999 Temperature and Precipitation

Table 1 shows historical extremes for January-December, the 1961-1990 normal, and the Annual 1999 value for each of the 9 regions and the contiguous U.S. for precipitation and temperature. It should be noted that the 1999 values may change when the final data are processed.

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

      NORTHEAST          31.77 1930 53.79 1996  41.63  41.89
      EAST NORTH CENTRAL 19.81 1910 36.63 1951  30.50  31.81
      CENTRAL            30.56 1930 53.38 1990  43.05  37.54

      SOUTHEAST          37.56 1954 62.39 1929  51.03  47.12
      WEST NORTH CENTRAL 11.49 1934 22.86 1915  16.92  18.06
      SOUTH              23.40 1917 46.91 1973  35.72  31.64

      SOUTHWEST           7.68 1956 22.10 1941  13.64  13.68
      NORTHWEST          19.00 1929 37.30 1996  27.50  27.41
      WEST                9.97 1947 31.47 1983  16.51  12.83

      NATIONAL           25.98 1917 37.69 1983  29.46  29.93*


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

      NORTHEAST           43.1 1904  49.4 1998   46.1   48.3
      EAST NORTH CENTRAL  39.5 1917  48.0 1931   43.5   46.2
      CENTRAL             50.6 1917  56.9 1921   53.2   55.1

      SOUTHEAST           61.0 1901  65.0 1921   62.4   63.6
      WEST NORTH CENTRAL  39.9 1916  46.7 1934   43.3   45.9
      SOUTH               60.4 1979  64.9 1921   62.0   64.0

      SOUTHWEST           49.5 1912  54.6 1934   51.8   53.6
      NORTHWEST           44.1 1955  50.2 1934   46.7   47.5
      WEST                53.1 1911  57.8 1934   55.0   55.6

      NATIONAL            50.1 1917  56.4 1998   52.4   56.0*

*U.S. national 1999 value and extremes for January-December are based on U.S. HCN data.
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Based upon preliminary data, January-December 1999 was the 17th driest year on record for the Central Region. This was the first year of significantly drier than normal conditions since 1988. Dry Region - Annual
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Based upon preliminary data, January-December 1999 was the fifth warmest year on record for the East-North Central Region. Just last year, the region had the second warmest year on record. These two years mark the first two years of much above normal temperature since 1987, the third warmest year on record. Warm Region - Annual
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Jan-Dec Tmp Map
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Twenty-five states ranked within the top ten warm portion of the historical distribution for January-December 1999 including:
Rhode Island - 2nd warmest Maine - 3rd warmest Montana - 3rd warmest

Forty-six of the contiguous 48 states ranked within the warm-third portion of the historical distribution for 1999. No state ranked within the cool third portion of the distribution.

January-December 1999 was the sixth driest year on record for Georgia and the tenth driest year on record for Kentucky. Fifteen other states ranked within the dry-third portion of the distribution. No state ranked within the top ten wet portion of the historical distribution while 16 ranked within the wet third portion.
Jan-Dec Pcp Map
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Top of Page December 1999 Temperature and Precipitation

Table 1 shows precipitation and temperature ranks for each of the 9 regions and the nation for December 1999, the two-month period of November-December 1999, the six months of July-December 1999, and the past 12 months, January-December 1999.

             PRECIPITATION AND TEMPERATURE RANKS, BASED
             ON THE PERIOD 1895-1999.  1 = DRIEST/COLDEST,
             105 = WETTEST/WARMEST FOR DEC 1999,
             105 = WETTEST/WARMEST FOR NOV-DEC 1999,
             105 = WETTEST/WARMEST FOR JUL-DEC 1999,
             105 = WETTEST/WARMEST FOR JAN-DEC 1999.

                        DEC    NOV-DEC    JUL-DEC    JAN-DEC
    REGION              1999     1999       1999       1999
    ------              ----  ---------  ---------  ---------

              PRECIPITATION:

   NORTHEAST             23       18         71         66
   EAST NORTH CENTRAL    25        9         44         76
   CENTRAL               52       21          5         17

   SOUTHEAST             14       13         41         32
   WEST NORTH CENTRAL    60       47         46         78
   SOUTH                 43        7          5         22

   SOUTHWEST             12        2         55         60
   NORTHWEST             43       49         33         59
   WEST                   3        9          7         21

   NATIONAL              15        4          7         22*

              TEMPERATURE:

   NORTHEAST             91      100        100         98
   EAST NORTH CENTRAL    91      103         98        101
   CENTRAL               79      102         93         92

   SOUTHEAST             67       82         79         82
   WEST NORTH CENTRAL   104      105        102        101
   SOUTH                 78      101         96         99

   SOUTHWEST             72       96         91        100
   NORTHWEST             79      102         93         82
   WEST                  76       95         91         80

   NATIONAL              95      105        101         99**
* U.S. National precipitation rank for January-December 1999 of 22 (22nd driest) is based on U.S. HCN data for the period 1900-1999.

**U.S. National temperature rank for January-December 1999 of 99 (2nd warmest) is based on U.S. HCN data for the period 1900-1999.

It should be emphasized that all of the temperature and precipitation ranks in Tables 1 through 3 are based on preliminary data. The ranks may change when the final data are processed.

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Table 2 shows historical extremes for December, the 1961-1990 normal, and the December 1999 value for each of the 9 regions and the contiguous U.S. for precipitation and temperature. It should be noted that the 1999 values may change when the final data are processed.

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

      NORTHEAST           0.98 1955  6.74 1973   3.45   2.21
      EAST NORTH CENTRAL  0.37 1943  2.62 1982   1.44   0.88
      CENTRAL             0.90 1958  7.58 1990   3.44   3.00

      SOUTHEAST           1.18 1955  7.05 1953   3.87   2.18
      WEST NORTH CENTRAL  0.19 1986  1.20 1917   0.65   0.66
      SOUTH               0.64 1917  5.51 1911   2.49   2.22

      SOUTHWEST           0.11 1929  2.29 1965   0.96   0.32
      NORTHWEST           1.17 1976  8.42 1996   4.03   3.38
      WEST                0.09 1989  7.05 1955   2.33   0.38

      NATIONAL            1.22 1958  3.60 1982   2.30   1.60*

                          * PRELIMINARY VALUE, CONFIDENCE
                            INTERVAL + OR - 0.09 INCHES

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

      NORTHEAST           13.3 1989  34.5 1923   26.6   30.8
      EAST NORTH CENTRAL   6.9 1983  29.0 1923   18.6   25.2
      CENTRAL             21.9 1989  42.0 1923   33.0   36.3

      SOUTHEAST           39.3 1989  55.9 1931   47.3   48.3
      WEST NORTH CENTRAL   4.3 1983  30.0 1939   19.4   28.9
      SOUTH               33.6 1983  51.0 1933   43.5   46.2

      SOUTHWEST           24.8 1909  39.9 1980   32.6   34.2
      NORTHWEST           21.9 1990  37.9 1917   29.4   32.5
      WEST                33.0 1990  45.6 1929   38.7   40.9

      NATIONAL            25.8 1983  38.4 1939   32.8   36.7*

                          *PRELIMINARY VALUE, CONFIDENCE
                           INTERVAL + OR - 0.1 DEG. F.

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Table 3 shows statistics for selected river basins: Precipitation rankings are for October-December 1999, where 1 = driest, and 105 = 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, as of December 1999.

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

  MISSOURI BASIN                      9          1.4%   16.3%
  PACIFIC NORTHWEST BASIN            48          0.0%    0.6%
  CALIFORNIA RIVER BASIN             13         37.6%    0.0%

  GREAT BASIN                         1         32.0%    0.0%
  UPPER COLORADO BASIN                2          0.0%    0.0%
  LOWER COLORADO BASIN                1         14.2%    0.0%
  RIO GRANDE BASIN                    3         36.2%    0.0%

  ARKANSAS-WHITE-RED BASIN           28          0.0%   16.3%
  TEXAS GULF COAST BASIN              8          9.3%    0.0%
  SOURIS-RED-RAINY BASIN              2          0.0%   16.9%
  UPPER MISSISSIPPI BASIN             7         20.4%    0.0%

  LOWER MISSISSIPPI BASIN             9         35.6%    0.0%
  GREAT LAKES BASIN                  16         25.2%    0.0%
  OHIO RIVER BASIN                   25         70.7%    0.0%
  TENNESSEE RIVER BASIN              11         39.6%    0.0%

  NEW ENGLAND BASIN                  23          0.0%    0.0%
  MID-ATLANTIC BASIN                 19          6.8%    0.0%
  SOUTH ATLANTIC-GULF BASIN          30          2.6%    0.0%


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

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Based upon preliminary data, December 1999 was the second warmest December on record for the West-North Central Region. High pressure dominated the region and kept cool air north of the Canadian border. Warm Region - December
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Wheat Belt - Oct-Dec
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Preliminary December precipitation data for the Primary Hard Red Winter Wheat Belt indicate that the five-month growing season to-date continued the trend of being drier than normal. The October-December 1999 period was the 20th driest such growing season to-date since 1895. The growing season runs through February.
December Tmp Map
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Eight states ranked within the top ten warm portion of the historical distribution for December 1999 including the warmest December since 1895 for Montana. Other ranks included:
North Dakota - third warmest South Dakota - fourth warmest Minnesota - seventh warmest

No state ranked within the cool third portion of the distribution.

December 1999 was the ninth wettest such month on record for Wyoming. Seven other states ranked within the wet-third portion of the historical distribution. Six states ranked within the top ten dry portion of the distribution including:
Arizona - driest Nevada - second driest California - third driest North Carolina - eighth driest Minnesota - ninth driest North Dakota - tenth driest

Twenty-five other states ranked within the dry-third of the distribution.

December Pcp Map
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Top of Page The Tropics: A Historical Perspective

The official 1999 Atlantic hurricane season ended on November 30th. It was an active one. There were 16 defined tropical systems during the six-month season including 12 named storms. The season produced eight hurricanes of which five were considered major hurricanes of category 3 or greater on the Saffir-Simpson hurricane scale.

Three hurricanes made a direct impact on the U.S. mainland. Hurricane Bret, the first category 4 storm to hit the U.S. since Andrew in 1992, made landfall along the south Texas coast on August 22nd with maximum winds of 140 mph. Hurricane Floyd, with maximum winds of 110 mph at landfall, moved onshore into eastern North Carolina on September 16th causing unprecedented flooding and more than 60 fatalities. And, Hurricane Irene, with maximum winds of 75 mph, struck south Florida on October 15th.

Additionally, two tropical storms made landfall along the U.S. coast during 1999. Tropical storm Dennis, with maximum winds of 70 mph, hit eastern North Carolina on September 4th bringing widespread flooding, and tropical storm Harvey, with maximum winds of 50 mph, moved across southwest Florida on September 21st.
1999 North Atlantic Tropical Cyclone Activity
Period Named Storms Hurricanes Major Hurricanes U.S. landfalling Hurricanes
1999 12 8 5 3
Normal 10 6 3 2

A normal season would include ten named storms providing six hurricanes. Three of these six hurricanes would become major hurricanes. Based on climatology, two hurricanes can be expected to hit the U.S. mainland in any given year.
Based on data from the National Weather Service National Hurricane Center, a total of 12 hurricanes and tropical storms developed in the North Atlantic basin during 1999. This is above the long-term mean of about 10 hurricanes and tropical storms. 1886-1999 Names Storms
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For a preliminary summary of the 1999 season as well as historical information for past seasons, visit the National Hurricane Center's web site. For maps of U.S. landfalling major hurricanes and special reports on recent noteworthy storms visit the NCDC Hurricanes page. Satellite images and loops of each of the 1999 storms as well as storms of the recent past are located at the NCDC Online Images web site. Additional information, including near real-time data can be found at the Weather Underground tropical page.

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Top of Page Palmer Drought Indices

The Palmer Z Index shows how monthly moisture conditions depart from normal (short-term drought and wetness). The December 1999 pattern shows extremely dry conditions stretching from California into the Great Basin and Southwest. Another area of very dry conditions is centered in the southern Appalachians and Ohio Valley and stretches to the Gulf and Atlantic coasts. The Z Index also indicates short-term drought across portions of the Northeast, Great Lakes, and upper Mississippi Valley. Short-term wet conditions occurred in parts of the northern Rockies and central Plains.
U.S. Animated Z
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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. The drought of 1999 continued across the Ohio Valley and into the eastern Great Plains states. Drought conditions worsened during December in the Northeast, Southeast, southern Plains, and Far West. Remnants of the unusually wet conditions from earlier in the year were over parts of the northern Plains and central Rockies.
U.S. Animated PDI
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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.

Preliminary streamflow measurements by the United States Geological Survey revealed persistently low daily streamflows associated with drought from the Great Lakes to the southern Plains and Southeast during November. More streamflow information can be found at the United States Geological Survey's web page.

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Top of Page West and Central Regions Drought Update

The last five months have averaged drier than normal across the West region (which consists of California and Nevada). The moisture deficits of the last two months have been especially important because November marks the beginning of the region's wet season (see graph below left). December 1999 ranked as the third driest December on record (see graph below right) and 1999 had the ninth driest November-December on record. Other 1999 ranks include: fourth driest September-December, fifth driest August-December, seventh driest July-December, and 1999 tied with 1989 as the eighth driest October-December since 1895.

West Region Pcp Norm/Dep
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West Region Dec Pcp
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Central Region
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The Central region, which is centered on the Ohio Valley, has experienced extremely dry conditions persistently for the last six months, with July-December ranking as the fifth driest such 6-month period since 1895 and 1999 ranking as the 17th driest year on record. The regional aggregate Palmer Drought Index had reached the extreme drought category by the end of 1999. Based on the PDI, the intensity of this drought is comparable to the magnitude of the 1988 drought, but there have been several droughts in the past which have been more intense and which have lasted longer.

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.

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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.

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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
For further information on the historical climate perspective presented in this report, contact:

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