Back to the trend of the day: Typhoon 30 heads toward Kyushu as heavy rain threatens (in Japanese)
Poly Rating · from the trend of the day

Kyushu heavy rain forecast, flood & landslide risk Oct 2026

Tsushima had already taken more than 300 mm of rain before the main band arrived, more than the 200 mm forecast for all of northern Kyushu over the next day.

  • No. 1: Saga Plain — Saga City and Takeo (Rokkaku and Kase rivers)
  • 10 places

01Final list

The leading AIs each built their own list of ten independently. Here is one result that is easy to check: every place has a reason, a source, and the list of AIs that included it.

Order: from most to least AI agreement.

A bright badge means this AI put the entry on its list. A dim badge means it did not.

  1. 1

    Saga Plain — Saga City and Takeo (Rokkaku and Kase rivers)

    Three separate bulletins give Saga 150 mm and 50 mm/h, falling on a flat plain. The Oct 26 full-moon spring tide also slows drainage into the Ariake Sea.

    Included it: Grok, Claude, Gemini, StepFun, Kimi, Wenxin, Qwen. Did not include: ChatGPT, Nemotron.

    In their lists: Grok: 2 · Claude: 6 · Gemini: 4 · StepFun: 4 · Kimi: 4 · Wenxin: 9 · Qwen: 3

    What each AI noted 7
    • Grokplace 2

      150 mm 24-h forecast meets dense landslide warning zones on steep Tertiary slopes

      Source ↗
    • Claudeplace 6

      Saga has the highest prefectural 24-hour forecast outside Nagasaki (150 mm) and a 50 mm/h hourly ceiling, so the rain falls on lowland rivers.

      Source ↗
    • Geminiplace 4

      A saucer-shaped basin draining to Ariake Sea where tidal backflow and extreme flat topography trap stormwater for days in the Rokkaku River floodplain.

    • StepFunplace 4

      A bowl-shaped plain that swallowed ~3 metres of water across 4 km² in 2021.

      Source ↗
    • Kimiplace 4

      A full-moon spring tide on Oct 26 means the Kase and Rokkaku may not be able to drain into the Ariake Sea at the height of the rain.

      Source ↗
    • Wenxinplace 9

      Low-lying river plains in northern Kyushu facing elevated inundation risk from rising water levels

      Source ↗
    • Qwenplace 3

      A flat, low-lying basin where 200mm of forecast rain acts like a plugged drain, amplified by recent linear precipitation bands that overwhelmed the Saga Plain.

    7 AIs put it here
    Source ↗
  2. 2

    Nagasaki City, Isahaya and Shimabara (southern Nagasaki)

    Forecast 150 mm for the south versus 200 mm for the prefecture as a whole. It has the longest high-risk window in Nagasaki, from midday on the 25th to the morning of the 26th.

    Included it: ChatGPT, Grok, Claude, StepFun, Kimi, Wenxin. Did not include: Nemotron, Gemini, Qwen.

    In their lists: ChatGPT: 8 · Grok: 3 · Claude: 7 · StepFun: 5 · Kimi: 3 · Wenxin: 4

    What each AI noted 6
    • ChatGPTplace 8

      A high-rainfall regional outlook makes this a watch area, but no prefecture-specific millimeter figure or gauge reading was verified.

      Source ↗
    • Grokplace 3

      200 mm forecast plus 60 mm/h peaks over historic landslide terrain of 1982 scale

      Source ↗
    • Claudeplace 7

      Rain risk becomes high from midday on the 25th until the morning of the 26th, a longer window than any other part of the prefecture.

      Source ↗
    • StepFunplace 5

      Already saturated and shaken: Unzen's volcanic slopes cracked in the 2026 quake.

      Source ↗
    • Kimiplace 3

      The joint-highest rain forecast in Japan today — 200 mm in 24 h — falls on hills that drop straight into the sea.

      Source ↗
    • Wenxinplace 4

      5m high waves forecast for Oct 26, paired with 100mm 24-hour projected rainfall

      Source ↗
    6 AIs put it here
    Source ↗
  3. 3

    Asakura and Toho Village, Fukuoka (Chikugo tributaries)

    Fukuoka's forecast is lower (120 mm in two bulletins, 150 mm in a third), but the 2017 flood that killed about 40 here came from small creeks nobody gauged.

    Included it: Grok, Gemini, StepFun, Kimi. Did not include: ChatGPT, Nemotron, Claude, Wenxin, Qwen.

    In their lists: Grok: 5 · Gemini: 2 · StepFun: 2 · Kimi: 1

    What each AI noted 4
    • Grokplace 5

      2017-scale landslide terrain under same 120–200 mm northern Kyushu rain band

      Source ↗
    • Geminiplace 2

      Steep Mount Hiko granitic slopes generate immediate debris torrents into unmonitored mountain tributaries within 90 minutes of stalled rainbands.

    • StepFunplace 2

      The 2017 flood that killed 39 came from creeks too small to make the flood-forecast list.

      Source ↗
    • Kimiplace 1

      A 4.5-km creek, the Kitagawa, killed dozens in 2017 — today Asakura sits under the 200 mm forecast bulls-eye with the same unmonitored small rivers.

      Source ↗
    4 AIs put it here
    Source ↗
  4. 4

    Hitoyoshi and Kuma Village, Kumamoto (Kuma River)

    Exposure is extreme, with 50 drowned in this basin in 2020. The rain figure is disputed: Kumamoto's forecast ranges from 60 to 200 mm depending on the bulletin.

    Included it: Grok, Gemini, StepFun, Kimi. Did not include: ChatGPT, Nemotron, Claude, Wenxin, Qwen.

    In their lists: Grok: 9 · Gemini: 5 · StepFun: 1 · Kimi: 2

    What each AI noted 4
    • Grokplace 9

      60–100 mm forecast over earthquake-damaged levees already under lowered flood criteria

      Source ↗
    • Geminiplace 5

      Isolated gorge communities pinned between 40-degree mountain slopes and the surging trunk stream of the Kuma River, leaving limited high-ground escape routes.

    • StepFunplace 1

      25 died here in 2020 on one of Japan's three great rapids — now rain falls on quake-loosened slopes.

      Source ↗
    • Kimiplace 2

      Water reached 4.3 m in Hitoyoshi in 2020 — double the 2.1 m record from 1965 — and 200 mm is forecast on the same basin tonight.

      Source ↗
    4 AIs put it here
    Source ↗
  5. 5

    Tsushima (Izuhara), Nagasaki

    333 mm already fallen at Izuhara (another count says 305.5 mm, different window), with up to 120 mm more forecast and a 'high' landslide-warning outlook.

    Included it: Grok, Claude, Wenxin. Did not include: ChatGPT, Nemotron, Gemini, StepFun, Kimi, Qwen.

    In their lists: Grok: 1 · Claude: 1 · Wenxin: 1

    What each AI noted 3
    • Grokplace 1

      Already 305.5 mm observed while forecast still calls for another 200 mm peak hour intensity 60 mm

      Source ↗
    • Claudeplace 1

      333 mm has already fallen at Izuhara in about two and a half days, more than the 200 mm forecast for the whole of northern Kyushu in the next 24 hours.

      Source ↗
    • Wenxinplace 1

      Already recorded 172.5mm of rain in 12 hours by Oct 25 06:00, with prolonged heavy rain forecast

      Source ↗
    3 AIs put it here
    Source ↗
  6. 6

    Lower Chikugo plain — Kurume, Okawa and Omuta, Fukuoka

    Large rivers peak downstream hours after the rain stops, and the spring tide slows drainage. One report puts Omuta at 265.5 mm in a day; no second source confirms it.

    Included it: Gemini, StepFun, Kimi. Did not include: ChatGPT, Grok, Nemotron, Claude, Wenxin, Qwen.

    In their lists: Gemini: 3 · StepFun: 3 · Kimi: 6

    What each AI noted 3
    • Geminiplace 3

      The flat lowlands of the mid-Chikugo River suffer chronic compound inundation where tributary sluice gates close to prevent backwater, submerging urban interior plains.

    • StepFunplace 3

      Omuta logged 265.5 mm in a day — about 1.6× all of September.

      Source ↗
    • Kimiplace 6

      Big rivers flood downstream after the rain stops — the lower Chikugo can keep rising for hours after the clouds leave the mountains.

    3 AIs put it here
    Source ↗
  7. 7

    Northern Nagasaki — Hirado, Matsuura and Sasebo

    Two sources set Nagasaki's forecast at 200 mm; the local bulletin says 180–200 mm for the north. Hirado had already logged 232.5 mm (one source).

    Included it: Grok, Claude, Qwen. Did not include: ChatGPT, Nemotron, Gemini, StepFun, Kimi, Wenxin.

    In their lists: Grok: 6 · Claude: 3 · Qwen: 9

    What each AI noted 3
    • Grokplace 6

      Steep basalt-sediment slopes already mapped high landslide frequency under 200 mm rain

      Source ↗
    • Claudeplace 3

      232.5 mm is already recorded, second only to Tsushima, while the 180 mm forecast for northern Nagasaki is still to come.

      Source ↗
    • Qwenplace 9

      Nagasaki’s jagged topography concentrates the frontal rain into flash-flood zones that MLIT’s large-river sensors simply cannot see in time.

    3 AIs put it here
    Source ↗
  8. 8

    Hita, Oita (upper Chikugo River)

    The Chikugo near Hita and Oguni got a Level-5 'flooding now' alert in July 2026 (two sources). Oita's own forecast is 100 mm, below the north's 200 mm.

    Included it: Gemini, StepFun, Kimi. Did not include: ChatGPT, Grok, Nemotron, Claude, Wenxin, Qwen.

    In their lists: Gemini: 6 · StepFun: 6 · Kimi: 5

    What each AI noted 3
    • Geminiplace 6

      A junction of five converging upland rivers where torrential rainfall in Aso and Kuju ranges funnels into a single basin outlet along the Mikuma River.

    • StepFunplace 6

      One of the three towns at the heart of the 2017 flood — back in the 200 mm zone again.

      Source ↗
    • Kimiplace 5

      The Chikugo got a Level-5 'flood occurring' alert here in July — four months later the same basin faces another warning-level deluge.

      Source ↗
    3 AIs put it here
    Source ↗
  9. 9

    Kumamoto City and Aso (Shirakawa and Midori rivers)

    About 270,900 people in two Kumamoto City wards were put on Level 3 alert at 15:00 on Oct 25 (one source). Aso's volcanic slopes drain into both rivers.

    Included it: StepFun, Kimi, Qwen. Did not include: ChatGPT, Grok, Nemotron, Claude, Gemini, Wenxin.

    In their lists: StepFun: 9 · Kimi: 8 · Qwen: 1

    What each AI noted 3
    • StepFunplace 9

      Two wards holding ~270,900 people were already told to move before the typhoon landed.

      Source ↗
    • Kimiplace 8

      200 mm of rain on the caldera rim feeds the Shirakawa and Midori at the same time — terrain GSI maps as some of Kyushu's densest landslide zones.

      Source ↗
    • Qwenplace 1

      The Shirakawa’s notorious history of catastrophic breaching forces Level 4 evacuations for 140,000 people before the typhoon's outer bands even make landfall.

      Source ↗
    3 AIs put it here
    Source ↗
  10. 10

    Goto Islands, Nagasaki

    Nagasaki's top forecast: 200 mm in 24 h and 70 mm/h, on islands that already logged 227 mm. Only one bulletin gives these figures.

    Included it: Claude. Did not include: ChatGPT, Grok, Nemotron, Gemini, StepFun, Kimi, Wenxin, Qwen.

    In their lists: Claude: 2

    What each AI noted 1
    • Claudeplace 2

      The highest 24-hour forecast in Nagasaki (200 mm) and the highest hourly forecast (70 mm/h on the 26th) both apply here, on an already soaked island arc.

      Source ↗
    1 AIs put it here
    Source ↗

More about the top three ↓

02More about the top three

The ranking is above. Here is more about the three places at the top: what they are, why they are here, and what is worth knowing.

The forecasts cover different areas (a plain, a southern region, a prefecture), and the past floods cited are from different years, so the figures are not directly comparable.

1Saga Plain — Saga City and Takeo (Rokkaku and Kase rivers)

No. 1 — Saga Plain — Saga City and Takeo (Rokkaku and Kase rivers). On the lists of 7 of 9 AIs; median place there: 4. Heavy, fast rain on a flat plain, plus a full-moon high tide that blocks the rivers from draining into the sea.

Did you know

  • The sea beside the Saga plain has Japan's most extreme tides, with variations of up to 6 to 7 meters. The plain also has a network of creeks and canals with a total length of 2000 km.

    Source ↗
What it is
A flat, low plain around Saga City and Takeo, crossed by two rivers.
Its edge
Rain and the spring tide hit together, so water has nowhere to go.
Who should know
Useful for people living or driving on low, flat land near the Ariake Sea.
  • Forecast rain in 24 hours150 mm, 50 mm/h forecast
Why it is here

  • In the August 2021 rain, Ureshino in Saga Prefecture recorded 912 mm in 72 hours, a record high. The Rokkaku River overflowed in Takeo and flooded homes, so people had to leave. — Stars and Stripes

    Source ↗

  • Compared with its neighbours in that same event: Ureshino (Saga) 912 mm, Mt. Unzen (Nagasaki) 848.5 mm, Kurume (Fukuoka) 712.5 mm in 72 hours. Saga's reading was the highest of the three. — Stars and Stripes

    Source ↗
History

  • In late August 2019, record rain hit Takeo. JR Saga Station flooded, landslides were confirmed in the city, and at least two people died.

    Source ↗
Where to go further

  • Start at the red two-storied Rōmon gate, designed by Kingo Tatsuno in 1914. The page says it is 10 minutes on foot from JR Takeo Onsen Station. Opening hours vary by facility, so check before you go.

    Source ↗
Compare the top three ↓

2Nagasaki City, Isahaya and Shimabara (southern Nagasaki)

No. 2 — Nagasaki City, Isahaya and Shimabara (southern Nagasaki). On the lists of 6 of 9 AIs; median place there: 4.5. Its high-risk window is the longest in Nagasaki, running from midday on the 25th to the next morning.

Did you know

  • In 1792 part of Mount Mayuyama near Shimabara collapsed into the sea. An estimated 15,000 people died. The wave also hit Higo across the bay, so Japanese people called it "Shimabara suffered, Higo affected".

    Source ↗
What it is
Southern Nagasaki: Nagasaki City, Isahaya and Shimabara, between hills and sea.
Its edge
The danger lasts longer here than in any other part of the prefecture.
Who should know
Useful for people in hilly coastal towns, where slopes and rivers both threaten.
  • Forecast rain in 24 hours150 mm south forecast

Wikidata

Why it is here

  • On July 23, 1982, rain in the Nagasaki area reached up to 187 mm in one hour. That is a national record for hourly rainfall, and it fell during one cloudburst in a single evening. — Wikipedia

    Source ↗

  • A Japanese government report says that flood killed 299 people in Nagasaki Prefecture, plus 23 in Kumamoto Prefecture. That is why southern Nagasaki's long high-risk window is taken so seriously. — Wikipedia

    Source ↗
Did you know

  • The 1792 collapse left 99 islets or rocks near Shimabara. They are not the same as the famous 99 Islands (Kujūkushima) elsewhere in Nagasaki Prefecture.

    Source ↗
History

  • In July 1957, three days of rain sent a river flood into Isahaya. A debris flow then came down from upstream. More than 500 people died in Isahaya City alone.

    Source ↗
Keep in mind

  • Most people may not leave. In the August 2021 Kyushu rains, evacuation advisories covered more than 3 million residents. They are not mandatory, and the article says only a small fraction of people usually evacuate.

    Source ↗
Where to go further

  • Shimabara Castle is open 9:00～17:30, with admission JPY 700. Look first at the displays on the Shimabara Rebellion and local history. The page does not say how long a visit takes.

    Source ↗
Compare the top three ↓

3Asakura and Toho Village, Fukuoka (Chikugo tributaries)

No. 3 — Asakura and Toho Village, Fukuoka (Chikugo tributaries). On the lists of 4 of 9 AIs; median place there: 2. Less rain is forecast, but small unmonitored creeks here caused the deadly 2017 flood.

Did you know

  • Asakura has waterwheels that have turned for over 200 years and are called the oldest operating water wheels in Japan. Hishino has three wheels, and they lift river water into rice fields from mid-June to mid-October.

    Source ↗
What it is
Asakura and Toho Village in Fukuoka, a mountain area with small Chikugo River streams.
Its edge
Its danger comes from small creeks that nobody measures, not from the rain total.
Who should know
Useful for people in valleys, since forecasts alone can miss small-stream floods.
  • Forecast rain in 24 hours120–150 mm forecast

Wikipedia · Wikidata

Why it is here

  • The July 2017 northern Kyushu floods and landslides left 42 people dead and two missing. Asakura was one of the hardest-hit areas, even though the rain forecast for Fukuoka this time is lower. — Wikipedia

    Source ↗

  • In 2017, Asakura had 500 mm of rain within 12 hours on July 5, about 50% more than its average rainfall for the whole month of July. Tree trunks 50–60 cm wide blocked streams. — Wikipedia

    Source ↗
History

  • In 2017, landslides blocked the only road into Toho Village. Some residents were cut off for three days.

    Source ↗
Keep in mind

  • Driftwood made the 2017 damage worse. Researchers say it flowed in larger amounts because of driftwood conversion, mainly in cedar plantations. They also say the mountain streams lacked suitable terrain to catch it. This is a limit on what rainfall forecasts alone can show.

    Source ↗
Where to go further

  • Start with the Gyoja sugi, a giant cedar planted more than 600 years ago, 52 metres tall. Then see Koishiwara pottery. The page mentions the July 2017 heavy rain and says recovery takes time. It does not say how long a visit takes.

    Source ↗
Kimi put it first. What they saw in it

  • Kimi: A 4.5-km creek, the Kitagawa, killed dozens in 2017 — today Asakura sits under the 200 mm forecast bulls-eye with the same unmonitored small rivers.

Compare the top three ↓

The top three side by side

Saga Plain — Saga City and Takeo (Rokkaku and Kase rivers)Nagasaki City, Isahaya and Shimabara (southern Nagasaki)Asakura and Toho Village, Fukuoka (Chikugo tributaries)
In the AIs' lists7 / 96 / 94 / 9
Forecast rain in 24 hours150 mm, 50 mm/h forecast150 mm south forecast120–150 mm forecast
Put first by——Kimi

Places with the same number of AIs are ordered by their average place in the AIs' own lists.

More ratings

03Worth knowing

What the AIs noticed while building the list.

Rain already fallen beats the forecast at the top of the list: Izuhara logged 333 mm since the morning of the 23rd (305.5 mm in another count, 172.5 mm in 12 hours in a third), against a 200 mm forecast for northern Kyushu.

Noticed by:
Included it: Grok, Claude, Wenxin. Did not include: ChatGPT, Nemotron, Gemini, StepFun, Kimi, Qwen.
Source ↗

The worst flooding may come after the rain. The Oct 26 full-moon spring tide slows drainage at river mouths, and big rivers like the Chikugo peak downstream hours later; the JMA/MLIT briefing lists both as main cautions.

Noticed by:
Included it: StepFun, Kimi. Did not include: ChatGPT, Grok, Nemotron, Claude, Gemini, Wenxin, Qwen.
Source ↗

'200 mm' is not one number. Weathernews gives northern Kyushu 200 mm to 06:00 on Oct 26, while the prefecture tables to 18:00 on Oct 26 range from Nagasaki 200 mm to Fukuoka 120 mm. Kumamoto appears as 60, 120, 150 and 200 mm in different bulletins.

Noticed by:
Included it: ChatGPT, Grok, Claude, StepFun, Kimi. Did not include: Nemotron, Gemini, Wenxin, Qwen.
Source ↗

The typhoon weakened sharply, from 955 hPa on Oct 23 to 996 hPa on Oct 25, but rain and landslide alerts stayed at full strength because the storm feeds a stalled autumn front.

Noticed by:
Included it: StepFun, Kimi, Qwen. Did not include: ChatGPT, Grok, Nemotron, Claude, Gemini, Wenxin.
Source ↗

04How we counted

In plain words, no formulas.

1The question

Top 10 Kyushu places where forecast rain meets flood and landslide exposure

2Why this topic

It combines forecast, live river conditions, and mapped exposure to show where multiple warning signals overlap.

3Where it applies

Kyushu, Japan

4What we looked at

  • Compare JMA forecast rainfall by area and time with MLIT observed rainfall, river levels, and flood forecasts.
  • Overlay those signals with GSI flood and landslide hazard zones; show which signals drive each place’s position.
  • Japan Meteorological Agency (JMA) — area forecasts and warnings — Maximum 24-hour and hourly rainfall forecast by area and period, plus the early-warning chance of warning-level rain and landslides
  • JMA Fukuoka + MLIT Kyushu joint Typhoon 30 briefing (23 Oct) — 24-hour rain table for each prefecture, spring-tide window (full moon Oct 26), Class-A rivers, warning on small rivers
  • JMA AMeDAS observed rainfall (as reported by NCC Nagasaki) — Rain already fallen at each station, 23 Oct 08:00 to 25 Oct 16:00 (preliminary)
  • MLIT River Disaster Prevention Information — Observed river levels against flood-danger thresholds, and flood forecasts for monitored rivers (no live station readings for this snapshot)
  • GSI / MLIT Hazard Map Portal — Mapped flood-inundation zones, landslide warning zones and evacuation sites (exposure layers, not forecasts)
  • JMA Kikikuru risk map — 5-level landslide, inundation and river-flood risk per 1-km grid square, including small rivers

5Who ranked

The leading AIs, each building its own list of ten independently and naming a source for every place: ChatGPT, Grok, Nemotron, Claude, Gemini, StepFun, Kimi, Wenxin, Qwen.

6How the places were set

The same entry written differently by different AIs was counted as one. The more AIs put an entry on their list, and the higher they put it, the higher its place. "AI agreement" shows how many of the AIs had it on their own list. Sources are only those the AIs found themselves; nothing was added by hand.

05Each AI's own list

🇺🇸 ChatGPT10 places · 3 notes

The same question, answered by ChatGPT alone. The final list above combines all the AIs.

  1. 1
    Amakusa, Kumamoto, Japan (2026)

    JMA’s local note puts the 24-hour maximum at 120 mm, with up to 50 mm in one hour.

    Source ↗
  2. 2
    Satsuma, Kagoshima, Japan (2026)

    A report puts Satsuma’s forecast at up to 150 mm, while the broader northern Kyushu headline is higher at 200 mm.

    Source ↗
  3. 3
    Osumi Peninsula, Kagoshima, Japan (2026)

    It is among the southern Kyushu areas named for Monday heavy-rain warnings, but no area-specific rainfall total was verified in the available sources.

    Source ↗
  4. 4
    Tanegashima, Kagoshima, Japan (2026)

    The island is specifically included in the reported Monday warning outlook; a local rainfall total was not available to compare.

    Source ↗
  5. 5
    Yakushima, Kagoshima, Japan (2026)

    Yakushima appears in the warning outlook alongside the peninsula and islands, but the retrieved report supplies no island-specific millimeter figure.

    Source ↗
  6. 6
    Northern Kyushu, Japan (2026)

    The 200 mm headline is the largest published total found, but it covers a broad region rather than a specific river basin or town.

    Source ↗
  7. 7
    Kumamoto Prefecture, Japan (2026)

    The available prefecture-wide JMA support note forecasts 120 mm in 24 hours, distinct from the 200 mm northern Kyushu report.

    Source ↗
  8. 8
    Nagasaki Prefecture, Japan (2026)

    A high-rainfall regional outlook makes this a watch area, but no prefecture-specific millimeter figure or gauge reading was verified.

    Source ↗
  9. 9
    Miyazaki Prefecture, Japan (2026)

    Its position reflects the southern Kyushu rain setup and terrain exposure; the retrieved sources do not establish a current gauge-based ranking against other prefectures.

    Source ↗
  10. 10
    Fukuoka Prefecture, Japan (2026)

    It belongs to the broad northern Kyushu 200 mm report, but that regional maximum cannot be assigned to Fukuoka or any one river basin.

    Source ↗

What ChatGPT noticed

The clearest local figure retrieved is for Kumamoto: up to 120 mm in 24 hours and 50 mm in one hour, with very heavy rain possible.

Source ↗

Northern Kyushu’s reported 200 mm is a regional maximum through the morning of Oct. 26; it should not be treated as the expected rainfall at every town or river gauge.

Source ↗

The JMA portal puts forecast risk on maps, while MLIT’s river portal reports monitored river conditions; both are needed because a rainfall forecast alone does not establish river flooding.

Source ↗
🇺🇸 Grok10 places · 3 notes

The same question, answered by Grok alone. The final list above combines all the AIs.

  1. 1
    Tsushima City (Nagasaki)

    Already 305.5 mm observed while forecast still calls for another 200 mm peak hour intensity 60 mm

    Source ↗
  2. 2
    Saga City / Saga Prefecture northern areas

    150 mm 24-h forecast meets dense landslide warning zones on steep Tertiary slopes

    Source ↗
  3. 3
    Nagasaki City / Nagasaki Prefecture mainland

    200 mm forecast plus 60 mm/h peaks over historic landslide terrain of 1982 scale

    Source ↗
  4. 4
    Fukuoka City / Fukuoka Prefecture

    120 mm forecast intersects urban steep-slope sediment zones and Chikugo lowlands

    Source ↗
  5. 5
    Asakura City / eastern Fukuoka mountains

    2017-scale landslide terrain under same 120–200 mm northern Kyushu rain band

    Source ↗
  6. 6
    Sasebo City (Nagasaki)

    Steep basalt-sediment slopes already mapped high landslide frequency under 200 mm rain

    Source ↗
  7. 7
    Kitakyushu City

    120 mm forecast plus urban-mountain interface sediment zones

    Source ↗
  8. 8
    Oita Prefecture western / northern areas

    100 mm forecast meets residual 2017 landslide scars and river systems

    Source ↗
  9. 9
    Kumamoto Prefecture northern / Kuma River areas

    60–100 mm forecast over earthquake-damaged levees already under lowered flood criteria

    Source ↗
  10. 10
    Southern Kyushu (Kagoshima / Miyazaki fringe)

    100 mm forecast still intersects coastal flood and steep-slope zones as system exits

    Source ↗

What Grok noticed

Tsushima has already recorded 305.5 mm while the 24-hour forecast still expects another 200 mm across northern Kyushu, creating a rare double-load on soils already saturated.

Source ↗

JMA has issued strict sediment-disaster vigilance for all of northern Kyushu from late night 25 October through the morning of 26 October as Typhoon 30 transitions to an extratropical low.

Source ↗

Hourly rates of 50–60 mm are forecast for Saga and Nagasaki—enough to turn ordinary streams into flash-flood channels on the steep Tertiary and volcanic slopes that dominate the region.

Source ↗
🇺🇸 Claude10 places · 4 notes

The same question, answered by Claude alone. The final list above combines all the AIs.

  1. 1
    Tsushima (Izuhara), Nagasaki

    333 mm has already fallen at Izuhara in about two and a half days, more than the 200 mm forecast for the whole of northern Kyushu in the next 24 hours.

    Source ↗
  2. 2
    Goto Islands, Nagasaki

    The highest 24-hour forecast in Nagasaki (200 mm) and the highest hourly forecast (70 mm/h on the 26th) both apply here, on an already soaked island arc.

    Source ↗
  3. 3
    Hirado, Nagasaki

    232.5 mm is already recorded, second only to Tsushima, while the 180 mm forecast for northern Nagasaki is still to come.

    Source ↗
  4. 4
    Matsuura, Nagasaki

    185.5 mm already fallen, and the forecast peak comes after midday on the 25th and on the 26th.

    Source ↗
  5. 5
    Northern Nagasaki (Sasebo–Omura area)

    The forecast rose from 150 mm for the 24 hours to 6 pm on the 25th to 200 mm for the following 24 hours in a single JMA bulletin.

    Source ↗
  6. 6
    Saga Prefecture

    Saga has the highest prefectural 24-hour forecast outside Nagasaki (150 mm) and a 50 mm/h hourly ceiling, so the rain falls on lowland rivers.

    Source ↗
  7. 7
    Southern Nagasaki (Nagasaki city, Shimabara area)

    Rain risk becomes high from midday on the 25th until the morning of the 26th, a longer window than any other part of the prefecture.

    Source ↗
  8. 8
    Iki, Nagasaki

    The Iki/Tsushima area was forecast at up to 250 mm for the first 24 hours, then 120 mm for the second, so its peak may already have passed.

    Source ↗
  9. 9
    Kumamoto Prefecture

    A 50 mm/h guide, equal to Saga's, on a 120 mm 24-hour forecast, with steep terrain and the largest rivers poorly represented by a prefecture-wide number.

    Source ↗
  10. 10
    Fukuoka Prefecture (northern Kyushu)

    The forecast is 120 mm (24 h) with a 40 mm/h guide, but the front plus the extratropical low can still produce 30–50 mm/h bursts.

    Source ↗

What Claude noticed

Observed rain is already larger than the forecast at the top of the list: Izuhara has recorded 333 mm since the morning of the 23rd, while the northern Kyushu forecast peaks at 200 mm for the next 24 hours. Saturated ground is the main reason landslide risk is high.

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The typhoon is expected to become an extratropical low before it reaches Kyushu, but Weathernews notes it still brings tropical moisture and 30–50 mm/h bursts.

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The rain peaks at different times. Iki/Tsushima peaks first, from the night of the 24th. Northern Nagasaki and Goto peak later, on the 26th, and tenki.jp expects the heavy rain in northern and southern Kyushu from early morning to early afternoon on the 26th.

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tenki.jp advises staying away from rivers and irrigation channels, which can rise faster than expected. That is the gap in monitoring of smaller streams that Kikikuru is meant to fill.

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🇺🇸 Gemini10 places · 1 notes

The same question, answered by Gemini alone. The final list above combines all the AIs.

  1. 1
    Hitoyoshi, Kumamoto Prefecture

    A mountain-encircled basin where over 60% of core built areas sit directly within MLIT flood inundation zones and narrow canyon bottlenecks throttle Kuma River discharge.

  2. 2
    Asakura, Fukuoka Prefecture

    Steep Mount Hiko granitic slopes generate immediate debris torrents into unmonitored mountain tributaries within 90 minutes of stalled rainbands.

  3. 3
    Kurume, Fukuoka Prefecture

    The flat lowlands of the mid-Chikugo River suffer chronic compound inundation where tributary sluice gates close to prevent backwater, submerging urban interior plains.

  4. 4
    Takeo, Saga Prefecture

    A saucer-shaped basin draining to Ariake Sea where tidal backflow and extreme flat topography trap stormwater for days in the Rokkaku River floodplain.

  5. 5
    Kuma Village, Kumamoto Prefecture

    Isolated gorge communities pinned between 40-degree mountain slopes and the surging trunk stream of the Kuma River, leaving limited high-ground escape routes.

  6. 6
    Hita, Oita Prefecture

    A junction of five converging upland rivers where torrential rainfall in Aso and Kuju ranges funnels into a single basin outlet along the Mikuma River.

  7. 7
    Omuta, Fukuoka Prefecture

    Reclaimed coal-mining coastal lowlands where torrential downpours meet high sea tides to overwhelm gravity drainage across the Suwa River basin.

    Source ↗
  8. 8
    Satsumasendai, Kagoshima Prefecture

    Unconsolidated volcanic Shirasu ash bluffs collapse abruptly upon heavy soaking rain, directly threatening downstream Sendai River floodplain settlements.

  9. 9
    Yatsushiro (Sakamoto District), Kumamoto Prefecture

    A downstream gateway where Kuma River peak discharges encounter mountainous canyon squeeze points, leaving riverside highway arteries cut off.

  10. 10
    Nobeoka, Miyazaki Prefecture

    Eastern coastal terrain where steep Kyusho mountains funnel rapid orographic downpours directly into the Gokase and Kita rivers within hours.

What Gemini noticed

Over 200 mm of rainfall in 24 hours can saturate Kyushu's mountainous catchments to 100% field capacity, after which nearly all additional precipitation transforms immediately into surface runoff.

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🇨🇳 StepFun10 places · 4 notes

The same question, answered by StepFun alone. The final list above combines all the AIs.

  1. 1
    Hitoyoshi–Kuma (Kuma River), Kumamoto

    25 died here in 2020 on one of Japan's three great rapids — now rain falls on quake-loosened slopes.

    Source ↗
  2. 2
    Asakura & Toho Village, Fukuoka (Chikugo tributaries)

    The 2017 flood that killed 39 came from creeks too small to make the flood-forecast list.

    Source ↗
  3. 3
    Fukuoka & the Chikugo lower basin (Omuta–Kurume)

    Omuta logged 265.5 mm in a day — about 1.6× all of September.

    Source ↗
  4. 4
    Saga plain — Takeo & the Rokkaku/Kase Rivers

    A bowl-shaped plain that swallowed ~3 metres of water across 4 km² in 2021.

    Source ↗
  5. 5
    Nagasaki — Unzen & Isahaya (steep coastal)

    Already saturated and shaken: Unzen's volcanic slopes cracked in the 2026 quake.

    Source ↗
  6. 6
    Hita, Oita (Chikugo headwaters)

    One of the three towns at the heart of the 2017 flood — back in the 200 mm zone again.

    Source ↗
  7. 7
    Yame & the Chikugo upper basin (Minou foothills), Fukuoka

    Steep Minou foothills that feed the river flooding Saga's plain downstream.

    Source ↗
  8. 8
    Minamiaso–Aso, Kumamoto (volcanic highlands)

    Quake landslides cut off ~20,000 people; now rain falls on cracked volcanic slopes.

    Source ↗
  9. 9
    Kumamoto City (Shira & Midori Rivers)

    Two wards holding ~270,900 people were already told to move before the typhoon landed.

    Source ↗
  10. 10
    Southern Kyushu — Miyazaki & Kagoshima (Sakurajima)

    Half the north's rain (100 mm vs 200 mm) — over the same debris-flow-prone volcanic slopes.

    Source ↗

What StepFun noticed

A pure rain-forecast table would put Northern Kyushu first (200–250 mm); this list weights mapped exposure and the monitoring gap, so the earthquake-loosened, fast-rising Kuma basin tops it — a moderate forecast sitting on extreme, under-gauged exposure.

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JMA itself lists the July 2017 Northern-Kyushu line-shaped-precipitation-band event as a 'hard-to-forecast' case — the same setup now returning, which is why small steep rivers are weighted heavily here.

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Typhoon 30 became a global forecasting test: some agencies' intensity was questioned as too weak, and AI models (which caught the recurve toward Japan) split sharply from physical models that had sent it toward Taiwan/China.

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The rain is not even across one island: Northern Kyushu 200–250 mm vs Southern Kyushu ~100 mm, a 2–2.5× gap driven by the autumn front stalling over the Tsushima Strait while the typhoon weakens to a tropical storm south of Shikoku.

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🇨🇳 Kimi10 places · 3 notes

The same question, answered by Kimi alone. The final list above combines all the AIs.

  1. 1
    Asakura City, Fukuoka (Chikugo River tributaries: Kitagawa, Akatani, Otoishi)

    A 4.5-km creek, the Kitagawa, killed dozens in 2017 — today Asakura sits under the 200 mm forecast bulls-eye with the same unmonitored small rivers.

    Source ↗
  2. 2
    Hitoyoshi City and Kuma-mura, Kumamoto (Kuma River)

    Water reached 4.3 m in Hitoyoshi in 2020 — double the 2.1 m record from 1965 — and 200 mm is forecast on the same basin tonight.

    Source ↗
  3. 3
    Nagasaki City area, Nagasaki Prefecture

    The joint-highest rain forecast in Japan today — 200 mm in 24 h — falls on hills that drop straight into the sea.

    Source ↗
  4. 4
    Saga City and the Saga Plain, Saga (Kase and Rokkaku Rivers)

    A full-moon spring tide on Oct 26 means the Kase and Rokkaku may not be able to drain into the Ariake Sea at the height of the rain.

    Source ↗
  5. 5
    Hita City, Oita (upper Chikugo River)

    The Chikugo got a Level-5 'flood occurring' alert here in July — four months later the same basin faces another warning-level deluge.

    Source ↗
  6. 6
    Okawa City and the lower Chikugo River, Fukuoka/Saga

    Big rivers flood downstream after the rain stops — the lower Chikugo can keep rising for hours after the clouds leave the mountains.

  7. 7
    Oita City, Oita (Oita River)

    The Oita River basin flooded 995 homes in 1993, and today's official hazard map still puts the city center inside the inundation zone.

    Source ↗
  8. 8
    Aso City, Kumamoto (Shirakawa and Midori River headwaters)

    200 mm of rain on the caldera rim feeds the Shirakawa and Midori at the same time — terrain GSI maps as some of Kyushu's densest landslide zones.

    Source ↗
  9. 9
    Miyazaki City, Miyazaki (Oyodo River)

    The Oyodo flooded ~3,800 homes above floor at a record level in 2005 — and it already carried a Level-4 flood-danger alert as recently as August 2025.

    Source ↗
  10. 10
    Makurazaki and the Satsuma Peninsula, Kagoshima (Kimotsuki River)

    The typhoon is forecast to die exactly here — turning extratropical just west of Makurazaki, piling wind-driven water into a full-moon high tide at the Kimotsuki mouth.

    Source ↗

What Kimi noticed

Northern Kyushu's 200 mm is roughly twice a normal October month's rain falling in a single day — the JMA explicitly frames it as warning-level rain driven by the typhoon feeding a stalled front.

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The worst flooding may come after the rain: spring tides with a full moon on Oct 26 slow estuary drainage, and large rivers like the Chikugo peak downstream hours later — MLIT's own briefing lists both as headline cautions.

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July 2026 is still fresh: a linear rainband over the same northern-Kyushu mountains put the Chikugo at Level 5 four months ago, which is why Hita and the lower Chikugo rank above some places with higher rain forecasts.

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🇨🇳 Wenxin10 places · 4 notes

The same question, answered by Wenxin alone. The final list above combines all the AIs.

  1. 1
    Tsushima, Nagasaki Prefecture (Kyushu)

    Already recorded 172.5mm of rain in 12 hours by Oct 25 06:00, with prolonged heavy rain forecast

    Source ↗
  2. 2
    Northern Kyushu broad region

    Highest regional 200mm 24-hour rainfall forecast across all Kyushu zones

    Source ↗
  3. 3
    Nagasaki Prefecture mainland (excluding Tsushima)

    Located directly under the active stagnant rain front with persistent downpours

    Source ↗
  4. 4
    Southern Kyushu region

    5m high waves forecast for Oct 26, paired with 100mm 24-hour projected rainfall

    Source ↗
  5. 5
    Fukuoka Prefecture

    Major populated urban hub in northern Kyushu overlapping high landslide and river flood hazard zones

    Source ↗
  6. 6
    Kumamoto Prefecture

    Seismically active terrain loosened by recent M7.1 quake elevating landslide risk even at lower rainfall totals

    Source ↗
  7. 7
    Okinawa (Miyako/Yaeyama Islands, Sakishima)

    Ground already loosened by prior prolonged Typhoon 30 stagnation, with 5m high waves persisting Oct 25

    Source ↗
  8. 8
    Kagoshima Prefecture

    Southern Kyushu high-risk typhoon zone with historical 6-7 typhoon landfalls per year on average

    Source ↗
  9. 9
    Saga Prefecture

    Low-lying river plains in northern Kyushu facing elevated inundation risk from rising water levels

    Source ↗
  10. 10
    Oita Prefecture

    Steep inland terrain in northern Kyushu vulnerable to sudden debris flows with projected heavy rain

    Source ↗

What Wenxin noticed

Tsushima already hit 172.5mm of rain in just 12 hours by the morning of Oct 25, far higher than initial regional forecast averages, making it the highest immediate risk site

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2026 marks the first time since 1965 and 2015 that typhoons formed every single month from January to October, showing this year's extremely active early typhoon pace

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Typhoon 30 is forecast to transition to an extratropical low south of Shikoku after approaching Kyushu, but the active stationary rain front is driving broader heavy rain across west to east Japan far beyond the typhoon's direct path

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Northern Kyushu is facing 6m high waves on Oct 26, combining heavy rain, strong wind and storm surge to amplify compound disaster risk

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🇨🇳 Qwen10 places · 2 notes

The same question, answered by Qwen alone. The final list above combines all the AIs.

  1. 1
    Kumamoto City (Shirakawa River Basin)

    The Shirakawa’s notorious history of catastrophic breaching forces Level 4 evacuations for 140,000 people before the typhoon's outer bands even make landfall.

    Source ↗
  2. 2
    Nankan Town (Sekigawa River)

    A rural tributary that hit flood danger levels days ago, proving that major MLIT sensors miss the flash-flood reality of Kyushu's smaller valleys.

    Source ↗
  3. 3
    Saga City (Rokkaku River Basin)

    A flat, low-lying basin where 200mm of forecast rain acts like a plugged drain, amplified by recent linear precipitation bands that overwhelmed the Saga Plain.

  4. 4
    Tara Town (Saga Prefecture)

    Evacuation orders for all 7,620 residents highlight the lethal blind spot where steep coastal slopes outpace broader flood warning algorithms.

    Source ↗
  5. 5
    Kikuchi City (Kikuchi River Basin)

    The Kikuchi River threatens to breach its 2020 flood benchmarks as upstream runoff from the Aso caldera collides with a saturated downstream plain.

    Source ↗
  6. 6
    Miyazaki City (Oyodo River Basin)

    Facing a localized 200mm forecast, the Oyodo River’s reinforced levees are the only thing standing between the city and a repeat of its catastrophic Typhoon 14 overtopping.

    Source ↗
  7. 7
    Kagoshima City (Shirasu Plateau)

    The forecast 150mm of rain interacts dangerously with Kyushu’s volcanic 'Shirasu' soil, creating pyroclastic mudflows that GSI hazard maps flag as uniquely lethal.

    Source ↗
  8. 8
    Kitakyushu (Murasaki River Headwaters)

    Northern Kyushu’s 200mm rain forecast collides with steep, urbanized slopes where concrete channels bottleneck the deluge before it reaches the sea.

    Source ↗
  9. 9
    Sasebo City (Nagasaki)

    Nagasaki’s jagged topography concentrates the frontal rain into flash-flood zones that MLIT’s large-river sensors simply cannot see in time.

  10. 10
    Yame City (Chikugo River Headwaters)

    The mountainous source of Kyushu’s largest river holds mapped GSI landslide zones that threaten to choke the Chikugo with debris long before the floodwaters reach Kurume.

    Source ↗

What Qwen noticed

The volcanic 'Shirasu' soil in southern Kyushu absorbs water rapidly but loses all cohesion when saturated, making 150mm of rain far more deadly here than 250mm in the northern plains.

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Typhoon 30 is interacting with a stagnant autumn front, meaning the heavy rain is not just from the typhoon's eyewall but from a massive, stationary rain shield covering the entire island.

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