Tropical depression 16W weakens; shifts direction slightly northward

(NWS graphic)

Tropical Depression 16W has weakened and shifted direction slightly northward, the National Weather Service reported.

In a weather briefing Monday morning, NWS lead forecaster Brandon Aydlett said 16W remains a tropical depression with 30 miles per hour sustained winds.

Although the tropical depression has weakened, Aydlett said a tropical storm watch is still in effect for Guam and Rota.

“We’re still looking at the possibility of those damaging tropical storm winds of 39 miles per hour or more on Tuesday. However, this possibility is gradually decreasing with the latest trends that we’re seeing with 16W. Wind speeds are ultimately expected to decrease Tuesday evening, as the entire system of 16W moves to the west of the Marianas. Some changes that we’re seeing such as a wind speed and direction could widely vary based on location,” he said.

According to Aydlett, one thing to keep in mind is that the strongest winds are found on the north side of the center of 16W.

“Those easterly winds will be buffeting much of the Marianas, much weaker winds out of the west are found to the south of the center. We’re still looking at the potential for some heavy rainfall, although the overall amounts have been lowered a little bit, we’re still looking at the potential for three to five inches of rainfall, a month from tonight into Tuesday night, and that could lead to some short-term nuisance flooding …. streams, rivers, and the poor drainage areas,” Aydlett said.

He added that they’re not looking at significant risk of major flash flooding, probably just floods at the more notable flood-prone areas like Umatac.

“We’re not looking to the extreme scenarios at this point, but more of a nuisance flooding,” Aydlett said.

As of 8 a.m., 16W was located 12.9 degrees north latitude and 152.9 degrees east longitude, about 483 miles east-southeast of Saipan and 477 miles east of Guam. It is currently moving west at 18 mph with maximum sustained winds of 30 mph.

Guam remains in Condition of Readiness (COR) 3 at this time. Further assessments will be conducted this afternoon, based on all available data, to determine if there will be any change to COR.

A tropical storm watch remains in effect for Guam and Rota. Damaging winds of 39 mph or more are possible Tuesday. Winds are then expected to decrease by Tuesday evening.

What to Expect

16W is expected to remain weak as it transits through the Marianas Tuesday. Based on the current forecast, intensification is increasingly likely to hold off until it is west of the Marianas. Hazardous winds may cause damage to the flimsiest lean-to types of structures and minor damage to trees.

Although the possibility of damaging winds are becoming less likely, it is important to note that wind speed and direction could widely vary based on the exact location of the system when it passes Guam. There is still a potential for heavy rainfall. Rainfall amounts have been slightly lowered to 3-5 inches Monday through Tuesday night and possible short-term flooding of streams and rivers and poor drainage areas is still possible.

Prepare Now

Any change in the system’s track or intensity could bring heavier winds to Guam as it passes Tuesday. To prepare for any scenario, the community is advised to take the following precautionary measures now:

Those living in flood-prone areas should take action; clear drainage areas and unblock clogged storm drains in your area to minimize flooding.

Be prepared to take action if flood advisories are issued. In inclement weather, avoid camping, parking, or hiking along streams, rivers, and creeks during heavy rainfall. These areas can flood quickly and with little warning. Visit to learn more.

Clear loose debris around your yard and store any items such as tents and canopies that may become airborne with heavy winds before inclement weather arrives.

Stay up to date with the latest information. The system track or intensity may change, and advisories may be issued.

Locate or prepare your emergency preparedness kits for your household; stock up on non-perishable food items and water, flashlights, first-aid kits, batteries, matches or lighters, portable stove, toiletries, etc. Visit for more information on what to include in your supplies list.

Secure important documents such as birth certificates, tax papers, and insurance documents and keep copies in a water-proof bag.

Gas your vehicles and get fuel for your generators now while the weather is clear.

Visit the following links for the latest advisory information:

NWS Website:

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GHS/OCD Website:

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For more information, contact the Joint Information Center at (671) 478-0208/09/10.