Valley fog go/no-go

What it is

In winter, the Grand Valley can sit under a temperature inversion. Cold, dense air pools on the valley floor beneath warmer air above it. When there's enough moisture, that pooled air can hold low clouds or fog for days at a time, until a storm system or strong wind mixes it out. The National Weather Service office in Grand Junction covers this area and issues Dense Fog Advisories and Air Quality Alerts when conditions call for them.

Why it matters for a fishing trip

  • Driving: Dense fog cuts visibility. NWS fog-driving guidance is to slow down, use low-beam headlights, leave extra following distance, and pull fully off the road if you can't see.
  • Freezing fog: When the temperature is below freezing, fog can leave ice on roads, bridges, and your gear. Watch NWS forecasts for freezing fog.
  • On the water: Under fog it's harder to spot other boaters, hazards, and shorelines. Reservoir ice in early winter is never guaranteed safe. Check CPW ice safety guidance and current ice conditions before you go out.
  • Flows: Fog doesn't change river flow. Check the current gauge on USGS Water Data before you leave.

Go/no-go checklist

  1. Check the NWS Grand Junction forecast and active alerts for your route and destination. No-go or delay if a Dense Fog Advisory or freezing fog is in effect for the road you'll drive.
  2. Read the forecast discussion (the Area Forecast Discussion on the NWS Grand Junction page) to see when the inversion is expected to break.
  3. Check the USGS gauge for your water. No-go if flows are outside what you can wade or float safely.
  4. Check the CPW park or water page for closures, ramp status, and ice information. No-go if your access is closed.
  5. Getting above the fog layer can mean clearer skies. Driving up into it means poor visibility on the climb. Plan extra time and daylight margin.
  6. Tell someone your route and when you expect to be back. In fog, phone coverage and spotting help both get harder.
  7. Turn around if visibility drops below what lets you stop safely within the distance you can see.

Sources for this post