Fire danger increases this week as an area of low pressure slips in from the north. A Fire Weather Watch goes up for much of Northern Nevada Friday morning and goes through Saturday as a result. The difference between a watch and a warning has to do with the confidence level.
A watch means ingredients are there and we’re watching for it to happen. A warning means it’s happening.  You can demonstrate this with a taco. A watch would be when you have the ingredients for a taco, and a warning is when the taco is made. As confidence builds, the National Weather Service will either replace the watch with a Red Flag Warning or get rid of the alert all together.
A Fire Weather Watch goes into effect for much of Northern Nevada on Friday, going through Saturday. Wind gusts could reach 45 mph and relative humidity values will be low.
Highs on Thursday will be in the lower 90’s, but on Friday we’ll be in the low 80’s. Highs will be in the 70’s over the weekend. This is a large enough drop to increase wind speeds and tighten the pressure gradient. Wind speeds are linked to temperature and pressure differences. The low is impressive for the end of June, but will mainly come through dry.
Wind speeds will range from 20-30 mph sustained, with gusts up to 45mph. It will also be windy for 2-4 hours on Friday and 3-8 hours on Saturday. Relative humidity values will range between 10-20 percent. While humidity values will be higher Friday night into Saturday, wind speeds will stay strong on mid slopes and ridges. By Sunday, wind speeds will be much lighter.
Fire danger goes down on Sunday but it is not zero. Our fuels are drying out and we can count on the Washoe Zephyr to kick in almost every late afternoon and evening during the summer season. The Washoe Zephyr is a local wind that develops due to temperature differences between Lake Tahoe and central Nevada, like Lovelock. The bigger the temperature difference, the stronger the Washoe Zephyr will be.
This means that even on summer days when there are not any fire watches or warnings, you still want to stay fire aware, as the fire risk can reach high or critical levels for a short time. Strong winds can spread a fire quickly.