Hurricane Alex: A Rare January Storm in the Atlantic

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.

Hurricane Alex's forecast track. Credit: NOAA/NHC

The forecast track for Hurricane Alex. Credit: NOAA/NHC

From Drought to Flood: Weather Whiplash in Texas

Bouncing between the extremes of drought and flood, the weather whiplash in Texas continued this weekend. For the second time this year, torrential rain caused widespread flooding across the Lone Star State.

The city of Corsicana, south of Dallas, saw more than 18 inches of rain between Friday and Saturday. Flash floods caused extensive damage and even derailed a Union Pacific freight train. In Houston, where they received 8 inches of rain on Saturday and Sunday, bayous swelled out of their banks and flooded roadways. Local officials say Buffalo Bayou near the downtown area rose 20 feet in just 12 hours.

The cause of this prolonged rain event involved the interaction of a few key atmospheric players. First, an area of high pressure over the east coast – with a clockwise circulation – pushed tropical moisture across the Gulf of Mexico and into Texas. Then, there was a strong upper level low – with a counter clockwise circulation – over the southwest and a cold front moving southeast. These added lift to the atmosphere. When the warm saturated air was forced to rise, it cooled. Since cool air holds less moisture than warm air, the moisture was wrung out of the atmosphere in the form of intense rain. Then, on the heels of all that, remnants of Hurricane Patricia from the Pacific Ocean traveled across Mexico and into Texas. It brought even more tropical moisture into the mix.

Ironically, much of Texas was in a drought just last week. It was considered a “flash drought” as it developed very quickly this summer after intense rains and catastrophic flooding in May brought the previous drought to an abrupt end. From drought to flood to drought and back to flood, Texas certainly has had a wild ride with weather this year.

Credit: NBC Train derailed by flood waters near Dallas, TX

Freight train derailed by flood waters near Corsicana, TX. Credit: NBC News

Drought Update: Autumn 2015

This autumn season has been marked by a number of intense rain and flooding events across the US, from South Carolina to California.  Drought, however, continues to plague large sections of this country.

According to the latest report from the US Drought monitor, 58.96% of the nation is in some form of drought. Many areas in the mid-west and the northeast are listed as abnormally dry or experiencing moderate drought. But, it is the western and southern states that have been particularly dry.

In California, despite some unusually heavy rain recently, the long-term drought continues. In fact, 99.86% of the state is experiencing conditions of moderate drought or worse, with 46% in exceptional drought – the worst possible category. These extremely parched conditions have helped fuel an explosive wildfire season across the Golden State.

As discussed in an earlier post, the multi-year drought in Texas came to an abrupt end this past spring with intense rainfall and catastrophic flooding across the region. Over the summer, however, drought conditions returned. Developing fairly quickly, this is known as a flash drought. As of this week, 65.25% of the massive Lone Star State is in some form of drought and 21.40% is in extreme drought. That is serious weather whiplash!

The Drought Monitor is a weekly publication produced by a partnership of government agencies, including the National Drought Mitigation Center, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration.

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Credit: US Drought Monitor.

Heavy Rain Unleashes Massive Mudslide in LA County

Powerful, but slow moving, thunderstorms brought heavy rain to the mountainous region of northern Los Angeles County, California on Thursday afternoon. With the soil hardened from years of drought, the water ran off downhill and unleashed flashfloods and mudslides across the area.

Local officials say the mud – up to 5 feet deep in some spots – trapped hundreds of motorists in their vehicles on Interstate-5 and Route 58. Homes in the Elizabeth Lake area were also surrounded by mud and debris flows. Luckily, no fatalities have been reported.

According to the NWS, Antelope Valley, which sits between I-5 and Rt. 58, received 1.81 inches of rain in 30 minutes. They have described that as a “1,000 year rain event”, which means there is a 1-in-1,000 (0.1%) chance of this type of event happening in any given year. It is interesting to note that this is the second “1,000 year rain event” to happen in the US this month. The other was the historic flooding in South Carolina.

The intensity of this California deluge had two main drivers. The first was a cut-off low-pressure system over the area that provided lift. The second involved the warmer than normal sea surface temperatures in the Pacific Ocean, which allow for increased amounts of evaporation and higher levels of humidity.  Combined, these two factors were able to generate enough instability in the atmosphere to produce heavy thunderstorms.

While experts say this storm was not related to El Niño, it does offer a glimpse of what may be in store for the Southwest over the next few months. The impacts of El Niño are typically strongest during the winter season.

Vehicles stuck in the mud along California's Rt. 58. Credit: Caltrans/EPA

Vehicles stuck in the mud along California’s Rt. 58. Credit: Caltrans/EPA

Drought Update: Summer 2015

This summer has been marked by heavy rain and even flooding in many parts of the United States.  Drought, however, continues to plague large sections of the country.

According to the latest report from the U.S. Drought Monitor, 36% of the nation is in some form of drought. While this number represents improvement for some areas, such as Texas and the southern plains, the western states remain very dry. Conditions of moderate drought or worse cover 61% of that region.

In California, despite some unseasonably heavy rain recently, the long-term drought – now in its fourth year – continues. 97% of the state is experiencing conditions of moderate drought or worse and 46% is in extreme drought, the worst possible category.

On the other side of the country, drought is also impacting parts of Florida.  This is fairly unusual as summer is considered the rainy season there. Currently, 45% of the Sunshine state – mostly along the east coast – is experiencing some form of drought. That is up from 15% from just three months ago. Portions of the highly populated areas of Broward and Miami-Dade Counties, on the southeastern tip of the peninsula, are dealing with extreme drought.

The Drought Monitor is a weekly publication produced by a partnership of government agencies, including the National Drought Mitigation Center, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration.

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Tropical Storm Bill Slams Texas

Tropical Storm Bill, the second named storm of the 2015 Atlantic Hurricane Season, made landfall on Tuesday at Matagorda Island, which is between Houston and Corpus Christi in Texas. It slammed the southeast section of the Lone Star state with winds measured up to 60 mph and relentless heavy rain.

Rainfall totals, according to the NWS, averaged around 3 inches for most places, but some areas southwest of Houston saw much heavier precipitation. The cities of Ganado and El Campo received 11.77 inches and 9.91 inches, respectively. With the soil already saturated from a record wet May, there was widespread flash flooding. Luckily, no serious injures have been reported.

Moving inland toward Oklahoma, another state that experienced a record wet May, the storm was downgraded to a tropical depression on Wednesday. The rain, nonetheless, is ongoing. Looking ahead, the storm is forecast to travel northeast, riding a large ridge of high pressure situated over the southeastern states. The rainy remnants of Bill will likely arrive here in the NYC area by Sunday.

Given that this is an El Niño year – a time when the number of Atlantic hurricanes is usually below average – it is interesting to note that two named storms have already made landfall in the US this season. First Ana in May and now Bill. This shows that land-falling storms can occur even in “quiet” years and that it is important to be prepared throughout the hurricane season. 

Tropical Storm Bill making landfall on Texas coast. Credit: NOAA

Tropical Storm Bill making landfall on Texas coast. Credit: NOAA

Remnants of Tropical Storm Bill are forecast to impact the east coast by the weekend.  Credit: NOAA

Traveling from the Gulf of Mexico across the mid-west, remnants of Tropical Storm Bill are forecast to impact the east coast by the weekend. Credit: NOAA

When it Rains, it Pours

Torrential rain events and the flooding they cause are nothing new.  Global warming, however, is helping to make them more likely.

According to the most recent National Climate Assessment, heavy rain events – defined as the heaviest 1% of all rain events – have become heavier and more frequent across most of the US. The greatest increases have been observed in the northeast, mid-west, and southeast.

Climate scientists attribute this increase in heavy precipitation to our warming atmosphere. Simply put, warm air holds more moisture than cold air. And, the more moisture that builds up in the air, the more rain can fall.

The relentless rain and deadly floods in Texas last month made national headlines, but there are many other examples of similar events in the recent past. In September 2013, Colorado experienced catastrophic flooding caused by overwhelming amounts of rain in a short period of time. Locally, here in the NYC area, the town of Islip on Long Island saw more than 13 inches of rainfall in a single day last August. That equates to 29% of their average annual rainfall. The damage caused by that single event was estimated at $35 million.

As our global temperature continues to rise, experts say we should expect to see more extreme rain events, even in areas where overall precipitation is projected to decrease. In other words, when it rains, it will likely pour.

The map shows percent increases in the amount of precipitation falling in very heavy events (defined as the heaviest 1% of all daily events) from 1958 to 2012 for each region of the continental United States. These trends are larger than natural variations for the Northeast, Midwest, Puerto Rico, Southeast, Great Plains, and Alaska. The trends are not larger than natural variations for the Southwest, Hawai‘i, and the Northwest. The changes shown in this figure are calculated from the beginning and end points of the trends for 1958 to 2012.

The map shows percent increases in the amount of precipitation falling in very heavy events  from 1958 to 2012 for each region of the continental United States. These trends are larger than natural variations for the Northeast, Midwest, Puerto Rico, Southeast, Great Plains, and Alaska. The trends are not larger than natural variations for the Southwest, Hawai‘i, and the Northwest. Credit: 2014 US National Climate Assessment

Catastrophic Flooding in Texas

Relentless rain unleashed catastrophic floods across southeast Texas this past weekend. Coming out of a prolonged drought, officials say this was the worst flooding the region has seen in years.

In Houston, more than 10 inches of rain fell Monday night into Tuesday morning. With the ground already saturated from plentiful spring rains, rivers and bayous swelled out of their banks.  The floodwaters inundated homes, businesses, and major roadways, paralyzing large parts of this country’s 4th largest city.  Rainfall rates reached as high as 4 inches per hour, which prompted the NWS to issue a flash flood emergency – the highest level of flood alert – for the area.  Local officials say 3 people were killed and more than 80,000 people lost power as a result of the flood.

On Sunday, torrential rain in Hays County, TX caused the Blanco River to rise more than 30 feet in 3 hours. Before the river gauge was washed away, it reported a crest of 40.21 feet, which is about 7 feet above the previous record set in 1929. Officials there say the raging water destroyed more than 350 homes and that 13 people are still missing.

Just north of Texas, the Oklahoma City area also experienced severe weather and flooding this holiday weekend. Across both states, floodwaters caused a number of fatalities. The combined death toll currently stands at 14, but is expected to rise.

The intensity of these rain events had two main drivers. First, a mass of warm and deeply saturated air moved north from the Gulf of Mexico.  It then ran into a deep dip in the jet stream, which has been locked in place over the western states recently. This collision triggered intense thunderstorms that wrung tremendous amounts of moisture out of the air.  The result was a series of deadly and destructive deluges across the region.

The Governor of Texas, Greg Abbot, has declared 37 counties from the Red River to the Rio Grande to be disaster areas as a result of recent weather events.  More rain, unfortunately, is forecast for the region this week.

Flooded roadway in Houston.  Credit: KTRK

Flooded roadway in Houston. Credit: KTRK

Drought Update: Spring 2015

Drought has plagued the western and southwestern regions of the US for years, with the highly populous states of Texas and California being particularly hard hit. In recent weeks, however, plentiful spring rain has brought the Lone Star state some much needed, if not complete, relief.

According to the latest report from the US Drought Monitor, exceptional drought, the worst possible category is no longer present in Texas. This is the first time this has happened since July 2012. While this is good news, other categories of drought still persist across 36% of the massive state. The intense rain has also caused flooding.

California, in its fourth year of drought, also received some much-needed rainfall recently. On Thursday, San Diego received 1.63 inches of rain making it their wettest May since 1921. This impressive daily total was not only unusual as the region is now in its “dry season”, but was also more than that city typically gets all summer. Despite this recent rain in the southern part of the state, 98% of California remains in some form of drought with nearly 50% in exceptional drought.

The Drought Monitor is a weekly publication produced by a partnership of government agencies, including the National Drought Mitigation Center, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration.

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Subtropical Storm Ana: First Named Storm of 2015 Atlantic Season

Subtropical storm Ana, the first named storm of the 2015 Atlantic Hurricane Season has officially formed. With winds measured at 45mph earlier today, the center of this pre-season storm is located about 180 miles southeast of Myrtle Beach, SC.

According to the National Hurricane Center (NHC), Ana is expected to bring heavy rain and gusty winds to parts of both North and South Carolina over the next few days. It will also produce rough surf and dangerous rip currents along the coast.

A subtropical storm is a hybrid of a regular storm, fueled by the clash of warm and cold air, and a tropical storm, powered by the heat and moisture of warm ocean waters. Ana’s hybrid nature means that it has the potential to transition into a fully tropical system, especially as it sits over the warm waters of the Gulf Stream. This is why the NHC assigned it a name.  In May 2012, this type of transition happened with Tropical Storm Beryl, which was the strongest pre-season tropical cyclone to make landfall in the US.

While pre-season storms tend to occur every five years of so, Ana is the earliest named storm to form in the Atlantic since April 2003 when a tropical storm also named Ana developed. The Atlantic hurricane season officially begins on June 1.

Satellite view of Subtropical Storm Ana off the Carolina coast.  Image Credit: NASA

Satellite view of Subtropical Storm Ana off the Carolina coast. Image Credit: NASA