Tag Archives: storms

Weather Lingo: Lake Effect Snow

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Winter snowstorms have a variety of names, such as Nor’easters and Alberta Clippers. It all depends on where and how they develop. In the Great Lakes region of the US, the vast bodies of fresh water influence the weather and create something known as lake effect snow.

Lake-effect snowstorms, according to NOAA, develop when cold air blows across the warmer waters of a large unfrozen lake. The bottom layer of the air mass is warmed by the water and allows it to evaporate moisture, which forms clouds. When the air mass reaches the leeward side of the lake its temperature drops again, because the land is cooler than the water. This releases the water vapor as precipitation and enormous amounts of snow can accumulate. The effect is enhanced if the air is lifted upward by local topography.

With the clouds typically forming in bands, the snowfall is highly localized. Some places can see the snow come down at a rate of more than 5 inches per hour, while nearby, others will only get a dusting. The shape of the lake and the prevailing wind direction help to determine the size and orientation of these bands.

Fetch, the distance wind travels over a body of water, also plays a key role. A fetch of more than 60 miles is needed to produce lake effect snow. In general, the larger the fetch, the greater the amount of precipitation, as more moisture can be picked up by the moving air.

The impressive depths of the Great Lakes allow them to remain unfrozen longer into the winter season than more shallow bodies of water. This combined with their massive surface area, make them excellent producers of  lake effect snow. With northwesterly winds prevailing in the region, communities along the southeastern shores of the lakes are often referred to as being in the “Snowbelt.”

Credit: NOAA

Destructive 2018 Atlantic Hurricane Season Comes to a Close

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The 2018 Atlantic Hurricane Season officially ends today.  It marked the third year in a row with above average activity.

According to NOAA, there were fifteen named storms this season. Of these, eight developed into hurricanes and two were major hurricanes with ratings of category 3 or higher on the Saffir-Simpson Scale. An average season produces twelve named storms, six hurricanes, and three major hurricanes.  It is also interesting to note that this season was the first since 2008 to have four named storms active at the same time – Florence, Helene, Isaac, and Joyce.

Officially running from June 1 to November 30, the season got off to an early start with Tropical Storm Alberto forming in May. This was the fourth consecutive year to see a pre-season storm develop. The biggest names of the season, however, were Florence and Michael.

In September, Hurricane Florence made landfall in North Carolina and dumped a massive amount of rain on the area. Traveling inland, it caused catastrophic flooding in parts of both North and South Carolina. In Elizabethtown, NC, 35.93 inches of rain was reported, making the wettest tropical cyclone on record for the state. For the contiguous US, it ranked as the eighth wettest.

A few weeks later, Hurricane Michael hit the Florida panhandle as a cat-4 storm. With winds measured up to 155mph, it was the strongest storm on record to strike the region and the third strongest storm to make landfall in the continental US. Its powerful winds and storm surge flooding decimated the Panama City area.

Causing so much destruction, both Florence and Michel will likely be retired from the World Meteorological Organization’s list of storm names.

This active hurricane season was largely the result of above-average sea surface temperatures in the Atlantic and ENSO neutral conditions in the Pacific. With warm water to fuel storms coupled with reduced wind shear across the Gulf of Mexico, tropical development in the Atlantic basin was essentially unhindered.

Overall, the season is reported to have claimed the lives of 154 people and caused an estimated $33 billion in damages. The official tally from NOAA will not be available until early 2019.

Source: NOAA

First Nor’easter of the Season Slams NYC

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The first nor’easter of the season slammed the northeastern United States on Saturday. Heavy precipitation, strong winds, and coastal flooding were reported across the region.

Here in New York City, the storm dumped 1.34 inches of rain in Central Park. Its powerful winds knocked down trees and caused power outages around the city’s five boroughs. The storm also caused significant travel delays, including shutting down part of the FDR Drive because of flooding.

While nor’easters are not uncommon at this time of year, this one was interesting because it started off as a hurricane in the eastern Pacific. Hurricane Willa made landfall near Mazatlan, Mexico on Tuesday night and then moved inland toward Texas. From there, the storm’s remnants merged with a cold front and became re-energized. Traveling in the jet stream, it worked its way up the eastern seaboard and became a nor’easter.

First nor’easter of the season downed trees and branches in Queens. Credit: D. Herrick

Hurricane Michael Devastates Florida Panhandle

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Hurricane Michael, the 13th named storm of this Atlantic Hurricane season, made landfall near Mexico Beach, Florida on Wednesday. It was the strongest storm on record to hit the Florida Panhandle.

Coming ashore with sustained winds measured up to 155mph, Michael was classified as a high-end category-four hurricane. Its powerful winds sheared roofs off buildings, uprooted trees, and toppled power lines. Storm surge flooding was also a major force of destruction. The NHC estimates the water reached between nine and fourteen feet above normally dry ground from Mexico Beach eastward through Apalachee Bay.

Fueled by the unseasonably warm waters of the Gulf of Mexico, Michael intensified rapidly as it moved closer to shore. According the NWS, Michael was the strongest hurricane to make landfall in the US since Hurricane Andrew in 1992. It was also the strongest storm to ever hit this country in the month of October.

Moving quickly, the storm traveled across the Florida Panhandle toward the northeast. Its strong winds and heavy rain caused flashing flowing and power outages in several states.

As of Friday, the death toll from this historic storm stands at sixteen. But sadly, officials say that number is expected to rise as search and rescue efforts continue in the hardest hit areas.

Hurricane Michael makes landfall near Mexico Beach, FL. Credit: NOAA

Remnants of Hurricane Florence Soak NYC and Its Subways

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The remnants of Hurricane Florence swept through New York City on Tuesday. While significantly weaker when compared to its time over the Carolinas, the storm still made its presence known with strong thunderstorms and bands of torrential downpours.

According to the NWS, 1.19 inches of rain was measured in Central Park. As impressive as that total is, it did not break the daily rainfall record for the date. That honor belongs to September 18, 1936 when 3.92 inches of rain was reported. New York City, on average, gets 4.28 inches of rain for the entire month of September.

The heavy rain caused flash flooding on roadways and disrupted travel across the city. Impacts were also felt underground as torrents of water poured into several subway stations through leaks in the ceiling and down the entrance/exit steps. Even the city’s infamous rats were seen sheltering from the rushing water.

This type of heavy rain event, according to NOAA, is expected to become more common as global temperatures continue to rise.

Heavy rain created underground waterfalls at several NYC subway stations on Tuesday. Credit: R.Mondshein/Twitter

 

Hurricane Florence Swamps the Carolinas

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Hurricane Florence, the 6th named storm of the Atlantic Hurricane season, slammed North and South Carolina this weekend.

Steered across the Atlantic by a strong area of high pressure, Florence made landfall near Wrightsville Beach, NC on Friday morning as a category-1 storm.  It peaked at category-4 strength while still over the ocean, but weakened as it moved closer to the US coast.

Despite this downgrade, Florence still packed a powerful punch. Its strong winds, flooding rains, and storm surge forced people to evacuate their homes and caused significant property damage as well as widespread power outages across the region. In the hard hit city of New Bern, NC, at the mouth of the Neuse River, a storm surge of more than ten feet was reported. Local officials there say upward of 4000 homes and businesses were damaged or destroyed.

Moving as slowly as 2 mph at one point, Florence essentially stalled out over the region, allowing it to unleash massive amounts of precipitation. Preliminary reports show that the storm set new state records for rainfall from a single tropical cyclone in both North and South Carolina. In Elizabethtown, NC, 35.93 inches was reported, crushing the previous record of 24.06 inches set by Hurricane Floyd in 1999. In South Carolina, the town of Loris, about 25 miles north of Myrtle Beach, reported 23.63 inches of rain, eclipsing the old record of 17.45 inches set by Tropical Storm Beryl in 1994.

If these numbers are confirmed by the NWS, that would mean four state tropical cyclone rainfall records were broken in the last thirteen months. The other two being Texas with 60.58 inches of rain from Hurricane Harvey in August 2017 and Hawaii with 52.02 inches from Hurricane Lane just last month.

Measuring 400 miles wide, Florence’s successive bands of heavy rain also caused catastrophic inland flooding as several rivers in the region overflowed their banks and inundated communities. In Fayetteville, NC – nearly 100 miles from the coast – more than 15 inches of rain was reported as of Monday. The Cape Fear River, which runs through the city, is forecast to crest at 61.8 feet on Tuesday, which is more than 25 feet above flood stage.

The death toll from this storm currently stands at 20, with most fatalities being water related. Sadly, as the rivers across the area continue to rise, that number is expected to increase in the coming days.

Hurricane Florence off the coast of the Carolinas. Credit: NOAA

How Hurricanes are Classified

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Hurricanes are one of nature’s most powerful storms. When formed in the Atlantic Ocean or North-Eastern Pacific, they are rated according to the Saffir-Simpson Scale.

Developed in the early 1970’s by Herbert Saffir, a civil engineer, and Dr. Robert Simpson of the National Hurricane Center, the scale classifies hurricanes into five categories based on the strength of their sustained winds. Each category is considered an estimate of the potential damage that a storm will cause if it makes landfall.  As conditions change within a storm, its category is re-assessed.

The different categories, 1 through 5, represent increasing wind speeds and escalating degrees of damage. Storms rated category 3 or higher are considered major hurricanes. The last category 5 storm to make landfall in the US was Hurricane Andrew in 1992.

While a useful tool, the Saffir-Simpson scale does not tell the whole story of the dangers to life and property posed by a hurricane. Regardless of category, these storms can produce dangerous storm surges in coastal areas and flooding rains further inland. Recent examples of these types of impacts were seen during Sandy and Harvey, respectively.

The Deadly Danger of Lightning

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Thunderstorms are impressive displays of the power of nature. However, they are also extremely dangerous.

On average, according to NOAA, lightning claims the lives of 47 people every year in the US and seriously injures hundreds more. To date in 2018, lightning has killed 16 people across eight states. The most recent victim was struck this Saturday at Sunken Meadows State Park on Long Island, NY. Local officials say the man was sheltering under a tree during an early evening storm.

Lightning comes in variety of forms, but the cloud to ground variety is the most threatening to people. A typical bolt carries a current of about 300 million volts and can heat the air around it to 50,000°F. That is five times hotter than the surface of the sun.

This type of lightning, NOAA says, strikes the US about 25 million times a year. However, 70% of lightning fatalities occur during the summer months. The season marks not only the peak of thunderstorm activity in the US, but also the time of year when people spend more time outdoors.

Top ten activities that contributed the most to lightning deaths in the US, 2006-2017. Credit: NWS

According to a NWS report on lightning deaths in the US from 2006 to 2017, the vast majority of victims were men engaged in an outdoor leisure activity. Listing a variety of different pastimes at the time they were struck, fishing topped the list as the most deadly. It accounted for nearly 10% of the lightning fatalities during that period.

To avoid becoming a statistic, follow the advice of the NWS – “When thunder roars, go indoors.”

Credit: NWS/NOAA

Tornado Touches Down in Queens, NYC

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A tornado barreled through the New York City borough of Queens on Thursday night as powerful thunderstorms moved through the area. With winds between 70 and 85 mph, it was rated EF-0 on the Enhanced Fujita scale.

According the NWS, the twister touched down in College Point, Queens and traveled 0.7 miles east before dissipating in the Melba neighborhood. Measuring 100 yards wide, it knocked down at least 50 trees and numerous power lines. It also pulled the siding off several homes. No fatalities have been reported.

Tornadoes, historically, have been rare in New York City. In recent years, however, they have been happening more frequently. This latest twister was the 7th to hit NYC since 2010 and the 14th since 1950, when the NWS began tracking these destructive storms.

Tornado damage in Queens, NYC. Credit: WABC

Powerful Thunderstorm Brings Funnel Cloud and Flooding to NYC

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An intense thunderstorm swept through New York City on Tuesday afternoon. With bands of torrential downpours, it unleashed nearly half a month’s worth of rain in just a few hours.

According to the NWS, 2.24 inches of rain was measured in Central Park. While that is an impressive total, it did not break the daily rainfall record for the date. That honor belongs to June 17, 1995 when 3.13 inches of rain was reported. New York City, on average, gets 4.60 inches of rain for the entire month of July.

Funnel cloud forms over NY Harbor. Credit: Michael Uturn/Twitter

The powerful storm also produced a funnel cloud over New York Harbor. However, according to the NWS, it did not reach down to the surface and therefore was not a tornado.

The heavy rain, on the other hand, produced a number of problems on its own. It caused flash floods and disrupted travel across the city. Torrents of water poured into several subway stations creating underground waterfalls and parts of the FDR Drive, a major highway on the east side of Manhattan, were closed due to flooding. Significant delays and cancellations were also reported at the area’s airports.

This type of heavy rain event, according to NOAA, is expected to become more common in the northeast as global temperatures rise and precipitation patterns change.

Heavy rain causes flooding on FDR Drive in NYC. Credit: Patch