The rains stopped. Two years of drought led to record fires in Arizona and New Mexico, then the rains stopped completely as New Mexico entered its third year of drought. This week New Mexico faces extreme fire weather while water supplies are the worst experts have ever seen.
With the preliminary April 1 runoff forecast numbers in hand, this is “the worst year ever” on the Rio Grande, according to Phil King, New Mexico State University professor and the water management adviser to the Elephant Butte Irrigation District. “Ever” in this case translates to a century of water management on the river system through modern New Mexico.
Where's the water? The Rio Grande in New Mexico faces its "worst year ever".
This weekend New Mexico will face extreme fire danger with forecast relative humidities in the single digits, warm temperatures and winds around 20 miles per hour. Parched reservoirs will be hard pressed to supply water to fight fires. And the fire season in the west is just starting.
West of the 100th meridian, from Mexico to Canada, with the exception of a few lucky areas such as northern Colorado, the past 100 days in north America have been extraordinarily dry.
Brief rains in California in late January raised hope that the western drought, entering its third year, was breaking, but the opposite happened. High pressure intensified off the coast of California and Oregon pushing the jet stream far north of its normal track. The intense sudden stratospheric warming in January coupled with a semi-cyclic oscillation in the Pacific called the Pacific Decadal Oscillation (PDO) to produce areas of strong atmospheric subsidence over the Arctic and the eastern north Pacific oceans. These areas of sinking air produced exceptionally strong and dry high pressure areas. Cold air, pushed out of the Arctic by the huge high pressure areas, plunged into the central U.S. The jet stream pushed up over the north Pacific then dove down the eastern slope of the Rocky mountains, bringing cold weather to the central and eastern U.S. while leaving the western states parched. Europe also had a very cold spring because exceptionally high pressure over the Labrador sea blocked the normal storm track, pushing it south of its normal track across the Atlantic.
The breakdown of the polar vortex in mid-January distorted the northern hemisphere's atmospheric circulation for the following three months.
Today, the Climate Prediction Center released its forecasts for June July and August, that the west is likely to be hotter and drier than normal.
When the mountain west gets hotter and drier than normal in June, a dome of hot air can begin to form over the region. By July that heat dome can spread across the whole United States, as it did last summer. NOAA is predicting that's going to happen this summer. Expect another brutal summer like last year's. The Climate Prediction Center is forecasting New Mexico to be at the center of the excessive heat.
Drought conditions, which already extend across the western states will get worse west of the 100th meridian unless there are surges of tropical moisture that the climate models have failed to forecast.
The official forecasts predicts improving conditions are likely in the plains east of the 100th meridian, but the 1 and 3 month precipitation forecasts don't support that prediction. Likewise, the 3 month temperature forecast, above, is inconsistent with drought improvements in the high plains. Medium range weather forecasts do give hope for significant rains in the Dakotas and Minnesota, improving the drought conditions in those states.
Western droughts are associated with specific ocean/atmosphere circulation patterns which tend to create domes of hot air over the northeastern Pacific ocean and southwestern north America. When the north Atlantic ocean is warmer than normal and the equatorial eastern Pacific has more cool water upwelling than normal large high pressure areas form over the eastern north Pacific ocean and the jet stream is pushed to the north on the west coast. That's exactly what's happening now.
Climate change models have predicted increasing droughts in the southwest as the hot and dry subtropical high pressure areas expand. We may be entering a period of prolonged intense western drought like the drought that led to the abandonment of Mesa Verde and other western pueblos. The ocean/atmosphere circulation was apparently stuck in a warm Atlantic/ cool Pacific ocean phase throughout the medieval warm period (a period of low volcanism) that brought prolonged warmth to Europe and prolonged drought to the southwest. Human caused climate change may be reproducing the conditions that led to the megadroughts that devastated the pueblos of the southwest.
Pueblo Bonito, Chaco Canyon, New Mexico
May 1, 2013 western snowpack was way below normal in the southwest.
The Sierra Nevada snowpack in California, yesterday May 16, was less than 10% of normal for the date. Nothing will be left for the normal June snowmelt, so stream levels will be very low and California's reservoir levels will drop early in the summer season. California is going to have a very challenging water year and fire season.
Across the southwest, the low snowpack bodes ill for summer stream flow and water supplies. Moreover, dry soils and parched vegetation have a feedback effect that leads to less summer rainfall, because trees and desert plants close up their pores to prevent evaporation and save water. Excessive heat in the mountains can lead to extreme heat events in the plains when those air masses move east as they did last summer.
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