Click the link to read the briefing on the Western Water Assessment website:

November 13, 2024 – CO, UT, WY

October precipitation varied widely across the region, particularly in Colorado with southern Colorado seeing above normal conditions and northern Colorado generally seeing below normal conditions. October temperatures were above to much above normal throughout the region, with Utah experiencing its warmest October on record and Colorado and Wyoming their second warmest. Regional snow-water equivalent (SWE) was variable, with the majority of Utah and southern Colorado observing above normal SWE and northern Colorado and Wyoming observing below normal SWE. By the end of October, drought conditions expanded since September, now covering 53% of the region. ENSO-neutral conditions continued in October and there is a 53% chance of La Niña conditions developing by early winter. The NOAA seasonal outlook for November-January suggests an increased probability of below normal precipitation for much of Colorado and southern Utah and above normal temperatures for the whole region.

Regional precipitation was variable in October, ranging from above to below normal conditions in each state. Colorado experienced the widest variance of conditions, from as low as 5-25% of normal precipitation along the Front Range and in northeastern Colorado, to 200-300% of normal precipitation in southern Colorado. A small area in Las Animas County, Colorado experienced greater than 300% of normal precipitation. October precipitation was 5-25% of normal in southeastern Wyoming. October precipitation was in the bottom 10% of the period of record in northwestern and southeastern Wyoming as well as northern Colorado, while precipitation was in the top 10% of all years in southern Colorado.

October temperatures were 4-8ºF above normal throughout the region. Pockets of 8-10°F above normal temperatures were observed in northern and eastern Utah, northern Colorado, and southern Wyoming. A few pockets of 2-4°F above normal temperatures occurred in each state, and one small pocket of near normal (0-2°F) temperatures occurred in Mineral County, Colorado. Large areas throughout the region experienced record-warm temperatures for October. Regionally, Utah experienced its warmest October on record, while Colorado and Wyoming had their second warmest. Additionally, many other states in the West experienced their warmest or second warmest Octobers on record, including Arizona, New Mexico, and Texas, and California and Montana, respectively.

As of November 1, snow-water equivalent (SWE) was variable across the region. SWE was above normal for the majority of Utah, with much above normal conditions in the Upper Colorado-Dolores River (592%), Great Salt Lake (588%), and Jordan River Basins (204%). Much above normal SWE also was observed in southwestern Colorado and northeastern Wyoming basins. Below normal SWE was observed in the majority of Wyoming, with much below normal SWE in the Upper Yellowstone (41%) and Snake Headwaters Basins (41%). The South Platte Basin in Colorado also experienced much below normal SWE at 37% of normal. In Colorado, most SNOTEL sites reported 0-2″ of SWE with a high of 6” at Beartown near Telluride. In Utah, most SNOTEL sites reported 0-1″ of SWE with a high of 2.4” at Steel Creek Park in the Uinta Mountains. Lastly, in Wyoming, most SNOTEL sites reported 0-1″ of SWE with a high of 2.3” at Bald Mountain in the Bighorn Mountains. 

Note: Current SWE as a percent of normal maps are often skewed at this time of year due to the very low average SWE this early in the season.

At the end of October, drought covered 53% of the region, up from 31% drought coverage in September. As of mid-October, drought conditions covered the entire state of Wyoming. Severe (D2) drought coverage more than doubled and extreme (D3) drought coverage tripled in Wyoming, and a small pocket of exceptional (D4) drought emerged in northeastern Wyoming. In Colorado, D1 drought coverage nearly doubled, D2 drought nearly tripled, and D3 drought emerged along the northern Front Range. Lastly, in Utah, D1 drought coverage doubled and D2 drought emerged in Washington County.

Regional streamflow conditions were near to below normal during October. Below normal streamflow conditions were observed in multiple river basins of each state with much below normal conditions in parts of the Gunnison, North Platte, South Platte, Republican, and Arkansas River Basins in Colorado; the Lower Green and Lower Colorado River Basins in Utah; and the Big Horn, Upper Green, and North Platte River Basins in Wyoming. Much above normal conditions were observed in the East Fork Sevier River Basin in Utah.

ENSO-neutral conditions continued during October with near to below average sea surface temperatures in the Pacific Ocean, which triggered a La Niña Watch from the NOAA Climate Prediction Center. There is a 53% chance of La Niña emerging by December and a 53% chance of it persisting through December-February. There is a 55% chance of ENSO-neutral conditions returning by January-March, according to the IRI Model-Based Probabilistic ENSO Forecast. Note, there is a discrepancy between the NOAA and IRI ENSO forecasts at this time. The NOAA seasonal outlook for November-January suggests an increased probability of below normal precipitation for southern Colorado and southeastern Utah, and above normal precipitation for northwestern Wyoming. There is an increased probability of above normal temperatures for the entire region, particularly in southern Colorado and southeastern Utah.

Significant climate event: Record October heat. Salt Lake City experienced its warmest October on record in 2024, with the first 16 days reaching 80°F or above. The average temperature for the month was 62.4°F, surpassing the previous record of 60.5°F set in 2015. Other Utah cities also saw record-breaking average temperatures: St. George at 69.9°F, Provo at 61°F, Fillmore at 60.7°F, Escalante at 60.6°F, Price at 58.6°F, Lehi at 57.9°F, Manti at 56.6°F, Park City at 52.9°F, and Alta at 47.1°F. Northern Colorado experienced very dry weather and significantly above normal temperatures as well, with only two days of measurable precipitation and 26 days of above normal temperatures. Colorado was on track to have its warmest October on record, but a cold front in the last two days caused the average monthly temperature to slip to the second warmest on record. In Denver, the mean October temperature was 59.1°F, which was 8.0°F above normal, making it the second warmest October on record. Precipitation was much below average at 0.11 inches, which is 0.88 inches below normal. No snow was observed, which is 3.9 inches below the average October snowfall.

Click the link to read the discussion on the Climate Prediction Center website:

November 14, 2024

ENSO Alert System Status: La Niña Watch

Synopsis: La Niña is most likely to emerge in October-December 2024 (57% chance) and is expected to persist through January-March 2025.

Over the past month, ENSO-neutral continued, as evidenced by overall near-average sea surface temperatures (SSTs) observed across the central and eastern equatorial Pacific Ocean. Similar to last month, the latest weekly Niño indices ranged from +0.2°C (Niño-4) to -0.3°C (Niño-3.4. Below-average subsurface temperatures persisted across the east-central and eastern equatorial Pacific Ocean. For the monthly average, low-level wind anomalies were easterly over a small region of the east-central equatorial Pacific, and upper-level wind anomalies were near average. Convection was suppressed over the Date Line and was weakly enhanced over eastern Indonesia. The traditional and equatorial Southern Oscillation indices were positive. Collectively, the coupled ocean-atmosphere system reflected ENSO-neutral.

The IRI plume predicts a weak and a short duration La Niña, as indicated by the Niño-3.4 index values less than -0.5°C. The latest North American Multi-Model Ensemble (NMME) forecasts are cooler than the IRI plume and predict a weak La Niña. Due to this guidance and La Niña-like atmospheric circulation anomalies over the tropics, the team still favors onset of La Niña, but it is likely to remain weak and have shorter duration than other historical episodes. A weak La Niña would be less likely to result in conventional winter impacts, though predictable signals could still influence the forecast guidance (e.g., CPC’s seasonal outlooks). In summary, La Niña is most likely to emerge in October-December 2024 (57% chance) and is expected to persist through January-March 2025.

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

Storm systems brought significant precipitation and drought relief to broad areas in the central Rockies, central and southern Plains, Lower and Middle Mississippi Valley, Lower and Middle Ohio Valley, and the South Atlantic Region. Meanwhile, subnormal precipitation and some unseasonable warmth led to deterioration in dryness and drought conditions in portions of the Southwest, southern and western Texas, the interior Southeast, the northeastern Gulf Coast, the central and southern Appalachians, the mid-Atlantic region, the Northeast. Excessive precipitation totals fell on some areas. From central South Carolina through much of southeastern Georgia, amounts of 4 inches to locally a foot of rain were reported. Similar totals fell on central Louisiana, a band through central and north-central Texas, small parts of the Lower Ohio Valley, and orographically-favored areas in the Northwest. In addition, a broad area covering the eastern half of Colorado and adjacent areas in New Mexico and the central High Plains recorded 2 to 4 inches of precipitation, much of which fell as snow in the middle and higher elevations. A few scattered sites reported 3 to 4.5 feet of snow, mainly in the higher elevations of Colorado…

High Plains

A potent 500-hPa low triggered widespread heavy precipitation over southern half of the Region, except along the eastern fringe, while amounts were limited to several tenths of an inch at most farther north. Between 2 and 4 inches of precipitation fell on a large swath covering the eastern half of Colorado, most of central and western Kansas, and adjacent Nebraska. In nearby areas, amounts ranging from a few tenths of an inch to a couple of inches were observed over the western half of Colorado amounts of 0.5 inch to approaching 2 inches in spots was observed across southeastern Wyoming, most other areas in Nebraska, and eastern Kansas. Moderate amounts fell on a swath across the central and southwestern Dakotas the remainder of this region reported little or no precipitation, as well as most of Wyoming. In some of the higher elevations of Colorado, this precipitation fell as heavy snow, with a few locations reporting snow piling up 3 to 4.5 feet deep (50 to 54 inches buried Fort Garland CO while 44 to 47 inches were reported near La Veta, Elbert, and Trinidad CO). All of this resulted in a large area of improvement depicted over southern and western Kansas, most of northern and eastern Colorado, part of southwestern Nebraska, and a few spots in eastern Wyoming. There were a few areas of 2-class improvement in southeastern Colorado, northwestern Kansas, and the fringes of south-central and southeastern Kansas. Elsewhere, due to relatively cool weather, the dry week didn’t engender much deterioration, with most of these locations remaining unchanged from last week. One exception was in a small patch of northeastern Nebraska and adjacent South Dakota, where a new patch of extreme drought (D3) was identified…

West

Heavy precipitation In northeastern New Mexico, with snow reported in some of the higher elevations, produced areas of improvement to dryness and drought. A few high spots in New Mexico reported near 3 feet of snow, including locations near Las Vegas NM and Folsom NM. The only other area of improvement in the West Region was in eastern Washington. Not much precipitation fell last week…

South

Like the Southeastern Region, the South Region experienced highly variable rainfall this past week. Heavy precipitation – in some areas for the second consecutive week – soaked a swath from Louisiana and eastern Texas northward through much of the Lower and Middle Mississippi Valley and the Tennessee Valley. A broad swath reaching as far west as central Arkansas recorded at least 1.5 inches in most places, with some areas recording much higher amounts (3 to 8 inches in part of western Tennessee, and over a foot in parts of central Louisiana). This resulted in reductions in dryness and drought severity across affected areas of the Lower Mississippi Valley and eastern Texas, with some 2-class improvements imposed in a small part of both southwestern Louisiana and an area straddling southwesternmost Mississippi and adjacent southeastern Louisiana. To the north, the heavy rains also removed abnormal dryness from across western Tennessee. Farther west, another area of heavy precipitation accompanied a frontal passage in a swath from central Texas into the central Red River (south) Valley, where totals reached 4 to 8 inches along the axis of heaviest amounts. To the north, heavy precipitation associated with a pair of potent upper-level low pressure systems dropped over 2 inches on a large part of central and western Oklahoma and much of the Texas Panhandle, with localized totals exceeding 4 inches in the eastern Texas Panhandle northward to the Oklahoma/Kansas border. There was also a patch of heavy rainfall to the east across portions of eastern Oklahoma, where isolated amounts peaked at around 3 inches. Dryness and drought affecting these areas were significantly eased, with a couple patches of 2-class improvements in north-central and northeastern Oklahoma. In stark contrast, little or no precipitation was observed from parts of southeastern Oklahoma southward through Deep South Texas, and across western Texas as well. Dryness and drought worsened in some of the areas, with the most widespread deterioration noted in western Texas. The broad area of exceptional drought (D4, the most intense category) expanded there to cover most or all of eastern Hudspeth, Culberson, western Reeves, Jeff Davis, Presidio, and Brewster Counties. Also, D3 (extreme drought) also expanded to cover most of the remainder of the Big Bend of Texas…

Looking Ahead

During the next five days (November 14-18), moderate to heavy precipitation is again expected from the Cascades westward to the Pacific Coast, with totals expected to exceed 5 inches expected in some of the higher elevations and orographically-favored sites. One or more inches are also anticipated in the Sierra Nevada, with several tenths of an inch possible along most of the California Coast down to the Mexican border. Parts of the northern Intermountain West are expected to receive over an inch of precipitation, with 2 to locally 4 inches forecast across the Idaho Panhandle. A low pressure system and trailing front should trigger another round of heavy precipitation in the central and southern Great Plains from central Texas northward into southeastern Nebraska and the Middle Mississippi Valley, with 1.5 to locally 4.0 inches anticipated from central and east-central Kansas southward through the Red River (south) Valley and adjacent northern Texas. At least an inch is also anticipated east of the Lower and Middle Mississippi River through the interior Southeast, Lower Ohio Valley, central and southern Appalachians, and the mid-Atlantic region. Over 2 inches may fall on parts of the central Appalachians and adjacent Piedmont. Meanwhile, moderate amounts should fall on the southern Rockies and adjacent High Plains and across the Great Lakes region and the northern Ohio Valley. In contrast, little or no precipitation is expected across much of the Northeast, Florida and the adjacent South Atlantic region, southern Texas, the northern Plains, the central and southern Rockies, and the Southwest.

The Climate Prediction Center’s 6-10 day outlook (valid November 19-23) features enhanced chances for both above-normal precipitation and temperatures across the Upper Midwest and across most areas east of the Mississippi River, with odds for significantly above-normal rainfall reaching 50 to near 70 percent on the Florida Peninsula. Wetter than normal weather is also slightly favored across Hawaii. Meanwhile, subnormal precipitation seems more likely across Texas and adjacent locations as well as the western Rockies, most of the Intermountain West, and the Sierra Nevada. Below normal temperatures are favored across the central and southern Plains and adjacent Mississippi Valley, the Rockies, and the Intermountain West. Southeastern Alaska should also average colder than normal while in Hawaii, neither extreme of temperature is favored.

Click the link to read the release on the WMO website:

November 11, 2024

Baku, Azerbaijan (WMO) – The year 2024 is on track to be the warmest year on record after an extended streak of exceptionally high monthly global mean temperatures, according to the World Meteorological Organization (WMO).

Key messages

• Jan-Sept 2024 global average temperature 1.54 (±0.13) °C above pre-industrial level
• Long-term warming measured over decades remains below 1.5°C
• Past 10 years are warmest on record and ocean heat rises
• Antarctic sea ice second lowest on record and glacier loss accelerates
• Extreme weather and climate events lead to massive economic and human losses

The WMO State of the Climate 2024 Update once again issues a Red Alert at the sheer pace of climate change in a single generation, turbo-charged by ever-increasing greenhouse gas levels in the atmosphere. 2015-2024 will be the warmest ten years on record; the loss of ice from glaciers, sea-level rise and ocean heating are accelerating; and extreme weather is wreaking havoc on communities and economies across the world.

The January – September 2024 global mean surface air temperature was 1.54 °C (with a margin of uncertainty of ±0.13°C) above the pre-industrial average, boosted by a warming El Niño event, according to an analysis of six international datasets used by WMO.

“Climate catastrophe is hammering health, widening inequalities, harming sustainable development, and rocking the foundations of peace. The vulnerable are hardest hit,” said UN Secretary-General António Guterres.

The report was issued on the first day of the UN Climate Change Conference, COP29, in Baku, Azerbaijan. It highlights that the ambitions of the Paris Agreement are in great peril.

“As monthly and annual warming temporarily surpass 1.5°C, it is important to emphasize that this does NOT mean that we have failed to meet Paris Agreement goal to keep the long- term global average surface temperature increase to well below 2°C above pre-industrial levels and pursue efforts to limit the warming to 1.5°C,” said WMO Secretary-General Celeste Saulo.

“Recorded global temperature anomalies at daily, monthly and annual timescales are prone to large variations, partly because of natural phenomenon such as El Niño and La Niña. They should not be equated to the long-term temperature goal set in the Paris Agreement, which refers to global temperature levels sustained as an average over decades,” she said.

“However, it is essential to recognize that every fraction of a degree of warming matters. Whether it is at a level below or above 1.5°C of warming, every additional increment of global warming increases climate extremes, impacts and risks,” said Celeste Saulo.

“The record-breaking rainfall and flooding, rapidly intensifying tropical cyclones, deadly heat, relentless drought and raging wildfires that we have seen in different parts of the world this year are unfortunately our new reality and a foretaste of our future,” said Celeste Saulo. “We urgently need to reduce greenhouse gas emissions and strengthen our monitoring and understanding of our changing climate. We need to step up support for climate change adaptation through climate information services and Early Warnings for All,” she said.

Highlights

Temperature

The global mean temperature in 2024 is on track to outstrip the temperature even of 2023, the current warmest year. For 16 consecutive months (June 2023 to September 2024), the global mean temperature likely exceeded anything recorded before, and often by a wide margin, according to WMO’s consolidated analysis of the datasets.

One or more individual years exceeding 1.5°C does not necessarily mean that “pursuing efforts to limit the temperature increase to 1.5°C above pre-industrial levels” as stated in the Paris Agreement is out of reach. The exceedance of warming levels referred to in the Paris Agreement should be understood as an exceedance over an extended period, typically decades or longer, although the Agreement itself does not provide a specific definition.

As global warming continues, there is an urgent and unavoidable need for careful tracking, monitoring and communication with regard to where the warming is relative to the long-term temperature goal of the Paris Agreement, to help policymakers in their deliberations. To support this, WMO has established an international team of experts, and the initial indication is that long-term global warming is currently likely to be about 1.3°C compared to the 1850-1900 baseline.

Greenhouse Gases

Greenhouse Gases reached record observed levels in 2023. Real time data indicate that they continued to rise in 2024. The atmospheric concentration of carbon dioxide (CO2) has increased from around 278 ppm in 1750 to 420 ppm in 2023, an increase of 51%. This traps heat and causes temperatures to rise.

Ocean 

Ocean heat content in 2023 was the highest on record and preliminary data show 2024 has continued at comparable levels. Ocean warming rates show a particularly strong increase in the past two decades. From 2005 to 2023, the ocean absorbed on average approximately 3.1 million terawatt-hours (TWh) of heat each year. This is more than 18 times the world’s energy consumption in 2023.

About 90% of the energy that has accumulated in the Earth system is stored in the ocean and it is therefore expected that ocean warming will continue – a change that is irreversible on centennial to millennial timescales.

Sea level rise

Sea level rise is accelerating because of thermal expansion of warmer waters and melting glaciers and ice sheets. From 2014-2023, global mean sea level rose at a rate of 4.77 mm per year, more than double the rate between 1993 and 2002. The El Niño effect meant it grew even more rapidly in 2023.  Preliminary 2024 data shows that, with the decline of El Niño, it has fallen back to levels consistent with the rising trend from 2014 to 2022. 

Glacier loss

Glacier loss is worsening. In 2023, glaciers lost a record 1.2-meter water equivalent of ice – about five times the amount of water in the Dead Sea. It was the largest loss since measurements began in 1953 and was due to extreme melting in North America and Europe. In Switzerland, glaciers lost about 10% of their remaining volume in 2021/2022 and 2022/2023.

Sea ice extent

Antarctic sea-ice extent – both the annual minimum in February and the maximum in September – was the second lowest in the satellite record (1979-2024) after 2023. Arctic sea-ice minimum extent after the summer melt was the seventh lowest in the satellite record and the maximum was just below the long-term average of 1991-2020.

Weather and climate extremes

Weather and climate extremes undermined sustainable development across the board, worsening food insecurity and exacerbating displacement and migration. Dangerous heat afflicted many millions of people throughout the world.  Heavy precipitation, floods and tropical cyclones led to massive loss of life and damage. Persistent drought in some regions was worsened by El Niño.

The section on climate impacts, provided by United Nations partners, will be expanded in the final report on the State of the Global Climate 2024, due to be published in March 2025.

Climate services and early warnings

Climate services and early warnings have made progress in the past five years. There have been advances in Early Warnings for All (EW4All) to ensure that everyone is protected from hazardous weather, water, or climate events through life-saving early warning systems by the end of 2027. 108 countries report having a Multi-Hazard Early Warning System.

Understanding climate variability and change is crucial for optimizing renewable energy generation, ensuring energy system resilience, and analyzing energy demand patterns, especially for heating and cooling.

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

November 8, 2024

Higher temperatures caused by anthropogenic climate change made an ordinary drought into an exceptional drought that parched the American West from 2020-2022, according to a new study
 by scientists from the University of California, Los Angeles (UCLA), NOAA’s National Integrated Drought Information System (NIDIS), and the Cooperative Institute for Research in Environmental Sciences.

The scientists found that evaporative demand, or the thirst of the atmosphere, has played a bigger role than reduced precipitation in droughts since 2000. During the 2020–2022 drought, evaporation accounted for 61% of the drought’s severity, while reduced precipitation only accounted for only 39%. 

“Research has already shown that warmer temperatures contribute to drought, but this is, to our knowledge, the first study that actually shows that moisture loss due to demand is greater than the moisture loss due to lack of rainfall,” said Rong Fu, a UCLA professor of atmospheric and oceanic sciences and the corresponding author of the study, which was published in the journal Science Advances.

They predict that droughts will last longer, cover wider areas, and become more severe as the climate warms.

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Historically, drought in the West has been caused by lack of precipitation, while evaporative demand played a smaller role. Climate change caused primarily by burning fossil fuels has resulted in higher average temperatures that complicate this picture. Now, droughts induced by natural fluctuations in rainfall still exist, but there’s more heat to suck moisture from bodies of water, plants, and soil. 

“For generations, drought has been associated with drier than normal weather,” said Veva Deheza, Director of NOAA’s National Integrated Drought Information System and study co-author. “This study further confirms we’ve entered a new paradigm where rising temperatures are leading to intense droughts with precipitation as a secondary factor.”

A warmer atmosphere can hold more water vapor before the air mass becomes saturated, and precipitation can form. This creates a cycle in which the warmer the planet gets, the more water can evaporate from the landscape and remain stored in the atmosphere longer before it returns to earth as rain or snow. Droughts can form even if precipitation patterns remain within a normal range as higher temperatures and evaporation remove water from soils. They can last longer, cover wider areas, and be even drier with every little bit that the planet warms.

To tease out the effects of higher temperatures on drought, the researchers have separated “natural” droughts due to changing weather patterns from droughts due to human-caused climate change in the observational data over a 70-year period. Previous studies have used climate models forced by increasing greenhouse gases to conclude that rising temperatures contribute to drought. But without observational data about real weather patterns, they could not pinpoint the role played by evaporative demand due to naturally varying weather patterns. 

When these natural weather patterns were included, the researchers were shocked to find that climate change accounts for 80% of the increase in evaporative demand since 2000. During the drought periods, that figure increased to more than 90%, making it the single biggest driver of increasing drought severity and expansion of drought area since 2000. 

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Compared to the period 1948–1999, the average drought area increased 17% over the western United States from 2000–2022 due to an increase in evaporative demand.  The new analysis showed that since 2000, in 66% of the historical and emerging drought-prone regions, high evaporative demand alone could cause drought, meaning drought can occur even without precipitation deficit. Before 2000, that was only true for 26% of the area.

“During the drought of 2020–2022, moisture demand really spiked,” Fu said. “Though the drought began through a natural reduction in precipitation, I would say its severity was increased from the equivalent of ‘moderate’ to ‘exceptional’ on the drought severity scale due to climate change.”

The U.S. Drought Monitor classifies Moderate Drought (D1 on a scale of D0–D4) as falling in the top 10%–20%of historic droughts, while ‘Exceptional’ Droughts (D4) fall in the top 2%. Further climate model simulations corroborated these findings and projected that fossil fuel pollution will turn droughts like the 2020–2022 from exceedingly rare events that once happened only every 1,000 years to events that happen every 60 years by the mid-21st century, and every six years by the late 21st century.

“Even if precipitation looks normal, we can still have drought because moisture demand has increased so much, and there simply isn’t enough water to keep up with that increased demand,” said Fu. “This is not something you could build bigger reservoirs or something to prevent because when the atmosphere warms, it will just suck up more moisture everywhere. The only way to prevent this is to stop temperature increase, which means we have to stop emitting greenhouse gases.” 

The study was supported by NOAA’s National Integrated Drought Information System and the Climate Program Office, as well as the National Science Foundation. Learn more about NIDIS-supported research.

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

Over the last week, weather systems tracked over the southern Plains and into the Midwest, bringing much-needed precipitation. Some areas of Arkansas and Missouri reported over 10 inches of rain for the week. The active pattern also continued over the Pacific Northwest, with the coastal areas and inland recording 2-4 inches of rain that helped to alleviate dryness. Temperatures over the West were below-normal for the week, by as much as 6-9 degrees in parts of Nevada, Utah and Arizona. The rest of the country had warmer-than-normal temperatures, especially in Texas and into Louisiana, Mississippi, Arkansas and Alabama, where they were 9-12 degrees above normal. Many areas that received rain during the period had these rains come on the cusp of record-setting dryness in October, but many records were still set for areas that didn’t receive rain at the end of October and early November…

High Plains

Significant rains fell over much of Kansas, into southeast Nebraska and southeast Colorado. Rain and snow fell from portions of eastern Colorado into Wyoming and into the Dakotas too, reversing the trend of very dry conditions. Not all areas were as fortunate, with northeast Colorado, western Nebraska, eastern and southwest South Dakota and northwest North Dakota remaining dry this week. The region was split, with temperatures in the western areas 3-6 degrees below normal, and temperatures 9-12 degrees above normal in much of eastern Nebraska and eastern Kansas. Much of eastern Kansas saw a full category of improvement this week, with extreme drought being removed from the southeast. Severe drought was removed from far southeast Nebraska. In western North Dakota and in eastern Montana, severe and extreme drought expanded slightly. Some improvements were made to abnormally dry conditions over central to southern Colorado and to moderate drought over northeast Colorado. Moderate drought expanded across central South Dakota this week…

West

Precipitation was scattered over much of the West, with the greatest rain over the Pacific Northwest, where 200% of normal rain was recorded for the week in much of Oregon and Washington. Cooler-than-normal temperatures dominated the region with many areas of Nevada, Utah, and Arizona and into western Wyoming 6-9 degrees below normal for the week. Dryness continued to dominate much of Montana with abnormally dry conditions expanding to fill the rest of the state and moderate and severe drought expanding in the west. Abnormally dry conditions spread to the rest of central Utah while moderate drought and abnormally dry conditions improved over much of western Oregon and Washington. Some improvements were made over eastern New Mexico this week as a result of the continued wetter conditions…

South

Temperatures were 12-15 degrees above normal over much of the South, with areas of the Texas Panhandle into Oklahoma 6-9 degrees above normal. Much of Oklahoma and north Texas and Arkansas received significant precipitation, with widespread reports of 800% of normal rain for the week. The dryness continued over much of Tennessee and into northern Mississippi as the active rain patterns brought some rains, but not the significant and widespread rains that were more common in the West. A full category improvement was made over much of Oklahoma and northern Texas and western Arkansas, with extreme drought removed from the region. Extreme drought emerged in southeast Mississippi. Severe drought improved in Louisiana with moderate drought and abnormally dry conditions also improving in southern Louisiana.

Looking Ahead

Over the next 5-7 days, it is anticipated that the wet pattern will continue over much of the southern Plains and into the South, Southeast, and Midwest. The active pattern along the coastal areas of the Pacific Northwest will also continue. Greatest precipitation is anticipated over the southern Plains, western Tennessee, western Kentucky, northern Mississippi, southern Georgia, western South Carolina and the Pacific Northwest coast, where 3 or more inches of rain is anticipated. Much of the West will remain dry. Temperatures will remain cooler than normal over much of the West with departures of 10-12 degrees below normal over northern New Mexico and southern Colorado. Much of the eastern half of the country will be warmer than normal, while areas of the Midwest and South are anticipated to be 10-12 degrees below normal for the week. Hurricane Rafael has formed in the Gulf of Mexico and is projected to track westward. It may not make landfall until the middle of next week but could impact the dryness over the South and southern Plains depending on its path.

The 6-10 day outlooks show that the probability of above-normal temperatures will be greatest over the eastern half of the United States, especially over the Midwest and into the Southeast. Chances of cooler-than-normal temperatures are greatest over the West, in particular over California and Nevada. Most of the country has a good chance of recording above-normal precipitation during the period, especially over the Pacific Northwest.

Just for grins here’s a slideshow of early November US Drought Monitor maps for the past few years.

Click the link to read the article on the NASA website (Emily Cassidy):

October 29, 2024

Unusually dry conditions gripped over half the contiguous United States in October 2024. On October 29, abnormal dryness and drought affected over 78 percent of the American population—the highest percentage in the U.S. Drought Monitor’s 25-year-long record.

Drier- and warmer-than-normal weather dominated the country during much of October, caused by a strong ridge of high pressure that lingered high in the atmosphere for weeks. According to the Southeast Regional Climate Center, 100 weather stations across the U.S. recorded no rain in October, including the cities of Philadelphia, Atlanta, Birmingham, Dallas, Las Vegas, and Sacramento. Over 70 weather stations recorded the driest October on record.

The map above shows conditions in the contiguous U.S. on October 29, 2024, as reported by the U.S. Drought Monitor, a partnership of the U.S. Department of Agriculture, NOAA, and the University of Nebraska-Lincoln. The map depicts drought intensity in progressive shades of yellow to red. It is based on an analysis of climate, soil, crop, and water condition measurements from more than 350 federal, state, and local observers around the country. NASA contributes several measurements and models that aid the drought monitoring effort.

Drought had expanded from covering just 12 percent of the country in June to 54 percent as of October 29. The rapid development created what NOAA describes as a “flash drought” in many parts of the country. Flash droughts are typically brought on by lower-than-normal rates of precipitation, accompanied by abnormally high temperatures, wind, or radiation.

“Although droughts usually develop slowly over the course of months and years, a flash drought rapidly intensifies over the course of a few weeks to a couple of months,” said Caily Schwartz, a scientist at the Global Water Security Center at the University of Alabama. Schwartz noted that in Nebraska, where the National Drought Mitigation Center is located, there has been little rain and higher-than-normal temperatures in October. Much of the state was in severe drought (represented as orange in the map) in late October.

Almost the entire country was warmer than normal the week of October 23-29, and drought was present in every state except Alaska and Kentucky. The High Plains and South were the warmest regions, with temperatures 10 to 12 degrees Fahrenheit (6 to 7 degrees Celsius) above normal.

Even in the Southeast where Hurricane Helene dropped significant precipitation in late September, many places dried out rapidly, with some recording zero precipitation since the hurricane.

“This fall has been a prime example of flash drought across parts of the U.S.,” said Jason Otkin, a meteorologist at the University of Wisconsin-Madison. “These events can take people by surprise because you can quickly go from being drought-free to having severe drought conditions.”

Otkin co-authored research published in Science that showed that droughts have intensified more rapidly since the 1950s due to human-caused climate change. According to the research team, flash droughts have become more common over much of the world, making drought monitoring and forecasting more difficult.

NASA Earth Observatory image by Michala Garrison, using data from the United States Drought Monitor at the University of Nebraska-Lincoln. Story by Emily Cassidy.

October 2024 was the 3rd driest October since 1895 according to (unofficial) Prism climate data. Extensive areas of record to near record dryness.

Click on a thumbnail graphic to view a gallery of snowpack data from the NRCS.

Click the link to read the article on the Summit Daily website (Robert Tann). Here’s an excerpt:

Amid warmer-than-average fall temperatures, Colorado’s snowpack levels are pacing above normal…As of Friday, Nov. 1, the statewide snowpack was at 143% of the 30-year median, which is considered the historical normal, according to data from the Natural Resources Conservation Service…Recent storms have delivered cooler weather to mountain and Western Slope areas that, in some places, were around 15 degrees above normal during the first half of October, Aleksa said. The bulk of the snowfall has been concentrated in the San Juans region, which netted between 1 to 2 feet of fresh powder during the two most recent storms that hit in late October…Snowpack levels for river basins in that area sit well above 200% of normal, helping boost the state’s overall numbers. Yet in the eastern part of the state, persistent dry weather has stymied snowpack.  In the South Platte River Basin, which stretches along the Front Range from Fort Collins down to Castle Rock, snowpack stood at 43% of normal as of Friday. In the Arkansas River Basin, which spans the south central part of the state, levels stood at 84%…

“The benefit of the last (storm) systems is it helped bring our temperatures from well above normal down to near or even slightly below-normal,” [Matthew] Aleksa said. “Needless to say, late this weekend and into next week it does look like we’re going to see more mountain snow and cooler conditions … (and) these systems coming in help reinforce that cold air and keep these temperatures lower.” 

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

The dry pattern that has been impacting much of the country has continued into this current period. The wettest areas were along the coast in the Pacific Northwest, with some locations recording over 2 inches of rain for the week. Other areas receiving some precipitation were in the Four Corners region, the Midwest and parts of the South, but many of these totals were minimal and did little to impact the drought conditions. The Southern Plains and South were the warmest regions, with departures of 10-12 degrees above normal this week. Almost the entire country was warmer than normal, with only areas of the Northeast and Pacific Northwest having near to slightly below normal temperatures. As the month is ending, many locations will be at or near record dryness across the country. For the Lower 48 states, there has not been this much drought shown on the U.S. Drought Monitor since December 2022. Areas of the Southeast that were impacted by significant precipitation associated with landfalling hurricanes have dried out rapidly, with some locations recording zero precipitation since the hurricanes. Some precipitation development at the end of the current period could help ease conditions into the next week, but that will be determined on the next map…

High Plains

Dryness again dominated the region with only areas of far southeast Nebraska and northeast Kansas, northeast Wyoming and northwest South Dakota recording any significant precipitation. Coupled with the dryness, temperatures have been unseasonably warm for the region with most all areas 4-8 degrees above normal for the week. Drought expanded and intensified across the region this week with severe and extreme drought expanding over western North Dakota, and moderate drought and abnormally dry conditions expanding over the southeast. Severe and extreme drought expanded over much of western and southern South Dakota and also over western and northern Nebraska. Eastern Nebraska saw both moderate and severe drought expand. In Kansas, severe and extreme drought expanded over the southeast while severe drought expanded over the northeast and western portions of the state. Moderate drought also expanded in western Kansas. In northeast Colorado, moderate drought and abnormally dry conditions expanded, with both moderate and severe drought expanding in southeast Colorado. Southeast Wyoming saw expansion of moderate, severe, and extreme drought while eastern Montana had severe and extreme drought expand to the west…

West

The West was the one region that had substantial precipitation during the week, with rains in the areas of central to northeast Arizona, western Colorado, central to western Wyoming, central Utah, southern Oregon into Idaho and along the coastal areas of the Pacific Northwest. Minimal improvements were made to the abnormally dry conditions along the Oregon coast. Moderate drought improved in northern California and northern Nevada as well as into southern Oregon and Idaho. Abnormally dry conditions disappeared from the rest of southwest Colorado. Severe and extreme drought expanded in northern Colorado into southern Wyoming and severe drought expanded in western Wyoming…

South

Temperatures were well above normal over the region with areas of north Texas and much of eastern Oklahoma 12-16 degrees above normal for the week. Some very light rains were reported in central Arkansas, but much of the region was dry this week. With the fall warmth and dryness impacting the region, drought intensified and expanded. In Oklahoma, the north-central and eastern portions of the state saw severe and extreme drought expand, with some moderate drought expanding in the east. Widespread degradation took place over much of northern and eastern Texas and into the southern portions of the state, where almost every drought category intensified, most now in severe drought or worse. Moderate and severe drought expanded over portions of West Texas as well. In Arkansas, most of the western portions of the state had degradation this week, now in severe to extreme drought. Moderate drought expanded over southeast Arkansas. Severe drought emerged in northwest and southwest Louisiana, and moderate drought expanded over more of the east and southeastern areas. In Mississippi, moderate and severe drought expanded in the southern half of the state and in a small area of the northeast part of the state. In Tennessee, the short-term dryness allowed slight expansion of the severe and moderate drought in the southern portions of the state. Abnormally dry conditions filled in the rest of northern Tennessee…

Looking Ahead

Over the next 5-7 days, it is anticipated that the dry pattern will break over much of the Plains, Midwest and into the South, with widespread precipitation from north Texas to Wisconsin. The Western portions of the country will also be in a more active pattern, with the coastal areas, the Great Basin, and part of the Rocky Mountains seeing some precipitation. Temperatures will continue to be warmer than normal out in front of the precipitation, with the eastern Midwest, South, and East all anticipated to be warmer than normal, including departures of 13-15 degrees above normal in the Ohio River basin. Cooler- than-normal temperatures will settle in over the West, with departures of 10-13 degrees below normal over much of Nevada.

The 6-10 day outlooks show that the best chance for above-normal temperatures is over the East while much of the West has the best chance for below-normal temperatures centered on the Southwest. The greatest chance for above-normal precipitation is over the southern Rocky Mountains with above normal chances in the Plains and into the Midwest while the greatest chance for below-normal precipitation is over northern California and much of the West.

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

October 24, 2024

Fast-growing fires were responsible for nearly 90 percent of fire-related damages despite being relatively rare in the United States between 2001-2020, according to a new CU Boulder-led study. “Fast fires,” which thrust embers into the air ahead of rapidly advancing flames, can ignite homes before emergency responders are able to intervene. The work, published today in Science, shows these fires are getting faster in the Western U.S., increasing the risk for millions of people.

The research highlights a critical gap in hazard preparedness across the U.S. — National-level fire risk assessments do not account for fire speed or provide insight into how people and communities can better prepare for rapid fire growth events.

“We hear a lot about megafires because of their size, but if we want to protect our homes and communities, we really need to appreciate and prepare for how fast fires move,” said Jennifer Balch, CIRES fellow, associate professor of Geography, and the lead author of the study. “Speed matters more for keeping people safe.”

Balch and her colleagues were inspired to look closer at fire speed after the Marshall Fire, which destroyed more than 1,000 homes in Boulder County, Colorado, in December 2021. The fire burned less than 6,100 acres (24.7 square kilometers) but grew quickly due to a combination of dry conditions and high winds. Less than an hour after the fire was reported, it had spread to a town 3 miles (4.8 kilometers) away, eventually prompting the evacuation of tens of thousands of people. In the aftermath, Balch’s team was eager to understand how fire growth rates impact fire risk across the country.

The researchers used satellite data to analyze the growth rates of over 60,000 fires in the contiguous U.S. from 2001-2020. Using a cutting-edge algorithm, which involves applying a set of calculations to each satellite pixel, they identified and recorded the perimeter of each fire for each day it was active.

“Until now, we had scattered information about fire speed,” said Virginia Iglesias, interim director of Earth Lab and co-author of the study. “We harnessed Earth observations and remote sensing data to learn about fire growth across the nation in a systematic manner.”

The team used the fire perimeter maps to calculate the growth rate of each fire as it progressed. They then zoomed in on the fastest fires, which grew more than 4,003 acres (16.2 square kilometers) in a single day, and probed how the highest growth rates changed over time. The analysis revealed a staggering 250 percent increase in the average maximum growth rate of the fastest fires over the last two decades in the Western U.S.

“Fires have gotten faster in the western U.S. in just a couple of decades,” Balch said. “We need to focus on what we can do to prepare communities: hardening homes and making robust evacuation plans.”

To evaluate the impacts of fast fires on people and infrastructure, the researchers compared the growth rates of the fastest fires to information recorded in incident reports about the number of structures damaged or destroyed per fire event. They found that fast fires accounted for 88 percent of the homes destroyed between 2001 and 2020 despite only representing 2.7 percent of fires in the record. Fires that damaged or destroyed more than 100 structures exhibited peak fire growth rates of more than 21,000 acres (85 square kilometers) in a single day.

“These results change how we think about wildfire risk because they position growth rate as a key determinant of a fire’s destructive potential,” Iglesias said.

The work also highlights a critical risk assessment gap. At the national level, wildfire risk models include parameters for area burned, intensity, severity, and probability of occurrence, but they do not incorporate growth rate or other measures of fire speed. Government agencies and insurance companies that use these models are therefore missing vital information about how fires spread, which homeowners could use to better protect themselves and their communities. The authors believe this needs to change.

“When it comes to safeguarding infrastructure and orchestrating efficient evacuations, the speed of a fire’s growth is arguably more critical than its sheer size,” Iglesias said.