Description

GEFS Wave Prob turns ensemble spread into ocean-wave probabilities. Instead of relying on one predicted wave height, it answers questions such as how likely a location is to exceed an operational wave-height threshold.

That matters for maritime routing, offshore work, ports, coastal planning, and recreational marine safety because the cost of underestimating waves is often asymmetric. A moderate probability of hazardous sea state can change route selection, work windows, or required safety margins.

Detail

Archive begins: 2020-10-01

Product page: https://www.ncei.noaa.gov/products/weather-climate-models/global-forecast/

Key Features:

Estimates probabilities of significant wave height exceeding specific thresholds.
Uses ensemble spread to quantify maritime risk instead of a single scenario.
Four cycles daily: 00, 06, 12, 18 UTC.
Lead times extend through 384 h, about 16 days.

Resolution: 0.25° global grid.

Temporal Coverage: Updated four times daily, with forecasts extending up to 384 hours (~16 days).

Primary Use Cases: maritime routing, offshore operations, coastal management, port planning, recreational marine activity, marine insurance, and alerts based on probability of exceeding wave thresholds.

Parameters

Click a parameter to reveal variants in a compact table with ready-to-copy JSON selectors.

HTSGW –Significant Wave Height (m)

8 variants

Significant wave height represents the average height of the highest third of waves. It is the standard metric for sea state and marine hazards.

Units: m.

Level	Info	Horizon	Introduced	Selector
`surface`	`prob >0.6`	0h-384h	2020-10-01	`{"name":"HTSGW","level":"surface","info":"prob >0.6"}`
`surface`	`prob >1`	0h-384h	2020-10-01	`{"name":"HTSGW","level":"surface","info":"prob >1"}`
`surface`	`prob >2`	0h-384h	2020-10-01	`{"name":"HTSGW","level":"surface","info":"prob >2"}`
`surface`	`prob >3`	0h-384h	2020-10-01	`{"name":"HTSGW","level":"surface","info":"prob >3"}`
`surface`	`prob >4`	0h-384h	2020-10-01	`{"name":"HTSGW","level":"surface","info":"prob >4"}`
`surface`	`prob >5.5`	0h-384h	2020-10-01	`{"name":"HTSGW","level":"surface","info":"prob >5.5"}`
`surface`	`prob >7`	0h-384h	2020-10-01	`{"name":"HTSGW","level":"surface","info":"prob >7"}`
`surface`	`prob >9`	0h-384h	2020-10-01	`{"name":"HTSGW","level":"surface","info":"prob >9"}`

PERPW –Primary Wave Mean Period (seconds)

8 variants

Primary Wave Mean Period (seconds).

Level	Info	Horizon	Introduced	Selector
`surface`	`prob >11`	0h-384h	2020-10-01	`{"name":"PERPW","level":"surface","info":"prob >11"}`
`surface`	`prob >13`	0h-384h	2020-10-01	`{"name":"PERPW","level":"surface","info":"prob >13"}`
`surface`	`prob >15`	0h-384h	2020-10-01	`{"name":"PERPW","level":"surface","info":"prob >15"}`
`surface`	`prob >17`	0h-384h	2020-10-01	`{"name":"PERPW","level":"surface","info":"prob >17"}`
`surface`	`prob >19`	0h-384h	2020-10-01	`{"name":"PERPW","level":"surface","info":"prob >19"}`
`surface`	`prob >5`	0h-384h	2020-10-01	`{"name":"PERPW","level":"surface","info":"prob >5"}`
`surface`	`prob >7`	0h-384h	2020-10-01	`{"name":"PERPW","level":"surface","info":"prob >7"}`
`surface`	`prob >9`	0h-384h	2020-10-01	`{"name":"PERPW","level":"surface","info":"prob >9"}`

SWELL –Significant Height of Swell Waves (meters)

8 variants

Significant Height of Swell Waves (meters).

Level	Info	Horizon	Introduced	Selector
`surface`	`prob >0.6`	0h-384h	2020-10-01	`{"name":"SWELL","level":"surface","info":"prob >0.6"}`
`surface`	`prob >1`	0h-384h	2020-10-01	`{"name":"SWELL","level":"surface","info":"prob >1"}`
`surface`	`prob >2`	0h-384h	2020-10-01	`{"name":"SWELL","level":"surface","info":"prob >2"}`
`surface`	`prob >3`	0h-384h	2020-10-01	`{"name":"SWELL","level":"surface","info":"prob >3"}`
`surface`	`prob >4`	0h-384h	2020-10-01	`{"name":"SWELL","level":"surface","info":"prob >4"}`
`surface`	`prob >5.5`	0h-384h	2020-10-01	`{"name":"SWELL","level":"surface","info":"prob >5.5"}`
`surface`	`prob >7`	0h-384h	2020-10-01	`{"name":"SWELL","level":"surface","info":"prob >7"}`
`surface`	`prob >9`	0h-384h	2020-10-01	`{"name":"SWELL","level":"surface","info":"prob >9"}`

SWPER –Mean Period of Swell Waves (seconds)

8 variants

Mean Period of Swell Waves (seconds).

Level	Info	Horizon	Introduced	Selector
`surface`	`prob >11`	0h-384h	2020-10-01	`{"name":"SWPER","level":"surface","info":"prob >11"}`
`surface`	`prob >13`	0h-384h	2020-10-01	`{"name":"SWPER","level":"surface","info":"prob >13"}`
`surface`	`prob >15`	0h-384h	2020-10-01	`{"name":"SWPER","level":"surface","info":"prob >15"}`
`surface`	`prob >17`	0h-384h	2020-10-01	`{"name":"SWPER","level":"surface","info":"prob >17"}`
`surface`	`prob >19`	0h-384h	2020-10-01	`{"name":"SWPER","level":"surface","info":"prob >19"}`
`surface`	`prob >5`	0h-384h	2020-10-01	`{"name":"SWPER","level":"surface","info":"prob >5"}`
`surface`	`prob >7`	0h-384h	2020-10-01	`{"name":"SWPER","level":"surface","info":"prob >7"}`
`surface`	`prob >9`	0h-384h	2020-10-01	`{"name":"SWPER","level":"surface","info":"prob >9"}`

WIND –Wind Speed (m/s)

8 variants

Wind speed is the magnitude of the horizontal wind at the specified level. It is used for transport, mixing, and hazards.

Units: m/s.

Level	Info	Horizon	Introduced	Selector
`surface`	`prob >11.31`	0h-384h	2020-10-01	`{"name":"WIND","level":"surface","info":"prob >11.31"}`
`surface`	`prob >14.39`	0h-384h	2020-10-01	`{"name":"WIND","level":"surface","info":"prob >14.39"}`
`surface`	`prob >17.48`	0h-384h	2020-10-01	`{"name":"WIND","level":"surface","info":"prob >17.48"}`
`surface`	`prob >21.07`	0h-384h	2020-10-01	`{"name":"WIND","level":"surface","info":"prob >21.07"}`
`surface`	`prob >24.67`	0h-384h	2020-10-01	`{"name":"WIND","level":"surface","info":"prob >24.67"}`
`surface`	`prob >3.6`	0h-384h	2020-10-01	`{"name":"WIND","level":"surface","info":"prob >3.6"}`
`surface`	`prob >5.65`	0h-384h	2020-10-01	`{"name":"WIND","level":"surface","info":"prob >5.65"}`
`surface`	`prob >8.74`	0h-384h	2020-10-01	`{"name":"WIND","level":"surface","info":"prob >8.74"}`

WVHGT –Significant Height of Wind Waves (meters)

8 variants

Significant Height of Wind Waves (meters).

Level	Info	Horizon	Introduced	Selector
`surface`	`prob >0.6`	0h-384h	2020-10-01	`{"name":"WVHGT","level":"surface","info":"prob >0.6"}`
`surface`	`prob >1`	0h-384h	2020-10-01	`{"name":"WVHGT","level":"surface","info":"prob >1"}`
`surface`	`prob >2`	0h-384h	2020-10-01	`{"name":"WVHGT","level":"surface","info":"prob >2"}`
`surface`	`prob >3`	0h-384h	2020-10-01	`{"name":"WVHGT","level":"surface","info":"prob >3"}`
`surface`	`prob >4`	0h-384h	2020-10-01	`{"name":"WVHGT","level":"surface","info":"prob >4"}`
`surface`	`prob >5.5`	0h-384h	2020-10-01	`{"name":"WVHGT","level":"surface","info":"prob >5.5"}`
`surface`	`prob >7`	0h-384h	2020-10-01	`{"name":"WVHGT","level":"surface","info":"prob >7"}`
`surface`	`prob >9`	0h-384h	2020-10-01	`{"name":"WVHGT","level":"surface","info":"prob >9"}`

WVPER –Mean Period of Wind Waves (seconds)

8 variants

Mean Period of Wind Waves (seconds).

Level	Info	Horizon	Introduced	Selector
`surface`	`prob >11`	0h-384h	2020-10-01	`{"name":"WVPER","level":"surface","info":"prob >11"}`
`surface`	`prob >13`	0h-384h	2020-10-01	`{"name":"WVPER","level":"surface","info":"prob >13"}`
`surface`	`prob >15`	0h-384h	2020-10-01	`{"name":"WVPER","level":"surface","info":"prob >15"}`
`surface`	`prob >17`	0h-384h	2020-10-01	`{"name":"WVPER","level":"surface","info":"prob >17"}`
`surface`	`prob >19`	0h-384h	2020-10-01	`{"name":"WVPER","level":"surface","info":"prob >19"}`
`surface`	`prob >5`	0h-384h	2020-10-01	`{"name":"WVPER","level":"surface","info":"prob >5"}`
`surface`	`prob >7`	0h-384h	2020-10-01	`{"name":"WVPER","level":"surface","info":"prob >7"}`
`surface`	`prob >9`	0h-384h	2020-10-01	`{"name":"WVPER","level":"surface","info":"prob >9"}`

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Global Ensemble Forecast System (GEFS Wave Prob)

Description

Detail

Parameters