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The Red River broke the 100 year flood crest record at Fargo, ND on Thursday, April 17th, 1997. The river crested at 39.6 feet, 22.6 feet above flood stage, which also broke the 100 year record of 39.1 feet. Federal disaster aid was made available for people and communities in the Dakotas and portions of Minnesota. The declaration covers damage resulting from flooding, severe winter storms, high winds, heavy spring rain, rapid snow melt, and ice jams.
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| Figure 1 400Kb Click on image for larger view. |
Figure 1 is a 1 KM resolution satellite image of the Northern Plains on April 12, 1997 at 19:47 GMT. (2:47 PM CDT). The image clearly shows a deep snowcover over parts of the Dakotas and most of Nebraska where up to 1 foot of snow fell during a recent storm. Lesser amounts of snow are visible in other areas while across portions of Minnesota a forest canopy and cloud cover obscure the lighter snowcover. The image highlights many rivers in the various river basins across the Northern plains. Many rivers show up well in contrast with the surrounding snowcover. Ice jams, frozen lakes and rivers can also be seen. The severity of spring flooding over the Northern Plains is impacted by the following factors: heavy spring rains/snows, snowmelt, deep snowcover, freeze/thaw cycles, ice jams, and ground saturation due to high water tables. The National Climatic Data Center has divisional monthly data that is useful in these types of analyses.
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| Figure 2 Click on image for larger view.
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Figure 2 and Figure 3 show trends for the January 1996 through December 1996 and January 1997 through March 1997 respectively. The graphs show the monthly values for North Dakota (Division # 6 - Fargo, ND area). Data plotted include, monthly divisional precipitation along with four Palmer Drought Indices: Palmer Drought Severity Index (PDSI), Palmer Hydrological Drought Index (PHDI), Palmer "Z" Index (ZNDX), and Modified Palmer Drought Severity Index (PMDI). The drought indices indicate the severity of a wet or dry spell. Indices generally range from -6 to +6, with negative values denoting dry spells and positive values indicating wet spells. Note the trend for positive Palmer Drought indices and fairly high precipitation amounts. The data and information on these indices for any of the 344 Climate Divisions in the U.S. can be plotted and then downloaded using our ClimVis system (select "Climate Division data"). |
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