Climate Monitoring / Climate of 1999 / Help
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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. | ![]() larger image |
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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. |
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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. |
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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.
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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.
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.
larger animated imageThe 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.
larger animated imageThe 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.
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.
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larger animated imageThe 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 DivisionFor further information on the historical climate perspective presented in this report, contact:
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-or-
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 Monitoring / Climate of 1999 / Help
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