The cooling trend will continue today with gusty southwest winds for the mountains and deserts this afternoon and evening with gusts to 35 mph. A Pacific storm will bring increasing chances for showers beginning tonight with precipitation becoming heavy at times for late Friday afternoon through Saturday with the most widespread and heaviest rainfall expected late Friday night and Saturday. There is also a chance of thunderstorms for Friday night into Saturday evening. More widespread south to southeast winds for Saturday mourning will gust to 35 mph. Scattered showers will continue into Sunday. Additional showers are likely at times next week, but with much lower confidence in the details.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
(today through Saturday), A low pressure system centered well off the northern California coasat will move slowly toward the east and southeast today and Friday with the storm centered to the southwest of Point Conception early Saturday morning. It will move slowly toward the east on Saturday, then toward the east and northeast for Saturday night and Sunday with growing model differences in the placement of the center.
High temperatures will continue to cool today. There will be greater cooling of high temperatures on Friday with high temperatures as much as 5 to 10 degrees below average for the mountains, valleys, and inland Orange County. High temperatures on Friday will be mostly in the mid 60s to lower 70s for the coast and valleys and around 80 for the lower deserts. There will be additional cooling on Saturday with the greatest cooling for the lower deserts. High temperatures on Saturday will be mostly in the 60s for the coast and valleys and around 70 for the lower deserts.
For today and Friday, there will be periods of gusty southwest winds for the mountains and deserts with gusts to 35 mph. More widespread southeast winds are expected on Saturday morning with gusts to 35 mph.
Please see the hydrology section below for additional information on rainfall through Sunday and related impacts.
(Sunday through Wednesday), Scattered showers will continue into Sunday with additional showers likely at times next week, but with much lower confidence in the details. Those systems are not expected to be as warm with snow levels falling to around 6000 feet at times.
A Pacific storm with a moisture feed from an atmospheric river will bring increasing chances for showers beginning tonight with precipitation becoming heavy at times for late Friday afternoon through Saturday with the most widespread and heaviest rainfall expected late Friday night and Saturday. There is also a chance of thunderstorms for Friday night into Saturday evening. Scattered showers will continue into Sunday. There will be additional chances for showers for much of next week, but with much lower confidence in the details.
Through Sunday, rainfall for Orange and southwestern San Bernardino Counties is expected to range from around 3 inches near the coast to 4 to 6 inches for the mountains, locally exceeding 7 inches on the south facing coastal slopes. For San Diego County, rainfall is expected to range from around 2.5 inches near the coast to 3 to 4 inches for mountains with locally greater amounts. For the high desert, 1.5 to 2.5 inches of rainfall is expected with 1 to 1.5 inch for the lower deserts.
These rainfall amounts along with the potential for periods of higher intensity rainfall for late Friday night through Saturday could produce debris flows in burn areas, significant ponding of water on roads and highways, and urban and small stream flooding. The current forecast for the San Diego River has the river at Fashion Valley rising to near monitor stage at 4 PM on Saturday, sufficient to flood low-water crossings.
Snow levels above 10000 feet will lower to around 8000 feet for late Saturday and 7000 to 7500 feet on Sunday. There could be 3 to 6 inches of snowfall for Saturday night and Sunday, mostly above 7500 feet.
131030z, Coasts/Western Valleys, SCT low clouds, BKN locally and intermittently at 800-1200 feet MSL, will continue through 16Z. Cigs and vis 3-5SM most likely 12-16Z. Low clouds will again struggle to form after 04Z tonight into Friday, with local and intermittent cigs around 1500 feet MSL. Increasing chances of -RA early Friday.
Otherwise, VFR conditions will continue today and tonight. Middle and high clouds at 5-15 kft will gradually increase.
A storm system will approach Friday and move through Saturday and Sunday, boosting southerly winds and seas. Occasional heavy rain Saturday could reduce visibility. There is a slight chance of thunderstorms Friday night through Saturday night.
Ca, None. PZ, None.
