Click the link to read the release on the Colorado State Univeristy website (Jennifer Dimas):

Snowpack is a victim of increasing western wildfires, causing some regions to have less peak snow accumulation and reducing the number of days snow is on the ground, according to new Colorado State University research.

In burned forests, trees no longer block as much energy from the sun and burned timber sheds soot making snow melt quicker in the late snow zone of mountain ranges – the highest area where snow is deepest and lasts the longest. Less snow could mean less water for a region that relies heavily on mountain snowpack for water supply, according to researchers.

Burned areas were snow-free earlier

At the highest elevations, burned areas were snow-free up to 14 days earlier than in nearby unburned areas and in lower elevations, snow-free dates occurred 27 days sooner, according to research conducted by Stephanie Kampf, professor in the Department of Ecosystem Science and Sustainability in the Warner College of Natural Resources at Colorado State University. Kampf is the lead author on the study, “Increasing wildfire impacts on snowpack in the western U.S.,” published Sept. 19 in the Proceedings of the National Academy of Sciences.

“We found that wildfire area has been increasing in many of the snowiest parts of the West, including the Sierra, Nevada, Cascades, and Rockies,” Kampf said.

Significant increases in wildfire in the west (punctuated by 2020 when more than 10 million acres burned) has compounded western water issues. In the Southern Rockies, site of the East Troublesome Fire, Cameron Peak Fire and Mullen Fire in 2020, the area burned in the late snow zone exceeded the total burned area over the previous 36 years combined. In other regions, like the Arizona-New Mexico mountains, wildfire activity has shifted from low snow zones to early/middle snow zones.

“The energy balance has been fundamentally altered,” said Dan McGrath, assistant professor in the Department of Geosciences at Colorado State and co-author of the study, explaining why burned areas become snow-free earlier. “These impacts can persist for a decade or longer.”

Early melting can lead to water shortages later

Steven Fassnacht, professor of snow hydrology and fellow at Colorado State’s Cooperative Institute for Research in the Atmosphere (CIRA), co-authored the study.

“Snow melting anywhere between two to four weeks earlier can create additional problems for water managers because it puts water in streams and rivers sooner,” Fassnacht said. “That water is often needed later in the season.”

Post-fire impacts will vary regionally, depending on the amount of sun impacting the snowpack energy balance. Mountain regions in Arizona and New Mexico could have greater fire impacts due to increased shortwave radiation at lower latitudes.

A shorter snow season can also reduce the productivity of the forest ecosystem and its carbon sequestration as drier conditions can inhibit vegetation recovery, causing fire impacts to the snowpack to last for decades.

Click the link to read “Wildfires are burning higher in the West, threatening water supplies” on The Washington Post website (Joshua Partlow). Here’s an excerpt:

Two years ago, a wildfire started burning in Colorado’s Arapaho National Forest. Fanned by high winds and parched conditions, the East Troublesome fire raced up the slopes of the Rocky Mountains, at one point crossing over the Continental Divide amid 12,000-foot-tall peaks. It would become the second largest wildfire in state history, and it happened to start on the same October day that another fire to the northeast, the Cameron Peak fire, would be crowned Colorado’s largest ever fire. Beyond their size, the two massive 2020 blazes represented prime examples of a troubling trend as our atmosphere warms: wildfires are burning at higher altitudes in the major mountain ranges of the West, including in areas that are normally cloaked in deep snows in winter…

Sampling snow at different elevations in the burned area from the big Colorado fires of 2020, the authors found that snow melted up to nearly a month earlier in charred areas compared to non-burned forests nearby. They attributed this in part to a dynamic that has been documented in earlier studies — particularly by Portland State University professor Kelly Gleason — where ash and soot from the fire scar blows over snow, darkening it and causing it to absorb more energy and melt quicker. Using historic wildfire maps and snow records, the authors also found that between 1984 and 2020 wildfires have burned 70 percent of what they call “late snow zones” — areas that don’t typically melt until May or later — in western mountains. More forest burned in 2020 in these areas than in the previous 36 years combined, [Dan McGrath, co-author Stephanie Kampf and colleagues at Colorado State University] found.

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

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

This Week’s Drought Summary

Two upper-level weather systems danced across the contiguous U.S. (CONUS) during this U.S. Drought Monitor (USDM) week (September 21-27). One partner of the pair was an upper-level low pressure trough which twirled from the West Coast to the northern Plains then migrated to the Northeast. The other partner was a high pressure ridge. As they did a kind of do-si-do, the ridge swung from the southern Plains to the western CONUS. Other players danced at the periphery – Hurricane Fiona moved across the Canadian Maritime Provinces, spreading rain over New England at the beginning of the week, while Hurricane Ian brought rain and wind to southern Florida as it bore down on the state just as the week ended. The high pressure ridge brought hot temperatures to the southern states at first, then to the West later in the period. The trough generated a storm track across the northern states, then sent a large cold front into the Southeast as the period ended. Monsoon showers joined in over the Southwest in these waning days of summer. The end result was a weekly precipitation pattern that was wetter than normal over parts of the West, southern Plains, Great Lakes, Northeast, and southern Florida. The rain missed large parts of the West, which received little to no precipitation, and much of the Plains, Mississippi to Ohio Valleys, and Southeast to Mid-Atlantic states were drier than normal as well. Temperatures for the week averaged warmer than normal over the southern Plains to Lower Mississippi Valley and across parts of the Southwest and Northwest. The week ended up cooler than normal from the northern Plains to Northeast and into parts of the Southeast. The hot temperatures and continued dry conditions, especially in the South, further dried soils. According to the U.S. Department of Agriculture (USDA), national topsoil moisture rated very short to short (dry or very dry) reached 54%, a high for the year to date and very close to the recent maximum of 56% achieved on October 18, 2020. This is the third year in a row that a peak greater than 50% has occurred. Drought and abnormal dryness contracted where it rained in the Southwest, Northeast, and southern Florida. Drought and abnormal dryness expanded where it didn’t rain, including the Northwest, Great Plains to Mississippi Valley, and Mid-Atlantic states…

High Plains

Half an inch or more of rain fell across parts of North Dakota and Wyoming, with locally an inch or more in parts of Colorado and Nebraska and over 2 inches in parts of Kansas. But most of South Dakota had less than a fourth of an inch of rain as did large parts of Nebraska and Wyoming. More than 70% of the topsoil moisture was short or very short in Kansas, Nebraska, South Dakota, and Wyoming, according to USDA statistics, with the numbers 67% in Colorado and 54% in North Dakota. According to media reports, heat and drought limited forage production in Nebraska and other drought-stricken areas, forcing cattle producers to weigh hay supplies against herd size for the winter. Many growers chopped drought-damaged crops for silage. D0-D2 were pulled back in a few parts of Wyoming, D0-D3 were trimmed in parts of Kansas and Colorado where the heaviest rains fell, and D3 was deleted in western South Dakota. But drought or abnormal dryness expanded in other parts of the High Plains region states, including North Dakota (D0-D2), Colorado (D0-D1), Nebraska (D2-D3), South Dakota (D0-D4), and Kansas (D0-D2 and D4)…

West

Monsoon showers dumped half an inch to locally 2+ inches of rain over parts of the Four Corners states, while a Pacific weather system gave parts of the northern Rockies half an inch to locally 2+ inches of precipitation. A few spotty areas of California, Nevada, Oregon, and eastern Montana received locally half an inch of precipitation. The rest of the West was dry. Low streams, dry soils, and a combination of hot temperatures with little to no rain prompted expansion of D0 across coastal Washington and Oregon. These conditions contributed to ponds drying up in central to eastern Washington where D1 expanded. In Oregon, most large reservoirs nearly empty to less than 10% full due to the prolonged dry weather. USDA reports indicated 95% of the topsoil moisture was short or very short in Montana, with the values 71% in Oregon and 65% in Washington. D0-D3 expanded in central to eastern Montana. Above-normal rain during this year’s monsoon season has resulted in contraction of drought in the Four Corners states. The rains this week contracted D1-D2 in Arizona and New Mexico. But 5 to 20 years of drought have brought many large reservoirs to very low levels, including Lake Powell which was still only 25% full and Elephant Butte which was 5% full. It will take several years of above-normal precipitation, and springtime melt of many winters of heavy mountain snowpack, to bring these reservoir levels back up…

South

About half an inch of rain fell across a few parts of Texas, Mississippi, and Tennessee, but otherwise the South region was dry this week. Hot and mostly dry conditions were observed this past week especially across the Arkansas-Louisiana-Texas area, with near record high temperatures recorded each day as readings neared the century mark. This marks nearly the third straight week with near cloud-free conditions, with below normal relative humidity for this time of year yielding high evaporation rates. Grounds have quickly dried out over much of the area, which has yielded an increased frequency of small wildfires especially across eastern Texas and portions of southeastern Oklahoma. In southeast Oklahoma, hydrological impacts were increasing as Broken Bow Lake was over 11 feet below conservation pool stage, with Pine Creek Lake down about 5 feet. USDA reports indicated 91% of the topsoil short or very short of moisture in Oklahoma. Rapid drying of soils has occurred in Arkansas, with the USDA statistic exploding from 40% on September 11 to 58% on September 18 and reaching 88% on September 25. According to news reports, fierce heat and drought in Arkansas have limited hay and grass growth; August rains allowed farmers to grow some hay, but farmers still do not have enough to get through the winter. Dried ponds, cracked earth, and no forage (pasture) for farm animals were common, especially in western Arkansas. D0 spread across much of Louisiana, Mississippi, and western Tennessee, with D0-D3 growing in Arkansas and D2-D4 expanding in Oklahoma. D0-D4 expanded in parts of northern, eastern, and central Texas, while contraction of D0-D1 occurred along parts of the Rio Grande River…

Looking Ahead

During the two days after the Tuesday morning cutoff time for the USDM, Hurricane Ian made landfall across Florida and an upper-level trough moved across the Northeast, with these systems bringing rain to these areas, while another Pacific trough moved into the Pacific Northwest. Dry high pressure dominated most of the rest of the CONUS. For the period September 29-October 4, the Pacific trough will move across the Pacific Northwest and northern to central Rockies, giving these regions 0.5-1.5 inches of rain with locally up to 2 inches. The remnants of Ian will be drawn over the Southeast, spreading a large area of 1-5 inches of rain across the Southeast to Mid-Atlantic states, with locally over 10 inches in parts of Florida. Ian’s rain will stretch into the eastern Tennessee Valley and southern New England, where up to an inch of rain is expected. Little to no precipitation is forecast for the rest of the CONUS where high pressure ridging will dominate. Temperatures are predicted to be warmer than normal in the West to Great Plains and cooler than normal in the Southeast to Mid-Atlantic states. For the period October 4-12, odds favor above-normal precipitation across most of Alaska and in the Four Corners states, with below-normal precipitation over the Alaska panhandle, northern portions of the West, and much of the Plains to East Coast. The West and Alaska panhandle are expected to get wetter as the period progresses. Odds favor warmer-than-normal temperatures for most of Alaska and most of the CONUS, except the period may begin cooler than normal along the East Coast.

Click the link to read the guest column on the USFS website (Cynthia West):

Record heat waves and drought are not only leading to more frequent and intense wildfires but are also putting one of life’s most valuable resources at risk: the water we drink.   

Quantifying the Role of National Forest System and Other Forested Lands in Providing Surface Drinking Water Supply for the Conterminous United States (GTR-WO-100), a new Forest Service research report, describes how extensively public drinking water systems rely on national forests and grasslands.

Access to high-quality water will be a defining feature of the 21st century. Water use per person has been declining for decades; however, a variety of factors are contributing to overall greater water demand, including population growth, increased demand for irrigated food crops, and impacts from drought and climate change. At the same time, warming will result in a reduction of water available to all ecosystems, including forested ecosystems. Maintaining the health and extent of current forests will be key to providing consistent water supplies into the future.   

I’d like to highlight a few key messages from the report that demonstrate how critical national forests are to our drinking water supply in the lower 48 states. In the West, national forests and grasslands supply drinking water to almost 90% of the people served by public water systems. Similarly, national forests and grasslands in the west comprise 19.2% of the total land area but contribute 46.3% of the surface water supply. Some western cities, like Aspen, Colorado, and Portland, Oregon, are over 90% dependent on national forests alone for their drinking water.

In the East, drinking water is still provided by forested lands, though these are mostly privately owned forests. Over a century of research has demonstrated that forested lands provide the cleanest and most stable water supply compared to other land types. Within the lower 48 states, over 99% of people who rely on public drinking water systems receive some of their drinking water from forested lands. 

This is the first report to assess the contribution of individual national forests and grasslands to surface drinking water supplies while also accounting for inter-basin water transfers—networks of pipelines and canals that divert water from its source to high-need areas. Inter-basin transfers can be an important source of drinking water, particularly for western cities. The Los Angeles area, which serves 7.1 million people, receives over 68% of its water supply from forested lands in California and Colorado.

By showing where our drinking water comes from at a fine scale, this report supports implementation of USDA’s Wildfire Crisis Strategy, the Bipartisan Infrastructure Investment and Jobs Act, and the Inflation Reduction Act. The actionable information provided in this report will help land managers to prioritize forests and watersheds for hazardous fuels reduction, watershed management and restoration treatments.

I’m excited to see how this  data helps land managers and policy makers in their efforts to protect communities from wildfire while maintaining clean and reliable drinking water.

Editor’s Note: Provide feedback about this column, submit questions or suggest topics for future columns through the FS-Employee Feedback inbox.

Click the link to read the article on the NOAA website:

Key Points:

– The average temperature of the contiguous U.S.  in August was 74.6°F, which is 2.5°F above average, ranking eighth warmest in the 128-year record. Generally temperatures were above average and/or record-warm across much of the U.S.

– The contiguous U.S. monthly average minimum temperature was record warm for the second month in a row during August. California, Oregon, Washington, Nevada and Idaho each ranked warmest on record for August nighttime temperatures.

– The meteorological summer (June-August) average temperature for the Lower 48 was 73.9°F,  2.5°F above average, ranking as the third-warmest summer on record.

– August precipitation  for the contiguous U.S. was 3.04 inches, 0.42 inch above average, ranking in the wettest third of the historical record.  Precipitation  was above average across parts of the Midwest, West, southern Mississippi Valley and Plains. Precipitation was below average across portions of the central and northern Plains, Northwest and parts of the northern Atlantic coastline.

– The National Weather Service deemed heavy rainfall episodes in southern Illinois, Death Valley National Park, and Dallas, TX as 1,000-year events. While extensive flooding occurred with the heavy rain, some of these events helped to reduce the severity of the drought across portions of the West and southern Plains.

– For the first time since 1997, there was no storm activity reported in the North Atlantic basin during the month of August.

– The wildfire season appears to be waning across Alaska but is still going strong across the West and southern Plains. Across all 50 states, more than 6 million acres burned from January 1 through August 31, 2022.

– According to the August 30 U.S. Drought Monitor report, 45.5 percent of the contiguous U.S. was in drought. Severe to exceptional drought was widespread from the Great Basin to the Pacific Coast, across portions of the central and southern Plains, and parts of New England.

Other Highlights:

Temperature

For the month of August, Washington, Oregon, Idaho, New Jersey, Connecticut, Rhode Island, Massachusetts and New Hampshire ranked warmest on record. In addition to this record warmth, near-record temperatures were widespread in the West and other parts of the Northeast. California had its second warmest August, with five additional states experiencing a top-five warmest August on record.

Summer temperatures  were above average across most of the contiguous United States. Texas, Massachusetts and  Rhode Island  ranked second warmest while seventeen additional states across the West, South and Northeast ranked among their warmest 10 summer seasons on record.

For the January-August period, the average contiguous U.S. temperature was 55.4°F, 1.5°F above average, ranking in the warmest third of the record. Temperatures were above average from Oregon to the Gulf Coast and from the Gulf to New England. Florida ranked fourth warmest and California ranked fifth warmest on record for this period. Temperatures were below average across parts of the Upper Midwest.

The Alaska statewide August temperature was 50.1°F, 0.6°F above the long-term average. This ranked among the middle one-third of the 98-year period of record for the state. Temperatures  were above average across much of eastern Alaska, Panhandle region, Kodiak Island and portions of the Kenai Peninsula. Temperatures were below average across portions of northwest Alaska.

The  Alaska summer temperature  was 52.1°F, 1.6°F above the long-term average, ranking in the warmest third of the record for the state. Temperatures were above average across most of the state with the Northwest and areas along the Arctic near average for the season. 

The Alaska January-August temperature was 31.2°F, 2.5°F above the long-term average, ranking in the warmest third of the record for the state. Above-average temperatures  were observed across much of the state with portions of the North Slope, West Coast and eastern interior regions experiencing near-average conditions for this eight-month period.

Precipitation

Record rainfall events during the month of August contributed substantiallyto the record-wet August for Mississippi as well as the third-wettest August for Nevada and Louisiana. Conversely, a lack of precipitation received during the month resulted in Nebraska  ranking second driest while Kansas had its seventh-driest August on record. 

The U.S. summer precipitation total was 8.18 inches, 0.14 inch below average, ranking in the middle third of the June-August record. Precipitation  was  above average along the West Coast, much of the Southwest, Midwest, lower Mississippi Valley and northern New England for the season.  Precipitation during June-August was below average across the Great Plains, southern New England, and other portions of the East Coast. Arizona  ranked seventh wettest while Nebraska  ranked third driest for the summer season. 

The January-August precipitation total for the contiguous U.S. was 19.68 inches, 1.03 inches below average, ranking in the driest third of the historical record.  Precipitation  was above average across parts of the northern Plains, Midwest, and much of the southern Mississippi, Tennessee and Ohio valleys. Precipitation was below average across much of the West, central and southern Plains and parts of the Northeast during the January-August period. California ranked driest on record while Nebraska ranked fifth driest and Nevada ranked seventh driest for this eight-month period.

Alaska had the 10th-wettest August in the 98-year record. Much of the state was wetter-than-average, with portions of eastern Alaska and lower Panhandle experiencing near-average conditions during the month. Homer recorded its wettest August and Anchorage ranked third-wettest on record.

For the summer season, precipitation ranked in the wettest third of the record for Alaska with wetter-than-average conditions observed in the North Slope, West Coast and southern portions of the state, with parts of the Northeast interior drier than average for the season. 

The January-August precipitation ranked 10th-wettest on record for Alaska, with above average precipitation observed across all but the central and northeast Interior and Aleutian regions.

Other Notable Events

Several notable flooding events, considered “1,000-year” rainfall events by the National Weather Service, occurred during the month of August:

– On August 2, parts of southern Illinois were drenched by 8 to 12 inches of rain in a 12-hour period. An area south of Newton, Illinois, recorded 14 inches of rainfall over the same period.

– On August 5, Death Valley National Park received 1.70 inches of rain, an unprecedented amount of rainfall for the area, resulting in substantial flooding and damage, and trapping visitors and staff members. This event broke the previous all-time 24-hour rainfall record of 1.47 inches recorded on April 15, 1988. 

– On August 22, parts of Dallas, Texas saw more than 13 inches of rainfall within 12 hours. The governor declared a disaster for 23 Texas counties, including Dallas, after storms caused damage and devastating flash flooding. 

On September 1, the Great Salt Lake, the largest saltwater lake in the Americas and eighth largest in the world, recorded its lowest water level since records began in 1847. 

August had no storm activity in the North Atlantic basin, with 2022 becoming only the third year, along with 1961 and 1997, since 1950 to have no activity during the month.

Drought

According to the August 30 U.S. Drought Monitor report, about 45.5 percent of the contiguous United States was in drought, down about 5.9 percent from the beginning of August. Drought conditions expanded or intensified across portions of the Northeast, central and northern Plains, Northwest and Hawaii. Drought contracted or was eliminated across portions of the Southwest, southern Plains, central to lower Mississippi Valley, Great Lakes, parts of the Northeast and Puerto Rico. Drought covered 93.95% of the state of Hawaii – the largest extent ever recorded for that state.

Monthly Outlook

According to the August 31 One-Month Outlook  from the Climate Prediction Center, much of the West to the Midwest and from the Midwest to the East Coast, as well as southeast Alaska, have the greatest chance of receiving above-normal temperatures in September, whereas the greatest chance for below-normal temperatures is projected to occur across portions of the southern Plains. Portions of the Southwest, Gulf Coast, Southeast and the Panhandle of Alaska are projected to have the greatest chance of above-normal precipitation, while the greatest chance for below-normal precipitation is expected to occur from Northwest to the Great Lakes and into New England. Drought is likely to persist across much of the West, central Plains, and Hawaii with some improvement and/or drought removal likely from the Southwest to the southern Plains, as well as across portions of Puerto Rico. Drought development is likely across small areas of the central and northern Plains, portions of the Mid-Atlantic and Hawaii.

According to the One-Month Outlook issued on September 1 from the National Interagency Fire Center, Hawaii and portions of the Northwest, Oklahoma and the Northeast have above normal significant wildland fire potential during September.

During the fall season water managers in the Colorado River Basin start looking at the outlooks from the Climate Prediction Center. This is particularly important in the Upper Basin where 90% of the river flows come from snowpack accumulation. Weather patterns this year will be influenced by a third La Niña in a row.

The southern tier of the CONUS trends drier in La Niña winters. Thankfully, La Niña influences in the Upper Basin (Colorado, Utah, and Wyoming) are mixed and snowfall can be ample in these headwater states.

So what is the Climate Prediction Center forecast through December 31, 2022? Here are the precipitation, temperature, and drought outlooks and it looks like much of the last year warm and dry. However, if you look at the Colorado River in Colorado drought is expected to re-develop in the headwaters there.

I said we’d look at the outlooks through March 31, 2022 so here you go.

The outlook through March 31, 2023 is mostly “Equal chances” which tells us that the CPC is leaning on history and the current La Niña.

This is the Upper Colorado River Basin dilemma — we won’t know how much water we have in our largest reservoir (the snowpack) until next Spring and actual streamflow until the end of the Summer runoff season.

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

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

This Week’s Drought Summary

An upper-level ridge dominated the central contiguous U.S. (CONUS) during this U.S. Drought Monitor (USDM) week (September 14-20). It was bracketed by an upper-level trough which moved out of the Northeast early in the week, and a Pacific upper-level trough that moved into the West as the week progressed. Pacific weather systems moved across the northern states between the troughs. This pattern resulted in above-normal precipitation across much of the West and parts of the Northeast. Fronts associated with the Pacific systems triggered showers and thunderstorms across parts of the central and northern Plains to Mid and Upper Mississippi Valley. For the rest of the CONUS, a large dry air mass covered much of the southern Plains and East throughout the week. Rain occurred along a stationary front draped across Florida that was associated with the southern edge of the air mass, but for much of the South, Southeast, Mid-Atlantic, and Midwest regions it was a dry week. Temperatures averaged warmer than normal across the Plains to Great Lakes, and cooler than normal across much of the West, Southeast, and northern New England. A tropical system brought heavy rain to Puerto Rico and the Virgin Islands. Drought or abnormal dryness expanded or intensified across northern parts of the West, from the central and northern Plains to the Mid- and Upper Mississippi Valley, and over parts of the Mid-Atlantic coast. Drought or abnormal dryness contracted where it rained, especially in parts of Florida, New Mexico, and the Northeast, in a swath from Iowa to Illinois, and across Puerto Rico…

High Plains

Parts of the High Plains region had rain while other parts were dry. Up to two inches fell locally in parts of several states. Especially dry areas occurred in parts of the Dakotas, Montana, Kansas, and Colorado. The lack of rain was accompanied by unusually hot temperatures regionwide, which increased evapotranspiration and accelerated the drying of soils. The drying soils and dry ponds and waterholes led to extensive expansion of D0-D2 in North Dakota and Montana, and D0-D4 in South Dakota and Kansas. Groundwater levels are low with wells in Wichita, Kansas, going dry. According to media reports, a water emergency developed in Caney, a town in southeast Kansas, when water stopped flowing over the Little Caney River’s dam; there are 6 weeks of water supply left. D1 and D2 expanded in parts of Colorado, and D3 expanded in southeast Wyoming while other parts of the state saw contraction of D0 and D1. Nebraska also had some contraction of D2, but expansion of D1-D3 in other parts of the state. According to USDA statistics, all states in the region had half or more of the topsoil moisture short or very short of moisture. In Nebraska and Kansas, three-fourths of the pasture and rangeland was in poor to very poor condition, while the value was 50% for Colorado, 55% for South Dakota, and 58% for Montana…

West

Pacific weather systems dropped locally 2 or more inches of rain across parts of central and northern California, and over local areas of the Great Basin and southern New Mexico. Half an inch or more of precipitation occurred over large parts of the interior West. Other parts, especially much of Washington, Oregon, northern Idaho to northwestern Montana, and southern California to parts of New Mexico, were dry this week. Groundwater continues low and many reservoirs were still very low to near record low. The water levels in most reservoirs in New Mexico are well below average. The August 2022 total combined end-of-month storage of 12 large reservoirs in the state ranked among the three smallest August totals since 1990. The precipitation that fell this week did little to make up deficits that have built up over the last 5 years, so little improvement was made on this week’s map over the areas that received precipitation. One exception was southern New Mexico and adjacent Arizona, where D1-D3 contracted in the wetter areas this week that have also benefited from a wet monsoon season. In northern parts of the West region, D0 was added to western Washington and northwest Oregon where streams were low, very warm temperatures increased evapotranspiration and continued to dry soils, and precipitation was below normal for the last 3 months. D1 expanded in northern Idaho where several indicators reflected the dry conditions of the last 3 months, and several dozen large wildfires continued to blaze. According to USDA statistics, all of the states in the region except California, Nevada, and Arizona had half or more of their topsoil moisture short or very short of moisture…

South

A few areas of the Gulf Coast and western Texas received up to half an inch of rain this week, but the South region was, for the most part, dry with no rain falling. Moderate and severe drought contracted slightly in a couple spots in southern Texas, and abnormal dryness and moderate drought expanded in a couple other areas of the Lone Star State and abnormal dryness expanded in Tennessee. But the biggest changes occurred in Oklahoma and Arkansas. D1-D4 expanded in Oklahoma and D0-D2 expanded in Arkansas. Soils continue to dry and groundwater and stream levels are low. According to U.S. Department of Agriculture (USDA) statistics, 82% of Oklahoma’s topsoil moisture is short to very short of moisture (dry to very dry). The only drier years in mid-September in data going back to 2010 were 2011 and 2012, which were very bad drought years. All states in the region except Louisiana and Mississippi had half or more of the topsoil moisture short or very short of moisture. Almost 70% of the pasture and rangeland in Oklahoma was in poor to very poor condition. Ponds in Oklahoma are drying up and 63% of the cotton crop is in poor to very poor condition…

Looking Ahead

A strong upper-level low pressure system will move across the northern half of the CONUS during September 22-27 while high pressure generally dominates the southern half of the country. By the end of the period, the upper-level circulation pattern will consist of a ridge over the West and a trough over the East. This scenario will result in above-normal temperatures in the West and South with below-normal temperatures in the Northeast. Half an inch or more of precipitation, locally up to 2 inches, is forecast to fall from the Four Corners states to the northern Rockies and eastward to the central and northern Plains, as well as across parts of the Great Lakes, much of the Northeast, and over southern Florida. Half an inch or less is expected over Oregon, the Mid to Upper Mississippi Valley, the Tennessee Valley to Appalachian chain, and Mid-Atlantic Coast. Little to no precipitation is predicted for Washington, California, and Nevada in the West, across the southern Plains to Southeast, and over parts of the Midwest. For September 28-October 5, the western ridge and eastern trough pattern is expected to persist. Odds favor warmer-than-normal temperatures across the West to Mississippi Valley and the Alaskan panhandle, with cooler-than-normal temperatures from the Northeast to southern Appalachians and over southwest Alaska. The circulation pattern will likely result in below-normal precipitation from the Pacific Northwest to Northeast, across the Great Plains to Mississippi Valley, and over the Ohio Valley as well as western Alaska. Odds favor above-normal precipitation over the coastal Southeast, the eastern half of Alaska, and a small area in the Four Corners states.

Click the link to read the article on the Colorado State University website (Nik Olsen):

Snowpack is a victim of increasing western wildfires, causing some regions to have less peak snow accumulation and reducing the number of days snow is on the ground, according to new Colorado State University research.

In burned forests, trees no longer block as much energy from the sun and burned timber sheds soot making snow melt quicker in the late snow zone of mountain ranges – the highest area where snow is deepest and lasts the longest. Less snow could mean less water for a region that relies heavily on mountain snowpack for water supply, according to researchers.

At the highest elevations, burned areas were snow-free up to 14 days earlier than in nearby unburned areas and in lower elevations, snow-free dates occurred 27 days sooner, according to research conducted by Stephanie Kampf, professor in the Department of Ecosystem Science and Sustainability in the Warner College of Natural Resources at Colorado State University. Kampf is the lead author on the study, “Increasing wildfire impacts on snowpack in the western U.S.,” published Sept. 19 in the Proceedings of the National Academy of Sciences.

“We found that wildfire area has been increasing in many of the snowiest parts of the West, including the Sierra, Nevada, Cascades, and Rockies,” Kampf said.

Significant increases in wildfire in the west (punctuated by 2020 when more than 10 million acres burned) has compounded western water issues. In the Southern Rockies, site of the East Troublesome Fire, Cameron Peak Fire and Mullen Fire in 2020, the area burned in the late snow zone exceeded the total burned area over the previous 36 years combined. In other regions, like the Arizona-New Mexico mountains, wildfire activity has shifted from low snow zones to early/middle snow zones.

“The energy balance has been fundamentally altered,” said Dan McGrath, assistant professor in the Department of Geosciences at Colorado State and co-author of the study, explaining why burned areas become snow-free earlier. “These impacts can persist for a decade or longer.”

Steven Fassnacht, professor of snow hydrology and fellow at Colorado State’s Cooperative Institute for Research in the Atmosphere (CIRA), co-authored the study.

“Snow melting anywhere between two to four weeks earlier can create additional problems for water managers because it puts water in streams and rivers sooner,” Fassnacht said. “That water is often needed later in the season.”

Post-fire impacts will vary regionally, depending on the amount of sun impacting the snowpack energy balance. Mountain regions in Arizona and New Mexico could have greater fire impacts due to increased shortwave radiation at lower latitudes.

A shorter snow season can also reduce the productivity of the forest ecosystem and its carbon sequestration as drier conditions can inhibit vegetation recovery, causing fire impacts to the snowpack to last for decades.