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Tropical Weather Update | Typhoon Hagupit – Dec 5, 2014

A potent and massive typhoon is taking aim at the northern Philippines, in particular, Samar Island. Some of these areas were devastated by Category 5 Super Typhoon Haiyan less than one year ago, which broke the record for strongest landfalling tropical cyclone with wind speeds measured in Tacloban of 190mph. If you have friends or family in the Northern Philippines, Hagupit certainly bears keeping an eye on. Luckily for Tacloban, the current forecast track should take the center and northern semicircle (the stronger portion) of the storm north of the area, which should spare the area worst hit by Haiyan from another direct hit and the worst effects of a typhoon.

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Infrared satellite imagery of Typhoon Hagupit – note the symmetrical appearance of the inner portion of the storm, along with a well-defined eye (classic signs of a very strong storm).

Forecast Track

From the image below, you’ll see that Hagupit is currently forecast to move slowly west-northwestwards over the next 48 hours. Due to the strength of the storm, and the uncertainty surrounding the steering mechanisms in place (a subtropical ridge – high pressure area to the north weakening, and a frontal boundary), there is a low degree of confidence over the overall track forecast. However, it does appear, even with the uncertainty factored in that the storm center will pass to the north of Leyte Island and Tacloban, which was devastated by Super Typhoon Haiyan. That’s good news, since this would mean the weaker, southern semicircle of Hagupit would pass over the Leyte Gulf area. This would significantly reduce the effect of a devastating storm surge, since the winds from the storm would not have the best fetch (distance over open water) to build up a storm surge. In effect, with the current track, the strongest winds would be deflected by the terrain of Samar Island, sparing Leyte Island.

It is worth noting, based on this current track, that Legazpi City in extreme southeastern Luzon Island would bear the worst of the storm, including what could be a devastating storm surge. The bay east of Legazpi could serve to funnel storm surge westward under the right conditions, amplifying the effect of the surge in a similar (though less intense) manner as Leyte Gulf and San Pedro and San Pablo Bay did for Tacloban in Haiyan.

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For comparison, the track of Super Typhoon Haiyan in November 2013. Dots indicate position of the center of the storm every 6 hours, the colors indicate strength, with red indicating Category 5.

Intensity Forecast

Typhoon Hagupit has well-established outflow in the northern quadrant, as you can see from the satellite image above (white streaks fanning out from the center of the storm). It is being affected by easterly vertical wind shear, hence the absence of the same outflow bands in that sector of the storm. Hagupit has already weakened from a Category 5 Super Typhoon, but is still forecast to approach the Philippines as either a strong Category 3 or weak Category 4 storm, which would mean wind speeds likely in the range of 110-120mph. After landfall, Hagupit should weaken dramatically as interaction with the mountainous terrain of the Philippines disrupts the typhoon’s dynamics.