NOAA NWS / Event history

Special Marine Warning issued October 19 at 9:47AM ChST until October 19 at 10:30AM ChST by NWS Tiyan GU

Special Marine Warning · Guam Coastal Waters. Severe; likely; urgency: immediate.

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Bulletin issued: 18 October 2026 at 23:48 UTC
First saved by us: 19 October 2026 at 00:02 UTC
Last included in a daily record: 19 October 2026
The linked daily edition preserves what we captured that UTC day; this event page is not a live warning.
Source classification: Severe · Source alert

A recent feed check does not mean a new observation. This page preserves source records; it does not establish current safety or warning status.

Issuer / area: NWS Tiyan GU · Guam Coastal Waters
Certainty / urgency: Likely / Immediate
Message expiry (not hazard end): 19 October 2026 at 00:30 UTC
Forecast onset / end: 18 October 2026 at 23:48 UTC / 19 October 2026 at 00:30 UTC

Archived official description

SMWGUM THE NATIONAL WEATHER SERVICE IN TIYAN GUAM HAS ISSUED A * SPECIAL MARINE WARNING FOR... GUAM COASTAL WATERS... * UNTIL 1030 AM CHST. * AT 945 AM CHST...A SEVERE THUNDERSTORM CAPABLE OF PRODUCING WATERSPOUTS WAS LOCATED OVER EASTERN GUAM COASTAL WATERS ...MOVING NORTH AT 25 KNOTS. HAZARD...WIND GUSTS TO NEARLY 50 KNOTS AND FREQUENT LIGHTNING. WATERSPOUTS POSSIBLE. SOURCE...RADAR. IMPACT...WATERSPOUTS CAN EASILY OVERTURN BOATS AND CREATE LOCALLY HAZARDOUS SEAS. SMALL CRAFT COULD BE DAMAGED IN BRIEFLY HIGHER WINDS AND SUDDENLY HIGHER WAVES. * THE SEVERE THUNDERSTORM WILL REMAIN OVER MAINLY OPEN WATERS.

Instructions in this archived message

MOVE TO SAFE HARBOR IMMEDIATELY AS GUSTY WINDS AND HIGH WAVES ARE EXPECTED. FREQUENT LIGHTNING IS OCCURRING WITH THIS STORM. IF CAUGHT ON THE OPEN WATER STAY BELOW DECK IF POSSIBLE...KEEP AWAY FROM UNGROUNDED METAL OBJECTS. MOVE TO SAFE HARBOR IMMEDIATELY AS GUSTY WINDS AND HIGH WAVES ARE EXPECTED. FREQUENT LIGHTNING IS OCCURRING WITH THIS STORM. IF CAUGHT ON THE OPEN WATER STAY BELOW DECK IF POSSIBLE...KEEP AWAY FROM UNGROUNDED METAL OBJECTS.

The saved record

What changed

0 updates · 1 first record

Each update compares two versions we saved. This may not include every update from the source. A missing report does not mean an event has ended.

First saved record · 19 October 2026 at 00:02 UTC

Saved by us

19 October 2026 at 00:02 UTC

Starting point

First saved record

Our first saved version of Special Marine Warning issued October 19 at 9:47AM ChST until October 19 at 10:30AM ChST by NWS Tiyan GU. We have no earlier saved version to compare.

Bulletin issued: 18 October 2026 at 23:48 UTC

View saved version 1

Original saved fields, unchanged. This is our record, not an archived copy of the external webpage.

{
  "id": "nws:c5cf5fb6aa5f69549fbde491",
  "authorityId": "urn:oid:2.49.0.1.840.0.23ae83307aa8c261b5a5090b522490f8bed264f5.001.1",
  "sender": "w-nws.webmaster@noaa.gov",
  "references": [],
  "category": "weather",
  "title": "Special Marine Warning issued October 19 at 9:47AM ChST until October 19 at 10:30AM ChST by NWS Tiyan GU",
  "eventType": "Special Marine Warning",
  "occurredAt": "2026-10-18T23:48:00.000Z",
  "issuedAt": "2026-10-18T23:48:00.000Z",
  "timeBasis": "Bulletin issued",
  "effectiveAt": "2026-10-18T23:47:00.000Z",
  "onsetAt": "2026-10-18T23:48:00.000Z",
  "expiresAt": "2026-10-19T00:30:00.000Z",
  "forecastEndAt": "2026-10-19T00:30:00.000Z",
  "severity": "Severe",
  "urgency": "Immediate",
  "certainty": "Likely",
  "messageType": "Alert",
  "status": "Source alert",
  "place": "Guam Coastal Waters",
  "coordinates": null,
  "issuer": "NWS Tiyan GU",
  "summary": "Special Marine Warning · Guam Coastal Waters. Severe; likely; urgency: immediate.",
  "description": "SMWGUM\n\nTHE NATIONAL WEATHER SERVICE IN TIYAN GUAM HAS ISSUED A\n\n* SPECIAL MARINE WARNING FOR...\nGUAM COASTAL WATERS...\n\n* UNTIL 1030 AM CHST.\n\n* AT 945 AM CHST...A SEVERE THUNDERSTORM CAPABLE OF PRODUCING\nWATERSPOUTS WAS LOCATED OVER EASTERN GUAM COASTAL WATERS ...MOVING\nNORTH AT 25 KNOTS.\n\nHAZARD...WIND GUSTS TO NEARLY 50 KNOTS AND FREQUENT LIGHTNING.\nWATERSPOUTS POSSIBLE.\n\nSOURCE...RADAR.\n\nIMPACT...WATERSPOUTS CAN EASILY OVERTURN BOATS AND CREATE LOCALLY\nHAZARDOUS SEAS. SMALL CRAFT COULD BE DAMAGED IN BRIEFLY\nHIGHER WINDS AND SUDDENLY HIGHER WAVES.\n\n* THE SEVERE THUNDERSTORM WILL REMAIN OVER MAINLY OPEN WATERS.",
  "instruction": "MOVE TO SAFE HARBOR IMMEDIATELY AS GUSTY WINDS AND HIGH WAVES ARE\nEXPECTED.\n\nFREQUENT LIGHTNING IS OCCURRING WITH THIS STORM. IF CAUGHT ON THE\nOPEN WATER STAY BELOW DECK IF POSSIBLE...KEEP AWAY FROM UNGROUNDED\nMETAL OBJECTS.\n\n\nMOVE TO SAFE HARBOR IMMEDIATELY AS GUSTY WINDS AND HIGH WAVES ARE\nEXPECTED.\n\nFREQUENT LIGHTNING IS OCCURRING WITH THIS STORM. IF CAUGHT ON THE\nOPEN WATER STAY BELOW DECK IF POSSIBLE...KEEP AWAY FROM UNGROUNDED\nMETAL OBJECTS.",
  "url": "https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.23ae83307aa8c261b5a5090b522490f8bed264f5.001.1",
  "source": "nws",
  "sourceName": "NOAA NWS"
}

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