After undergoing rapid intensification on Friday, Super Typhoon Lan has emerged as a force to reckoned with in the northwest Pacific.
Lan is forecast to strafe Okinawa, Japan’s southernmost prefecture on Sunday night local time, before making a run at the densely populated corridor between Osaka, Kyoto and Tokyo early next week.
The storm has sustained winds of 150 mph as of Friday afternoon, putting it on par with a Category 4 hurricane. The eye has cleared out dramatically over the course of Friday, and it’s 50 miles wide, or big enough to “encompass parts of New Jersey, the lower Hudson Valley of New York, southwestern Connecticut, and western Long Island” according to Mashable’s Andrew Freedman.
The Joint Typhoon Warning Center forecasts that it will maintain its Category 4 winds and could near Category 5 strength for the next day as it cruises over warm waters with minimal interference.
It will then slowly weaken as it approaches cooler waters to the north. Lan’s winds will make it the equivalent of a strong Category 1 or weak Category 2 storm by the time it reaches Japan’s main island, but the extent of its winds will be enormous.
Tropical storm-force winds—winds in excess of 39 mph—are forecast to extend up to 425 miles out from its center. In comparison, Hurricane Maria’s tropical storm wind field extended 210 miles out from its center (though its core obviously had stronger winds at landfall than Lan will).
The storm is also forecast to dump up to a foot of rain and bring powerful surf and storm surge flooding. The rain could trigger flash flooding and landslides on Japan’s steep slopes as well. Oh, and all this could be happening near the most densely-populated part of Japan.
Super Typhoon Lan is also influencing weather well beyond the northwest Pacific. It’s essentially created a bump in the jet stream that’s helped steer the duo of atmospheric rivers currently bringing heavy rain and snow to the Pacific Northwest. That kink is also likely partly responsible for the ridge of high pressure building over Southern California this weekend, increasing the risk of wildfires. It’s like we’re all connected, maaan.
Lan is just the third Super Typhoon of the year in the northwest Pacific. Normally the most active hurricane basin in the world, it’s been quieter than normal this year.
Accumulated cyclone energy (ACE) is one measure of how active a hurricane basin is based on the number of storms and sustained wind speeds (PSA: cyclone, typhoon and hurricane are all just different names for the same thing). So far this year, the northwest Pacific ACE is just 59% of what it would be normally.
The Atlantic basin, normally its sleepier cousin, has been gangbusters by comparison. Hurricanes Harvey, Irma and Maria have all pushed the Atlantic to more than double its normal ACE for this time of year and made it the most active hurricane basin in 2017.
When you average all the hurricane basins across the Northern Hemisphere, though, this has been an average year so far. Which just goes to show that even an average year can still be weird and downright be catastrophic.