TL;DR
The National Weather Service office in Tiyan issued a Typhoon Warning at 11:12 a.m. ChST on Oct. 17 for the coastal waters of Guam and Rota as Typhoon Champi approached. The alert forecast damaging winds from Saturday night, destructive winds Sunday morning and seas potentially reaching 35 feet near the storm’s closest passage.
The National Weather Service office in Tiyan issued a Typhoon Warning at 11:12 a.m. ChST on Oct. 17 for the coastal waters of Guam and Rota, forecasting damaging winds beginning Saturday night and destructive winds Sunday morning as Typhoon Champi approached the Marianas. The agency warned that seas could reach 35 feet near the storm’s closest passage, putting vessels at risk of damage, capsizing or sinking.
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The alert said typhoon conditions, including winds of 64 knots or more, were expected in the warned waters. Damaging winds were forecast to begin Saturday night, with destructive winds expected Sunday morning. The warning said damaging winds could continue through at least Sunday night, and dangerous sea conditions could persist into Monday.
NWS Tiyan said Champi, also identified as tropical cyclone 29W, was moving quickly toward the Marianas and was expected to strengthen further before passing through the region as a typhoon Sunday morning. The office forecast rapidly rising seas, with significant wave heights potentially reaching 35 feet during the closest passage. Heavy rain could sharply reduce visibility, according to the warning.
The agency advised mariners to prepare for the typhoon’s passage, secure vessels and remain in safe harbor as the storm approached. The warning described conditions as catastrophic for small craft and extremely dangerous for larger vessels. The alert’s listed response was “Avoid”, directing people to stay away from the hazardous marine conditions rather than attempt travel.
Severe Conditions for Mariners
The warning concerns Guam and Rota’s coastal waters, where high winds, large seas and rain-obscured visibility can make vessel operations hazardous. The forecast of waves up to 35 feet signals a serious threat to boats and crews near the storm, while the warning says even larger vessels could face extremely dangerous conditions.
For people making marine travel or work decisions, the timing matters: damaging winds were forecast to arrive Saturday night, followed by destructive winds Sunday morning. The potential for hazardous seas to continue into Monday means conditions may remain unsafe after the storm’s closest passage. NWS Tiyan’s advice to secure vessels and stay in safe harbor is the clearest action stated in the alert.
The alert applies to the coastal waters named in its area description. It does not, by itself, specify a separate warning for land areas or provide a detailed local impact assessment for communities ashore. Readers should distinguish the marine warning’s stated coverage from other alerts that may be issued for land or specific hazards.
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Champi’s Forecast Passage
The alert identified the approaching storm as Typhoon Champi (29W) and said it was moving quickly toward the Marianas. NWS Tiyan’s forecast at issuance called for Champi to strengthen further on Oct. 17 before moving through the region as a typhoon Sunday morning. The alert described the timing and intensity as a forecast, not as a report that those conditions had already occurred.
The warning also explicitly said the storm’s exact path remained subject to change. At the same time, the forecast guidance supported a passage through Guam coastal waters, with damaging winds expected late Saturday and continuing into at least Sunday night. This combination means the warning conveyed a serious marine threat while acknowledging uncertainty in the storm track.
The alert record provided by the National Weather Service lists an issue and effective time of 11:12 a.m. ChST on Oct. 17, 2026, and an initial expiration time of 6 a.m. ChST on Oct. 18. It also records that the alert was later replaced at 3:37 p.m. ChST on Oct. 17. That later update means the 11:12 a.m. notice should be treated as an earlier alert version, not necessarily the latest active wording.
Storm Track and Alert Status
The NWS alert said Champi’s exact path could change, and the forecast wave height and wind timing were prospective estimates. The source does not establish what conditions ultimately occurred, whether the storm followed the forecast track, or whether the projected 35-foot seas were observed.
The alert record also shows that the notice was replaced at 3:37 p.m. ChST on Oct. 17, but the supplied record does not include the replacement alert’s wording. It therefore does not confirm the later alert’s precise coverage, forecast, expiration time or whether the warning remained in effect. The initial record’s listed expiration was 6 a.m. ChST on Oct. 18, but that timestamp alone should not be treated as confirmation of the current alert status after replacement.
The supplied material is a marine warning for Guam and Rota coastal waters. It does not provide confirmed reports of injuries, vessel damage, observed wind speeds, closures or impacts on land. Those outcomes remain outside what this alert establishes.
Check the Latest Marine Alert
Because the Oct. 17 notice was later replaced, mariners and residents should consult the latest National Weather Service advisories for current warning status, coverage and timing rather than rely on the earlier alert alone. The source record does not include the replacement notice, so its specific updates cannot be reported here.
The forecast milestones in the original warning were damaging winds beginning Saturday night, destructive winds Sunday morning and damaging winds lasting into at least Sunday night. NWS Tiyan also said dangerous seas could continue into Monday. These were forecast windows; the alert does not document whether they occurred as predicted.
The agency’s stated precaution was to secure vessels and stay in safe harbor, with the alert warning against entering conditions it described as catastrophic for small craft and extremely dangerous for larger vessels. Updated official notices are the source to check for any changes to the storm’s track, expected marine conditions or warning period.
Key Questions
Which areas were covered by the Typhoon Warning?
The alert named the Guam Coastal Waters and Rota Coastal Waters. Its stated coverage was marine waters, not a general land warning.
What conditions did NWS Tiyan forecast?
The warning forecast typhoon conditions, including winds of 64 knots or more, with damaging winds starting Saturday night and destructive winds expected Sunday morning. It also warned of heavy rain reducing visibility and seas potentially reaching 35 feet near Champi’s closest passage.
What did the warning advise vessel operators to do?
NWS Tiyan advised mariners to secure vessels and remain in safe harbor. The alert characterized conditions as catastrophic for small craft and extremely dangerous for larger vessels.
Was the warning still active after it was issued?
The supplied alert record says the notice was replaced at 3:37 p.m. ChST on Oct. 17. It does not include the replacement alert’s details, so the current status and updated wording cannot be confirmed from this record alone.
Did Champi produce the forecast winds and waves?
The alert gives forecasts, not an account of observed conditions. The supplied information does not confirm the storm’s eventual path, measured winds, observed wave heights or resulting damage.
Source: hazard
