|Above: Infrared image of Super Typhoon Halong at 1800Z (1 pm EST) Tuesday, November 5, 2019. Image credit: RAMMB/CIRA/CSU.|
Super Typhoon Halong became the coolest type of tropical cyclone on Tuesday: a spectacular Category 5 equivalent unlikely to affect any creatures but fish. Halong was centered in the remote Northwest Pacific about 700 miles east-southeast of Iwo To at 12Z (8 am EDT) Tuesday. The Joint Typhoon Warning Center pegged its top sustained winds at 160 mph.
Halong may be even stronger than JTWC’s 12Z verdict. According to the satellite-based Advanced Dvorak Technique—developed by the Cooperative Institute for Meteorological Satellite Studies at the University of Wisconsin-Madison—Halong was a 7.8 on the Dvorak scale, with estimated top winds of 164 knots (189 mph) and a surface pressure of 894 mb. Update: In its 18Z advisory, JTWC raised Halong's peak winds to 180 mph.
#Halong is one of the strongest tropical cyclones we've ever observed in the satellite era, w/ Advanced Dvorak Technique (ADT) estimates supportive of nearly a 200 mph category 5 hurricane equivalent. Wow. pic.twitter.com/cI32JRz91Y— Eric Webb (@webberweather) November 5, 2019
At first glance, it’s hard to see why Halong has apparently transcended even the “ordinary” Category 5 storm. Sea surface temperatures are warm but not unprecedently so (around 29-30°C or 84-86°F). Halong is bordering a zone of high oceanic heat content, around 75-100 kilojoules per square centimeter, which is known to help with rapid intensification. The midlevel atmosphere around Halong is fairly moist but not sopping wet (relative humidity around 60%). Wind shear is on the strong side—around 15-20 knots—but this is largely made up of an outflow jet that's helping rather than hindering the storm.
None of these ingredients is itself enough to explain Halong’s freakish strength. The answer surely lies in how the various factors have come together as the storm has evolved (which could make an excellent topic for a graduate student’s thesis!).
It's no stretch to say Super Typhoon #Halong this morning is one of the strongest storms observed *globally* since satellite records began in 1979. An extreme event, but thankfully no threat to land. (satellite via @UWSSEC) pic.twitter.com/IZ2vUIGcvd— Michael Lowry (@MichaelRLowry) November 5, 2019
Halong’s time as a Category 5 storm won’t be long. The typhoon is carrying out a classic recurvature track that will soon take it over cooler waters. JTWC is predicting that Halong will steadily weaken to Cat 3 strength by Wednesday and could be no more than a tropical storm as soon as Friday.
Halong is Earth’s fifth Cat 5 of 2019
Halong is the planet’s fifth Category 5 storm of 2019. The other four were Dorian and Lorenzo in the Atlantic, and Super Typhoons Wutip and Hagibis in the Northwest Pacific. Lorenzo, Wutip, and Hagibis all peaked with 160 mph winds, while Dorian peaked with 185 mph winds at landfall in The Bahamas. Earth averaged 5.3 Category 5 storms per year between 1990 and 2018, according to ratings made by NOAA's National Hurricane Center and the U.S. Navy's Joint Typhoon Warning Center. Last year (2018) saw the second highest number of Cat 5s on record—eleven.
Halong is the 24th named storm and 12th typhoon of the year in the Northwest Pacific, according to the Japan Meteorological Agency. The Joint Typhoon Warning Center lists 21 named storms and 11 typhoons so far this year. From 1981-2010, an average of 26 Northwest Pacific named storms formed each year, 17 of which became typhoons. The Atlantic basin averages 12 named storms and 6 hurricanes per year.
Elsewhere in the tropics
After making landfall as a tropical storm in Vietnam on October 30, then crossing Southeast Asia, Tropical Depression Matmo will be cruising northward across the Bay of Bengal—one of the world’s most notorious locations for deadly tropical cyclones—over the next several days. Very warm SSTs (29-30°C) and moderate to strong wind shear (10-15 knots) should allow Matmo to intensify steadily, perhaps to Category 1 strength, but there’s model disagreement over Matmo’s fate toward the weekend as it nears the north end of the bay.
Meanwhile, Invest 90W, now west of the Philippines, will head west, approaching the coast of Vietnam this weekend perhaps as a strong tropical storm or Category 1 typhoon. Maha, still a Cat 2 cyclone, is expected to weaken dramatically as it boomerangs eastward toward the coast of far western India, likely arriving there around week’s end as a tropical depression or remnant low.
Dr. Jeff Masters contributed to this post.