Jun 4, 2012 2:10 PM
Nature's weather rollercoaster has provided no amusement for western Kentucky residents.
After widespread flooding during the spring of 2011, drought has crept into western Kentucky in 2012. While some areas received much needed rain as May turned to June, other areas saw only enough to settle the dust.
The U.S. Drought Monitor highlights an area of severe drought emerging in the Jackson Purchase and Pennyrile regions of Kentucky and a broader area of abnormal dryness extending eastward. Winter and spring normally bring abundant, widespread precipitation across Kentucky. Instead, spring was ushered in by unusually warm, dry weather.
"Like flooding, drought is a recurrent feature of Kentucky's climate," said Dr. Stuart Foster, state climatologist and director of the Kentucky Climate Center at Western Kentucky University. "Last year was the wettest year on record across Kentucky going back to 1895. Now, the same areas of the state that experienced widespread flooding last spring are in drought."
The contrast is evident in the following April and May precipitation totals from some Kentucky Mesonet stations and highlights the extremes of Kentucky's climate:
County 2012 2011
Fulton 1.44 21.55
Graves 2.82 20.52
Calloway 3.18 21.06
Marshall 3.87 24.17
Caldwell 2.46 23.78
Trigg 2.18 21.67
Clinton 3.56 16.79
Cumberland 5.80 19.13
When drought develops, agriculture is the first sector to be impacted as moisture is drawn out of the upper levels of the soil. That can have an impact on both row crops and pastures that support livestock herds.
With further intensification, stream flows decrease and water levels in ponds and lakes drop. This spring, reservoirs operated by the U.S. Army Corps of Engineers have been slow to reach summer pool. Kentucky Lake on the Tennessee River and Lake Barkley on the Cumberland River, along with Barren River Lake, Nolin River Lake and Rough River Lake in the Green River Basin, have struggled to reach summer pool. Though runoff from the recent rain should help.
If drought spreads and intensifies over the summer months, some communities across Kentucky could experience threats to municipal water supplies. At that point, residential and some commercial customers might be requested to curtail water use. Such actions were required during droughts in 1988, 1999-2000, and more recently in 2007 and 2008. Fortunately, municipal water supplies in areas that are currently the driest are generally more resistant to drought. Meanwhile, rainfall has been much more abundant is those areas of the state where municipal water supplies are more vulnerable to drought.
A return to more normal rainfall in early June would help to alleviate present concerns. However, drought vulnerability will rise if the dry weather pattern persists. The current 6-10 day and 8-14 day outlooks issued by the National Weather Service's Climate Prediction Center (CPC) indicate that warm, dry weather is likely.
If the dry weather pattern persists while daily temperatures continue to make their seasonal climb, then impacts of drought will quickly become more evident and likely spread beyond agriculture. With summer approaching, the demand for water to support crops, livestock and municipalities will continue to increase, and the amount of rainfall required to alleviate drought will increase.
The CPC outlooks for summer do not give much clarity to the situation. The precipitation outlook indicates equal chances of above or below normal precipitation, while there is a slightly enhanced likelihood of above normal temperatures based on historical averages.
In the meantime, history provides some perspective on the current situation and what may lie ahead.
Based on climatic records from the Paducah area, the 2012 precipitation total through the end of May of 10.69 inches recorded at the Barkley Regional Airport is only 50 percent of normal and marks it as the third driest start to a year dating back to 1892. Only 1941 and 1987 were drier. Looking at the past two months, the total precipitation of 0.95 inches was only 10 percent of normal, making it the driest combined April and May on record.
The story is similar at other locations. The National Weather Service cooperative observer station at Murray in Calloway County has recorded 12.15 inches of precipitation year-to-date, exactly 50 percent of normal, third driest on record. The April and May total of 2.12, just under 20 percent of normal, makes it the driest on record. In Henderson County, the year-to-date total of 9.33 inches is 46 percent of normal, second driest on record. April and May produced 3.02 inches, about 30 percent of normal, and is the driest on record.
An abnormally dry start to a year does not always foretell an intense summer drought. But the odds are increased. Following the development of drought in 1940, the dry start to 1941 led to extreme drought throughout much of the Kentucky during that summer. Likewise, dry conditions early in 1987 in western Kentucky led to severe drought that spread to other parts of Kentucky later that summer and was followed by drought in 1988.
"The unusually early dry spell is definitely no guarantee that drought conditions will continue to intensify across the state as we move into the summer," Foster said. "But farmers, water supply managers, and others involved in weather-sensitive enterprises should take note of the current situation and be prepared for that possibility."
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