Moisture from the remnants of Tropical Storm Juliette will bring more clouds and cooler high temperatures today with greater chances for showers to the south with lesser chances to the north. There is also a slight chance of thunderstorms for this afternoon. There will be drying and warming for Friday through Sunday. Monsoonal moisture may begin to return for next week with the greater chances for afternoon thunderstorms for Tuesday through Thursday.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
(today through Saturday), Moisture from the remnants of Tropical Storm Juliette will bring more clouds and cooler high temperatures today with the greater chances for measurable rainfall to the south and less toward the north. The depth of the saturated layer with mid and high clouds extends down to around 10 thousand feet. This may eventually extend down to around 5000 feet as rain falling from mid level cloud bases gradually saturates the drier layer below.
As the saturated layer gradually lowers, light to locally moderate rainfall could develop this morning with the greatest coverage over Riverside and San Diego Counties and more isolated showers northward. Higher resolution guidance shows rainfall rates mostly 0.10 inch per hour or less, though as the remnant upper low moves northward into the area today, there could be enough lift and weak elevated instability to produce local rainfall rates of 0.25 to 0.5 inch per hour. There is a slight chance of thunderstorms for this afternoon. If there are enough breaks in the overcast, thunderstorms capable of producing isolated flash flooding could occur over the Riverside County mountains and San Bernardino Mountains.
It will be cooler today with high temperatures 10 to 15 degrees below average for the mountains and deserts with high temperatures ranging from the mid 70s to lower 80s near the coast to the 80s to around 90 for the Inland Empire with high temperatures mostly in the lower 90s for the lower deserts.
There will be drying and warming for Friday through the weekend with Saturday high temperatures a few degrees below average, ranging from the mid 70s lower 80s near the coast to the 90s for the Inland Empire with 104 to 108 for the lower deserts.
(Sunday through Wednesday), Drying and warming will continue into Sunday with Sunday high temperatures within a few degrees of average for most areas. High temperatures on Sunday will range from the mid 70s to lower 80s near the coast to the 90s to around 100 for the Inland Empire with 106 to 110 for the lower deserts.
Monsoonal moisture may begin to increase for the early and middle part of next week with south to southeast flow aloft between a weak low pressure system near the California coast and high pressure to the east. Chances for afternoon and early evening showers and thunderstorms for the mountains and deserts will increase to 20 to 30 percent for Tuesday through Thursday.
280940z, Considerable clouds at or above 10000 feet MSL will continue today and decrease early Friday. There could be a patch or two of coastal low clouds based around 1000 feet MSL. Chances of -RA increase this morning, peak this afternoon, and fade this evening. There is also a slight chance of TSRA 19-00Z, with gusty winds near any storm. Rain and tstorm chances are greatest in southern and eastern parts of the region. Clouds will eventually thin and scatter Friday morning.
There is a slight chance of thunderstorms this afternoon. Any thunderstorm could produce gusty, erratic winds leading to locally rough seas, along with lightning and hail. Otherwise, no hazardous marine conditions are expected through Monday.
Ca, None. PZ, None.
