The unseasonable wintertime hurricane that developed over the Northeast Atlantic on Thursday has been downgraded to Post-Tropical Cyclone Alex
, but its place in the annals of hurricane history is secure. Alex became a hurricane at 15Z (10 am EST) Thursday and maintained Category 1 strength for almost 24 hours. Alex’s western eyewall made landfall on the island of Terceira in the central Azores, roughly 1000 miles west of Portugal, at around 8:15 am EST
with tropical-storm force winds of 60 knots (70 mph). No major damage was reported. While approaching Terceira at 7 am EST, Alex was still classified as a minimal hurricane
(75 mph winds). Most of Terceira was on the west (weaker) side of Alex, so hurricane-force winds might have been observed if Alex had tracked just a bit further west. The eyewall passed over Lajes Air Force Base, producing a minimum pressure of at least 29.18” (988 mb)
(no wind observations from within an hour of landfall were available). Wind gusts to 58 mph
were observed at Ponta Delgada, more than 100 miles southeast of Terceira, and gusts to 55 mph
were reported at Santa Maria, roughly 200 miles southeast of Terceira. At 4 pm EST Friday
, Alex was located about 300 miles north of Terceira, racing northward at 40 mph with sustained winds of 60 knots (70 mph).Figure 1.
MODIS visible satellite image of Tropical Storm Alex at 9:20 am EST Friday, January 15, 2016. About an hour earlier, Alex’s western eywall passed over the Azores island of Terceira (black outline below the center of Alex). Image credit: NASA
.Not unprecedented, but very unusual
In records going back to 1851, only one other tropical cyclone in the Atlantic has made landfall in January: Hurricane Alice
, which moved from northeast to southwest over the islands of Saint Martin and Saba on January 2. Alice’s heavy rain and rough seas caused damage totaling more than $4 million in current US dollars. Alice’s winds peaked at 90 mph, just above Alex’s peak sustained winds of 85 mph. The only other January hurricane in the Atlantic was Hurricane One
on January 4, 1938. Three weaker cyclones have been observed in January: Tropical Storm Zeta
(2005-06), Tropical Storm One
(1951), and Subtropical Storm One
At any time of year, it’s quite uncommon for a hurricane to develop where Alex did. In a tweet on Thursday (see bottom), Alex Lamers noted that only one other tropical cyclone in Atlantic records is known to have become a hurricane north of 30°N and east of 30°W. That would be Hurricane Vince
, one of the many oddities of the blockbuster 2005 Atlantic season. Vince went on to become the first tropical storm known to strike the Iberian Peninsula in more than 150 years
The Northeast Atlantic is a challenging location for hurricane development thanks in large part to its relatively cool water. Alex took on its tropical characteristics while over waters that were 20-22°C (68-72°F). Although these are up to 1°C above average for this time of year, they are far cooler than usually required for tropical cyclone development. However, upper-level temperatures near Alex were unusually cold for the latitude, which meant that instability--driven by the contrast between warm, moist lower levels and cold, drier upper levels--was higher than it would otherwise be. That instability allowed showers and thunderstorms to blossom and consolidate, strengthening the warm core that made Alex a hurricane as opposed to an extratropical or subtropical storm. One could make a case that Alex was the last hurricane of 2015 rather than the first of 2016, as I discussed in a post on Thursday
.What about El Niño and climate change?
Sea-surface temperatures across the entire North Atlantic south of 35°N are warmer than average, part of a huge swath of above-average readings covering much of the globe. Some of these unusually warm waters are the result of El Niño, but the extent of the warmth--at record levels in many places--strongly suggests a link to longer-term climate change. It’s impossible to say without further research whether the extra oceanic warmth associated with Alex tipped the scales toward development, but it certainly didn’t hurt.
Alex doesn’t appear to be a classic manifestation of El Niño, based on previous January tropical cyclones since reliable El Niño records
began in 1950:Tropical Storm One (1951):
La NiñaHurricane Alice (1955):
La NiñaSubtropical Storm One (1978):
El NiñoTropical Storm Zeta (2006):
neutral, but leaning toward La NiñaElsewhere in the tropics
The other hurricane shocker of this month, Hurricane Pali
, has finally dissipated after toying with a run at the equator. Peaking at Category 2 strength during its eight-day life, Pali was the earliest tropical storm and earliest hurricane to develop between the International Date Line and the Americas, and it was closer to the equator than all but two other hurricanes in global records
. Only two other tropical cyclones have been observed in January in the Central Pacific.
In the Southwest Pacific, a more seasonable Tropical Cyclone Victor
is strengthening quickly about 300 miles east of Pago Pago. Victor could peak at Category 4 strength this weekend
as it moves south, although it should not threaten any land areas.
We’ll be back with a new post on Martin Luther King, Jr., Day (Monday). Have a great weekend, everyone!