Fire weather watch for southern Arizona starts Sunday
The National Weather Service in Tucson issued a fire weather watch for Sunday through Monday because strong gusty winds and very dry relative humidity are in the forecast, the weather service tweeted Friday.
Tucson, Green Valley, Nogales, Wilcox and Sierra Vista are some of the regions expected to be impacted through the watch, the tweet stated.
The wind, humidity and fire danger rating for the days outlined are expected to occur for at least three hours or longer, Tucson weather service meteorologist Glenn Lader said.
Typically, the most critical conditions will occur from the late morning into the early evening hours because that is when the winds will be strongest, then in the daytime because the relative humidity gets low as temperatures start to warm up, and an increase in humidity as temperatures cool down in the evening, Lader said.
Contrary to popular belief, wildfire weather conditions are not determined by temperature.
Ingredients for the spread of wildfires — hot, dry and windy conditions — are expected to be across the desert Southwest, according to a tweet by the National Weather Service in Phoenix.
However, determining whether a fire weather watch or red flag warning should be issued comes down to three things: wind speeds at 20 mph or greater, relative humidity at 15% or less and fire danger rating, according to Lader.
Those three ingredients in turn result in the most critical fire weather conditions, Lader said. Fire weather watches or red flag warnings are largely determined by how confident meteorologists are that the three conditions will merge together, Lader said. Not necessarily how hot a certain region might be.
Weather watches are usually issued between three to four days. Watches can sometimes be upgraded to warnings if certain conditions come together within a day or two of the original watch, Lader said. They also depend on current weather systems, not necessarily seasonality.
Spring tends to have the biggest issues with fire weather and fire weather concerns, Lader said.
"We could say that it looks like these conditions in general are more favorable for fire weather concerns going through the spring," Lader said.
Watches and warnings raise public awareness about fire-weather-related conditions, even though they are geared more towards the fire community, Lader said.
"Folks that live in or are near the urban wildland interface should be particularly attuned to the potential risk" as we move towards the summer months, Lader said.
In this case, that means avoiding outdoor burning, checking for dragging trailer chains, avoiding sparks from outdoor tools and equipment, and using extra caution with outdoor recreational activities, the weather service in Tucson recommends.