NOAA NWS / Event history

Flash Flood Warning issued October 18 at 3:23AM ChST until October 18 at 5:30AM ChST by NWS Tiyan GU

Flash Flood Warning · Guam, GU. Severe; likely; urgency: immediate.

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Bulletin issued: 17 October 2026 at 17:23 UTC
First saved by us: 17 October 2026 at 09:32 UTC
Last included in a daily record: 17 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 update

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, GU
Certainty / urgency: Likely / Immediate
Message expiry (not hazard end): 17 October 2026 at 19:30 UTC
Forecast onset / end: 17 October 2026 at 17:23 UTC / 17 October 2026 at 19:30 UTC

Archived official description

FFWGUM The National Weather Service in Tiyan has extended the * Flash Flood Warning for... Guam... * Until 530 AM ChST. * At 323 AM ChST, Doppler radar indicated thunderstorms producing heavy rain across the warned area with the inner eyewall of Champi approaching southern Guam. Between 2 and 4 inches of rain have fallen. Flash flooding is ongoing or expected to begin shortly and will last through Sunday morning. HAZARD...Flash flooding caused by thunderstorms. SOURCE...Radar indicated. IMPACT...Flash flooding of small creeks and streams, urban areas, highways, streets and underpasses as well as other poor drainage and low-lying areas. * Some locations that will experience flash flooding include... Dededo, Tamuning, Yigo, Mangilao, Chalan Pago-Ordot, Barrigada, Yona, Hagatna Heights, Andersen AFB, Talofofo, Mongmong-Toto-Maite, Sinajana, Inarajan, Asan, Merizo, Piti, Santa Rita and Umatac.

Instructions in this archived message

Turn around, don't drown when encountering flooded roads. Most flood deaths occur in vehicles. Be especially cautious at night when it is harder to recognize the dangers of flooding.

The saved record

What changed

2 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.

Showing 2 changes

Saved by us
17 October 2026 at 17:32 UTC
Version 3
8 recorded details changed
Title
Before
Flash Flood Warning issued October 17 at 9:23PM ChST until October 18 at 3:30AM ChST by NWS Tiyan GU
After
Flash Flood Warning issued October 18 at 3:23AM ChST until October 18 at 5:30AM ChST by NWS Tiyan GU
Source updated
Before
17 October 2026 at 11:23 UTC
After
17 October 2026 at 17:23 UTC
Effective from
Before
17 October 2026 at 11:23 UTC
After
17 October 2026 at 17:23 UTC
Forecast onset
Before
17 October 2026 at 11:23 UTC
After
17 October 2026 at 17:23 UTC
Message expiry
Before
17 October 2026 at 17:30 UTC
After
17 October 2026 at 19:30 UTC
Forecast end
Before
17 October 2026 at 17:30 UTC
After
17 October 2026 at 19:30 UTC
Official description
Before
At 923 PM ChST, Doppler radar indicated heavy rain across the warned area. Between 1 and 2 inches of rain have fallen. Torrential rain will continue through the night. TY Champi is anticipated to bring 8 to 14 inches of rain as it passes. Flash flooding is ongoing or expected to begin shortly. HAZARD...Flash flooding caused by heavy rain. SOURCE...Radar indicated. IMPACT...Flash flooding of small creeks and streams, urban areas, highways, streets and underpasses as well as other poor drainage and low-lying areas. Some locations that will experience flash flooding include... Guam
After
FFWGUM The National Weather Service in Tiyan has extended the * Flash Flood Warning for... Guam... * Until 530 AM ChST. * At 323 AM ChST, Doppler radar indicated thunderstorms producing heavy rain across the warned area with the inner eyewall of Champi approaching southern Guam. Between 2 and 4 inches of rain have fallen. Flash flooding is ongoing or expected to begin shortly and will last through Sunday morning. HAZARD...Flash flooding caused by thunderstorms. SOURCE...Radar indicated. IMPACT...Flash flooding of small creeks and streams, urban areas, highways, streets and underpasses as well as other poor drainage and low-lying areas. * Some locations that will experience flash flooding include... Dededo, Tamuning, Yigo, Mangilao, Chalan Pago-Ordot, Barrigada, Yona, Hagatna Heights, Andersen AFB, Talofofo, Mongmong-Toto-Maite, Sinajana, Inarajan, Asan, Merizo, Piti, Santa Rita and Umatac.
External source link
Before
https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.30438307a09b9d065860127f9a4633169499f03b.001.1
After
https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.cd2b16d8066810fabc926b9874f3602c4569d069.001.1
Bulletin issued: 17 October 2026 at 17:23 UTC
View saved version 3
Original saved fields, unchanged. This is our record, not an archived copy of the external webpage.
{ "id": "nws:aa3a72a958cfdcdec09d9d04", "authorityId": "urn:oid:2.49.0.1.840.0.cd2b16d8066810fabc926b9874f3602c4569d069.001.1", "sender": "w-nws.webmaster@noaa.gov", "references": [ { "identifier": "urn:oid:2.49.0.1.840.0.186b246c6f9ab08c17bb9c37c0282eaa81a8a198.001.1", "sender": "w-nws.webmaster@noaa.gov" }, { "identifier": "urn:oid:2.49.0.1.840.0.30438307a09b9d065860127f9a4633169499f03b.001.1", "sender": "w-nws.webmaster@noaa.gov" } ], "category": "weather", "title": "Flash Flood Warning issued October 18 at 3:23AM ChST until October 18 at 5:30AM ChST by NWS Tiyan GU", "eventType": "Flash Flood Warning", "occurredAt": "2026-10-17T17:23:00.000Z", "issuedAt": "2026-10-17T17:23:00.000Z", "timeBasis": "Bulletin issued", "effectiveAt": "2026-10-17T17:23:00.000Z", "onsetAt": "2026-10-17T17:23:00.000Z", "expiresAt": "2026-10-17T19:30:00.000Z", "forecastEndAt": "2026-10-17T19:30:00.000Z", "severity": "Severe", "urgency": "Immediate", "certainty": "Likely", "messageType": "Update", "status": "Source update", "place": "Guam, GU", "coordinates": null, "issuer": "NWS Tiyan GU", "summary": "Flash Flood Warning · Guam, GU. Severe; likely; urgency: immediate.", "description": "FFWGUM\n\nThe National Weather Service in Tiyan has extended the\n\n* Flash Flood Warning for...\nGuam...\n\n* Until 530 AM ChST.\n\n* At 323 AM ChST, Doppler radar indicated thunderstorms producing\nheavy rain across the warned area with the inner eyewall of Champi\napproaching southern Guam. Between 2 and 4 inches of rain have\nfallen. Flash flooding is ongoing or expected to begin shortly and\nwill last through Sunday morning.\n\nHAZARD...Flash flooding caused by thunderstorms.\n\nSOURCE...Radar indicated.\n\nIMPACT...Flash flooding of small creeks and streams, urban areas,\nhighways, streets and underpasses as well as other poor\ndrainage and low-lying areas.\n\n* Some locations that will experience flash flooding include...\nDededo, Tamuning, Yigo, Mangilao, Chalan Pago-Ordot, Barrigada,\nYona, Hagatna Heights, Andersen AFB, Talofofo, Mongmong-Toto-Maite,\nSinajana, Inarajan, Asan, Merizo, Piti, Santa Rita and Umatac.", "instruction": "Turn around, don't drown when encountering flooded roads. Most flood\ndeaths occur in vehicles.\n\nBe especially cautious at night when it is harder to recognize the\ndangers of flooding.", "url": "https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.cd2b16d8066810fabc926b9874f3602c4569d069.001.1", "source": "nws", "sourceName": "NOAA NWS" }
Visit the external source ↗
The external page may have changed since this version was saved.
Saved by us
17 October 2026 at 11:47 UTC
Version 2
Source status changed
Title
Before
Flash Flood Warning issued October 17 at 7:28PM ChST until October 18 at 3:30AM ChST by NWS Tiyan GU
After
Flash Flood Warning issued October 17 at 9:23PM ChST until October 18 at 3:30AM ChST by NWS Tiyan GU
Source updated
Before
17 October 2026 at 09:28 UTC
After
17 October 2026 at 11:23 UTC
Effective from
Before
17 October 2026 at 09:28 UTC
After
17 October 2026 at 11:23 UTC
Forecast onset
Before
17 October 2026 at 09:28 UTC
After
17 October 2026 at 11:23 UTC
Message type
Before
Alert
After
Update
Source status
Before
Source alert
After
Source update
Official description
Before
FFWGUM The National Weather Service in Tiyan has issued a * Flash Flood Warning for... Guam... * Until 330 AM ChST Sunday. * At 728 PM ChST, Doppler radar indicated heavy rain across the warned area. Between 1 and 2 inches of rain have fallen and torrential rain will continue through the night. Flash flooding is ongoing or expected to begin shortly. HAZARD...Flash flooding caused by heavy rain. SOURCE...Radar indicated. IMPACT...Flash flooding of small creeks and streams, urban areas, highways, streets and underpasses as well as other poor drainage and low-lying areas. * Some locations that will experience flash flooding include... Dededo, Tamuning, Yigo, Mangilao, Chalan Pago-Ordot, Barrigada, Yona, Hagatna Heights, Andersen AFB, Talofofo, Mongmong-Toto-Maite, Sinajana, Inarajan, Asan, Merizo, Piti, Santa Rita and Umatac.
After
At 923 PM ChST, Doppler radar indicated heavy rain across the warned area. Between 1 and 2 inches of rain have fallen. Torrential rain will continue through the night. TY Champi is anticipated to bring 8 to 14 inches of rain as it passes. Flash flooding is ongoing or expected to begin shortly. HAZARD...Flash flooding caused by heavy rain. SOURCE...Radar indicated. IMPACT...Flash flooding of small creeks and streams, urban areas, highways, streets and underpasses as well as other poor drainage and low-lying areas. Some locations that will experience flash flooding include... Guam
External source link
Before
https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.186b246c6f9ab08c17bb9c37c0282eaa81a8a198.001.1
After
https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.30438307a09b9d065860127f9a4633169499f03b.001.1
Bulletin issued: 17 October 2026 at 11:23 UTC
View saved version 2
Original saved fields, unchanged. This is our record, not an archived copy of the external webpage.
{ "id": "nws:fd3394104a7d7dd2f0696ee6", "authorityId": "urn:oid:2.49.0.1.840.0.30438307a09b9d065860127f9a4633169499f03b.001.1", "sender": "w-nws.webmaster@noaa.gov", "references": [ { "identifier": "urn:oid:2.49.0.1.840.0.186b246c6f9ab08c17bb9c37c0282eaa81a8a198.001.1", "sender": "w-nws.webmaster@noaa.gov" } ], "category": "weather", "title": "Flash Flood Warning issued October 17 at 9:23PM ChST until October 18 at 3:30AM ChST by NWS Tiyan GU", "eventType": "Flash Flood Warning", "occurredAt": "2026-10-17T11:23:00.000Z", "issuedAt": "2026-10-17T11:23:00.000Z", "timeBasis": "Bulletin issued", "effectiveAt": "2026-10-17T11:23:00.000Z", "onsetAt": "2026-10-17T11:23:00.000Z", "expiresAt": "2026-10-17T17:30:00.000Z", "forecastEndAt": "2026-10-17T17:30:00.000Z", "severity": "Severe", "urgency": "Immediate", "certainty": "Likely", "messageType": "Update", "status": "Source update", "place": "Guam, GU", "coordinates": null, "issuer": "NWS Tiyan GU", "summary": "Flash Flood Warning · Guam, GU. Severe; likely; urgency: immediate.", "description": "At 923 PM ChST, Doppler radar indicated heavy rain across the warned\narea. Between 1 and 2 inches of rain have fallen. Torrential rain\nwill continue through the night. TY Champi is anticipated to bring 8\nto 14 inches of rain as it passes. Flash flooding is ongoing or\nexpected to begin shortly.\n\nHAZARD...Flash flooding caused by heavy rain.\n\nSOURCE...Radar indicated.\n\nIMPACT...Flash flooding of small creeks and streams, urban areas,\nhighways, streets and underpasses as well as other poor\ndrainage and low-lying areas.\n\nSome locations that will experience flash flooding include...\nGuam", "instruction": "Turn around, don't drown when encountering flooded roads. Most flood\ndeaths occur in vehicles.\n\nBe especially cautious at night when it is harder to recognize the\ndangers of flooding.", "url": "https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.30438307a09b9d065860127f9a4633169499f03b.001.1", "source": "nws", "sourceName": "NOAA NWS" }
Visit the external source ↗
The external page may have changed since this version was saved.

First saved record · 17 October 2026 at 09:32 UTC

Saved by us

17 October 2026 at 09:32 UTC

Starting point

First saved record

Our first saved version of Flash Flood Warning issued October 17 at 7:28PM ChST until October 18 at 3:30AM ChST by NWS Tiyan GU. We have no earlier saved version to compare.

Bulletin issued: 17 October 2026 at 09:28 UTC

View saved version 1

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

{
  "id": "nws:1f4a81b8b54591bdf18f6f38",
  "authorityId": "urn:oid:2.49.0.1.840.0.186b246c6f9ab08c17bb9c37c0282eaa81a8a198.001.1",
  "sender": "w-nws.webmaster@noaa.gov",
  "references": [],
  "category": "weather",
  "title": "Flash Flood Warning issued October 17 at 7:28PM ChST until October 18 at 3:30AM ChST by NWS Tiyan GU",
  "eventType": "Flash Flood Warning",
  "occurredAt": "2026-10-17T09:28:00.000Z",
  "issuedAt": "2026-10-17T09:28:00.000Z",
  "timeBasis": "Bulletin issued",
  "effectiveAt": "2026-10-17T09:28:00.000Z",
  "onsetAt": "2026-10-17T09:28:00.000Z",
  "expiresAt": "2026-10-17T17:30:00.000Z",
  "forecastEndAt": "2026-10-17T17:30:00.000Z",
  "severity": "Severe",
  "urgency": "Immediate",
  "certainty": "Likely",
  "messageType": "Alert",
  "status": "Source alert",
  "place": "Guam, GU",
  "coordinates": null,
  "issuer": "NWS Tiyan GU",
  "summary": "Flash Flood Warning · Guam, GU. Severe; likely; urgency: immediate.",
  "description": "FFWGUM\n\nThe National Weather Service in Tiyan has issued a\n\n* Flash Flood Warning for...\nGuam...\n\n* Until 330 AM ChST Sunday.\n\n* At 728 PM ChST, Doppler radar indicated heavy rain across the\nwarned area. Between 1 and 2 inches of rain have fallen and\ntorrential rain will continue through the night. Flash flooding is\nongoing or expected to begin shortly.\n\nHAZARD...Flash flooding caused by heavy rain.\n\nSOURCE...Radar indicated.\n\nIMPACT...Flash flooding of small creeks and streams, urban areas,\nhighways, streets and underpasses as well as other poor\ndrainage and low-lying areas.\n\n* Some locations that will experience flash flooding include...\nDededo, Tamuning, Yigo, Mangilao, Chalan Pago-Ordot, Barrigada,\nYona, Hagatna Heights, Andersen AFB, Talofofo, Mongmong-Toto-Maite,\nSinajana, Inarajan, Asan, Merizo, Piti, Santa Rita and Umatac.",
  "instruction": "Turn around, don't drown when encountering flooded roads. Most flood\ndeaths occur in vehicles.\n\nBe especially cautious at night when it is harder to recognize the\ndangers of flooding.",
  "url": "https://api.weather.gov/alerts/urn:oid:2.49.0.1.840.0.186b246c6f9ab08c17bb9c37c0282eaa81a8a198.001.1",
  "source": "nws",
  "sourceName": "NOAA NWS"
}

Visit the external source ↗

The external page may have changed since this version was saved.