The National Weather Service (NWS) will be providing burn area flash flood threat levels during the summer monsoon months for the Calwood burn scar at Heil Valley Ranch. Here’s what the levels mean:
During the thunderstorm season
🟢 Green would indicate no (or a very minimal threat) of flash flooding. If we did get rain it wouldn’t produce anything more than a minor flow of debris or water that would stay in stream channels. There would be no threat to life.
🟡 Yellow means “limited” threat, so the chances or risk level of a thunderstorm producing flash flooding is not very high as either intensity or coverage of thunderstorms would be lacking. However, an isolated strong thunderstorm could still produce a significant flash flood but over a smaller area and carry with it a threat to life and property. Forecaster confidence may also be lower than normal on these days, but there is still a threat nonetheless.
🟠 Orange means “elevated”, and the threat of a flash flood in/near a burn area is considerable. Storms will be capable of producing heavy rain and causing significant flash flooding and a threat to life and property.
🔴 Red means “significant” threat of flash flooding. The chances of a storm or multiple storms producing significant flash flooding are much higher than a typical day. Storms on these days will likely produce heavy rain and life threatening flash flooding with considerable property damage. Forecaster confidence is high that heavy rain and flash flooding will occur. We will typically reserve this threat level for days when numerous storms are expected to produce heavy rainfall – like when the monsoon fully establishes itself or other heavy rain producing ingredients come together.
In all Yellow, Orange, and Red scenarios, it’s advisable to have a plan and stay out of harm’s way (lower elevations in/near recent burn areas) if thunder or rain is observed nearby. Riding in/near flood prone burn areas should be avoided altogether on Orange or Red days. Should you get caught in heavy rain, or flooding is observed, move to higher ground or a ridgeline immediately.
Some days the NWS will further refine the time (e.g. 11 am, 1 pm, 3 pm) of the higher threat. Those, too, will be found in the linked graphic. Thus, it may be safe to ride before 10 or 11 am, but be sure to avoid all areas prone to flash flooding thereafter.
This graphic can be found on the NWS Weather Story page.