Tropical disturbance developing north of Chuuk

A weak tropical disturbance, Invest 99W, continues its slow westward trek toward the Mariana Islands. Invest 99W is expected to continue toward the Marianas in the next few days, tracking generally toward the west-northwest.

National Weather Service Guam meteorologist Landon Aydlett said 99W has maintained a rating of “sub-low” for development by the Joint Typhoon Warning Center, meaning that development into a significant tropical cyclone in the next day or two is unlikely.

Numerical forecast model trends have stepped back on the rate of development with this disturbance as it approaches the Marianas. Early morning forecast scenarios range from a wet and windy weekend from a passing surface trough to a weak circulation—possibly a tropical depression or a weak tropical storm. The range of possibilities remain in place as we have 30-40 hours before this disturbance pushes through, or near, the Marianas.

“While we still have wiggle room for this disturbance to evolve, we’ll have to keep a close watch on the evolution of this disturbance while it remains east of the Marianas,” said Aydlett.

CNMI and Guam residents are advised to keep a close watch on weather forecasts and discussions now and through the weekend via NWS’ webpage – www.weather.gov/gum. As this situation evolves, weather conditions and forecasts can change significantly in short time.

A Hydrologic Outlook remains in effect for Guam and the CNMI for the possibility of 6-11 inches of rainfall between Saturday night and Tuesday. Based on morning trends, this information will be refined, and likely reduced, with today’s afternoon forecast cycle. Please check the hyperlink, above, later this afternoon for the most updated information from the Hydrologic Outlook.

“We’re still looking at the likelihood of a two-part weather event over the next week with the inbound tropical disturbance/weak tropical cyclone, followed by a monsoon surge. Indications are not showing a monsoon near as strong as those experienced in September,” said Aydlett.

Baseline preparations ahead of the weekend weather should focus on those loose, outdoor items: Tents, canopies, tarps and trash bins. Seas may become hazardous to small craft as early as Saturday, with hazardous surf following shortly after. Stay tuned to weather forecasts and discussions as the outlook and forecasts regarding Invest 99W take shape in the coming days. (PR)