Official forecast

Cyclone Wind Exposure: Which Registered Places Are Inside the Forecast Wind Field

A forecast advisory for a tropical cyclone states how far tropical-storm-force winds are expected to reach in each direction from the centre. Off-Nadir Delta takes those radii from the U.S. National Hurricane Center advisory and lists the registered ports, plants, bases and straits that lie inside them, now and over the next 48 hours. It is a forecast applied to a registry. For the forecast itself, and for any warning, read the National Hurricane Center.

See them on the Watchfloor API reference

Quick answer — what cyclone wind exposure is here

Cyclone wind exposure is a record, one per active tropical cyclone, of the registered facilities and straits that lie inside the 34-knot (tropical-storm-force) wind radii of the U.S. National Hurricane Center forecast advisory, at the current position or at a forecast position within 48 hours. It is updated with each advisory. A storm whose wind field covers no registered facility or strait produces no record. It covers the Atlantic, the eastern Pacific and the central Pacific. A wind radius is the maximum extent expected in its quadrant, so a place inside it will not necessarily have 34-knot winds; forecast positions carry track error; and the record does not establish damage. It is not an official forecast or warning. Records are events on the Watchfloor map under the category Cyclone Wind Exposure.

What is cyclone wind exposure?

The U.S. National Hurricane Center issues a Forecast/Advisory for each active tropical cyclone “every six hours at 0300, 0900, 1500, and 2100 UTC”. It gives the position and intensity of the cyclone and “the maximum radial extent of winds of 34, 50, and 64 kt in each of four quadrants around the storm”, for the present and for forecast times (NHC: product descriptions). The same page says these are issued for Atlantic, eastern Pacific and central Pacific cyclones; those for the central Pacific are Central Pacific Hurricane Center advisories, carried in the same National Hurricane Center feed.

That text is written for forecasters and software. It answers “how wide is the wind field” and leaves “what is inside it” to the reader. This record does the second step for one fixed list of places: the facilities and straits of the location registry.

So cyclone wind exposure is not a measurement by this product and not an observation of wind. It is the official forecast wind field, laid over registered places, with the distance of each from the centre.

How a storm is matched to places

Each active tropical cyclone with a National Hurricane Center forecast advisory is read.
The 34-knot wind radii are used: one radius for each quadrant (north-east, south-east, south-west, north-west), at the current position and at each forecast position.
Forecast positions up to 48 hours ahead are used. Later positions are not, because track error grows with time.
A registered facility or strait is inside when its distance from the centre is within the radius of the quadrant it lies in.
Sea areas are not counted: a storm at sea is always inside some sea area.
A storm with no registered facility or strait inside its radii produces no record.
There is one record per storm. Each new advisory updates it.

Forecast advisories: NOAA National Hurricane Center (product descriptions). National Weather Service information is in the public domain, on the condition that it is not presented as official government material once modified and that no endorsement is implied (NWS disclaimer). Off-Nadir Delta is not affiliated with NOAA or the National Weather Service. Facility positions: OpenStreetMap contributors and Wikidata.

What a record states

Which storm, the advisory number and when it was issued.
The centre, the maximum sustained winds and the central pressure given in the advisory.
How many registered places are inside the 34-knot radii now, and how many more within 48 hours on the forecast.
The nearest of those places by name, with the kind of each and its distance from the centre.
For a place inside a forecast radius, the first forecast time at which it is inside.

What it does not state

That the wind will reach a place. A radius is the maximum extent expected in its quadrant. Being inside one does not mean 34-knot winds will occur at that place.
That the wind did reach a place. It is a forecast, not an observation. Forecast positions carry track error.
Damage or a closure. Nothing in the record says a facility was damaged, closed or evacuated.
Storm surge, rain or stronger winds. Only the 34-knot wind radii are used. Storm surge, rainfall and the 50- and 64-knot radii are not in this record.
Anything outside its area. It covers the Atlantic, the eastern Pacific and the central Pacific. Typhoons in the western Pacific and cyclones in the Indian Ocean are not covered, so no record there says nothing.
An official forecast or warning. The National Hurricane Center advisory is that. This record points to it.

A forecast, next to the reporting

Reporting about a hurricane says what it did. A forecast says where its winds are expected. This record answers a narrower question: which of the places in the registry are inside the forecast wind field at this advisory.

It is its own event and is not merged into reporting about the same storm. Its title and summary are written by a fixed rule from the advisory and the distances, not by a model. Each listed place is linked as nearby, never as the place of a report or of a measurement.

Cyclone wind exposure over the API

These records are events, so they come back from the events endpoint with their category. A page costs 3 tokens.

curl "https://offnadir-delta.com/api/v1/signals?categories=cyclone_exposure" \
  -H "Authorization: Bearer ond_..."

Each one carries measured: true and measured_kind: cyclone_exposure. The same query works through the MCP tool query_signals. A reader for this kind alone is GET /api/v1/cyclone-exposures, and client.cyclone_exposures in the Python SDK. Parameters and response fields are in the API reference.

What each plan sees

On every plan, the Watchfloor map shows that a tropical cyclone’s forecast wind field covers registered places, when, and where on the map. The marks are there without paying.

Which storm it is, which places are inside the wind field and how far each is from the centre are part of the full account of each event, in the app, through the Delta Agent and over the API. Pricing shows which plan opens it.

How It Works

Open the Watchfloor

These records are on the map next to reported events. To see only these, pick “Cyclone Wind Exposure” under Category in the filters.

Find the spiral marks

Each spiral is one tropical cyclone whose forecast wind field covers at least one registered facility or strait.

Open one

Read which places are inside the 34-knot radii now and which enter them within 48 hours, with the distance of each from the centre.

Read the advisory

For the forecast itself, and for watches and warnings, go to the National Hurricane Center advisory.

Frequently Asked Questions

What is cyclone wind exposure?▼

A record of the registered facilities and straits that lie inside the 34-knot (tropical-storm-force) wind radii of a U.S. National Hurricane Center forecast advisory, at the current position of the storm or at a forecast position within 48 hours. There is one record per storm, updated with each advisory.

Is this a hurricane forecast or warning?▼

No. It is not an official forecast or warning. It takes the wind radii from the National Hurricane Center forecast advisory and lists the registered places inside them. For the forecast, and for watches and warnings, read the National Hurricane Center.

Does being inside the wind field mean a place will be hit?▼

No. The advisory gives, for each quadrant, the maximum extent of 34-knot winds expected in that quadrant, so the winds do not reach every point inside the radius. Forecast positions also carry track error, and the record does not establish damage.

Which oceans are covered?▼

The Atlantic, the eastern Pacific and the central Pacific. Typhoons in the western Pacific and cyclones in the Indian Ocean are not covered, so the absence of a record there says nothing about a storm.

Why only 34 knots and 48 hours?▼

34 knots is the lower bound of tropical-storm force, so its radius is the widest of the wind fields the advisory gives. Forecast positions later than 48 hours are left out because track error grows with time.

Why does a storm at sea have no record?▼

A record is made only when a registered facility or strait is inside the wind radii. A storm over open water that covers none of them produces nothing, and sea areas are not counted.

Is there an API?▼

These records are events: GET /api/v1/signals with categories=cyclone_exposure returns them, each with measured: true and measured_kind: cyclone_exposure, at 3 tokens a page. A reader for this kind alone is GET /api/v1/cyclone-exposures, and client.cyclone_exposures in the Python SDK; the API reference has the parameters.

What does each plan see?▼

Every plan sees that a tropical cyclone’s forecast wind field covers registered places, when, and where on the map. Which storm, which places and their distances are part of the full account of each event, which not every plan includes. The Pricing page shows which plan opens it.