Lake Powell Wind

Forecast wind, reshaped by every canyon wall and cliff

Wind

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Air mixing

Lake level

Elevation

Map

Heat map

Units

Times in

Heat map

Satellite Places Forecast arrows

Model tuning

Replay a storm you remember, then adjust these until the map matches what the water did. Settings are saved in this browser.

Wind shadow

How far behind a cliff the calm reaches, in cliff heights (neutral air; stable air stretches it, a hot afternoon shortens it).

Funnelling

How strongly the wind speeds up through narrows between tall walls (0 = off, 1 = all the air squeezes through). Stable air funnels more, a deep convective afternoon layer much less.

Water speed-up

Wind blows faster over smooth water than over the land the forecast describes: about +15% at 10 mph, fading to nothing in a gale (Shore Protection Manual). 1 = that curve, 0 = off.

Lee gusts

Extra gustiness in a cliff's wind shadow, where air tumbles off the rim.

How the model works

The forecast gives the wind over the open plateau around the lake (all its sample points sit on NOAA's plateau cells, 3 km apart). The terrain is mapped every 15 m along the lake, 61 m farther out. For every 30 m of open water the model looks upwind along 21 directions fanned ±75° around the forecast direction. Along each one it finds the steepest terrain the wind must clear (the canyon rim, a cliff, a butte), measured from 5 m above the water.

A barrier of height H leaves a wind shadow that recovers over roughly 5–20 H downwind, depending on how well mixed the air is (taken from NOAA's boundary-layer depth: a few hundred metres at night, kilometres on a hot afternoon). A wall close to the water on the downwind side also slows and turns the flow. The wind takes whichever path is most open, weighted by how closely that path lines up with the forecast. That is how a canyon bends the wind along its axis, and why a side canyon across the wind sits nearly calm.

The terrain also speeds the wind up. Air that can't get over the walls has to squeeze through, so where the open water across the flow narrows compared with upwind (a gap between buttes, a bend, a point jutting out) the wind accelerates, and the taller the walls the more of it is forced through. Where a canyon opens into a wide bay the jet spreads and slows. Stable air (night, winter) funnels; a deep convective layer mostly spills over the rims. In a cliff's wind shadow, air tumbling off the rim makes the gusts larger relative to the mean wind.

Waves are then grown every 15 m by following the local wind back upwind through the water, bend by bend, adding up wave energy from the wind along that path (USACE Coastal Engineering Manual growth law, deep water, which matches measured lake waves to within ~5%). The map is shaded by the biggest wave you're likely to meet in about an hour on the water: 1.86× the significant (typical) wave height. The readout gives both. So waves keep building around a gentle bend and roll on into a reach where the wind has eased, but stop at a point that cuts the path. They are also limited by how long the wind has been blowing from that direction (a fresh wind needs a couple of hours to raise its full fetch-limited sea), and the wind itself picks up a little over the first few hundred metres of smooth water.

This is a diagnostic terrain model, not a flow simulation. It does not model thermal canyon breezes, thunderstorm outflows, or gusts dropping off the rims. Treat it as a guide to where shelter is likely, and keep an eye on the sky.

Data

Lakebed: USGS Modified Topobathymetric DEM for Lake Powell (2021, 1 m), on the Reclamation gauge datum, every 15 m. Land: USGS 3DEP via AWS Terrain Tiles (15 m along the lake, 61 m beyond). Lake level: Bureau of Reclamation. Forecast: NOAA HRRR/GFS via Open-Meteo (10 m wind, gusts, boundary-layer depth). Observations: NWS ASOS at Page airport (KPGA) and Halls Crossing (U96) via the Iowa Environmental Mesonet. Imagery: Esri World Imagery.

Drag to pan, scroll or pinch to zoom, hover or tap the water for a readout. Space plays the forecast, ←/→ step an hour.

Water conditions

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USGS · Reclamation · NOAA via Open-Meteo · Not for navigation

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