Is California's Drought Finally Ending?

Konrad Fiedler/AFP/Getty Images
Konrad Fiedler/AFP/Getty Images

One of the most devastating weather disasters in the past decade wasn’t a tornado tearing through the Plains or a hurricane swirling ashore, but rather the slow-motion dehydration of the most populous state in the United States. California has spent the past five years mired in its worst drought in centuries, which devastated crops and water supplies across the state. While the adverse effects of the drought will take much longer to wear off, the state recently got some good news about its improving liquid fortunes.

The latest issue of the United States Drought Monitor (USDM) shows that just over half of California is still in a drought. More than half of an enormous state steeped in drought sounds pretty bad, but conditions have actually improved tremendously over the past couple of months.

The United States Drought Monitor for California on January 31, 2017. Image Credit: Dennis Mersereau

At the end of January 2016, 95 percent of California was in some level of drought, and 40 percent of that area was in that scale-topping "exceptional drought" category. Today, one-fifth of the state is still in a severe drought, and a tiny portion—just under 2 percent—is in an extreme drought. No part of California is experiencing an exceptional drought anymore, the most urgent level on the five-point scale used to determine drought status.

The USDM is a weekly analysis drawn by scientists who look at precipitation, groundwater, and soil data to determine how dry the ground is across the entire country. The lowest categories—abnormally dry and moderate drought—are usually transient and can come and go with unusual dry spells. But in the case of California’s water troubles, extreme and exceptional drought conditions have become commonplace over the past few years.

The worst drought in the modern history of California began at the beginning of 2012 and steadily worsened over the next five years. The intensely dry weather came to a head in 2014, leading some scientists to declare the presence of a “megadrought”—a lack of rain in the western United States so extreme and long-lasting that such conditions haven’t occurred in this region since the 12th century. But then conditions improved somewhat during the winters of 2015 and 2016, culminating with this winter’s drought-busting deluge.

The progression of California’s drought as seen through the USDM’s weekly drought analyses. Image Credit: Dennis Mersereau

 
The solution to drought is always a prolonged period of steady, soaking rainfall and, in the case of mountainous regions, decent storms with accumulating snow. Weather patterns began to shift early this winter into a configuration that let ample moisture flow over drought-stricken areas of the West Coast. A steady flow of tropical moisture, a phenomenon known as an “atmospheric river,” helped storm systems wring out as much precipitation as possible over areas that needed it the most.

The recent period of much-looked-for rain in California started in earnest around the middle of December 2016 and continued through the end of January. After just above average precipitation in December in San Francisco, the Bay Area saw nearly twice its normal January rainfall by the end of January. It’s a similar story across the rest of California.

Precipitation between November 3, 2016 and February 1, 2017, as compared to normal. Image Credit: Dennis Mersereau

There’s even better news in the mountains, where springtime runoff contributes significantly to reservoirs and groundwater in lower-lying areas of the state. The storms that brought rain to the rest of California brought even greater amounts of snow to the mountains. Some mountainous towns have snow depths taller than most houses. A ski resort near Lake Tahoe saw so much snow in one January snowstorm that their chair lifts were buried.

But the latest forecast from the Climate Prediction Center calls for a general trend of below-average rainfall during the month of February and equal chances for below- or above-average precipitation through the early spring months. It’s worth noting that another long period of dry weather could erase the gains California has seen over the past month or two. More often than not, drought begets drought, and it can be a tough cycle to break once it begins. Still, the recent rainfall is a welcome sign nonetheless, and one that will hopefully continue in rainy seasons to come.

12 Powerful Facts About Hurricanes

iStock/shaunl
iStock/shaunl

Hurricanes are a stunning, and dangerous, display of nature’s power. They’re some of the largest and most intense storms nature can produce. Today, we know more about these systems and have an easier time measuring and predicting them than ever before. There’s more than meets the eye when it comes to hurricanes. As the 2019 hurricane season kicks off (it runs from June 1st through November 30th), here are some things you might not know about these dangerous storms.

1. Hurricanes are only "hurricanes" around North America.

A tropical cyclone is a compact, low-pressure system fueled by thunderstorms that draw energy from the heat generated by warm ocean waters. These tropical cyclones acquire different names depending on how strong they are and where in the world they form. A mature tropical cyclone is called a hurricane in the Atlantic and eastern Pacific Oceans. What’s known as a hurricane in the Atlantic is called a typhoon near Asia and simply a cyclone everywhere else in the world.

2. Hurricanes come in all shapes and sizes.

Not all hurricanes are picture-perfect. Some storms can look so disorganized that it takes an expert eye and advanced technology to spot them. A full-fledged hurricane can be as small as a few dozen miles across or as large as one-half of the United States, as was the case with Typhoon Tip in the western Pacific Ocean in 1979. The smallest tropical cyclone on record was 2008’s Tropical Storm Marco, a tiny storm in the Gulf of Mexico that almost made it to hurricane strength. Marco’s strong winds only extended 12 miles from the eye of the storm—a distance smaller than the length of Manhattan.

3. The greatest danger in a hurricane is in the eyewall.

The spiraling bands of wind and rain that radiate from the center of a hurricane are what give these storms their distinctive buzzsaw shape. These bands can cause damage, flooding, and even tornadoes, but the worst part of a hurricane is the eyewall, or the tight group of thunderstorms that rage around the center of the storm. The most severe winds in a hurricane usually occupy a small part of the eyewall just to the right of the storm’s forward motion, an area known as the right-front quadrant. The worst damage is usually found where this part of the storm comes ashore.

4. The eye of a hurricane is very warm.

The core of a hurricane is very warm—they are tropical, after all. The eye of a hurricane is formed by air rushing down from the upper levels of the atmosphere to fill the void left by the low air pressure at the surface. Air dries out and warms up as it rapidly descends through the eye toward the surface. This allows temperatures in the eye of a strong hurricane to exceed 80°F thousands of feet above the Earth's surface, where it’s typically much colder.

5. You can tell a lot about a hurricane by its eye.

Like humans, you can tell a lot about a hurricane by looking it in the eye. A ragged, asymmetrical eye means that the storm is struggling to strengthen. A smooth, round eye means that the storm is both stable and quite strong. A tiny eye—sometimes called a pinhole or pinpoint eye—is usually indicative of a very intense storm.

6. Some hurricanes have two eyes.

An eye doesn’t last forever. Storms frequently encounter a process known as an “eyewall replacement cycle,” which is where a storm develops a new eyewall to replace the old one. A storm weakens during one of these cycles, but it can quickly grow even more intense than it originally was once the replacement cycle is completed. When Hurricane Matthew scraped the Florida coast in October 2016, the storm’s impacts were slightly less severe because the storm underwent an eyewall replacement cycle just as it made its closest approach to land.

7. The strong winds that a hurricane creates are only part of the danger.

While strong winds get the most coverage on the news, wind isn’t always the most dangerous part of the storm. More than half of all deaths that result from a landfalling hurricane are due to the storm surge, or the sea water that gets pushed inland by a storm’s strong winds. Most storm surges are relatively small and only impact the immediate coast, but in a larger storm like Katrina or Sandy, the wind can push deep water so far inland that it completely submerges homes many miles from the coast.

8 California rarely sees tropical cyclones.

It can seem odd that California occupies hundreds of miles of coastline but always seems to evade the hurricane threat faced by the East Coast. California almost never sees tropical cyclones because the ocean is simply too cold to sustain a storm. Only a handful of tropical cyclones have ever reached California in recorded history—the worst hit San Diego in 1858. The San Diego Hurricane was an oddity that’s estimated to have reached category 1 intensity as it brushed the southern half of the Golden State.

9. Hurricane hunters fly planes into storms.

Aside from satellite and radar imagery, it’s pretty hard to know exactly what a hurricane is doing unless it passes directly over a buoy or a ship. This is where the Hurricane Hunters come in, a brave group of scientists with the United States Air Force and NOAA who fly specially outfitted airplanes directly into the worst of a storm to measure its winds and report back their findings. This practice began during World War II and has become a mainstay of hurricane forecasting in the decades since.

10. Hurricane hunters drop sensors to measure waves.

The Hurricane Hunters assess the storm with all sorts of tools that measure temperature, pressure, wind, and moisture, and have weather radar onboard to give them a detailed view of the entire storm. They regularly release dropsondes to "read" the inside of the storm. Dropsondes are like weather balloons in reverse: instead of launching weather sensors from the ground into the sky, they drop them down through the sky to the ground. The Hurricane Hunters also have innovative sensors that measure waves and sea foam and use the data to accurately estimate how strong the winds are at the surface.

11. We started naming storms to keep track of them.

Meteorologists in the United States officially started naming tropical storms and hurricanes in the 1950s to make it easier to keep track in forecasts and news reports. Since then, naming tropical cyclones has become a worldwide effort coordinated by the World Meteorological Organization, the United Nations agency responsible for maintaining meteorological standards. Today, the Atlantic Ocean and eastern Pacific Ocean each receive a list of alternating masculine and feminine names that are reused every six years.

12. Names are retired if the storm was especially destructive.

If a storm is particularly destructive or deadly, the WMO will “retire” the name from official lists so it’s never used again out of respect for the families of the storm’s victims and survivors. When a name is retired, another name starting with the same letter takes its place. More than 80 names have been retired from the Atlantic Ocean’s list of names since 1954. Earlier this year, it was announced that the names Florence and Michael were being retired as a result of the damage they caused during the 2018 hurricane season; they will be replaced with Francine and Milton when the list is reused in 2024.

This piece originally ran in 2017; it has been updated for 2019.

Denver is About to Experience Summer and Winter Temperatures Within 24 Hours

iStock.com/mphotoi
iStock.com/mphotoi

In a story tailor-made for exhaustive Weather Channel coverage, Denver, Colorado is about to experience one of the more bizarre weather shifts in recent memory. After an expected Tuesday high of 80°F, residents can anticipate a dramatic shift down to 32°F by midday Wednesday, with an initial half-inch of snow accumulation increasing to up to 7 inches by Wednesday night.

Put another way: Citizens who need to make sure they hydrate in the warm temperatures Tuesday will have to bring out the parkas the following day.

The Denver Post reports that the warm air coming ahead of the cold can result in a clash of air masses, prompting areas of low pressure that can create forceful and damaging weather conditions. The storm could bring winds of up to 60 miles per hour and possibly even cause power outages. Snow accumulation should dissipate by the weekend, when temperatures are expected to climb back into the 60s.

The high temperature record for April 9 in Denver is 81°F, set in 1977.

[h/t The Denver Post]

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