Day: March 30, 2023

#Drought news March 30, 2023: Heavier snows occurred in some of the mountainous areas of #Colorado and #Wyoming, leading to some improvements

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

US Drought Monitor map March 28, 2023.
High Plains Drought Monitor map March 28, 2023.
West Drought Monitor map March 28, 2023.
Colorado Drought Monitor map March 28, 2023.

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

This Week’s Drought Summary

After the wet pattern continued in parts of the West this week, building off of widespread wet and snowy weather this winter, widespread improvements were made to the drought depiction, especially in northern California, northern Nevada, southern Idaho and Utah, with scattered changes, mostly improvements, also taking place in other western states. East of the Rockies, drought and abnormally dry conditions mostly stayed the same or worsened in the Texas and Oklahoma panhandles, northwest Oklahoma, and central and southeast Texas. The western edge of heavy rains this week fell mostly along and southeast of the Interstate 44 corridor in Oklahoma and western north Texas, leading to further tightening of an already tight drought condition gradient in these areas. Farther west in northwest Oklahoma and western Kansas, extreme and exceptional drought persisted or intensified. Very dry recent weather continued in the Florida Peninsula, where severe drought expanded in coverage and extreme drought developed in response to quickly increasing fire danger. In the Mid-Atlantic, short- and long-term drought and abnormal dryness grew a bit in coverage this week. Conditions also worsened in northwest Puerto Rico and the southern Puerto Rico coast, the latter of which reported nearby forest fires. For more specific details, please refer to the regional paragraphs below…

High Plains

The High Plains region generally saw drier weather this week, with a few areas of the central and northern Great Plains seeing some precipitation. Heavier snows also occurred in some of the mountainous areas of Colorado and Wyoming, leading to some improvements to drought and abnormal dryness areas there. Colder-than-normal weather occurred over the entire region. Compared to normal, the coldest temperatures, in some cases 15 to 20 degrees below normal, occurred in North Dakota, western Wyoming and western Colorado. In southern Colorado, abnormal dryness and moderate drought lessened in coverage in the San Luis Valley and Sangre de Cristo Mountains. Recent precipitation and lessening long-term precipitation deficits, as well as deep snowpack in some areas, led to some localized improvements to ongoing drought areas in the Dakotas, western Nebraska and far northeast Colorado, while mounting precipitation deficits and low soil moisture led to localized worsening of conditions in eastern Nebraska and northeast North Dakota…

Colorado Drought Monitor one week change map ending March 28, 2023.

West

A wet pattern continued in parts of the West this week, especially western Oregon and Washington and coastal California and parts of the Sierra Nevada. Locally heavy precipitation amounts also fell in parts of Utah and central Arizona. Colder-than-normal temperatures also occurred over most of the West region this week. Temperatures generally ranged from 5 to 10 degrees below normal in the northern, western and southern parts of the region, while Nevada, Utah and southern Idaho experienced temperatures ranging from 10 to 20 degrees colder than normal. The recent snowfall in southern Colorado in the Sangre de Cristo Mountains also allowed for improvements to conditions across the border in New Mexico. Large areas of the Intermountain West saw improvements to drought conditions this week, as long-term precipitation deficits lessened, snowpack remained high or grew, soil moisture and streamflow increased or remained high and groundwater conditions improved. Extreme drought was removed from central Utah, while moderate and severe drought lessened in coverage there. Much of southern Idaho and northern Nevada saw improvements this week after hefty precipitation amounts this winter. Conditions also improved west of Las Vegas, where long-term precipitation deficits lessened and groundwater and soil moisture locally improved. Moderate drought was removed in parts of northern California as well, where long-term precipitation deficits continued to lessen. For similar reasoning, drought coverage lessened in a few parts of Montana as well. Due to recent precipitation and large snowpack and lessening long-term precipitation deficits, moderate drought and abnormal dryness lessened in coverage in western Oregon…

South

Aside from Oklahoma and southwest Texas, near-normal or warmer-than-normal temperatures were common across much of the South region, with some locations seeing temperatures 5-10 degrees warmer than normal. Parts of north-central Texas and Oklahoma (especially southeast of Interstate 44) saw moderate to heavy rain amounts from thunderstorms, exceeding an inch or two in a few spots. Over 2 inches of rain fell across large areas of Arkansas and Tennessee, while heavier rains farther south in Louisiana and Mississippi were more scattered in nature. Some of this rainfall was associated with a severe thunderstorm outbreak, which was responsible for a destructive tornado that reached a maximum intensity of EF4 in Rolling Fork, Miss. Most of the rest of Texas, and Oklahoma northwest of Interstate 44, remained mostly or completely dry. The recent dry weather, very low groundwater and streamflow and mounting long-term precipitation deficits in central Texas and parts of the Edwards Plateau led to the expansion of moderate, severe, extreme and exceptional drought in some areas. Short-term dryness and decreasing streamflow also led to expanding drought conditions farther east in Texas, except for areas that saw heavier rain amounts this week. Short- and long-term extreme and exceptional drought also increased in coverage in the Texas Panhandle, the Oklahoma Panhandle and parts of northwest Oklahoma, the latter of which has recently experienced blowing dust and sand and a struggling winter wheat crop. Along the Interstate 44 corridor, the gradient in drought conditions increased further, with areas west of Oklahoma City experiencing extreme drought, while southern suburbs of Oklahoma City are only abnormally dry now, with dryness-free conditions nearby to the southeast…

Looking Ahead

From the morning of Wednesday, March 29 through the evening of Monday, April 3, the National Weather Service Weather Prediction Center is forecasting precipitation in some of the higher elevation areas of California, with heavier amounts likely in western Oregon and Washington. Some mountainous areas of Idaho, Colorado, southwest Montana, Wyoming and Utah will likely see over 0.75 inches of precipitation, with some locally heavy amounts possible. Farther east, the southern Great Plains are likely to remain dry, while precipitation is likely from South Dakota into the Upper Great Lakes, and from the Lower Great Lakes southwest toward the Lower Mississippi Valley as a strong storm system traverses the central Great Plains and Midwest. Localized precipitation amounts at or exceeding 0.75 inches are possible for northeast New York and Vermont as well.

From April 4-8, the National Weather Service Climate Prediction Center forecast strongly favors colder-than-normal weather in the West and warmer-than-normal conditions in the Southeast, with the dividing line between warmer and colder than normal running from Chicago southwest to St. Louis southwest to the Texas Big Bend region. Northwest of this line, below-normal temperatures generally become more likely, with the opposite true southeast of this line. Below-normal temperatures are slightly favored in much of Alaska, especially in the southeast regions. Above-normal precipitation is favored across much of the contiguous U.S., excluding the Florida Panhandle, western Montana, southern Arizona, New Mexico, and the El Paso area. The highest confidence for above-normal precipitation for this time period is over South Dakota, North Dakota and Minnesota. Wetter-than-normal weather is also favored in Alaska.

US Drought Monitor one week change map ending March 28, 2023.

It’s all white: #Colorado statewide #snowpack tops 140%, though reservoirs still low — @WaterEdCO (March 30, 2023)

Ultra deep snows in Silverton, Colorado. Credit: Flickr_creative commons

Click the link to read the article on the Water Education Colorado website (Jerd Smith):

Colorado is awash in white this spring, with statewide snowpack topping 140% of average this week, well above the reading a year ago, when it stood at just 97% of normal.

“Conditions in the American West are way better than they were last year at this time,” said state climatologist Russ Schumacher at a joint meeting Tuesday of the state’s Water Availability Task Force and the Governor’s Flood Task Force. “In Colorado we went from drought covering most of the state to most of the state being out of drought.”

Like other western states, mountain snowpacks in Colorado are closely monitored because as they melt in the spring and summer, their runoff delivers much of the state’s water.

A drought considered to be the worst in at least 1,200 years has devastated water supplies across the West. While no one is suggesting the dry spell is over, Colorado water officials said 2023 will likely allow for a significant recovery in reservoirs and soil moisture.

Colorado snowpack basin-filled map March 29, 2023 via the NRCS.

The snow is deepest in the southwestern part of the state, where the San Juan/Dolores river basin is seeing a snowpack of 179% of average.

The Yampa Basin, in the northwest corner of Colorado, is also nearing historic highs, with snowpack registering 145% of average, according to the Natural Resources Conservation Service Snow Survey.

There is considerably less white stuff east of the Continental Divide in the Arkansas River Basin, where snowpack remains slightly below average and in the South Platte Basin, where snowpack is just above average.

The outlook for the seven-state Colorado River Basin has improved dramatically as well, with the U.S. Bureau of Reclamation, in its March 15 report, showing that Lake Powell is likely to see some 10.44 million acre-feet of new water supply by the end of September, or inflows at 109% average.

The Colorado River Basin includes seven states, with Colorado, New Mexico, Utah and Wyoming comprising the Upper Basin and Arizona, California and Nevada making up the lower basin. And it is in the mountains of the Upper Basin, especially in Colorado, where most of the water for the entire system is generated.

That Colorado is seeing such spectacular snow levels this spring, bodes well for everyone. “This is good news for the Colorado River Basin, no doubt about that,” Schumacher said.

Still the drought-strapped Colorado River system will see little storage recovery this year, according to Reclamation, which is forecasting that Lake Powell will see storage at just 32% of capacity by the end of the year. It had dropped to just 23% of capacity last year, prompting ongoing emergency releases from Utah’s Flaming Gorge Reservoir to help keep the system from crashing.

Within Colorado, statewide reservoir storage this month stands at 80% of average, up slightly from this time last year when it registered 75% of average.

Reservoirs within Colorado are expected to see a significant boost in storage levels. Colorado’s largest reservoir, Blue Mesa, was just 36% full earlier this month, but is projected to receive enough new water this year that it will be 71% full by the end of the year, according to Reclamation.

Flood task force officials said the deep snows, particularly in the southwestern and northwestern corners of the state, could cause flooding this spring and summer, especially if there is a series of hot, dry, windy days or major rain storms.

“We are blessed in large part because our snowpack tends to run off in a well-behaved manner,” said Kevin Houck, section chief of watershed and flood protection at the Colorado Water Conservation Board. “But I will say that I am watching things more closely this year. It’s not just the presence of snow that creates our problems. It needs to have a trigger as well. The classic trigger is the late spring warmup. And what can cause even more damage is when we get rain on snow as well.”

Jerd Smith is editor of Fresh Water News. She can be reached at 720-398-6474, via email at jerd@wateredco.org or @jerd_smith.

West snowpack basin-filled map March 29, 2023 via the NRCS

The Upper #GunnisonRiver #Water Conservancy District awards 2023 grant program

Lower Spring Creek Ditch Improvement. Photo credit: Upper Gunnison River Water Conservancy District

Click the link to read the release on the Upper Gunnison River Water Conservancy District website:

2023 GRANT FUNDS SUPPORT NUMEROUS PROJECTS THROUGHOUT UPPER GUNNISON BASIN 

The Board of Directors of the Upper Gunnison River Water Conservancy District (UGRWCD) voted at the March 27th Board meeting to award $297,170 to organizations and individuals in the Upper Gunnison River Basin.  These grant funds will be used for projects that will enhance water supply, improve stream and irrigation conditions, conserve water, provide water education benefits and restore wetlands.  There was a diverse group of project applications from all over the Upper Gunnison River. Examples include a City of Gunnison native plant xeriscape project at 11th & Quartz Street intersection with educational signage, Coal Creek Dam Construction (Lake Irwin), and irrigation demonstration projects – one utilizing a combined plastic irrigation pipe, headwall, and turnout gate for improved irrigation water management and another utilizing an IntelliDitch HDPE Liner to prevent seepage loss.

All applicants were required to provide a 50 percent cost match and their projects had to be consistent with the District’s purpose, mission, and objectives.

UGRWCD General Manager Sonja Chavez noted during this year’s funding cycle, the District received requests for funding that totaled $370,613. 

“It was a very competitive cycle and I strongly encourage those who were not funded to reach out to us to discuss their project and how they can make it stronger for the next cycle,” said Sonja. 

Sonja also pointed out the District Grant Funding Program is a prime example of the District’s responsible allocation of tax revenues to directly benefit diverse water improvement projects in the basin.  “I am delighted to report that during this cycle, our District grant funds were leveraged at a ratio of 1:3 with outside funding sources which just amplifies returns on District investment.

The UGRWCD Grant Program follows an annual cycle with applications due in February each year.  General Manager Chavez urges potential applicants or individuals, even those just wondering about a water project, to reach out to the District now so that the District can help with infrastructure assessment or engineering that can assist in ensuring that the project can be funded.  If you have a water project in mind, please call the District at (970) 641-6065 to schedule a consultation.

Bridge 40 Diversion. Photo credit: Upper Gunnison River Water Conservancy District
Chittendon Diversion Improvement. Photo credit: Upper Gunnison River Water Conservancy District

Why tornadoes are still hard to forecast – even though storm predictions are improving

A series of images in this photo montage shows the evolution of a tornado. JasonWeingart via Wikimedia, CC BY-SA

Chris Nowotarski, Texas A&M University

As a deadly tornado headed toward Rolling Fork, Mississippi, on March 24, 2023, forecasters saw the storm developing on radar and issued a rare “tornado emergency” warning. NOAA’s Weather Prediction and Storm Prediction centers had been warning for several days about the risk of severe weather in the region. But while forecasters can see the signs of potential tornadoes in advance, forecasting when and where tornadoes will form is still extremely difficult.

We asked Chris Nowotarski, an atmospheric scientist who works on severe thunderstorm computer modeling, to explain why – and how forecast technology is improving.

Why are tornadoes still so difficult to forecast?

Meteorologists have gotten a lot better at forecasting the conditions that make tornadoes more likely. But predicting exactly which thunderstorms will produce a tornado and when is harder, and that’s where a lot of severe weather research is focused today.

Often, you’ll have a line of thunderstorms in an environment that looks favorable for tornadoes, and one storm might produce a tornado but the others don’t.

The differences between them could be due to small differences in meteorological variables, such as temperature. Even changes in the land surface conditions – fields, forested regions or urban environments – could affect whether a tornado forms. These small changes in the storm environment can have large impacts on the processes within storms that can make or break a tornado.

Scientists stand near a truck outfitted with measuring devices with a dramatic storm on the horizon.
One way scientists gather data for understanding tornadoes is by chasing storms. Annette Price/CIWRO, CC BY

One of the strongest predictors of whether a thunderstorm produces a tornado relates to vertical wind shear, which is how the wind changes direction or speed with height in the atmosphere.

How wind shear interacts with rain-cooled air within storms, which we call “outflow,” and how much precipitation evaporates can influence whether a tornado forms. If you’ve ever been in a thunderstorm, you know that right before it starts to rain, you often get a gust of cold air surging out from the storm. The characteristics of that cold air outflow are important to whether a tornado can form, because tornadoes typically form in that cooler portion of the storm.

How far in advance can you know if a tornado is likely to be large and powerful?

It’s complicated. Radar is still our biggest tool for determining when to issue a tornado warning – meaning a tornado is imminent in the area and people should seek shelter.

The vast majority of violent tornadoes form from supercells, thunderstorms with a deep rotating updraft, called a “mesocyclone.” Vertical wind shear can enable the midlevels of the storm to rotate, and upward suction from this mesocyclone can intensify the rotation within the storm’s outflow into a tornado.

If you have a supercell and it has strong rotation above the ground, that’s often a precursor to a tornado. Some research suggests that a wider mesocyclone is more likely to create a stronger, longer-lasting tornado than other storms.

Forecasters also look at the storm’s environmental conditions – temperature, humidity and wind shear. Those offer more clues that a storm is likely to produce a significant tornado. https://www.youtube.com/embed/R7CD6MpTefs?wmode=transparent&start=0 What radar showed as a tornado headed toward Rolling Fork on March 24, 2023.

The percentage of tornadoes that receive a warning has increased over recent decades, due to Doppler radar, improved modeling and better understanding of the storm environment. About 87% of deadly tornadoes from 2003 to 2017 had an advance warning.

The lead time for warnings has also improved. In general, it’s about 10 to 15 minutes now. That’s enough time to get to your basement or, if you’re in a trailer park or outside, to find a safe facility. Not every storm will have that much lead time, so it’s important to get to shelter fast.

What are researchers discovering today about tornadoes that can help protect lives in the future?

If you think back to the movie “Twister,” in the early 1990s we were starting to do more field work on tornadoes. We were taking radar out in trucks and driving vehicles with roof-mounted instruments into storms. That’s when we really started to appreciate what we call the storm-scale processes – the conditions inside the storm itself, how variations in temperature and humidity in outflow can influence the potential for tornadoes.

Scientists can’t launch a weather balloon or send instruments into every storm, though. So, we also use computers to model storms to understand what’s happening inside. Often, we’ll run several models, referred to as ensembles. For instance, if nine out of 10 models produce a tornado, we know there’s a good chance the storm will produce tornadoes.

The National Severe Storms Laboratory has recently been experimenting with tornado warnings based on these models, called Warn-on-Forecast, to increase the lead time for tornado warnings.

A destroyed home with just one wall standing and furniture strewn about in Rolling Fork, Mississippi, after the tornado March 24, 2023.
An early warning can be the difference between life and death for people in homes without basements or cellars. Chandan Khanna/AFP via Getty Images

There are a lot of other areas of research. For example, to better understand how storms form, I do a lot of idealized computer modeling. For that, I use a model with a simplified storm environment and make small changes to the environment to see how that changes the physics within the storm itself.

There are also new tools in storm chasing. There’s been an explosion in the use of drones – scientists are putting sensors into unmanned aerial vehicles and flying them close to and sometimes into the storm.

The focus of tornado research has also shifted from the Great Plains – the traditional “tornado alley” – to the Southeast.

US map showing highest number of tornadoes in Mississippi, Alabama and western Tennessee.
A map of severe tornadoes from 1986 to 2015 shows a large number in the Southeast. NOAA Storm Prediction Center

What’s different about tornadoes in the Southeast?

In the Southeast there are some different influences on storms compared with the Great Plains. The Southeast has more trees and more varied terrain, and also more moisture in the atmosphere because it’s close to the Gulf of Mexico. There tend to be more fatalities in the Southeast, too, because more tornadoes form at night.

We tend to see more tornadoes in the Southeast that are in lines of thunderstorms called “quasi-linear convective systems.” The processes that lead to tornadoes in these storms can be different, and scientists are learning more about that.

Some research has also suggested the start of a climatological shift in tornadoes toward the Southeast. It can be difficult to disentangle an increase in storms from better technology spotting more tornadoes, though. So, more research is needed.

Chris Nowotarski, Associate Professor of Atmospheric Science, Texas A&M University

This article is republished from The Conversation under a Creative Commons license. Read the original article.