by tyler | Oct 4, 2023 | CNN, weather
Tropical Storm Philippe will interact with a potent cold front this weekend and funnel tropical moisture across the Northeast, raising the risk of flooding rainfall in an area that has been soaked repeatedly in recent weeks.
The storm is still far from the US mainland and just north of the Caribbean. But its projected track has echoes of Hurricane Lee in September, when the much-weakened system brought strong winds and rain to parts of the Northeast and Canada.
Philippe is expected to approach New England as a tropical storm on Sunday, but may lose some of its tropical nature as it approaches the coast. The severity of rain and wind will be the same regardless of whether it’s a tropical storm or a post-tropical storm at landfall.
A soggy weekend is likely across much of the mid-Atlantic and Northeast, but exactly where the heaviest rain falls will depend on Philippe’s track over the next several days.
For now, portions of New England and northern New York are most likely to experience heavy rain and potential flooding. A Level 2 of 4 slight risk of excessive rainfall was issued for Saturday in these areas by NOAA’s Climate Prediction Center.
But the bull’s-eye of heaviest rainfall could shift if low pressure moving across the eastern US pulls Philippe closer to the Northeast. This potential shift could move the risk closer to the mid-Atlantic – an area where another deluge would be particularly worrisome.
Parts of the mid-Atlantic and Northeast were inundated by record-breaking rainfall last week. The most intense rainfall hit the New York City tri-state, where floodwaters inundated subways, roads and basements and several locations recorded the wettest day in history.
Heavy rainfall is not expected to be as severe as last week, but a widespread 1 to 2 inches of rain is possible across New York and New England. Higher amounts closer to 2 to 4 inches could fall where the heaviest rain sets up, likely in a more focused portion of New England.
In addition to heavy rain, gusty winds are possible across portions of New England and Atlantic Canada Saturday and Saturday night as Philippe nears landfall. Philippe’s winds are expected to remain at tropical-storm strength, but the cyclone itself may not be fully tropical at the time of landfall.
Philippe has quite a distance to travel before approaching the US and Canada. The tropical storm was less than 200 miles north of the US Virgin Islands on Wednesday and on track to come in close contact with Bermuda.
Bermuda is only 15 miles across, so landfalls are rare. Only eleven systems have made landfall on the island since 1851, according to data from NOAA.
The Bermuda Weather Service issued a tropical storm watch for the island on Wednesday, since Philippe won’t have to make landfall in order to unload strong wind gusts and heavy rain.
The storm’s severity on Bermuda will depend on just how strong it is and how close it tracks to the island. Tropical-storm-force wind gusts are likely when Philippe makes its closest pass on Friday. Rain will arrive ahead of any wind and could begin as early as Thursday across the island.
Philippe is expected to be a tropical storm as it swipes the island, so the risk of widespread damage is limited, but power outages are possible.
by tyler | Sep 28, 2023 | CNN, weather
There is a growing risk for flash flooding for millions in the Northeast Friday, including the New York City area, as moisture from the remains of long-dead Tropical Storm Ophelia combines with a new coastal storm to deliver heavy rainfall.
“The remnant of Ophelia will merge with a new low pressure developing along the Carolina coast today before strengthening as it heads northeastward tonight and Friday, spreading rain back across the region, especially coastal areas,” the National Weather Service office in Philadelphia said Thursday morning.
The rain will begin for many starting Thursday, peaking on Friday and Friday night from Maryland to Massachusetts.
Rainfall totals are expected to range between 1 and 3 inches, but some areas could receive more than 4 inches. Up to 5 inches is possible in the New York City area through Saturday.
Uncertainty remains for exactly where the worst rain will fall since weather models are in disagreement with how close the low pressure system will be to the coast.
A track closer to the coast would increase rainfall totals. A more offshore track would keep the heaviest rain and storms out to sea.
Flooding could happen even in areas that only receive one inch of rain, since the ground is already saturated across many areas of the Northeast from recent heavy rainfall. At least two inches of rain has fallen over the last seven days from Virginia through Massachusetts, with some areas picking up over four inches.
The system will be very slow to exit the region this weekend, so more rain is expected from Boston to Virginia Beach on Saturday. The sun finally returns in full force on Sunday as rainfall-limiting high pressure returns to the Northeast and mid-Atlantic.
Another factor may exacerbate flooding across the Northeast and mid-Atlantic – a supermoon.
The fourth and final supermoon of 2023 will occur Friday morning, creating more extreme tidal cycles that could increase the flood potential in communities along the East Coast.
As a result, coastal flood advisories extend more than 300 miles from Bridgeport, Connecticut, through Virginia Beach.
Up to one foot of inundation above ground level is expected in low-lying areas near shorelines and tidal waterways. The weather service warns some partial or full road closures are possible.
Rip currents and very high surf are another concern. At least 76 people have died in rip currents so far this year, NOAA data shows.
by tyler | Sep 8, 2023 | CNN, weather
Hurricane Lee has strengthened into a major Category 4 storm with maximum sustained wind speeds of 130 mph, according to the 5 p.m. EDT advisory from the National Hurricane Center.
“Additional strengthening is expected tonight. Fluctuations in intensity are expected after that, but Lee is forecast to remain a powerful major hurricane well into next week,” the center said.
Lee, which was a Category 1 storm earlier Thursday, has been intensifying with exceptional speed in the warm waters of the Atlantic Ocean, strengthening by 50 mph in the last 12 hours. The hurricane is expected to reach Category 5 strength as soon as Friday morning as it approaches the eastern Caribbean.
The hurricane is located about 780 miles east of the northern Leeward Islands, the hurricane center said in its 5 p.m. update.
The storm will likely reach its peak intensity this weekend and is still expected to be a dangerous hurricane over the southwestern Atlantic early next week, though it’s too soon to know whether this system will directly impact the US mainland.
Dangerous surf and rip currents will spread across the northern Caribbean on Friday and begin affecting the United States on Sunday, the center said.
Even more rapid intensification is expected because the forecast track takes Lee across some of the warmest waters in the Atlantic Ocean and through relatively calm upper-level winds – ripe conditions for a hurricane to grow more fierce.
Lee’s winds are expected to peak at 160 mph, or Category 5-strength, Friday night as it approaches the eastern Caribbean and is still expected to be a dangerous hurricane over the southwestern Atlantic early next week.
There is increasing confidence that the center of Lee will pass to the north of the Leeward Islands, the Virgin Islands and Puerto Rico this weekend and into early next week. Tropical storm conditions, life-threatening surf and rip currents could occur on some of these islands over the weekend.
Also Thursday, a tropical depression in the eastern Atlantic strengthened into Tropical Storm Margot, just a few hundred miles west of the Cabo Verde Islands, the center said. Margot currently has winds of 40 mph and steady strengthening is expected – the center is forecasting Margot to become a hurricane over the weekend. The forecast track shows the storm turning to the north over the central Atlantic early next week, but it is not expected to threaten any land areas as of Thursday.
Computer model trends for Lee have shown the hurricane taking a turn to the north early next week. But exactly when that turn occurs and how far west Lee will manage to track by then will play a huge role in how close it gets to the US.
Here’s what will steer the storm and two potential scenarios meteorologists are watching for how the US threat could play out.
Several steering factors at the surface and upper levels of the atmosphere will determine how close Lee will get to the East Coast.
An area of high pressure over the Atlantic, known as the Bermuda High, will have a major influence in how quickly Lee turns. The Bermuda High is expected to remain very strong into the weekend, which will keep Lee on its current west-northwestward track and slow it down a bit.
As the high pressure weakens next week it will allow Lee to start moving northward.
Once that turn to the north occurs, the position of the jet stream – strong upper-level winds that can change the direction of a hurricane’s path – will influence how closely Lee is steered to the US.
Scenario: Out to Sea
Lee could make a quick turn to the north early next week if high pressure weakens significantly.
If the jet stream sets up along the East Coast, it will act as a barrier that prevents Lee from approaching the coast. This scenario would keep Lee farther away from the US coast but could bring the storm closer to Bermuda.
Scenario: Close to East Coast
Lee could make a slower turn to the north because the high pressure remains robust, and the jet stream sets up farther inland over the Eastern US. This scenario would leave portions of the East Coast, mainly north of the Carolinas, vulnerable to a much closer approach from Lee.
All these factors have yet to come into focus, and the hurricane is still at least seven days from being a threat to the East Coast. Any potential US impact will become more clear as the Lee moves west in the coming days.
by tyler | Sep 5, 2023 | CNN, weather
A newly-formed tropical depression in the Atlantic Ocean could soon become a named storm – then a powerful Category 4 hurricane – as the season approaches its typical peak in early September.
Tropical Depression 13 formed Tuesday morning in the central tropical Atlantic, almost 1,000 miles west-southwest of the Cabo Verde Islands, according to the National Hurricane Center. The depression is expected to become a tropical storm later Tuesday. The next tropical storm will be given the name Lee.
As the depression moves steadily west-northwest this week, it will enter conditions increasingly favorable for strengthening: Plenty of moisture, low wind shear and abnormally warm water stretch nearly the entire length of the potential cyclone’s projected path.
“The NHC intensity forecast is extremely bullish for a first forecast, but remarkably lies below the intensity consensus,” the National Hurricane Center’s storm discussion said. “All indications are that the depression will become a strong hurricane by the end of the forecast period.”
The system is forecast to become a hurricane as early as Thursday and would be the fourth to reach that status this season, following Don, Franklin and Idalia. The hurricane is expected to grow significantly stronger by the weekend and is forecast to become the season’s third Category 3 or stronger hurricane as the weekend begins.
It will track generally west-northwest across the tropical Atlantic through the end of the week and make a close pass at the Leeward Islands over the weekend as a hurricane. Any shifts along its track as it nears the islands could bring more of an impact there and beyond. Anyone in the eastern Caribbean – including the Leeward Islands, Puerto Rico and Hispaniola – as well as the Bahamas will need to keep a close eye on the forecast.
It’s too soon to know whether or not this system will directly impact the US mainland, but even if the hurricane stays out to sea, dangerous surf and rip currents could once again threaten the East Coast. One person was killed in a rip current in New Jersey over the Labor Day weekend.
Sunday, September 10, is the climatological peak of Atlantic hurricane season, when the basin is at its busiest on average. A flurry of tropical activity surrounding this date is not out of the ordinary, but it can turn hazardous fast.
The 2023 Atlantic season has already been busy: It is tracking above average for a number of different metrics including number of named storms, number of hurricanes and number of major hurricanes, according to Philip Klotzbach a research scientist at Colorado State University.
by tyler | Aug 26, 2023 | CNN, weather
An area of showers and thunderstorms in the Caribbean Sea could develop into a tropical system as soon as Sunday, posing a risk to Florida and the Gulf of Mexico coast early next week.
Forecasters at the National Hurricane Center are watching the disturbed weather near Central America, which is expected to track north this weekend through the Caribbean Sea toward the Gulf of Mexico, where it could form the Atlantic Ocean’s tenth tropical system this year.
A tropical depression or named storm could develop late this weekend or early next week if the currently disorganized showers and thunderstorms consolidate into one swirling mass with a defined center.
As of Friday morning, the National Hurricane Center said there is a high chance of this happening within the next seven days.
Who should pay attention? Nothing has formed yet, so it’s too early to pinpoint an exact track. But Mexico’s Yucatan Peninsula, Cuba and the northern Gulf and Florida coast should monitor the forecast in the coming days. The direction and strength of the upper-level steering winds around this system will dictate where it will move and how quickly.
How soon could it form? A tropical depression is likely to form within the next day or two.
When could it affect the US? If a tropical system does develop, it could affect the US as soon as Monday if it is pulled northward by strong steering winds. Weaker steering winds would lead to a slower track and impact midweek.
How strong could it get? It’s still too soon to tell how strong this system could get – or how fast it could strengthen. But it will be tracking through the warmest waters in the entire Atlantic basin – a vast source of energy for a developing storm. Exceptionally warm water can provide storms the fuel needed to strengthen and sometimes undergo rapid intensification.
Sea surface temperatures are record warm in the Gulf of Mexico and extremely high across the northwestern Caribbean Sea. Water temperatures need to be around 80 degrees Fahrenheit to sustain tropical development, and portions of the Caribbean and Gulf are well above that threshold.
A hurdle to development: Warm water isn’t the only factor at play. This potential tropical system would also need upper-level winds to cooperate. High wind shear – the wind’s change in direction or speed with altitude – can tear a developing storm apart.
How much wind shear this potential system faces is a critical factor in its formation and final strength. One forecast model shows more wind shear, limiting its development. Another shows less wind shear, allowing the system to develop.
Either way, wind shear may decrease for a time early next week across the far northern Caribbean and eastern Gulf of Mexico, allowing any system that forms to hold together.
Franklin to strengthen and approach Bermuda
Meanwhile, out in the central Atlantic, Franklin is on track to pass near Bermuda as a hurricane after slamming Hispaniola with flooding rainfall and strong winds.
The storm will track away from Hispaniola and Turks and Caicos through Friday night before making a turn to the north on Saturday. The storm is expected to strengthen into a hurricane over the weekend as it enters an area of low wind shear and very warm water.
Small variations in Franklin’s track through the weekend will determine exactly how close it gets to Bermuda when it make its closest pass Monday and Monday night.
Franklin’s winds and rainfall will extend beyond its center. Tropical-storm-force wind gusts are possible across Bermuda early next week as Franklin makes its closest approach. A few showers and thunderstorms are also possible across Bermuda as Franklin passes.
by tyler | Aug 21, 2023 | CNN, weather
After making landfall in Mexico earlier Sunday, Tropical Storm Hilary has crossed into California, where it is unleashing heavy rain and turning roads into gushing streams as officials warn of potentially deadly floods.
“We are not used to this level of precipitation, generally. Certainly not in the middle of summer,” San Diego Mayor Todd Gloria told CNN’s Jim Acosta Sunday afternoon, saying he was worried about potential power outages from the wind as well as flooding. “We’re not built for this kind of rainfall.”
Authorities across southern California pleaded with residents not to drive, warning of mudslides, road deterioration and dangerous debris flows and flooding, as some communities declared emergencies to respond to the storm. One California official has warned Hilary could be among the most devastating storms to hit the state in recent years.
The National Weather Service said parts of Los Angeles and Ventura counties were already experiencing “dangerous flooding” Sunday evening, writing on social media, “THIS IS LIFE THREATENING FLOODING!”
Cars were getting stuck in floodwaters and local authorities were conducting rescues, the service said.
Hilary’s core – in other words, its center – crossed into Southern California Sunday evening, but the state began feeling the storm’s effects much earlier in the day and rain totals have added up. Parts of Palm Springs saw more than 2 inches of water in just six hours Sunday – nearly half of what they average over an entire year, the weather service said.
And with the day not yet over, there were multiple other rainfall records broken Sunday, including in downtown Los Angeles, Burbank and Palmdale.
In Palm Springs, the city manager declared a local emergency due to “unprecedented rainfall and flooding,” with city officials saying there had already been one swift water rescue by Sunday afternoon.
Live updates: Tropical Storm Hilary to bring major flooding risk to California
Though the storm is expected to weaken, it will continue lashing the region with severe weather as it moves further into the US.
In Arizona, authorities issued evacuation orders in parts of Lake Mead National Park urging residents to seek higher ground ahead of potential floods. And Nevada’s governor declared a state of emergency Sunday as the storm drew closer.
More than than 1,000 flights within, into or out of the US have been canceled Sunday and more than 4,900 have been delayed. The three most-impacted airports are all in Hilary’s range: Harry Reid International Airport in Nevada, San Diego International Airport and Phoenix Sky Harbor International Airport, according to flightaware.com.
And as Hilary triggered flood warnings across Los Angeles, a magnitude 5.1 earthquake shook the area and other parts of Southern California Sunday afternoon, according to the United States Geological Survey.
More than 7 million people, including those in downtown Los Angeles, are under a flash flood warning through early Monday morning. Parts of Los Angeles and Ventura counties could see up to 1.5 inches of rain dumped per hour, the National Weather Service has said.
Schools in the San Diego Unified School District announced they would be postponing the first day of the school year to Tuesday. The Los Angeles Unified district, the country’s second largest school district, also said schools would be closed Monday.
Hilary weakened from a Category 1 hurricane to a tropical storm before it made landfall over the northern Baja California Peninsula early Sunday.
At least one death is already attributed to the storm. A person died when their vehicle was swept away near Santa Rosalía in Mexico, along the Baja California Peninsula, Mexican officials said in a news release Saturday.
California Gov. Gavin Newsom proclaimed a state of emergency Saturday for a large swath of Southern California to support hurricane response and recovery efforts.
In a Saturday news conference, Nancy Ward, director of the California Governor’s Office of Emergency Services, warned Hilary “could be one of the most devastating storms that we’ve had hit California in more than a decade.”
Parts of California, Nevada and Arizona that are unaccustomed to rain could suddenly receive a year’s worth or more. And along the coast, large swells generated by Hilary are likely to create life-threatening surf and rip current conditions.
Death Valley saw triple its average August rainfall in just a few hours Sunday morning. Nearly a month’s worth of rain fell in one hour on Sunday. It normally receives an average of 0.21 inches of rain the entire month of August, but the Furnace Creek observation site reported 0.63 inches since Sunday morning.
Roads within Death Valley National Park were expected to eventually become “impassable,” the park said on Instagram, sharing photos that showed floodwaters flowing over roads.
The threat triggered California’s first ever tropical storm warning extending from the state’s southern border to just north of Los Angeles – presenting an “unprecedented weather event” to a city with “deep experience” responding to natural disasters like wildfires and earthquakes, Mayor Karen Bass said at a news conference.
“It is critical that Angelenos stay safe and stay home unless otherwise directed by safety officials,” Bass said. “If you do not need to be on the road, please don’t get in your car. Make sure your emergency kit and essential devices are on hand. And ensure that all of your devices are charged in the event of life-threatening emergency.”
Residents of the San Bernardino County communities of Oak Glen, Forest Falls, Mountain Home Village, Angelus Oaks, and Northeast Yucaipa were all ordered to evacuate Saturday.
Visitors and some residents of Catalina Island, part of California’s Channel Islands, were “strongly encouraged” to leave the island ahead of the storm in a news release from the City of Avalon.
Meanwhile, helicopters from the Los Angeles County Sheriff’s Office were flying over riverbed areas Saturday afternoon, making announcements in both English and Spanish to warn homeless people about the extreme weather.
Los Angeles opened three more emergency shelters Sunday and provided transportation to help get more people to safety before the storm – bringing the total number of emergency shelters opened to eight.
Concern for deserts and recent burn areas
California has been particularly focused on preparing residents in areas that typically receive the least rain, or that were most recently scorched by wildfires, authorities said.
“We’re keeping a very close eye on our desert regions, east of San Diego and Los Angeles. Some parts of these areas may receive double their yearly amount of water in just a single day,” said Brian Ferguson, the deputy director of the California Governor’s Office of Emergency Services.
Lingering burn scars from wildfires can create a steep, slick surface for water and debris to flow off. People who live downhill and downstream from burned areas are very susceptible to flash flooding and debris flows.
“Rainfall that would normally be absorbed will run off extremely quickly after a wildfire, as burned soil can be as water repellant as pavement,” the National Weather Service said.
In Orange County, a voluntary evacuation warning was issued for Silverado Canyon and Williams Canyon in the Bond Fire burn area due to possible debris flows along or near the burn scar.
Residents have been offered sandbags to fortify their property in counties across Southern California, where some of the natural buffers against flooding have been burned away.
