Cool, wet July is expected
June 18, 2015
As El Nino increases in strength this summer, its impacts on our summer conditions in North America are becoming evident, said Laura Edwards, SDSU Extension Climate Field Specialist, referencing the latest climate outlook from National Oceanic Atmospheric Administration's (NOAA) Climate Prediction Center.
"The July outlook indicates increased likelihood of cooler and wetter conditions throughout South Dakota this July," Edwards said. "These temperature and precipitation projections strongly reflect a summertime El Nino pattern over North America."
The outlook indicates that throughout the central states – including South Dakota – cooler than median temperatures are favored in the month ahead. "In addition to El Nino, this temperature outlook is also a response to the very wet soils and ample rainfall that has fallen in this region over the last several weeks, which tends to reduce the high temperatures in the summer season," Edwards said.
In South Dakota, the median temperatures for July range from the low 80s in the northeast, to upper 80s across most of the south and west for highs. Median lows are in the upper 50s in the northwest to lower 60s in the southeast.
Most of the Rocky Mountain region and the central states are favored to be above median for precipitation in July. "There is strong consensus in the forecast models for this precipitation signal, according to the Climate Prediction Center," said Dennis Todey, SDSU Extension Climate Specialist and South Dakota State Climatologist.
90 percent likely to continue
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Todey added that a recent update on the El Nino conditions, from NOAA Climate Prediction Center, stated that El Nino is 90 percent likely to continue through the fall season, and 85 percent likely to continue or intensify into the winter. "This may sound like a bold prediction, however many climate models have been accurately forecasting the temperature and precipitation over the last couple of months," Todey said. "There is some confidence that the long-range climate models may have now captured how the sea surface temperatures in the Pacific Ocean will impact our climate for the rest of the year."
For much of South Dakota, El Nino in the summer season generally tends to be wetter and cooler, particularly in July and August. The Climate Prediction Center outlook is consistent with that climatology.
Looking ahead to the next three months (July-September), South Dakota looks to be wetter than average. In the same period, Todey explained that the area most likely to experience cooler temperatures is concentrated to the Central Plains and the heart of the Mississippi River Valley region. "As a result, South Dakota is currently projected to have equal chances of below, above or near median temperature in the next 90 days," he said.
What El Nino means to South Dakota crops
For croplands, pastures, yards and gardens, the El Nino summer season ahead may mean less heat stress than average, Edwards explained. "There is ample moisture currently in most of the soils and a continuation of the rainfall pattern like the one we have seen over the last few weeks will reduce drought or water stress as well," she said. Combined with the likely cooler conditions crop water use should be reduced.
Disease issues, like stripe rust, have already become apparent in many wheat fields, and given the higher humidity and moisture in the atmosphere, Edwards said scouting fields will be increasingly important. "Growers may also be more concerned about weeds, as the recent wet conditions have made some field work difficult for pesticide application," she said. "A few warm, dry days are all a weed needs to grow quickly, and frequent scouting is suggested."
With this much moisture high stress conditions for livestock could appear periodically because of higher dew point, even with less extreme high air temperatures.
Drought eliminated in South Dakota
The short window of drought our state experienced in the early months of 2015 has been all but eliminated given our recent wet and cool pattern over the last six weeks. "This week's U.S. Drought Monitor shows virtually no change from last week in our area, with the southeast part of the state continuing to be slightly drier than average for the year so far," Todey said.
The drought outlook through September indicates continued improvement or removal of the remaining drought affected areas in South Dakota, given the likelihood of wetter and cooler conditions for the remainder of the growing season.