August 27, 2019 – The National Weather Service in Sacramento has issued a Red Flag Warning, which is in effect from 11 AM to 8 PM PDT Wednesday. The Fire Weather Watch is no longer in effect.
Moisture and instability are enough over the northern Sierra this afternoon for a few thunderstorms to develop along the crest south of Highway 50. More thunderstorms are possible overnight moving north to south as subtropical moisture with elevated instability moves into the area. Even a few isolated dry thunderstorms are possible over the Valley. A better chance of these is over the mountains late Wednesday morning through the early evening, where a Red Flag Warning for high based thunderstorms with little or no rainfall is in effect. Fire starts are possible from any lightning strikes, due to cured fuels. A strong lifting mechanism not evident as broad weakening circulation associated with the remnants of Tropical Storm Ivo moves north mainly offshore to our west.
* THUNDERSTORMS: Potential for dry thunderstorms with little or no rainfall associated with them.
* Timing: Wednesday morning through Wednesday evening.
* WIND: Upslope or southwest winds 5 to 15 mph. Gusts up to 25 mph mainly over ridges and higher peaks.
* HUMIDITY: Minimum 15-25 percent.
* IMPACTS: Fire starts from dry lightning.
A Red Flag Warning means that critical fire weather conditions are either occurring now, or will shortly. A combination of gusty and erratic thunderstorm winds, low relative humidity, and warm temperatures can contribute to extreme fire behavior.