Three new named storms, Tropical Storm Wilfred in the eastern Atlantic, Subtropical Storm Alpha near the coast of Portugal, and Tropical Storm Beta in the Gulf of Mexico, joined the burgeoning number of 2020 storms in the Atlantic on September 18. This marks the first time the National Hurricane Center has named three storms in one day, and is just the second time on record the Atlantic has had three named storm form on the same day, along with August 15, 1893. The Atlantic has now recorded an extraordinary 23 named storms for the year. The 10 storms named so far in September are the most on record for any September.
And if the National Hurricane Center (NHC) had responsibility for the Mediterranean Sea, a hybrid “medicane” storm named Ianos that hit Greece overnight might well have qualified as an Atlantic named storm.
Medicane Ianos pummels the Ionian Islands of Greece
Winds shrieking at gale force swept across the southern Ionian Islands of western Greece with the landfall early Friday of Ianos, an unusually strong “medicane” (the name for a cyclone with tropical or subtropical characteristics over the Mediterranean Sea).
One or two medicanes typically form each year, generally at tropical depression or tropical storm strength. Medicanes are not tracked or named by NHC, nor formally catalogued by the World Meteorological Organization. Since 2017, the National Observatory of Athens has been naming medicanes that affect Greece, and it dubbed this week’s system Ianos.
Ianos moved across the southernmost Ionian island group – Kefalonia, adjacent Ithaca, and Zakynthos – on Friday morning with a central pressure in the vicinity of 995 mb. Ianos boasted a distinct eye on satellite as it crossed the Ionian Sea, and analysis from Florida State University showed that Ianos had a symmetric warm core typical of a strong tropical storm.
Downed trees and power outages were reported on Kefalonia, and residents were urged to stay indoors, according to Greek Reporter. Wind gusts reached 69 mph on Kefalonia and Zakynthos, according to Etienne Kapikian (Meteo-France). “Clear eye surrounded by intense convection, winds worthy of a strong tropical storm,” Kapikian summarized on Twitter. Meteo.gr on twitter posted some impressive videos and damage images from Ianos.
Torrential rains developed across the higher terrain of western Greece as Ianos pushed strong winds carrying ample moisture upslope. Satellite-based rainfall estimates were as high as 50 mm/hr (2″/hr). As of 1 p.m. EDT Friday, a personal weather station (PWS) in a mountainous region of central Greece, at Fylakti Karditsas, recorded 12.53 inches of rain from Ianos, while a PWS on the island of Lefkada recorded 8.82 inches.
Ianos is predicted to drift southward along or near the southwest coast of Greece on Friday night. Prolonged heavy rains will continue to drench southern Greece, with a risk of additional flooding and mudslides. Over the weekend, Ianos – weakened by its traverse of rugged terrain – may regain some strength en route to a possible landfall on the northeast coast of Libya on Sunday night. Models differ on whether Ianos will move ashore or gradually weaken across the southeast Mediterranean Sea.
As with tropical cyclones across the globe, medicanes may become slightly less frequent in a future warmer climate. However, the most potent ones may become even stronger and longer-lasting, with some potentially developing hurricane-force sustained winds and dangerous heavy rains, according to a 2019 study in Geophysical Research Letters led by Juan J. González‐Alemán, using the high-resolution (25km grid) HiFLOR model, “Potential Increase in Hazard From Mediterranean Hurricane Activity With Global Warming.” These results agree with a 2017 study in Global and Planetary Change led by Raquel Romera that examined a large suite of regional climate model projections, and a 2013 study in JGR-Atmospheres by Romu Romero and MIT’s Kerry Emanuel.
Subtropical Storm Alpha makes landfall in Portugal
Subtropical Storm Alpha formed at 12:30 p.m. EDT Friday, September 18, near the coast of Portugal. Alpha’s initial location, 75 miles north of Lisbon, the capital of Portugal, was the most easterly ever for the formation of an Atlantic named storm. Alpha made landfall in Portugal at 2:30 p.m. EDT Friday with sustained winds of 50 mph and a central pressure of 996 mb, marking the first time in recorded history that a named storm has hit Portugal. Alpha was moving inland at 17 mph over Portugal Friday evening local time, and is expected to dissipate by Saturday. Alpha is predicted to bring one to two inches of rain, with localized amounts of up to three inches, along its path. Extensive inland damage, storm surge flooding, and two tornadoes have been reported in Portugal from Alpha’s landfall.
Tropical cyclone history of Portugal and Spain
There are no historical records of any tropical or subtropical cyclones ever hitting Portugal. Spain has been hit by two tropical cyclones, most recently on October 11, 2005, when Tropical Depression Vince hit southern Spain. Vince brought heavy rains to both Spain and Portugal, but no significant damage. Vince developed into a hurricane farther east than any other known storm, at 18.9° W.
NHC declared that Vince was the first tropical cyclone on record to have made landfall on the Iberian Peninsula. Historical documents, however, suggest that a possibly stronger tropical cyclone, the 1842 Spain hurricane, struck southern Spain on October 29, 1842.
Tropical Storm Wilfred forms in the eastern Atlantic
Tropical wave 98L in the eastern Atlantic developed a closed circulation and enough heavy thunderstorm activity to be upgraded to Tropical Storm Wilfred on Friday morning. Wilfred was the last name on Atlantic’s 2020 list of storms. The hurricane season will now progress through the Greek alphabet, something that has only occurred once, in 2005.
Satellite images on Friday afternoon showed that Wilfred had a modest amount of poorly organized heavy thunderstorm activity. The system had favorable conditions for development through Saturday, with moderate wind shear of 10 – 20 knots predicted, along with warm ocean temperatures of 28 Celsius (82 °F) and a moist atmosphere. Models support modest intensification through Saturday. Beginning on Sunday, Wilfred will encounter high wind shear, which is expected to lead to dissipation of the storm by Tuesday.
The 2020 parade of record-early named storms continues
Wilfred’s arrival on September 18 marks the earliest date that any Atlantic season has produced its twenty-first tropical storm, topping the record held by Vince from October 8, 2005. The arrival of Subtropical Storm Alpha on September 18 marks the earliest date for the Atlantic’s twenty-second named storm, formerly held by Wilma from October 17, 2005. Tropical Storm Beta is the record-earliest twenty-third named storm, beating Alpha from October 22, 2005, by more than a month.
With the Atlantic hurricane season just over a week past the climatological half-way point, we’ve already had 23 named storms, eight hurricanes, two intense hurricanes, and an accumulated cyclone energy (ACE) index of 85 (31% above average for the date). Only one Atlantic hurricane season since 1851 has had more named storms during an entire season – 2005, with 28 named storms. According to Colorado State University hurricane scientist Phil Klotzbach, the averages for this point in the season are eight named storms, four hurricanes, two intense hurricanes, and an ACE index of 65.
Tropical Storm Beta expected to threaten Texas as a hurricane by Monday
Tropical Storm Beta, in the southwestern Gulf of Mexico, was named at 5 p.m. EDT Friday. The storm might have been named on Friday morning had the Air Force hurricane hunter plane flying out to investigate it not been hit by lightning and forced to return to base.
Conditions for development are expected to be favorable through the weekend, with light to moderate wind shear of 5 – 15 knots, warm ocean temperatures of 30 – 31.5 Celsius (86 – 87°F), and a moist atmosphere. Beta is predicted to move at speeds of less than 10 mph over the next five days. Beta will initially move north under the steering influence of a trough of low pressure to its north, then turn to the west by Sunday as the trough weakens and a weak ridge of high pressure builds to Beta’s north. By Monday, when Beta is expected to be near hurricane strength off the coast of Texas, it will interact with a cold front moving off the coast, which will inject some dry air into the western Gulf of Mexico, potentially weakening the system.
Given its very slow motion and the very warm Gulf waters feeding it, Beta is expected to be a prodigious rainmaker, with some model forecasts predicting over a foot of rain along the lower and middle Texas coast. Heavy coastal rains may extend further northeast if Beta holds together and drifts in that direction later next week, as suggested by the 12Z Friday runs of the GFS and European models.
Category 4 Teddy expected to brush Bermuda, then hit Nova Scotia
Powerful Hurricane Teddy maintained category 4 strength overnight, but weakened slightly to a category 3 hurricane with 125 mph winds by 5 p.m. EDT Friday. Teddy it is expected to brush Bermuda with tropical storm-force winds on Sunday night as the hurricane turns north toward an expected Tuesday landfall in Nova Scotia, Canada.
At 5 p.m. EDT Friday, Teddy had top sustained winds of 125 mph and a central pressure of 951 mb. Teddy was headed northwest directly towards Bermuda at 14 mph.
Teddy is a large hurricane, with tropical storm-force winds extending out up to 230 miles from the center. This large wind field has created waves up to 45 feet high near the center, and Teddy has generated big swells and dangerous surf conditions and riptides along the north coast of South America and the north-facing shores of the Caribbean islands. Swells from Teddy will affect most of the U.S. East Coast this weekend, and the Canadian Maritime Provinces by Monday.
Forecast for Teddy
Teddy has favorable conditions for intensification through Saturday, with moderate wind shear (10-20 knots) and ocean temperatures of 28 – 29 degrees Celsius (82 – 84°F). On Sunday, Teddy will encounter the cool water wake left behind by Hurricane Paulette, which should limit intensification.
A strong ridge is steering Teddy over the central Atlantic. As Teddy approaches the west side of the ridge, a trough of low pressure to the north is expected to turn the hurricane northwards, bringing it to the east of Bermuda Sunday night through Monday morning. Bermuda is no longer in the NHC cone of uncertainty, but the hurricane’s large size gives the island a 60% chance of experiencing tropical storm-force winds, according to the 5 p.m. EDT Friday wind speed probability product from NHC.
Beyond Teddy’s encounter with Bermuda, the crucial factor in determining the storm’s track is the evolution of a strong upper low swinging through southeast Canada this weekend. That upper low is expected to leave behind a small remnant “cutoff” low along the U.S. East Coast. That cutoff low is expected to keep Teddy headed to the north, and possibly induce a bend to the north-northwest as the counterclockwise flow around the cutoff low swings Teddy around. This steering pattern makes it likely that Teddy will make landfall in Nova Scotia on Tuesday, a scenario on which the GFS and European models have come into closer agreement since Thursday.
Once Teddy moves north of Bermuda, upper-level winds from the trough of low pressure steering the hurricane will accelerate the storm to a forward speed of 15 – 20 mph, and likely create a high 25 – 45 knots of wind shear. This wind shear is likely to weaken Teddy, as will the cooler waters it will traverse once it moves north of the Gulf Stream, at the latitude of New Jersey.
Landfall in Nova Scotia will likely be as a strong tropical storm or low-end category 1 hurricane, with heavy rain and widespread gale-force winds likely to be the main threat. Teddy will be transitioning to an extratropical storm near the time of landfall, which will spread out its impact over a larger area. The 5 p.m. EDT Friday wind speed probability product from NHC was giving eastern Maine a 20 – 30% chance of experiencing tropical storm-force winds from Teddy.
Still 300,000-plus customers without power after Hurricane Sally
The cleanup in Alabama and Florida continues in the wake of Hurricane Sally, which made landfall near the Alabama/Florida border as a category 2 hurricane with 105 mph winds on Wednesday. Poweroutage.us showed over 300,000 customers in Florida and Alabama remained without power on Friday afternoon compliments of Sally. Over 40,000 customers remain without power in Louisiana as a result of Hurricane Laura’s impacts on August 27.
Editor’s note: This post was updated at 5:30 p.m. EDT Friday to include the upgrade of TD 22 to Beta and the landfall of Subtropical Storm Alpha in Portugal. The next post will not be until Sunday afternoon.
Posted on September 18, 2020 (4:49pm EDT).