#Drought news: Moderate and severe short-term drought continued across the southern portion of the #Colorado high plains

Click on a thumbnail graphic to view a gallery of drought data from the US Drought Monitor.

Click here to go to the US Drought Monitor website. Here’s an excerpt:

This Week’s Drought Summary

Over the past week, primarily light to moderate precipitation fell from east Texas northeast through New England. Heavier precipitation amounts of 2 to 6 inches were embedded within the larger precipitation swath, affecting areas from southwest Louisiana to the southern Appalachian Mountains. Heavy precipitation amounts, including mountain snow, fell in the Pacific Northwest and in the central and northern Rocky Mountains. Warmer than normal temperatures also covered most of the continental U.S., with the warmest conditions (compared to normal) taking place in the northern states. In the West, many areas that received significant mountain snow in the past few weeks saw an improvement in drought conditions, while areas that missed out on the snow or still had significant precipitation deficits did not see improvements to their drought depiction. Improvements or degradations in conditions east of the Rocky Mountains were primarily in response to significant precipitation occurring, or lack thereof, over the past several weeks. Degradations made in parts of central and southern Texas also occurred due to high evaporative demand and the associated negative impacts on soil moisture. For more details on changes to this week’s U.S. Drought Monitor depiction, please see the regional paragraphs below…

High Plains

Moderate and severe short-term drought continued across the southern portion of the Colorado high plains and adjacent southwest Kansas, and moderate short-term drought also continued in south-central Kansas, after a mostly warm and dry week across the High Plains region. Temperatures ranged from 5 to 10 degrees warmer than normal in Kansas to as much as 20 degrees above normal in North Dakota and eastern Montana…

West

Heavy precipitation, including mountain show, fell in many of the higher elevation portions of the West this week, with the exception of the Sierra Nevada and mountainous regions of Arizona and New Mexico. Cooler than normal temperatures prevailed in southwest Colorado and eastern Utah and adjacent parts of Arizona and New Mexico, while near or above normal temperatures were commonplace elsewhere in the West. In the Four Corners region, recent precipitation in higher elevation areas improved conditions, such that severe drought lessened to moderate drought around the Chuska Mountains. Lower elevation areas, however, are still suffering from severe precipitation deficits due to the paltry rainfall from the 2019 North American monsoon, and severe drought conditions remained in some of the lower elevation portions of the Four Corners region. Moderate to large snow packs in the San Juan and Sangre de Cristo Ranges in northern New Mexico and southern Colorado led to improvement from severe to moderate drought in the high country, though the San Luis Valley and other lower elevation areas in southern and western Colorado and northern New Mexico remained in severe drought. In the Pacific Northwest, large precipitation amounts, including mountain snow, improved conditions in some of western Washington, leading to the removal of moderate drought around Puget Sound and in southwest Washington. Farther east, mountain snows also occurred in northern Idaho and western Montana, as well as eastern Idaho and the Wyoming, Teton, and Wind River ranges of western Wyoming. Conditions improved as a result of this precipitation in eastern Idaho and western Wyoming. Moderate drought coverage also lessened in the Idaho Panhandle as a result of this heavy precipitation. Meanwhile, short-term moderate drought expanded in coverage in central Idaho, where recent precipitation was not enough to curtail short-term precipitation shortages and snow pack deficits…

South

Over the past week, moderate to heavy precipitation occurred in southeast Texas and Louisiana, and from central and southeast Arkansas eastward. The heaviest rain fell from southwest Louisiana to central Mississippi, where amounts ranged from 2 to 6 inches. With warmer than normal temperatures occurring across the region, drought expansion occurred in the parts of northeast Texas, southwest Arkansas, and northwest Louisiana that were missed by the heavier rains. Widespread drought expansion was made from northeast Texas to central and south-central Texas and the Edwards Plateau, as low precipitation this week continued short-term precipitation deficits in these regions. In south Texas, some improvement to drought conditions occurred in areas that received precipitation recently, thus making short-term precipitation deficits less severe or removing them altogether. Moderate drought was removed from the northwest Texas Panhandle, where short-term precipitation deficits had lessened. Moderate and severe drought continued in the Red River Valley in southwest Oklahoma and western north Texas…

Looking Ahead

A strong storm system is forecast to move across the central and eastern continental U.S. over the next week, delivering 1-3 inches of precipitation, with locally higher amounts, from the south-central U.S. to the Lower Great Lakes region between January 8 and 13. High elevation areas in the West (generally north of the Colorado/New Mexico state line) are forecast to receive precipitation this week as well, with amounts in excess of 3 inches possible in the Cascades and Olympic Range and along the Pacific Coast from northern California into Washington. Primarily warmer than normal temperatures are forecast in the eastern continental U.S. through Tuesday, January 14, while below-normal temperatures will be more common in the West. Temperature swings will occur in the central and southern Great Plains as a series of storm systems and cold fronts progress across the continental U.S., while temperatures in the northern Great Plains will be primarily colder than normal. From Monday, January 13 to Friday, January 17, the National Weather Service Climate Prediction Center is forecasting high probability for warmer than normal temperatures in the southeast half of the continental U.S., and high probability for colder than normal temperatures in the northwest half of the continental U.S. Excepting parts of the southern High Plains and southwest Texas, as well as the Florida Peninsula, the forecast is in favor of above-normal precipitation. In Alaska, above-normal precipitation is forecast from January 13-17, except for southern coastal areas. During this time period, warmer than normal temperatures are forecast for the northern half of Alaska, and colder than normal temperatures are forecast for the southern half of Alaska.

US Drought Monitor one week change map ending January 7, 2020.

NRCS: After Dry Start to Water Year #Colorado has Above Normal #Snowpack

Click here to read the release (Brian Domonkos):

Similar to what was observed throughout the 2019 water year, 2020 has so far displayed widely varying patterns of precipitation and snow accumulation month-to-month and across the mountain basins of Colorado. October exhibited the continued dry spell of the late summer and early fall in southern Colorado, while the northern basins received above normal precipitation. Precipitation was more evenly distributed in November. December brought above normal precipitation to all basins except the combined Yampa, White, and North Platte in northwest Colorado. This ample December accumulation was mostly received as snow across the state. “Increased accumulation as snow in December compared to the drier previous months has led to above normal snowpack and below normal water year precipitation. As of January 1st, water year-to-date precipitation was 92 percent of normal and snowpack was 119 percent” explains NRCS Hydrologist Karl Wetlaufer. All individual major basins in the state are currently holding above normal snowpack as well, ranging from 104 to 129 percent of normal.

The contributing factors of snowpack and precipitation have led streamflow forecasts to be relatively consistent across the state. “While it is common to see notable geographic trends in forecasts across the state, current water supply forecasts are generally for near to slightly below average volumes in all major basins of Colorado. Ninety percent of water supply forecasts in Colorado currently lie between 85-115 percent of their average volumes.” Wetlaufer notes. On the high end, the average of forecasts in the Arkansas Basin are for 104 percent of normal volumes. On the low end, the Gunnison and combined San Miguel, Dolores, Animas, and San Juan Basins have an average forecast value of 88 percent of normal.

Statewide reservoir storage has remained above average only dropping a few percentage points over the last few months to where it resides at 106 percent of average. Only the Arkansas and Upper Rio Grande Basins are holding below average storage at 98 and 86 percent of average, respectively. All other basins in the state are carrying between 104 and 129 percent of their average reservoir storage for this time of year.

Overall things are off to a good start with respect to prospective water supply with ample reservoir storage and above normal snowpack. We have just surpassed the accumulation of 50 percent of what the normal snowpack peak is, which generally occurs in April. That said, there are still several months until the primary snowmelt runoff season and a lot can change so it is always worth keeping an eye on current conditions as time progresses.

For more detailed information about January 1 mountain snowpack refer to the January 1, 2020 Colorado Water Supply Outlook Report. For the most up to date information about Colorado snowpack and water supply related information, refer to the Colorado Snow Survey website.

Yale #Climate Connections: “With #ClimateChange, a larger fraction of the [#snowpack] sublimates and evaporates” — Paul Brooks

Snowstorm photo via NOAA.

From Yale Climate Connections (Erin Chessin):

Snow is not just for family skiing trips or the winter Olympics every four years. Mountain snow provides water for billions around the world and is a key part of annual water cycles. About 75% of water supplies in the western U.S comes from snowmelt, according to the U.S. Geological Survey. But scientists say global warming is causing snow to finish melting earlier in the springtime than historically has been the case – and in smaller quantities – putting western water resources at still more risk.

What is snowmelt? Snowmelt is water runoff that flows into rivers, streams, and lakes, replenishing ground and surface water reserves for agriculture and consumer uses. In western U.S. water supply systems, mountains act as natural water reservoirs, filling up large bodies of surface water to be distributed for a variety of uses – growing crops, drinking, bathing – essentially everything humans do. Eastern parts of the U.S generally receive sufficient precipitation throughout the year in the form of rainfall, but still benefit from water from snowmelt through recharging of groundwater, rather than surface water, supplies.

The amount of snowfall varies based on current climate conditions each year, whether it is influenced by the natural environment or humans. Some years are high snow years, others low snow years. Water managers use April 1 as a standard date to begin estimating how much water will be available once it melts based on the level of snowfall. Mountain landscapes across the world vary on when their snow melts. At higher elevations, snow doesn’t start melting until much later in the year, while at lower elevations it melts far sooner. In the U.S., snowmelt period typically begins in the springtime and extends throughout the duration of the summer.

‘Waters of the world’ provide timely needed resources

But the warming of the atmosphere is causing snow to melt earlier in the spring than usual. As a result, there isn’t enough water to extend throughout the summer in some cases. But what is causing such a large-scale change? The answer lies in the human activities that produce carbon emissions – in particular the burning of coal and other fossil fuels – causing global temperatures to rise. As long as carbon emissions and greenhouse gases continue to be emitted and atmospheric concentrations continue to increase, snow will melt earlier and earlier in the year, and that trajectory has troubling consequences for water resources.

Mountains are often referred to as “water towers of the world.” They provide major water resources for humans thousands of miles away, not just for nearby communities. Rainfall is another key source of water for regions that have no mountains, but most global regions are dependent on mountains as their primary source of water. In the U.S, cities nowhere near mountain regions, like Los Angeles, benefit from snowmelt in the distant Colorado Rockies. More than 40 million people between the seven states the Colorado River passes through – Arizona, California, Colorado, Nevada, New Mexico, Utah, and Wyoming – rely on snowmelt that runs off into that river.

Water managers, ranchers, farmers face timing uncertainties

In Colorado, snow is melting as much as a month earlier than the historical norm, and the change is affecting when water will be available in reservoirs for down-stream urban communities. The acceleration of snowmelt timing resulting from higher global temperatures is causing a myriad of issues for water managers, increasingly challenged, given the uncertainties, to predict how much water will be available with snowmelt.

“What climate change is doing is it’s making it warmer and more humid,” said Paul Brooks, professor of hydrology at the University of Utah. “With climate change, a larger fraction of the snow and snowmelt sublimates and evaporates, so there is just less snow overall.”

Farmers and ranchers are affected by earlier snowmelt, mainly because agricultural production relies heavily on an influx of water to arrive on time for growing season. With snowmelt happening a month earlier than expected, irrigation systems receive too much water too early, and human-designed irrigation systems are ill-suited for holding large amounts of water for long periods of time. Farmers accordingly are facing major water deficits, leading to water supply shortages in parts of the growing season.

Disadvantaged communities living in poorer regions of the U.S. are at the highest risk of being adversely affected. Several small towns in the western U.S. states, including Arizona, California, and New Mexico, are facing significant strains on their water supplies that will only intensify as global temperatures continue to rise. California, one of the driest states in the country, has seen major cut-backs to the state’s water availability in recent years.

Western water managers stress the importance of saving water. With snowmelt becoming so unpredictable, water is being allocated to the last drop.

“[In California] the impacts are very significant,” said Ryan Jacobsen, executive director and president of the Fresno Irrigation District. “The way that the snowpack comes off is literally what we live and die by on an annual basis.”

AUTHOR
Erin Chessin is a journalism master’s candidate at the University of California, Berkeley.

Westwide SNOTEL basin-filled map December 8, 2020 via the NRCS.