| Above: VIIRS natural-color image of Super Typhoon Hagibis west of the Mariana Islands at 0325Z Tuesday, October 8, 2019. Image credit: NASA Earth Observatory. |
The most intense Northwest Pacific storm of 2019, Super Typhoon Hagibis, is heading toward a potential encounter with the world’s largest metropolitan area, Tokyo. After a slight weakening in Tuesday (from peak winds of 160 to 155 mph), Hagibis was back at Category 5 strength on Wednesday, with top winds of 160 mph as of 8 am EDT.
The speed bump in Hagibis’ strength was the result of an eyewall replacement cycle (ERC), a process that typically dents the peak winds of a tropical cyclone while spreading the core kinetic energy across a larger area. Sometimes, but not always, a storm can rebuild its pre-ERC peak winds within this newly broadened envelope. That was the case with Hagibis, which has drawn on large-scale near-ideal conditions for tropical development.
Wow!! Check out the big CDO donut now surrounding the much larger eye of #Hagibis, with the old eyewall still rotating around inside. Amazing view of the final stages of this ERC. pic.twitter.com/xI43VFckYk
— Sam Lillo (@splillo) October 8, 2019
The very small original eye of Hagibis, only about 5 miles across, was replaced with the new 30-mile-wide eye that was in place on Wednesday. The original eye was encompassed by the new one in a spectacular evolution evident on infrared satellite. The new eye remains surrounded by a solid core of intense thunderstorms (convection), although the shield of strongest convection is now considerably smaller compared to the size of the eye itself.
#Hagibis from small eye to large eye (same map zoom level) pic.twitter.com/GCamUDd9MO
— Stu Ostro (@StuOstro) October 9, 2019
Most of the banding associated with Hagibis has pushed away from the core, leaving the typhoon with some resemblance to an annular “truck tire” storm. All else being equal, annular tropical cyclones tend to weaken more slowly than usual.
Tokyo may get a late-season hit from Hagibis
Strong typhoons do not typically threaten central Japan as late as mid-October, but Hagibis is an unusual storm. Forecast models are in close agreement on a classic recurving path that will bring the hurricane close to the Tokyo Bay region of Honshu island between Saturday and Sunday local time. The spread among models is more in timing than in track. Because of the angle of approach, though, only a slight shift left or right could result in either a high-impact Tokyo Bay landfall or a glancing brush offshore.
Hagibis is likely to be slow to weaken. The atmosphere around the typhoon will remain moist (mid-level relative humidity around 60%). Sea surface temperatures will gradually drop along the typhoon’s path from the very warm current values of around 30°C (86°F) to around 27°C (81°F) as the storm nears Honshu, which is still more than warm enough to support a typhoon. Wind shear will increase from light to moderate values (5 – 10 knots) to a strong 20 knots by this weekend, with a more dramatic increase after Hagibis reaches Japan. At first, some of this shear may be in the form of midlatitude flow on the north side of Hagibis that could help ventilate the storm. If Hagibis becomes a truly annular storm, that will slow the pace of weakening as well. Even so, Hagibis will be a considerably less potent storm than it is now by the time it nears Japan on Saturday (U.S. EDT).
The Joint Typhoon Warning Center predicted on Wednesday that the core of Hagibis will move over or near Tokyo Bay around 8 am EDT Saturday as a Category 2 typhoon. This is roughly comparable to the strength of Faxai, which struck Tokyo Bay as a Category 2 typhoon last month, damaging more than 20,000 structures and inflicting as much as $9 billion in damage. One major difference is that Hagibis will be a larger, more long-lived, and more powerful typhoon than Faxai as it approaches Japan, so Hagibis could pack more widespread impacts—including a more significant threat of storm surge—depending on its ultimate trajectory and strength.
Hagibis could affect the Rugby World Cup taking place this month in several sites in Japan. World Rugby will hold a press conference at 11 pm EDT Wednesday to discuss the storm and any needed actions, according to BBC.
The last Typhoon to impact the Tokyo region was Typhoon #Faxai (right) only a month ago. Super Typhoon #Hagibis (left) is much much larger as this to-scale comparison shows (uses NASA Worldview). #TyphoonHagibis #typhoonfaxai #SuperTyphoonHagibis pic.twitter.com/lfKePXpGi2
— YouStorm (@YouStormorg) October 9, 2019
Coastal storm could pack a startling punch in Northeast
A complex storm evolving just off the U.S. East Coast will linger for more than a day, leading to a long stretch of onshore flow against the Northeast coast. High winds, heavy rain, and coastal flooding are all possible, especially from the mid-Atlantic to southern New England.
A disturbance that moved off Florida early this week is now moving north and will be merging with a non-tropical low along a frontal zone off the mid-Atlantic coast. The resulting coastal storm is expected to intensify late Wednesday into Thursday as it carries out a tight loop about 200 miles south of Cape Cod. The National Hurricane Center has reduced the odds of any tropical development with these systems, predicting only a 10-20% chance in its 2 pm EDT Wednesday tropical weather outlook.
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| Figure 1. This week's coastal storm is predicted to cause a long swath of moderate coastal flooding from northern North Carolina to Long Island Sound, NY. The most significant flooding was predicted along the coasts of Maryland, Delaware, and New Jersey. Minor flooding was predicted at The Battery in NYC, and moderate flooding in Long Island Sound at Kings Point. One area close to major flooding was predicted to occur at Barnegat Bay, NJ (above) during the Friday morning high tide: just 0.1' shy of the major flooding threshold. Image credit: NOAA. |
Regardless of how it’s classified, this prolonged storm will be a serious weather-maker for southern New England. Widespread 1” – 3” rains can be expected, and totals could exceed 5” in far eastern Massachusetts, including Boston and Cape Cod. Wind gusts could reach 30 mph in Philadelphia and New York and 50 mph in Boston. Coastal flooding from the extended onshore flow will be exacerbated by high astronomical tides associated with Saturday’s full moon. Moderate flooding at high tide could extend from North Carolina to New York.
Jeff Masters contributed to this post.
