Tuesday, August 31, 2010

State drying out

Remember way back in June when it seemed that rain would never end? A look back at a map from June 14 shows that every single site in the state from the panhandle to the southeast had an SMI over 0.0, indicating moist conditions. Many sites had an SMI over 5.0, indicating soils that were over field capacity and had no further room to put additional water. Thus, at that time, there was fear that additional rainfall would cause flooding.

But summer in Nebraska is hardly ever wet from start to finish and the summer of 2010 has been no different. In late July, the mid level ridge began to build northward and much of the state began to dry out and heat up. For a few weeks, northeast Nebraska got quite the soaking and rainfall totals in some locations are near 30 inches since the 1st of June. But most of the state has had a relatively dry August and the combination of that and above average temperatures has contributed to a precipitous decline to soil moisture.

The statewide mean SMI currently stands at -1.5 and many sites have had an SMI below 0.0 for three plus weeks. Some panhandle sites have not had an SMI above 0.0 since the 4th of July. So is that unusual? Well, no. A long stretch with relatively dry soil profiles is typical in western Nebraska and late summer is often a bit dry even in the east. The point here is that just because we had an unusually long spell of wet weather earlier in the summer does not mean that some places aren't suffering mild levels of drought stress. Time will tell if the current dry spell is a dip in the overall wet trend the state has had for the past three years or if it is the beginning of a longer period of drought.

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