National Overview - March 2000


NCDC transitioned to the nClimDiv dataset on Thursday, March 13, 2014. This was coincident with the release of the February 2014 monthly monitoring report. For details on this transition, please visit our public FTP site and our U.S. Climate Divisional Database site.

U.S. March Temp 1895-2000

The North American 500 mb Maps for March

The upper-air pattern remained active during March with several deep, storm-producing troughs crossing the country from west to east. Pacific-borne systems dominated the month with limited intrusions of cooler arctic air.

A mean upper-level ridge over the eastern half of the country provided warmer than normal temperatures from coast to coast. Much warmer than normal temperatures were noted from the northern Rockies to the mid-Atlantic. The south and southwest flow on the west side of this ridge along with storminess in the Southwest provided mountain snowfall and lower elevation rains from the central Rockies eastward into portions of the southern Plains. Closer to the ridge axis, conditions were drier than normal from the central Plains through the Midwest. NA 500mb Map
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Additional information on hydrometeorological analysis and forecasting can be found at the Hydrometeorological Prediction Center's Web Page. The principles behind the 500 mb flow are briefly explained Here. Line separating section as of the report

Top of Page National Temperature - March

The March 2000 monthly mean temperature averaged across the contiguous United States, based on preliminary March 2000 data for the U.S.Historical Climate Network (USHCN), was warmer than normal and ranked as the fifth warmest March since 1895. Nearly 40% of the country was much warmer than normal while less than one percent of the country was much cooler than normal. US March Temp
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U.S. March Temperature Index, 1895-2000
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The preliminary national standardized temperature index ranked March 2000 as the fifth warmest March since 1895. The smoothed temperature value for March has been above the long-term mean since 1981.
This graph shows the percent area of the contiguous U.S. much warmer than normal and much colder than normal for each month from April last year through March this year. A shift to predominantly warmer than normal weather occurred in November 1999. This feature has persisted through the winter and early spring months. US Pct Area C/W
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The map to the right, based on approximately 250 airport stations, shows departures from the 1961-1990 normal of average temperatures for March 2000. Most of the country east of the Rocky Mountains averaged above normal, with the greatest departures in the northern Plains states to Northeast. Several stations averaged near normal west of the Rockies, with the coldest departures in the Pacific Northwest. Most of the Alaskan stations were much above normal, while the Hawaiian stations averaged near normal. U.S. March Temperature Departures
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Animated TZ Map, 199904/200003
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The map animation provided to the left shows the geographical pattern of temperature anomalies for the last 12 months, compared to a base period of 1931-1990.
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Top of Page National Precipitation - March

U.S. March Precipitation, 1895-2000
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Based upon preliminary precipitation data, March 2000 ranked near the long-term mean. About 15% of the country was much wetter than normal while about three percent of the country was much drier than normal.
The preliminary national standardized precipitation index also ranked March 2000 near the long-term mean. U.S. March Precipitation Index, 1895-2000
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U.S. March Surface Wetness
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Dominant high pressure over the eastern half of the country provided areas from central Texas, northeastward, with drier than average surface conditions. Lower than average surface wetness, reflecting drought conditions, is evident in the lower Mississippi Valley while some of the negative anomalies in the Pacific Northwest are due to snowcover. Less than average surface wetness is also evident over the northern Plains due to the absence of snow cover melt. Several storm systems provided wetter than average conditions through convective-type precipitation for portions of the central and southern Plains.

The map to the right, based on approximately 250 airport stations, shows March 2000 total precipitation as a departure from 1961-1990 station normals. Above-normal precipitation can be found in the Alaska panhandle and Aleutian chain, while most of the rest of the Alaskan stations were drier than normal. All of the Hawaiian stations reported below normal precipitation for March 2000. On the mainland U.S., stations were predominantly wetter than normal from Arizona to Kansas, in southern Texas, and in a cluster near the mid-Atlantic coast. Clusters of drier than normal stations occurred from Florida to central Texas, the Great Lakes to eastern Nebraska, and in parts of the West. U.S. March Precipitation Departures
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Long-term drought areal coverage (as measured by the Palmer Drought Index) decreased when compared to February, with about 19% of the country in severe to extreme drought during March. Several droughts in the past hundred years have covered a much larger area for a much longer time (see graph below right). The March 2000 drought is only about half as extensive as the 1988 drought was at its peak. The percent area of the country experiencing severe to extreme wetness had dropped steadily from August 1999 through February 2000 but increased to include greater than seven percent of the country by the end of March.

USPA, 03/2000
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USPA 1900-01/2000-03
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Snowcover, 03/2000
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The snow cover anomaly map to the left reflects the general upper-level pattern across the U.S during March. The dominant ridge over the eastern half of the country prevented the normal accumulation of snowfall for the central and northern Great Plains as well as portions of the central Appalachians, mid-Atlantic region, and Northeast. Portions of the inter-mountain west had slightly higher than average snow cover during the month.

An animation of daily snowcover for North America is available.

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Top of Page Tornadoes - March and Year-to-date

U.S. March Tornadoes, 1895-2000
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During March 2000, 80 tornadoes were documented across the contiguous United States. The 46-year average is 55. The most tornadoes observed in the March record was 180 in March 1976, while eight tornadoes were observed in March 1969.
For the year-to-date, January-March 2000, 145 tornadoes were documented across the contiguous United States. The 46-year average for the three-month period is 97. The most tornadoes observed in the January-March record was 295 in 1999, while 16 tornadoes were observed in the January-March period during 1969. U.S. Jan-Mar Tornadoes, 1895-2000
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It should be pointed out that the preliminary tornado count is traditionally higher than the final count and that the tornado observations have generally improved with time as better observing practices and instrumentation (especially weather radar and satellites) were utilized.

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Top of Page National Temperature - January-March 2000

The January-March 2000 mean temperature averaged across the contiguous United States, based on preliminary 2000 data for the U.S. Historical Climate Network (USHCN), ranked as the warmest such three-month period since 1895. Over 70% of the country was much warmer than normal while less than one percent of the country was much cooler than normal. The persistent warmth of the last five months has resulted in record warm ranks for several combinations of months ending in March 2000. These include each of the nine periods from February-March 2000, January-March 2000, back to June 1999-March 2000. This is illustrated by the table below. US Jan-Mar Temp
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Record Warm Consecutive Month Periods
Ending in March 2000
Warmest Period Value (F) 2nd Warmest Period Value (F)
June 1999-March 2000 55.2° June 1998-March 1999 55.1°
July 1999-March 2000 53.6° July 1998-March 1999 53.5°
August 1999-March 2000 50.9° August 1998-March 1999 50.6°
September 1999-March 2000 47.6° September 1998-March 1999 47.2°
October 1999-March 2000 44.7° October 1998-March 1999 43.5°
November 1999-March 2000 42.5° November 1998-March 1999 40.9°
December 1999-March 2000 40.7° December 1991-March 1992 39.6°
January-March 2000 41.7° January-March 1990 40.7°
February-March 2000 44.4° February-March 1992 43.3°

U.S. Jan-Mar Temperature Index, 1895-2000
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The preliminary national standardized temperature index ranked January-March 2000 as the warmest January-March since 1895. The smoothed temperature value for March has been above the long-term mean since 1982.

National Precipitation - January-March 2000

U.S. Jan-Mar Precipitation, 1895-2000
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Based upon preliminary precipitation data, January-March 2000 ranked near the long-term mean. About 15% of the country was much drier than normal while about four percent of the country was much wetter than normal.
The preliminary national standardized precipitation index also ranked January-March 2000 near the long-term mean. U.S. Jan-Mar Precipitation Index, 1895-2000
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Line separating section as of the report

Current data are based on preliminary reports from River Forecast Center stations and First and Second Order airport stations obtained from the National Weather Service (NWS) Climate Prediction Center and real time Global Telecommunications System (GTS) monthly CLIMAT summaries. THE CURRENT DATA SHOULD BE USED WITH CAUTION. These preliminary data are useful for estimating how current anomalies compare to the historical record, however the actual values and rankings for the current year may change as the final data arrive at NCDC and are processed.

The following NCDC datasets are used for the historical U.S. data: the climate division drought database (TD-9640), and the hurricane datasets (TD-9636 and TD-9697). It should be noted that the climate division drought database consists of monthly data for 344 climate divisions in the contiguous United States. These divisional values are calculated from the 6000+ station Cooperative Observer network.

Citing This Report

NOAA National Climatic Data Center, State of the Climate: National Overview for March 2000, published online April 2000, retrieved on September 16, 2014 from http://www.ncdc.noaa.gov/sotc/national/2000/3.