Quick Update -
A return to an upper air pattern from the southeast is occurring today, which will result in more humidity this week, along with a chance of thunderstorms.
As of Sunday afternoon, the current satellite shows large areas of moisture lurking to the east and south of us.
Deep, moist southeast flow is sourcing air masses from Southern Mexico and the Gulf of Mexico. Thunderstorms are beginning to develop in Sonora, Mexico, which will likely help create a shallow “gulf surge” tonight and tomorrow morning. As a result, expect dew points to rise significantly at times the next several days, especially during the morning hours. These will be accompanied by southeast breezes, haze, and more cloudiness.
Dew points in the low deserts will possibly rise into the 70-75 degree range tomorrow morning (and the next several days as well), perhaps even higher. This will shut down the efficiency of evaporative coolers/swamp coolers at times the next several days.
This pattern will bring a chance of thunderstorms, which are capable of producing heavy rain, excessive lightning, flash flooding, hail, strong winds, and blowing dust.
Rainfall chances will be highest in the nearby mountain ranges near Idyllwild and Big Bear, as well as the mountains from Morongo Valley to Joshua Tree.
It is impossible in a convective airmass to know exactly where storms will pop up, so just keep an eye on the sky from Monday through Saturday this week. As always, use common sense around normally dry washes that could be susceptible to flash flooding, especially along highway 62 in the Morongo/Yucca Valley/Joshua Tree/29 Palms corridor.
Be alert to any flash flood warnings issued by the National Weather Service.
Some drying of the airmass is possible around Friday or Saturday of next week, which may limit clouds and thunderstorms to the highest peaks of the nearby mountains.
COACHELLA VALLEY: High temperatures will likely remain in the 105-110 range most of the week, possible rising above 110 around Friday or Saturday if the airmass dries out as expected. Overnight lows will begin to settle into the 80s starting Monday night.
YUCCA VALLEY/JOSHUA TREE: High temperatures will be mostly in the 92-102 range this week, with overnight lows in the 68-78 range. Dew points are likely to be somewhat lower in these areas, mostly peaking in the 50s and 60s.
As always, stay hydrated and avoid excessive outdoor activities during the afternoon hours.