Red flag warning in Northern California. How is it different from a fire weather watch?
During wildfire season, the National Weather Service has two advisories that inform people of dangerous conditions that could lead to blazes: a fire weather watch and a red flag warning.
The difference between the two is the amount of time before the weather conditions start, said Anna Wanless, a meteorologist with the weather service’s Sacramento office.
A watch is issued up to 48 hours before the weather event starts, while a red flag warning is issued when critical fire conditions are expected within the next 24 hours.
“For a warning, it’s more like the conditions are happening right now, while the watch is more like in the next couple days, we’re going to see the conditions,” Wanless said.
A new warning: Potentially dangerous situation
The weather service last year introduced a new type of warning in California for even more dire conditions related to wildfires.
Forecasters can now issue a “particularly dangerous situation” alert designation. The warning will be issued rarely when there is a combination of extremely low humidity, high winds and dry vegetation that could act as fuel for a fire.
The warning alerts residents to the potential of new fires that could grow rapidly out of control, creating situations where some residents may not be able to get out safely as a fire approaches.
While the alert — which is used in other parts of the country to warn people of tornadoes — was introduced for fires last year in the southern San Joaquin Valley, the weather service office in Sacramento has not issued a potentially dangerous situation alert as weather conditions so far have not met the criteria.
“It’s still a red flag warning; it’s just an extra tag that we put on to alert our partners that this is an especially dire weather situation,” Wanless said.
This level of alert may occur later in the summer when wildfires are ongoing and weather conditions are extremely dry and windy, Wanless said.
What you should do to prepare
The weather service will usually issue a warning after a watch with a few exceptions, according to Wanless.
In addition, the weather service alerts suggest different measures people should take. A watch warns people to be ready for potentially critical conditions, while a warning urges people to take action.
“Red flag warning is to take action now, and a watch is more be prepared,” Wanless said.
During a watch, people who live in fire-prone areas should clear debris outside of their homes and create defensible space for safety, Wanless said. During a warning, people should avoid outdoor burning and using equipment that could create a spark.
But regardless of a watch or warning, the weather service puts out the same safety guidelines in order to drive the message home, Wanless said.
Critical weather in Sacramento Valley
Due to predicted strong wind gusts and low humidity levels, the weather service issued a red flag warning for the Sacramento Valley Monday morning. Gusts may reach up to 35 mph, the advisory said.
On Monday, forecasters extended the red flag warning through Wednesday.
Other fire safety tips include obeying local burn bans and not driving or parking vehicles in dry grass, which can be prone to catching fire.
In addition to critical fire conditions, forecasters say high temperatures are expected to be around 100 degrees Tuesday and Wednesday. Record highs are possible, according to the weather service.
During the heat advisory which begins Tuesday at noon, the weather service advises people to drink water frequently, wear sunscreen, take breaks in shaded areas and not leave pets or kids in unattended vehicles.
This story was originally published May 23, 2022 at 10:46 AM with the headline "Red flag warning in Northern California. How is it different from a fire weather watch?."