The drought and heat had their origins during the prior winter. A fast storm track over northern Canada during the winter of 2011-2012 prevented cold air from making many visits into the U.S. and kept the frigid air locked up near the Arctic Circle.
According to Expert Senior Meteorologist Brett Anderson, “This pattern, in turn, resulted in mild Pacific air over much of the U.S. and southern Canada. Additionally, a lack of snow cover over southern Canada then allowed any air coming southward to further warm up before entering the U.S.”
The lack of cold air in the U.S. then greatly limited the intensity of storms during the winter and influenced the form of precipitation. Many stream and river systems are fed by the melting of snow cover and the release of frozen water in the ground through the spring and early summer.
The warm start to the spring allowed some crops to be planted early in the Midwest. However, the soil also dried out very quickly. As the days lengthened and the angle of the sun increased, temperatures climbed much higher than average over the Midwest and occasionally spread into the East as a result of the dry landscape. Many cities over the middle of the nation had weeks of 100-degree temperatures.
From Westword (Alan Prendergast):
Drought contributes not only to wildfires but to the massive pine beetle epidemic that’s raged through the West for more than a decade, as detailed in last June’s feature “The Beetle and the Damage Done.” It’s hardly the only factor involved — warmer temperatures, the beetles’ accelerated reproduction cycle, decades of fire suppression policies, and other forces have contributed to the problem — but drought weakens the trees’ ability to fight off beetle invasions by oozing resin. And that means that, while the epidemic has slowed somewhat because it’s already devoured many of the lodgepole pines the beetles prefer, it doesn’t require that many beetles to take down a drought-weakened host.
A healthier snowpack can help limit the beetle invasion, as well as reduce the fires that are altering the forests around the state. Forest officials are learning how to think long-term about the epidemic and its aftermath, planning for new forests that won’t have quite the vulnerability of our current trees, but that’s a solution decades in the making.
From the Associated Press via the Soo Evening News:
The federal government says preliminary figures show that Lakes Michigan and Huron reached record low water levels in December. Keith Kompoltowicz of the U.S. Army Corp of Engineers tells The Detroit News that the measurements are expected to be made official later in the week. All of the Great Lakes have had lower water levels in the past year because of light snowfall in the winter and light rainfall in the spring. The previous all-time low mean level was set in 1964 at 576.2 feet above sea level. The preliminary mean for December 2012 is 576.15 feet.
From Reuters via Yahoo! News:
In a seasonal outlook released Thursday [December 20], the Climate Prediction Center said extreme to exceptional drought was likely to persist across the Plains for the next three months. “Most of the annual rainfall for the High Plains really occurs in the springtime and early summer, so that is going to be the critical period. They really do need a wet season this year to make any kind of dent in the drought,” Miskus said…
In its three-month outlook, the Climate Prediction Center said continued drought improvement is possible across the Midwest and in northern tier states including Minnesota, North Dakota and Montana…
Drought conditions eased in the South after storms brought two to four inches of rain from eastern Texas to the Carolinas, the Drought Monitor report said. In Alabama, about one-third of the state remained in moderate to extreme drought but the rain eliminated the “exceptional” drought category that had covered about 3.7 percent of the state a week earlier. However, the report cautioned that long-term moisture deficits persisted in the region, and dry weather continued across much of western, central, and southern Texas.
From the Grand Junction Free Press (Hannah Holm):
A snowy December was the perfect Christmas present for a parched Colorado, which ended November suffering from desiccated soils, depleted reservoirs and anxious ski resorts. A series of storms over the past few weeks made the state start to look like its proper winter self.
So the Drought of 2012 must be over, right? Not quite yet.
The Weekly Climate, Water and Drought Assessment Summary for the Upper Colorado River Basin, released by the National Integrated Drought Information System (NIDIS) on Jan. 1, notes that the water picture improved markedly in December, but the amount of water in the snowpack in western Colorado river basins is still only between about 70% and 85% of normal for this time of year.
The snowpack for the Upper Colorado River Basin as a whole (the area that drains into the Colorado River above Glenn Canyon dam) is doing better, at about 94% of average, because of higher accumulations in northeastern Utah and southwestern Wyoming river basins.
The NIDIS report also notes that as of Dec. 30, soil moisture levels were below 30% of average across all of western Colorado and eastern Utah, with an exceptionally dry area in southwestern Wyoming.
Looking more closely at the river basins that meet in Grand Junction, the Colorado River Basin snowpack in Colorado had 69% of its average water content for this time of year on Jan. 2. For some historical perspective, there’s more fluffy, frozen water in the hills now than there was at the beginning of 2012, and just about the same amount as at the beginning of 2002. The picture is similar in the Gunnison Basin…
So, with all this data, what’s the take-home for western Colorado?
It’s too early to panic about next year’s water situation, given that early spring is when we typically get most of our water, and large-scale, long-range projections aren’t terribly reliable for forecasting local conditions. But it’s also too early to breathe sighs of relief.