Chan-hom: Guam Fourth of July Threat; Typhoon Watch Issued (FORECAST)

Jon Erdman
Published: July 2,2015
Chan-hom has weakened to a tropical storm as of late Thursday evening (U.S. time). However, it is forecast to regain typhoon status again this weekend.
Wind shear is the primary reason for the weakening we saw late on Thursday. All of the shower and t-storm activity was sheared off to the west, leaving an exposed low-level center of circulation.
Chan-hom is currently located more than 300 miles southeast of Andersen Air Force Base, Guam. It has slowed down considerably as of late Thursday and is stationary at this time.

Enhanced Satellite: Chan-hom

The National Weather Service has issued a typhoon watch for Guam, Rota, Tinian and Saipan, meaning typhoon conditions - winds of 74 mph or more - are possible within 48 hours.
Guam has been placed in Condition of Readiness 3 Thursday afternoon, meaning destructive winds are possible within 48 hours. Tropical Cyclone Conditions of Readiness -- TCCOR -- is the system used by the U.S. military to help prepare for tropical cyclones.

Guam Radar/Current Winds

Steered by upper-level high pressure to the north, Chan-hom is expected to bend northwest Friday, then pass near, or over, Guam and the Mariana Islands Saturday night or early Sunday, local time. Guam is 14 hours ahead of U.S. Eastern daylight time.
Chan-hom is forecast to intensify again as it nears Guam, and may be a Category 1 equivalent typhoon on its closest approach.

Chan-hom Forecast Path

It remains a bit too soon to say precisely where the center of Chan-hom will track. Any short-term wiggles in the track and the precise timing of the northwest turn are critical for impacts in the Marianas. Also, the exact intensity of Chan-hom remains uncertain, which will dictate the eventual impacts.
The NWS office in Guam lists the following potential impacts:

• Winds: Tropical storm-force winds could begin as soon as Saturday early afternoon, continuing through midday Sunday. Typhoon-force winds are possible Saturday night.
• Surge:  2-4 feet of coastal inundation along east-facing shores
• Surf: 10-15 feet Friday, building to 17-22 feet Saturday evening, continuing Sunday morning before subsiding Sunday afternoon/night
• Rain:  8-12 inches possible through Sunday night

Interests in Guam and the Mariana Islands should finish typhoon preparations monitor the progress of Chan-hom.
(FORECAST: Guam)
If this sounds like a bit of deja vu, you're right.
Typhoon Dolphin's eye passed between Guam and Rota Island in mid-May as a strong Category 2 equivalent storm. Fortunately, Dolphin saved its rapid intensification to super typhoon status after leaving the Marianas.
After leaving Guam and the Marianas, Chan-hom is expected to continue to track northwest next week around the west and southwest side of high-pressure aloft.
Like Super Typhoon Dolphin in May, Chan-hom is expected to undergo a period of rapid intensification in this zone of the western Pacific Ocean.
Chan-hom could be a threat to the Japanese islands (including Okinawa and Iwo Jima), Taiwan, eastern China, or the Korean peninsula late next week. However, details at this time are highly uncertain.
Those with interests in Japan or near the coast of the East China Sea should monitor forecast updates on Chan-hom into next week.
Chan-hom isn't the only system we are tracking in the western Pacific. Tropical Storm Linfa has now formed and is forecast to pass near or north of the northern Philippines this weekend.
(MORE: Tracking Linfa)
Meteorologist Chris Dolce contributed to this report.

MORE: Super Typhoon Maysak Images (March-April 2015)