January 17, 2003
Long-term Forecast Gives a 'Slight Probability' for Above Normal Precipitation
LINCOLN, Neb. — Don't get your umbrellas out just yet, but Nebraska could see above normal precipitation over the next three months, according to long-term forecasts released by the National Oceanic and Atmospheric Administration Thursday.
The long-term forecast for February through April shows a slight chance of wetter than normal conditions, said Mark Svoboda, climatologist at the National Drought Mitigation Center in the University of Nebraska's Institute of Agriculture and Natural Resources.
It is slightly more likely that the state will have above normal precipitation than below or normal precipitation for the three month period, he said.
However, these models have consistently predicted above normal precipitation in the three-month forecast dating back to October 2002, said Al Dutcher, state climatologist.
"All people have to do is look outside and see that has not happened," Dutcher said.
January and February typically see 1-1.5 inches of total precipitation – only about 5-7 percent of the state's annual total. The key months in this forecast will be March and April, Svoboda said.
"If we can get good rainfalls in the spring we can be OK," he said. "It's the waiting and seeing what will happen with those spring rains. At least, they're not showing dry trends. If there is a slight probability (of above normal precipitation), we'll take it."
Dutcher said another critical factor in the drought's severity will be April's final snow pack in the Rocky Mountains.
Currently, snow pack is about 75 percent of normal and statistically it reaches its cumulative peak in mid-April. For every day snow fails to fall in the Rockies, the snow pack percentage decreases by .5 to 1 percent.
"The river basins that impact Nebraska in Wyoming and Colorado have been so dry that a portion of the snow pack will go into recharging soil profiles," he said. "Therefore, we would expect approximately 20 percent of that snow pack will not make its way through the rivers' systems. The Rockies would have to get 100 to 200 percent of normal snowfall by April to make up the deficits in the accumulated snow pack that have already occurred."
Beyond the precipitation trends, the long-term forecast shows equal chances of temperatures being above normal, below normal or normal February through April. The forecast for February continues to show the eastern half of Nebraska with a greater probability of being warmer than normal and precipitation slightly above normal for the southern one-third of the state, Svoboda said.
This week's snow storm in central and eastern Nebraska will provide great insulation for trees, shrubs, grass and winter wheat. However, water equivalency from the snow is at a 20 to 1 ratio. The 6-8 inches of snow that fell across eastern Nebraska resulted in a liquid water equivalency of only a .25 to a .5 inch, Dutcher said.
In 2002, western and southwest Nebraska had the driest year on record, while the state experienced its third driest year on record. The soil moisture profile for the western two-thirds of the state is gone, while parts of northeast Nebraska stand at 2 to 3 inches of available moisture.
As for any effects from El Nino, already it has peaked and is on its downward swing, Dutcher said.
"The drought took us a couple of years to get into and will take a couple of years to get out of," Dutcher said.
1/17/03-SA
Al Dutcher
School of Natural Resource Sciences
State Climatologist
(402) 472-5206
Mark Svoboda
National Drought Mitigation Center
Climatologist
(402) 472-8238
Sandi Alswager Karstens IANR News and Photography (402) 472-3030
Department: School of Natural Resource Sciences
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