Category 2 Typhoon Dolphin Hits Guam

Typhoon Dolphin blasted the islands of Guam and Rota in the U.S. Mariana Islands today as a Category 2 storm with sustained winds of 110 mph. The eye of Dolphin passed through the channel between the islands of Guam and Rota near 5 am EDT Friday, with Guam experiencing the weaker southern eyewall, and Rota seeing the stronger northern eyewall. Andersen Air Force Base on Guam experienced sustained winds as high as 84 mph at 7:55 pm local time; a peak gust of 106 mph occurred at 6:58 pm. Rainfall amounts tallied 9.30" in a 12-hour period. No damage reports have come out of Guam yet, but the damage is likely to be modest, given that Dolphin stayed below Category 3 strength, and the stronger northern eyewall missed the most heavily populated island in the chain--Guam. The 2 am EDT Friday advisory from the Joint Typhoon Warning Center (JTWC) put Dolphin's winds at 110 mph, just below the Category 3 threshold of 115 mph, and the Japan Meteorological Agency estimated that the central pressure had held steady at 955 mb. The lack of intensification was due to the fact that wind shear has been in the moderate range, 10 - 20 knots, driving dry air into the circulation. Satellite loops on Friday morning showed that Dolphin had changed little over the past 24 hours, and no eye was apparent. Sea surface temperatures (SSTs) were near 29°C (84°F), and warm waters extend to great depth along Dolphin's track, giving it plenty of heat energy to draw upon for intensification. Dolphin should be able to intensify to Category 4 typhoon status over the weekend as it takes advantage of lower shear and improved upper-level outflow. A strong trough of low pressure will recurve the storm to the north, and Dolphin may pass close enough to Iwo Jima on Tuesday to bring that island typhoon conditions.

The GFS model is no longer forecasting that a tropical disturbance near the Equator in the waters southeast of Guam (95W) will organize into a tropical depression.


Figure 1. Typhoon Dolphin as seen from the Guam radar just before it failed. The eye of Dophin was in the channel between the islands of Guam and Rota, with Guam experiencing the weaker southern eyewall, and Rota seeing the stronger northern eyewall.


Figure 2. Dolphin chews Guam: Typhoon Dolphin over Guam near 03 UTC May 15, 2015, as seen by the MODIS instrument on NASA's Aqua satellite. Image credit: NASA Worldview.

The last typhoon on Guam: thirteen years ago
As discussed in detail in Wednesday's post, the last typhoon to strike Guam was Typhoon Pongsona, which hit the island as a Category 4 super typhoon with 150 mph winds on December 8, 2002. The last tropical storm to affect Guam was Tropical Storm Saomai of August 2006, which had 50 mph winds when it moved over the island. May is exceptionally early for Guam to be worrying about a typhoon; according to NOAA's Historical Hurricane Tracks website, no typhoon has affected the island in the months of February through June since record keeping began in 1945.


Video 1. Storm chaser Jim Edds is on Guam, and has been documenting the impact of Dolphin on the island via his Twitter feed with videos like this one.

The NWS in Guam is putting out special advisories and local statements on Dolphin.

A remarkable super high-resolution (every 2.5 minutes at 0.5 km) visible satellite loop of Typhoon Dolphin at sunrise on May 15 has been put together by The University of Wisconsin CIMSS group, using imagery from the new Japanese Himawari-8 satellite. A larger-scale view is available from NOAA, resembling a witch's cauldron full of boiling, poisonous brew! More info and hi-res infrared loops can be found at the CIMSS satellite blog.

Later today, Bob Henson will have an update on the severe weather potential for the U.S. on Friday and Saturday.

Jeff Masters