Data health

Storm Mode / Tracked area

Guam

Wall mode

3 warnings total · 0 tornado warnings · 4 alerts including watches and advisories

Current alert feed · checked

Warnings in area

4 of 4 alerts
  1. Typhoon WarningGuam Coastal Waters; Rota Coastal Waters; Guam; RotaNWS Tiyan GU · until warning · alerts checked
  2. Coastal Flood WarningGuam; Rota; Tinian; SaipanNWS Tiyan GU · until warning · alerts checked
  3. High Surf WarningGuam; Rota; Tinian; SaipanNWS Tiyan GU · until warning · alerts checked
  4. Flood WatchGuam; Rota; Tinian; SaipanNWS Tiyan GU · until watch · radar-alerts checked

Watched places

Places saved on this device appear here with scripting enabled.

Find or save a place
Layers

Map

This map draws the contiguous United States, and Guam is beyond it. What is in force there is listed under “In force in this area”.

Agency warning geometry · no observed imagery displayed
North ↑

Interactive imagery loads separately. Missing radar does not remove warnings or imply clear weather.

Alert outlines: NOAA/NWS; cell points/observed segments: IEM/NEXRAD. A warning polygon is not a tornado footprint.

Lightning activity — GOES GLM

Total lightning, including in-cloud activity. Not ground-strike locations or a safe-to-go-outside signal.

Cached lightning observations have not loaded. An empty map is not zero lightning.

Cached lightning source details and text readings

Snow analysis — NOHRSC

Source-rendered snow depth and snow water equivalent for the lower 48. History changes this snow picture only; warnings and radar keep their own clocks.

Stored snow depth · footprint valid 2026-10-16 18:00:00 UTC, picture retrieved 2026-10-17 03:08:05.170 UTC.

No NOHRSC picture displayed on the interactive map.

  • 0 - 0.39 in
  • 0.39 - 2.0 in
  • 2.0 - 3.9 in
  • 3.9 - 9.8 in
  • 9.8 - 20 in
  • 20 - 39 in
  • 39 - 59 in
  • 59 - 98 in
  • 98 - 197 in
  • 197 - 295 in
  • 295 - 394 in
  • 394 - 787 in
NOHRSC snow analysis for the lower 48; see the adjacent source legend and time qualification
NOAA/NWS/NOHRSC’s original picture and legend. No station or address value is inferred.

NOHRSC footprint times are metadata; pixel analysis time is not independently verified. Snow-depth pixels have previously differed from the footprint time. This is modeled/assimilated snow analysis, not a measurement at a place. Unshaded and no-data areas do not establish zero snow.

Snow pictures, retained history and source provenance

Radar-derived cells (0) · unavailable

Collector checked not reported; feed generated not reported. Zero cells does not establish coverage or clear weather. Observations from different radars are not merged.

    Selected details

    Close

    Current NWS warning

    Guam Coastal Waters; Rota Coastal Waters; Guam; Rota

    Typhoon Warning

    Issued
    Updated
    Ends as issued
    Office
    NWS Tiyan GU
    Prepare for the passage of a typhoon Sunday morning. Secure all vessels. Conditions are expected to be catastrophic for small craft, and extremely dangerous for any vessels of larger size. As Tropical Storm Champi approaches, stay in safe harbor.

    Official NWS warning ↗

    The polygon is a warned area, not a tornado footprint. NWS detection tags are independent of radar algorithms and reports.

    Relevant watched places

    Save named places to check their point against every supported warning.
    Full official message

    Typhoon Warning issued October 17 at 11:12AM ChST by NWS Tiyan GU

    * WHAT....Typhoon conditions, including winds of 64 knots or more
are expected.

* WHERE...Guam and Rota Coastal Waters.

* WHEN...Onset of damaging winds beginning Saturday night. Onset of
destructive winds Sunday morning. Damaging winds will continue into
at least Sunday night, possibly longer if conditions warrant.

* IMPACTS...Destructive winds will produce dangerous seas that
could damage, capsize or sink vessels, along with drastically
reducing visibilities in heavy rain.

* ADDITIONAL DETAILS...Typhoon Champi (29W) continues to move quickly
toward the Marianas. The exact path of 29W remains subject to
change. However, guidance supports a passage through Guam coastal
waters, with damaging winds moving in late tonight and lasting
into at least Sunday night. Champi is expected to strengthen
further today as it approaches, then move through the region as a
typhoon Sunday morning. Seas will quickly rise, with significant
sea heights reaching as high as 35 feet during closest passage of
Champi. Dangerous sea conditions may continue into Monday.
    Prepare for the passage of a
typhoon Sunday morning. Secure all vessels. Conditions are expected
to be catastrophic for small craft, and extremely dangerous for any
vessels of larger size. As Tropical Storm Champi approaches, stay in
safe harbor.
    Warning-message history (4)

    Data: NOAA/NWS · PGUM.TY.W.4029

    Recent source changes

    Recording coverage and limits
    • warnings: retained from 2026-10-16T03:09:31.464Z through 2026-10-17T03:09:02.317Z
    • outlooks: retained from 2026-10-16T03:09:31.464Z through 2026-10-17T03:05:04.195Z
    • hydro: retained from 2026-10-16T03:09:31.464Z through 2026-10-17T03:05:04.276Z
    • analysis: retained from 2026-10-16T03:09:31.464Z through 2026-10-17T03:00:06.761Z
    • winter: retained from 2026-10-16T03:09:31.464Z through 2026-10-17T03:08:04.565Z

    Source-message history is not recorded imagery replay. Recorded radar/satellite imagery is not available in this view.

    Auto-updating checks this site’s cache every minute; each source keeps its own clock.

    Spotlight: Flash-flood risk, Day 1

    1 of 15

    Flash-flood risk, Day 1

    • Marginal

    WPC’s excessive rainfall outlook, to , issued : a chance of flash flooding, in four categories. Data: NOAA/WPC.

    River gauges in flood

    No river, coastal or lake gauge in this area is in flood, observed or forecast.

    NWS’s gauges at flood stage or above in the area, worst first, each with its forecast hydrograph on Rain & rivers. Data: NOAA/NWPS.

    Rain expected and rain that fell

    WPC’s rain forecast and MRMS’s radar estimate of the rain that fell, on the Briefing’s map for the area.

    Open Rain & rivers

    Data: NOAA/WPC, NOAA/NSSL MRMS.

    The tropics

    NHC’s and JTWC’s storms, their official graphics and the watches and warnings for them. Storm Mode’s own tropical panels arrive with its tropical events.

    Open the Tropics page

    Data: NOAA/NHC, JTWC.

    SPC Day 1 outlook

    • General Thunderstorms Risk

    SPC’s Day 1 categorical outlook, valid to , issued . SPC’s categories, as drawn. Data: NOAA/SPC.

    Watches

    No tornado or severe thunderstorm watch in force in this area.

    SPC’s watches, by number, matched by the counties they list. Data: NOAA/SPC.

    Mesoscale discussions

    No mesoscale discussion reaches this area.

    SPC’s mesoscale discussions whose outline reaches the area. Data: NOAA/SPC.

    Storm ingredients

    SPC’s hourly mesoanalysis, observed soundings and model guidance for the area, on the Analysis tab with its own clocks.

    Open the Analysis tab

    Drawn by the Analysis tab’s own renderer. Data: NOAA/SPC, NOAA/NCEP.

    Winter Storm Severity Index

    WPC: “WSSI does not depict official warnings and should always be used in context with official NWS forecasts and warnings.”

    • Winter Weather Area
    • Minor Impacts
    • Moderate Impacts
    • Major Impacts
    • Extreme Impacts

    Highest in this area, by day and by cause

    Day 1
    nothing drawn
    Day 2
    nothing drawn
    Day 3
    nothing drawn
    Snow amount, Days 1–3
    nothing drawn
    Snow load, Days 1–3
    nothing drawn
    Ice, Days 1–3
    nothing drawn
    Blowing snow, Days 1–3
    nothing drawn

    Each day and cause on the Winter tab, with its own issue time

    WPC’s WSSI, overall impact, Days 1–3, valid to , issued . WPC issues each day and cause on its own clock. Not a warning, and not a chance. Data: NOAA/NWS/WPC.

    Chance of Moderate impacts or worse, Day 1

    WPC: “WSSI does not depict official warnings and should always be used in context with official NWS forecasts and warnings.”

    • 5–10%
    • 10–20%
    • 20–30%
    • 30–40%
    • 40–50%
    • 50–60%
    • 60–70%
    • 70–80%
    • 80–90%
    • 90–95%
    • 95% or more

    Each level and day on the Winter tab

    WPC’s WSSI-P, the 24 hours to , WPC’s forecast from . Each band runs to the next. Data: NOAA/NWS/WPC.

    Chance of at least 4 inches of snow, Day 1

    WPC gives no chance of 4 inches of snow or more in this area over the next three days, so Day 1’s 4 inches is shown.

    • Slight: at least 10%
    • Moderate: at least 40%
    • High: at least 70%

    Every day and amount on the Winter tab

    WPC’s Probabilistic Winter Precipitation Forecast, to , issued . Outlines, as WPC draws them. Data: NOAA/NWS/WPC.

    Winter watches, warnings and advisories

    No winter or cold watch, warning or advisory in force in this area.

    NWS’s winter and cold alerts in force in the area, by event as issued, each counted once, with the offices that issued them and the latest end. Data: NOAA/NWS.

    Snow on the ground

    NOHRSC snow depth and snow water equivalent use the source’s original pictures and legends, with qualified footprint times. Open the cached source page for availability and retained history. This wall has no snow picture to rotate; missing imagery does not mean no snow.

    NOHRSC snow analysis and retained pictures

    Data: NOAA/NWS/NOHRSC. Snow analysis, not a measurement at a place.

    WPC’s heavy snow and icing discussion

    The whole discussion

    Issued , for to . WPC’s words, as written. Data: NOAA/NWS/WPC.

    Radar

    NOAA’s radar for the area, loaded by your browser as on the Radar page.

    Open the radar

    Live tiles; the radar keeps no last-good copy.

    What changed, last 60 minutes

    since , when this server began watching this area
    1. WPC Winter Storm Severity Index issued

    The products’ own words and times, and what is no longer in force since the last read. Never written by AI.

    Monitoring area, legacy alert summary and selection rules
    Area
    Guam (NWS states: GU)
    Hazards
    Every kind of warning, watch and advisory this site carries
    Window
    In force now, with the next days of SPC’s and WPC’s products
    Made by
    This address: anyone can make one, and nothing is stored. Change the area or hazards

    An area you chose, not a storm’s footprint: everything here is in force in this area, never “from this storm”.

    In force in this area 4

    1. Typhoon Warning1until 20:00Z
    2. Coastal Flood Warning11 not yet in effect · until 18 Oct 18:00Z
    3. High Surf Warning11 not yet in effect · until 18 Oct 18:00Z
    4. Flood Watch1until 18 Oct 06:00Z
    Every alert in this area, most urgent first
    1. Typhoon WarningGuam Coastal Waters; Rota Coastal Waters; Guam; Rotauntil · NWS Tiyan GU
    2. Coastal Flood WarningGuam; Rota; Tinian; SaipanFrom · until · NWS Tiyan GU
    3. High Surf WarningGuam; Rota; Tinian; SaipanFrom · until · NWS Tiyan GU
    4. Flood WatchGuam; Rota; Tinian; Saipanuntil · NWS Tiyan GU

    Most urgent first, by the Briefing’s ranking. Checked .

    Sources

    Choose another storm or areaChange monitoring areaSource status

    Not an official warning service. Warnings and watches are the National Weather Service’s, outlooks and reports the Storm Prediction Center’s and the Weather Prediction Center’s (Data: NOAA/NWS, NOAA/SPC, NOAA/WPC). When a warning is issued for you, act on it, and use weather.gov or a NOAA Weather Radio for where you are.