|Above: Expected winds and track of ex-Hurricane Leslie, from ESTOFEX. Wind gusts as high as 112 mph (180 km/h) were predicted over central Portugal.|
Ex-Hurricane Leslie made landfall on the coast of central Portugal near 5:30 pm EDT October 13, 2018, with top sustained winds of 70 mph, just 3 hours after being declared post-tropical. Leslie maintained hurricane status into the far Eastern Atlantic to a location where no hurricane had ever been observed: just 200 miles west of Portugal at 11 am EDT. But at 2 pm EDT Saturday, Leslie succumbed to cold 20°C (68°F) waters and the influence of a cold front overtaking it, and became a powerful extratropical storm with 70 mph winds.
|Figure 1. Peak wind gusts in km/h from Leslie; 176.4 km/h = 109 mph. Image credit: Meteorological agency of Portugal – IPMA (www.ipma.pt) and Severe Weather Europe.|
"Defiant" #Leslie, as @NHC_Atlantic put it. This entrancing satellite loop is 19 days ending yesterday. When I started compiling, little did I know it'd eventually be a hurricane going toward Portugal outside the map.. or that on the W edge would be a 919 mb landfall (#Michael).. pic.twitter.com/ZUAJcesw7q— Stu Ostro (@StuOstro) October 15, 2018
Even as an ex-hurricane, Leslie was still packing a powerful punch, with tropical storm-force winds that extended out up to 160 miles from the center at 5 pm EDT. Sustained winds of 33 mph, gusting to 63 mph, were measured at Cabo Carvoiero at 4 pm EDT. Leslie passed about 200 miles north of Portugal’s Madeira Island on Saturday morning. Funchal on Madeira Island recorded sustained 10-minute average winds of 40 mph at 9 UTC, and a wind gust of 45 mph at 18 UTC.
|Figure 1. MODIS image of Hurricane Leslie on Saturday morning, October 13, 2018. A cold front is overtaking Leslie from the west, and Portugal is visible to the east. Image credit: NASA.|
Leslie will likely cause widespread wind damage over Portugal Saturday night and Sunday morning. Peak wind gusts of 80 – 110 mph are expected in the central part of the system as ex-Leslie speeds east-northeast at 35 mph. Heavy rains and flash flooding are a lesser threat from the storm, as ex-Leslie is expected to bring rains of 1 – 3”, with isolated areas of up to 5”. The risk of tornadoes is low from the storm.
|Figure 2. Radar image of Leslie at 5:10 pm EDT October 13, 2018. Image credit: IPMA.|
After landfall, ex-Leslie should slow down and turn east and weaken over northern Spain. Some limited wind damage may occur in northern Spain near the border with Portugal.
|Figure 3. Leslie’s long and unusual path over the Eastern Atlantic, ending at 5 pm EDT October 13, 2018. Image credit: NHC.|
Unusual Eastern Atlantic tropical cyclone activity in recent years
There have been a number of unusual tropical cyclones in recent years in the far Eastern Atlantic, in locations or with intensities that are extremely rare or unheard of in the historical record. In most cases, we can say that the odds of these oddball storms forming were increased by human-caused global warming, since tropical storm formation in the far Eastern Atlantic is primarily limited by cool ocean temperatures. A short list of unusual Eastern Atlantic tropical cyclones since 2005:
|Figure 4. Hurricane Vince at peak strength on October 9, 2005. Image credit: NASA.|
Tropical Depression Vince in Spain and Portugal, 2005
Tropical Depression Vince hit southern Spain 2005, bringing 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. The National Hurricane Center 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 storm, the 1842 Spain hurricane, struck the Iberian Peninsula on October 29, 1842. Vince developed over waters that were about 1° C (1.8°F) above average. The official NHC summary for Vince noted that "the rain in Spain was mainly less than 2 inches, although 3.30 inches fell in the plain at Cordoba."
Hurricane Ophelia in Ireland, 2017
Ophelia spent its entire lifetime over the far eastern Atlantic Ocean, becoming the farthest-east major hurricane observed in the satellite era. Ex-Ophelia hit Southwest Ireland on October 16 with near-hurricane-force winds, killing three people and causing over $100 million in damage, according to Aon Benfield. Ophelia’s ascension to Category 3 status and subsequent impact on Ireland just 12 hours after becoming an ex-hurricane was made possible, in large part, by unusually warm ocean temperatures that were 1 - 2°C (1.8 - 3.6°F) above average.
One other way we know that Ophelia was an extremely unusual storm is that it broke some of the graphical displays we use to view the forecast. The National Hurricane Center graphical forecasts of the storm’s track had to be truncated east of 0° longitude (the Greenwich Prime Meridian), since they never planned for the possibility that an Atlantic hurricane or its identifiable remnants could make it so far to the northeast.
|Figure 5. MODIS image of Hurricane Fred from NASA's Terra satellite taken at approximately 11:15 am EDT Monday August 31, 2015. At the time, Fred had top sustained winds of 85 mph, as was passing through the Cabo Verde Islands. Image credit: NASA.|
Hurricane Fred in the Cabo Verde Islands, 2015
Hurricane Fred passed through the Cabo Verde Islands on August 31, 2015, becoming the first hurricane to do so since an 1892 storm. Fred was blamed for nine deaths and $1 million in damage. Fred was able to form and intensify at an unusually easterly location due to a pocket of anomalously warm waters (1-2°C above average, or about 27-28°C). Since ocean temperatures are often just marginally warm enough to support tropical cyclones near the islands, it is rare to see a tropical storm or hurricane affect them. When Fred initially became a hurricane at 2 am EDT Monday at 22.5°W longitude, this was the easternmost formation location for any hurricane in the historical record; the previous record was held by Hurricane Three of 1900, which became a hurricane at 23°W, south of the Cape Verde islands. There have been six other hurricanes in historical records that existed at a more easterly longitude, but all were recurving storms that formed much farther to the west than Fred. (The easternmost hurricane ever observed was Hurricane Faith of 1966, which maintained hurricane status to a position north of the British Isles, at 2.9°W.)