Subtropical Storm Alberto Makes Landfall in Florida and Travels North to Canada

Subtropical storm Alberto, the first named storm of the 2018 Atlantic hurricane season, made landfall near Laguna Beach in the Florida Panhandle on Monday. It was the second time this decade that a named storm hit the southeast coast on Memorial Day.

Classified as a subtropical storm, Alberto was a hybrid between a tropical storm and a regular low-pressure system usually found at higher latitudes. A tropical system is fueled by the latent heat released by the evaporation of ocean water while a regular storm is powered by the temperature contrast between air masses. Hybrids are able to access both energy sources.

Despite this somewhat confusing hybrid status, Alberto still packed a punch. Strong winds, downed trees, and heavy rain were seen across a large swath of the southeastern United States. A wind gust of 59-mph was reported at Fort Tyndall Air Force Base near Panama City, FL. Storm surge flooding was another concern. Water levels rose between 1 and 3 feet from Tampa Bay, FL to the Mississippi River delta in Louisiana.

Moving northward, heavy rain from the remnants of Alberto unleashed flash flooding in the several states and caused landslides in North Carolina’s Blue Ridge Mountains. Nearly 10 inches of rain was reported in Black Mountain, NC.

Forming in the waters off the Yucatán Peninsula in Mexico on May 25, Alberto traveled all the way to Lake Huron near the Canadian border before dissipating on May 31. It was the first named storm to reach that far north this early in the season, according to researchers at the University of Miami.

The Atlantic hurricane season officially begins on June 1.

Track of Subtropical Storm Alberto. Credit: Supportstorm

Catastrophic Flooding Hits Ellicott City Twice in Two Years

For the second time in less than two years, heavy rain unleashed catastrophic flooding in Ellicott City, Maryland this Sunday.

According to the NWS, the area received between 8 and 12 inches of rain in less than four hours. On average, the area gets 4 inches of rain for the entire month of May. This massive amount of precipitation in such a short period overwhelmed streams throughout the region and turned Ellicott City’s historic Main Street into a raging river. The floodwater, which reached as high as the second floor of most buildings, damaged or destroyed numerous businesses and swept away dozens of cars and trees. Local officials say that one man, a sergeant with the National Guard, was killed while trying to rescue people from the fast flowing water.

This type of rainfall is considered a one in one thousand year event. However, that does not mean it can only happen once every thousand years. It is the recurrence interval, a statistical calculation that means an event has a one in one thousand chance (0.1%) of happening in any given year in a given location. Ellicott City experienced an eerily similar event in July 2016.

There were several drivers behind this deadly deluge. First, “training” thunderstorms developed along a stationary front. This is a situation where strong thunderstorms continuously form over the same area – like train cars traveling along a track – dumping excessive amounts of rain.

Although climate change did not cause these storms, it has altered the environment in which they form and is making them more common. As greenhouse gases warm the atmosphere, the air is able to hold more water vapor. More specifically, according to the Clausius–Clapeyron relation, for every increase of 1°F, the saturation level of the atmosphere increases by about 4%. That means there is more evaporation from oceans, rivers, and lakes, and therefore more water vapor available to condense and fall as precipitation.

Another major player in Sunday’s flood was the area’s topography. Founded as a gristmill town in 1772, Ellicott City sits in a valley surrounded by several streams that feed into the Patapsco River. Just ten miles outside of Baltimore, it is a highly urbanized area with extensive amounts concrete and asphalt. These impervious surfaces leave the rainwater with no place to go but racing downhill and through the town.

All of these factors will have to be considered as Ellicott City decides how to rebuild for the second time in two years.

Torrential rain turned Main Street in Ellicott City, MD into a raging river. Credit: S. Baranoski

2018 Atlantic Hurricane Season Outlook: Average to Above Average

The number of hurricanes that develop in the Atlantic basin varies from year to year. For 2018, NOAA’s Climate Prediction Center is forecasting an average to above average season.

Tropical cyclones, known as hurricanes in the United States, develop around the globe at different times of the year. In this country, we are most impacted by the Atlantic hurricane season, which affects the North Atlantic Ocean, Caribbean Sea, and the Gulf of Mexico. It runs from June 1 through November 30.

Overall, NOAA predicts a 70% likelihood of ten to sixteen named storms forming this season, of which five to nine could become hurricanes, including one to four major hurricanes. An average season produces twelve named storms, including six hurricanes and three that become major hurricanes. A major hurricane is one that is rated category 3 or higher on the Saffir-Simpson scale.

This outlook, according to NOAA, is based on the possibility of the development of a weak El Niño and near-average sea surface temperatures in the tropical Atlantic. El Niño conditions in the Pacific tend to cause increased wind shear in the Atlantic, which suppresses tropical development in that basin.

Last year, 2017, was the most active Atlantic Hurricane season in more than a decade.  It produced seventeen named storms, including Harvey, Irma, and Maria. But regardless of the number of storms that actually form this year, it is important to remember that it only takes one land-falling system in your community to make it an impactful season.

Source: NOAA

 

April 2018: Earth’s Third Warmest on Record

Our global temperature continued its upward trend last month with April 2018 marking the third warmest April ever recorded on this planet. Only April 2016 and 2017 were warmer.

According to a report by NOAA’s National Centers for Environmental Information, Earth’s combined average temperature for the month – over both land and sea surfaces – was 58.19°F. That is 1.49°F above the 20th-century average. April was also the 400th consecutive month with a global temperature above its long-term norm. That means the last time any month posted a below average reading was December 1984.

While heat dominated most of the planet this April, some places were particularly warm, including Central Europe, eastern Russia, and parts of both South America and Australia. These soaring global temperatures are largely attributed to the long-term trend of human-caused climate change. In fact, ENSO neutral conditions were present in the Pacific during April, meaning neither El Niño nor La Niña influenced temperatures.

For many people in the US, however, especially in the eastern part of the county, this April was relatively cold. For the lower 48 states as a whole, it was the 13th coldest April on record. To put this disparity into context, consider that the contiguous United States constitutes less than 2% of the total surface of the Earth. This detail highlights the fact that climate change is a complex global phenomenon that involves much more than the short-term weather that is happening in our own backyards.

Year to date, the first four months of 2018 were the fifth warmest such period of any year on record. Global temperature records date back to 1880.

Credit: NOAA

What is Normal Weather?

When a significant weather event occurs, we often hear it being compared to “normal”. While this helps put an event into perspective, you may wonder – what is normal?

Climate normals, according to NOAA, are defined as the 30-year average at a given location. They are calculated for several climatological variables, including temperature and precipitation. Updated every decade, the current set of averages is based on the weather from 1981 through 2010.

These statistical measurements also help put climate trends into context. As greenhouse gas emissions continue to spew into the atmosphere, it should not come as a surprise that “normal” these days is warmer than it used to be. For the continental US, according to Climate Central, the average temperature has increased 1.4°F since 1980.

This may seem like a small number, but it is having big impacts. It reflects the increasing number of extremely hot days and the decrease in extremely cold days. Looking at daily temperature records across the US, record highs have outnumbered record lows in 26 of the last 30 years. In 2012, that ratio was as high as 7:1.  These changes and the effects they have are what is meant by human caused climate change ushering in a “new normal”.

Credit: Climate Central

Powerful Thunderstorm Batters NYC

The first severe thunderstorm of the season barreled through the New York City metro area early Tuesday evening. Strong winds and heavy rain were reported across the region.

After an unseasonably hot and humid day, a fast moving cold front moved in from the west and triggered the violent storm.  According to the NWS, 0.58 inches of rain was reported in Central Park and wind gusts at JFK airport reached 55 mph. It is also interesting to note that the temperature in the city dropped from 88°F to 68°F in less than one hour.

The powerful and fast moving storm knocked down trees and caused power outages throughout the area. Rolling through the city a little after 5PM, the storm also wreaked havoc on the evening commute. All MetroNorth Railroad lines out of Grand Central Terminal were suspended because of downed trees on the tracks. Additionally, the city’s three airports reported significant delays.

Outside of the city, the storm turned deadly claiming the lives of at least five people. That number includes an eleven year old girl who was crushed by a tree while sitting in a car in Newburgh, NY. No injuries or fatalities were reported in the five boroughs.

A powerful thunderstorm moves across NYC. Credit: southerlysweet/Instagram

Severe Weather: Watches and Warnings

Severe weather, the type that can cause property damage and loss of life, can take a variety of forms depending on season and location. But during spring and summer in the northeastern United States, it usually takes the shape of an intense thunderstorm. In addition to thunder and lightning, these storms produce strong winds, heavy rain, hail, and the possibility of a downburst or tornado. Therefore, it is important to understand the difference between the various alerts issued by the National Weather Service. They include advisories, watches, and warnings.

  • Advisory: Issued when significant, but not necessarily hazardous, weather conditions are likely to occur. Residents should exercise caution.
  • Watch: Issued when dangerous weather conditions are possible over the next several hours.  They generally cover a large geographic area.  Residents should be prepared to take action.
  • Warning: Issued when dangerous weather is imminent or already occurring.  They cover a smaller, more specific geographic area.  Residents should take action immediately.

Stay safe!

Weather Lingo: Downburst

Thunderstorms pose a number of familiar hazards, such as lightning and hail. The lesser-known downburst, however, is also a serious threat to life and property.

A downburst is a strong downward current of air that causes damaging winds on or near the ground. They initiate high up in the atmosphere, where relatively dry air is entrained inside of an intense thunderstorm. The dry air evaporates some of the storm’s raindrops, which has a cooling effect. Since this cooler air is denser than the warm air that surrounds it, it sinks rapidly toward the surface. When it hits the ground, it spreads out radially – in straight lines in all directions. Reaching speeds in excess of 100mph, a downburst will knock down trees and other obstacles leaving a trail of debris all facing the same direction.

These straight-line wind events, according to the NWS, can vary in size and duration. When they cover an area less than 2.5 miles, they are referred to as microbursts. These typically last between 5 and 15 minutes. Larger events, known as macrobursts, affect an area greater than 2.5 miles and last from 5 to 30 minutes.

While short-lived, these powerful winds can pose a threat to property on the ground as well as airplanes in the process of taking off or landing.

Credit: NWS

Volcanic Smog: Kilauea’s Other Threat

Lava is not the only thing flowing out of the fissures of Kilauea on Hawaii. Sulfur dioxide, a foul-smelling and toxic gas, has also driven people from their homes.

According to the USGS, sulfur dioxide levels near the volcano have been measured above 100 parts per million. That is a level considered dangerous to human health. Noxious on its own, sulfur dioxide is also the main ingredient in volcanic smog. Known as vog in Hawaii, it can have a variety of adverse health effects.

Vog occurs when the sulfur dioxide spewing from a volcano reacts with oxygen, moisture, and other particles in the air in the presence of sunlight. It is considered a form of air pollution, not unlike that given off by power plants burning sulfurous coal. Looking back to December 1948, a similar type of toxic smog caused by unregulated industrial pollution killed 26 people and sickened thousands of others in Donora, PA.

Volcanic smog can irritate the skin, eyes, nose, throat, and lungs. Shortness of breath and dizziness can also occur.  Its effects can be even worse for anyone with respiratory problems or lung disease.

This threat, on top of the flowing lava, has led public health officials to order an evacuation of areas around the fissures, such as the hard hit Leilani Estates.  Other parts of the Big Island, however, have reported moderate to good air quality. This is largely because the region’s prevailing northeast trade winds have been pushing the vog offshore. If those winds slacken and a southeasterly flow emerges, the vog could impact a wider area, including other islands in the Hawaiian chain.

Volcanic eruptions spew gas as well as lava. Credit: GoVisitHawaii

Suddenly Summer: Record Breaking Spring Heat in NYC

After a long cold winter and a chilly start to spring, it suddenly felt like summer in New York City this week.

According to the NWS, the temperature in Central Park hit 90°F on Wednesday. That marked the city’s first 90°F reading of the year and tied the daily record set in 2001. The sultry conditions continued on Thursday as the temperature climbed to 92°F, setting a new record high for the date. The previous record of 90°F had been in place since 2001.

Thursday’s low of 70°F was another record breaker, surpassing the old record of 68°F from 2001. In fact, this low reading was warmer than the date’s normal high. The city’s average high and low temperatures for this time of year are 67°F and 50°F, respectively.

These dramatic temperatures are the result of a Bermuda High, a large area of high pressure situated off the mid-Atlantic coast. Spinning clockwise, it has created a warm southwesterly flow of air into the northeast.

This summer-like weather brought many New Yorkers out of hibernation and into the city’s numerous parks and outdoor cafes. However, for some, the heat comes with a cost. It can lead to the formation of ground-level ozone, which is why an air quality advisory was issued for the area. Anyone with respiratory concerns, like asthma, has been advised to stay indoors.

While these temperatures are unseasonable, the city has seen 90° readings arrive even earlier. The earliest, according to NWS records, was April 7, 2010, when the mercury climbed to 92°F.

If you are not quite ready for summer, fear not. Conditions more typical of May are expected to return this weekend.

A week of weather whiplash for NYC. Credit: The Weather Gamut