During the summer months, a change in wind direction known as a monsoon brings a major shift in the weather for the southwestern US. The season is well known for producing intense dust storms known as haboobs.
Haboobs form when thunderstorms collapse and create a strong downward flow of wind. When this downdraft of air hits the ground ahead of the storm, it blows the loose sand and soil from the desert floor high up in the air, creating a giant wall of dust. Rising quickly, haboobs often reach heights between 5000 and 8000 feet and can span out nearly 100 miles in length. Traveling at speeds ranging from 30 to 60 mph, they can cover large distances rather quickly.
Often called “black blizzards”, these storms turn day into night. Engulfing entire communities in dust, they cause respiratory problems and create serious travel hazards both in the air and on the ground. Luckily, they usually only last a few hours.
Many dry regions of the world experience haboobs, but they were first described in Sudan, along the southern edge of the Sahara Desert. As such, the word comes from Arabic and means, “blowing or blasting furiously.”
A haboob moves across Phoenix, AZ in August 2018. Credit: ChopperGuy/Twitter
Hurricane Barry made landfall at Intracoastal City, Louisiana on Saturday. It was the second named storm and first hurricane of the 2019 Atlantic season.
Coming ashore with winds measured up to 75 mph, Barry was classified as a category one hurricane. But, it was rain rather than the wind that had the biggest impact on the area. Moving slowly at about 7mph, the storm dumped heavy precipitation across the region, causing widespread flooding. Some parishes even saw the water overtop levees in spots. The highest rainfall total of 23.58 inches was reported near Ragley, LA.
Extensive power outages were also reported across Louisiana. According to state energy officials, more than 120,000 customers were in the dark in the wake of the storm.
While downgraded to a tropical storm after landfall, Barry is still laden with moisture. It is expected to bring heavy rain and flooding to regions further inland as it travels north into Arkansas.
Hurricane Barry. Credit: NOAA
Hurricane Maria, the 13th named storm of this Atlantic Hurricane season, made landfall in Yabucoa, Puerto Rico on Wednesday morning. It was the strongest storm to hit the US Territory since 1928.
Coming ashore with sustained winds measured up to 155mph, Maria was classified as a high-end category-four hurricane. Its powerful winds sheared roofs and balconies off buildings, uprooted trees, and toppled power lines. In addition, the storm’s torrential rain unleashed devastating flooding across the island. More than 30 inches of rain was reported near Caguas, PR.
Local authorities say the entire island, home to 3.5 million people, is without power. They do not expect it to be fully restored for four to six months. This unusually lengthy timeframe is largely due to the fact that Puerto Rico is an island with rugged terrain and an electrical grid that has been crumbling for years from a lack of maintenance. The Puerto Rico Electric Power Authority, the territory’s sole provider of electricity, effectively filed for bankruptcy in July.
Before making landfall in Puerto Rico, Maria roared through the Caribbean and reached category-five strength. It battered several other islands, including the US Virgin Islands, which were still reeling from the devastation caused by Hurricane Irma less than two weeks ago. As of Thursday, the death toll from Maria stands at seventeen. But sadly, this number is expected to increase as search and rescue efforts continue across the region.
Maria was the third category-four hurricane to hit the US, or one of its territories, in less than a month. In 166 years of record keeping, this has never happened before.
Hurricane Maria moves across Puerto Rico. Credit: NOAA/NASA
Hurricane season in the eastern Pacific begins today.
Tropical cyclones, known as hurricanes in the United States, develop around the globe at different times of the year. In the northeastern Pacific, they tend to form between May 15 and November 30. This early start is related to the basin’s warm sea surface temperatures and relatively low wind shear.
While powerful, these Pacific storms are generally not as familiar to Americans as those that form in the Atlantic. This is because they rarely make landfall in this country. In fact, it has only happened twice. A hurricane slammed San Diego, CA in 1858 and a tropical storm battered Long Beach, CA in 1939. This low rate of occurrence is attributed to the cold water of the California Current that flows south along the west coast. Nonetheless, Pacific hurricanes can still impact the US.
Developing in the tropics, Pacific storms deteriorate as they travel north to cooler waters and in some cases over the mountains of Mexico. However, their remnants are still laden with moisture when they reach the southwestern US, where they often unleash flooding rains.
East Pacific storms can also cross into the Central Pacific and affect Hawaii. (The dividing line between the two basins is 140°W longitude.) One such storm was Hurricane Iniki in 1992, the worst hurricane in the state’s history. With wind speeds measured up to 145mph, it was rated category-4 on the Saffir-Simpson scale.
This year, the eastern Pacific hurricane season got off to a record early start, with the development of Tropical Storm Adrian on May 9. No other storm in the basin has formed earlier during the satellite era.
After a mostly mild winter in the northeast, a late season snowstorm blasted the region on Tuesday. In New York City, the storm was less intense than originally forecast but still packed a punch.
According to the NWS, 7.6 inches of snow was measured in Central Park setting a new daily record. The previous record of 4.1 inches had been in place since 1958. Strong winds were also part of the storm with gusts reported up to 38mph. The criteria for blizzard conditions, however, were not met in the Big Apple.
Developing from two different systems that merged off the southeast coast, this nor’easter intensified as it moved northward. In weather lingo, it underwent bombogenesis. The storm’s central pressure dropped from 1007mb on Monday night to 974mb on Tuesday afternoon.
While the storm’s precipitation was plentiful, it was more of a wintry mix than a full on snow event in NYC and other cities along the I-95 corridor. This was because the storm was an “inside runner”. It tracked west of the 40/70 benchmark and pulled warmer marine air onshore. More specifically, a shallow zone of air with a temperature warmer than 32°F was wedged between zones of subfreezing air around 5000 feet above the surface. This set-up allowed the snow to melt then refreeze as sleet before hitting the ground.
For areas further inland, to the north and west, the storm lived up to its hype. Numerous communities across eight states received more than 20 inches of snow. Hartwick, NY reported an impressive 48.4 inches, the highest snow total from the storm.
NYC went from 70°F to 7.6 inches of snow in just two weeks. Credit: Melissa Fleming
The weather world has some interesting words and phrases. One of these is “bombogenesis”.
Sounding rather ominous, it is a combination of the words cyclogenesis (storm formation) and bomb. It refers to the explosive or rapid intensification of an area of low pressure. More specifically, it means the central pressure of a storm system drops at least 24 millibars in 24 hours.
Air pressure is measured in millibars (mb) and the lower it is, the stronger the storm.
Taking place along steep temperature gradients, bombogenesis is most common along the east coast where cold continental air masses meet the relatively warm waters of the Gulf Stream. Disturbances in the jet stream above this type of temperature contrast help the air to rise and the pressure to drop.
This process can develop any time of the year but is most likely between October and March. When a system “bombs out” – a variation on the original phrase – strong winds, heavy precipitation, and even lightning can be expected. Nor’easters often become “weather bombs” – another popular variation – as they move up the coast.
The biggest snowstorm of the year is expected to blast the northeastern US on Tuesday. In New York City, on top of the significant snow totals that have been forecast, a blizzard warning is in effect.
Different than a typical winter storm, a blizzard is characterized more by wind speeds and reduced visibility than the amount of snow it produces. According to the NWS, the three main factors for blizzard conditions are:
- Wind – Sustained winds or frequent gusts of 35mph or higher.
- Visibility – Falling and/or blowing snow that reduces visibility to ¼ mile or less.
- Time – High winds and reduced visibility must prevail for at least 3 hours.
These conditions heighten the risk of power outages and often produce whiteout conditions on roadways, making travel extremely dangerous. Stay Safe!
A blizzard warning is in effect for NYC. Credit: NWS
January, a winter month in the northern hemisphere, is a time when we are usually talking about snowstorms. Nevertheless, Hurricane Alex, the first named storm of the 2016 Atlantic Hurricane season has officially formed.
According to the National Hurricane Center, Alex is the first Atlantic hurricane to form in January since 1938. With sustained winds of 85 mph, it is the second strongest January hurricane on record. Hurricane Alice, which formed at the end December 1954 and lasted through early January 1955, had winds that peaked at 90 mph.
Alex transitioned from a sub-tropical storm – a storm that has both tropical and non-tropical characteristics – into a fully tropical system on Wednesday and then strengthened into a category-one hurricane on Thursday morning. This type of rapid intensification is usually associated with the storm moving over very warm ocean waters. In this case, however, the sea surface temperatures in the area were above average, but just barely warm enough to support tropical development. So, according to NOAA, Alex likely got an extra boost from an unstable atmosphere. The wide temperature spread between the warm surface air and a pocket of unusually cold air aloft encouraged convection and helped strengthen the warm core of this off-season storm.
Alex is currently located 490 miles south of the Azores and moving north-northeast at about 20 mph. It is expected to bring strong winds, heavy rain, and storm surge flooding to that archipelago over the next 24 hours.
The Atlantic hurricane season traditionally runs from June 1 to November 30th.
The forecast track for Hurricane Alex. Credit: NOAA/NHC
Gonzalo, the 7th named storm of the 2014 Atlantic hurricane season, made landfall in Bermuda on Friday night. Despite being downgraded from a category-3 to a category-2 hurricane just prior to coming ashore, the storm still caused extensive damage.
Producing a top wind gust of 140-mph and generating waves over 40 feet high, the storm toppled trees and downed power lines. Approximately 90% of the island chain lost power. Crediting advanced preparations, local officials say no fatalities or serious injuries have been reported.
Gonzalo was the second tropical system to hit Bermuda is less than a week. Tropical Storm Fay slammed the popular vacation spot just last Sunday with strong winds and heavy rain. The last time Bermuda was hit twice in one week was when Tropical Storm Emily and Hurricane Floyd both moved over the archipelago in early September 1981.
Hurricane Gonzalo makes landfall in Bermuda. Credit: PTZ_TV
A rare winter storm paralyzed large sections of the southeastern United States yesterday. Serious impacts from snow, sleet, and freezing rain were felt from the Gulf Coast to Virginia.
According to the NWS, 2.6 inches of snow fell in Atlanta, GA – a new daily record for the region’s largest city. As a whole, the Deep South is not accustomed to wintry precipitation and most cities and towns are not equipped to deal it. Salt spreaders and snowplows are in short supply across the region. As a result, major roads turned into sheets of ice creating very hazardous travel conditions.
The timing of the storm made the situation even worse. Arriving in the afternoon, many people were caught on the roads trying to make their way home. Officials have reported hundreds of traffic accidents and stranded vehicles. Many people were even forced to shelter in place overnight in cars, schools, and stores.
Snow and ice bring travel to a stand still near Atlanta, GA. Image Credit: GuardianLV.com