Typhoon Dolphin and Japan: What the Forecast Spread Is Really Telling You

Search for this storm today and you will find maps with a confident red line running straight into somebody's coastline. Ignore them.

Five days out from a recurving western Pacific typhoon, the honest position is that the destination is unsettled. Japan is on the table. So is Korea. So is a stretch of Chinese coastline a thousand kilometres to the southwest. Understanding why that gap exists is worth more to a traveller than any single arrow.

The part everyone agrees on

Through roughly the second of August, the guidance is tight. Dolphin drifts west-northwest around 20 km/h, stays at the top of the intensity scale, and never comes near a coastline.

After that the steering pattern shifts. The storm is expected to swing more due west and accelerate to something near 25 km/h, generally pointed at the Fujian and Zhejiang shoreline.

Nearly every run produces that much. The disagreement starts later.

Where the runs come apart

Past the five-day mark, solutions scatter. Landfall candidates presently include eastern China, the Japanese archipelago, and South Korea — outcomes that could hardly be further apart if you are holding a ticket.

Certain runs steer the centre toward Hangzhou Bay. Others bend it further north, and that northern branch is what keeps Kyushu and the Korean Strait alive as possibilities.

None of this is unusual. A typhoon in the middle of a recurve is one of the harder forecast problems in the business.

Blame the eyewall

Dolphin has been cycling through eyewall replacements. An outer ring of convection builds, strangles the inner eye, and eventually inherits the job.

Three things happen while that plays out. The peak winds ease. The wind field widens. And the track wanders, sometimes by tens of kilometres.

Project that forward and the arithmetic gets unforgiving. Fifty kilometres of drift today can mean several hundred by day six, because position dictates which steering current the storm ends up riding. That is the entire reason the cone flares open.

Where to check this yourself

Do not take any single blog's word for a storm, including this one. These are the agencies that actually issue the warnings, and they are the sources the numbers in this article come from.

Japan Meteorological Agency (JMA) — the official authority for Japanese waters, warnings and landfall.
Korea Meteorological Administration (KMA) — Korean track guidance and warnings.
Joint Typhoon Warning Center (JTWC) — the US centre behind most Category-equivalent figures quoted for western Pacific storms.
Hong Kong Observatory — clear track maps, and useful because it shows several agencies side by side.
China National Meteorological Center — the authority for any Chinese landfall.

If those five disagree with each other, that disagreement is the story. It is the same spread this article is describing, and no blog resolves it faster than the agencies do.

The two things that will decide it

Neither has much to do with the typhoon itself.

First, the subtropical ridge sitting to the north. Should it hold and build westward, Dolphin gets shoved into China. Should it sag or slide east, the storm finds the weakness and hooks north toward Japan and Korea.

Second, timing. A system running at 25 km/h arrives at the decision point a full day sooner than one crawling at 20, and by then the ridge has moved on. Speed and track are tangled together, not separate.

Practical notes for travellers

Japan, roughly the fifth to the ninth. Monitor, do not react. Kyushu and Okinawa carry the exposure if the recurve happens; Tokyo sits well clear of the present spread.

Korea. A longer shot than Japan or China at the moment, though the northern solutions do put the Korean Strait in play.

Eastern China. Shanghai, Ningbo, Wenzhou and Fuzhou sit closest to the middle of the guidance. Anyone with dates in that window should be paying the most attention.

The advice is identical in all three cases: hold off until the runs on the second of August. The cone should compress quickly once the recurve either materialises or fails to.

What the cone actually is

Since this entire article is about the spread, it is worth saying plainly what the cone on those maps represents, because almost everyone reads it wrong.

The cone is not the storm. It is not the area that will get wind, or rain, or damage. A storm's wind field routinely extends far outside the cone, and places well outside it can be badly affected.

The cone is a statistical envelope built from how wrong the forecasts have been in the past. Agencies take their track errors over recent years and draw a shape wide enough to contain roughly two-thirds of them. That is all it is: a record of past accuracy, projected forward.

Two consequences follow. First, about one time in three the centre ends up outside the cone entirely. That is not a failure; it is the design. Second, the cone gets narrower every year as forecasting improves, which means an old cone and a new cone are not the same width for the same uncertainty.

So when the cone covers three countries, it is not saying the storm will hit all three. It is saying the forecast has not yet resolved which one, and history suggests the answer is probably somewhere in that shape. Treat it as a measure of confidence, not a map of impact.

A number worth discounting

The Category 5 figure making the rounds today is not the number that will matter at landfall.

Extended guidance has Dolphin down around Category 1 to 2 equivalent as it nears land, once it has moved into the cooler and more sheared air of the East China Sea. The storm that eventually arrives will be a considerably diminished version of what is spinning over open water tonight.

That is simply how these systems end. It is worth remembering whenever a headline leads with the peak.

Written 31 July 2026. Revisions to follow as the cone tightens.

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