U.S. Water News Online
KEARNEY, Neb. -- The tan patch covering most of the central Great Plains on the National Oceanic and Atmospheric Administration's January through March precipitation outlook map is an eyesore to people hoping for a break from the multiyear drought.
The map label predicts precipitation in most of Nebraska early in 2004 will be at least 33 percent less than the 1971-2000 average. A darker brown patch indicates some of southeast Nebraska probably will have 40 percent less precipitation than normal.
How accurate are such forecasts?
``Obviously, the farther you go into the future, the less reliable the prediction,'' said Stan Dart, associate professor of sociology, geography and Earth sciences at the University of Nebraska at Kearney. ``You can't predict (weather) with any accuracy far into the distance.''
However, he said the 90-day forecasts are based on enough reliable information to generally be more than 50 percent accurate. Dart knows that it's NOAA's precipitation outlook that ``makes everyone want to jump up and down.''
Predictions by another venerable forecaster, the Old Farmer's Almanac, are more positive. However, that publication already missed on its prediction that the central Great Plains would see a snowy period around Thanksgiving.
It's yet to be seen if the forecast for above-normal winter snowfall and a nother snowy period from late January until early February beats NOAA's forecast for dry weather.
``It's very nice to be surprised,'' Dart said about that dry forecast.
Dart said farmers shouldn't make any 2004 ag decisions based on current 90-day predictions. They should check NOAA maps again in February and March for some planting season forecasts.
The words ``weather'' and ``uncertainty'' always have gone together. ``You never know you're in a drought until you're in a drought. You never know you're out of a drought until you're out of it,'' Dart said.
Also complicating the weather picture are wet periods in dry years. Dart said that May was wet in an otherwise dry 2003. On the other hand, 1993 is remembered as a wet year even though there were stretches of four to six weeks when parts of Nebraska had no precipitation.
Dart listed four types of drought: meteorological, a shortage of precipitation; hydrological, which affects stream flows; agricultural, when soil moisture is depleted; and socio-economic. Nebraska is experiencing all four.
Four or five dry years aren't unusual in climatology time, he said, but they are wearing down the drought-resisting tools developed in the past 70 years.
The Great Plains were depopulated in the Dust Bowl years of the 1930s. Dart said fewer people left in the 1950s as land use, tillage and conservation methods changed. The dry years of the 1970s were mitigated by irrigation and more conservation.
Now, shrinking Nebraska reservoirs are harming surface water irrigation supplies and groundwater recharge. Dart said it's just too early to tell if 2004 will bring an end to drought or a dangerous continuation of it.
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