Heavy rain will move southward across the area today along with a slight chance of thunderstorms. The heavy rain will decrease from the northwest this evening with scattered showers continuing through Christmas Day. Another round of more widespread showers is expected for Thursday night and Friday. Gusty south winds will continue through this evening with gusts to 40 mph near the coast and to 55 to 75 mph along the desert slopes of the San Bernardino County mountains. Snow levels above 9000 feet this morning will fall to around 6500 to 7500 feet on Thursday and Thursday night, then fall to around 5500 feet for the weekend. Chances for showers will decrease for the weekend, then may increase again around Wednesday and Thursday of next week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Key Points:
* Widespread moderate to heavy rainfall today into this evening with the potential for roadway flooding and localized flash flooding from the coast to deserts. Rapid rises in small streams and increased flow in main stem rivers expected.
* There is a High Risk for flash flooding through this evening for for the San Bernardino County mountains and adjacent foothill areas of the Inland Empire, flash flooding that could result in damaging and potentially life-threatening flash flooding, mud slides, and debris flows.
* Gusty south winds will strengthen this morning and continue into the evening with gusts to 45 mph near the coast and to 55 to 75 mph along and below the desert slopes of the San Bernardino County mountains. Make sure to secure outdoor furniture. Tree damage is possible.
* Scattered showers will continue on Christmas Day with another round of more widespread showers some time during Thursday night and Friday. Snow levels will lower to around 7000 feet for Thursday into Thursday evening, then lower to around 6000-6500 feet by late Friday creating slick conditions on mountain highways.
* There is the potential for another storm system around New Year's Eve and New Year's Day, but confidence is extremely low with regards to timing.
(today through Friday), Movement of the heavier and widespread rainfall toward southwestern California has slowed overnight. However, the heavier rainfall will begin to spread into Orange and southwestern San Bernardino Counties around dawn, then move slowly east and south during the day, then move more quickly eastward during the evening. A Flood Watch continues for all of southwestern California today with the highest risk for flash flooding for the San Bernardino County mountains and adjacent foothill areas of the Inland Empire.
A High Wind Warning continues for the San Bernardino County mountains and adjacent high desert into Thursday afternoon. The strongest winds are expected through this afternoon along and near the desert slopes of the mountains. The strongest gust overnight has been 91 mph at Burns Canyon on the northeast slopes of the San Bernardino Mountains. That gust occurred around 11 PM Tuesday. Winds will strengthen along the coast this morning with gusts to around 45 mph near the coast from late morning through the afternoon.
Scattered showers will continue through Christmas Day with additional rainfall mostly one-quarter inch or less, though locally one-half to one inch on the coastal slopes to the west of the Cajon Pass.
Another round of more widespread showers is expected to move southward across the area for Thursday night and Friday, though with some differences in timing and amounts.
(Saturday through Tuesday), Chances for showers will decrease over the weekend and be lowest on Sunday with the chance for measurable precipiation on Sunday around 10 to 15 percent.
A cutoff low pressure system may develop well to the southwest of the area by early next week, possibly moving toward the area during the middle and latter part of next week. That would increase chances for precipitation to spread into the area from the south around Wednesday and Thursday of next week, New Year's Eve and New Year's Day.
A High Risk for flash flooding continues for the San Bernardino County mountains and adjacent foothill areas of the Inland Empire from 4 AM today to 4 AM Thursday with the greatest risk through through early evening with a greater risk for damaging and potentially life-threatening flash flooding. A Moderate Risk for flash flooding extends southward from the High Risk area into far northern San Diego County.
More widespread and heavier rainfall will begin to spread into Orange and southwestern San Bernardino Counties around 6 AM, then move slowly east and south during the day, then move more quickly eastward during the evening.
For Orange and southwestern San Bernardino Counties through tonight, rainfall will range from 1.5 to 2.5 inches near the coast to 6 to 8 inches in the mountains with local amounts exceeding 10 inches in the eastern San Gabriel Mountains. Amounts will decrease from north to south with amounts across far southern San Diego County ranging from around one inch near the coast to 1.5 to 2 inches in the mountains. For the high desert, 1.5 to 2.5 inches is expected with as much as 3 to 5 inches in the desert foothill areas below Wrightwood. For the lower deserts, one-quarter to one- half inch is expected.
The highest rainfall rates today are expected on the coastal slopes of the San Bernardino County mountains today. For the eastern San Gabriel Mountains, rainfall rates to one-half inch per hour are expected to begin by dawn with several hours of rainfall rates around 1 inch per hour between 8 AM and 4 PM with rainfall rates to around one-half inch per hour continuing until early this evening. For the San Bernardino Mountains, rainfall rates of around one-half inch per hour will begin by late morning and continue through the afternoon, locally to around one inch per hour during the afternoon.
Scattered showers will continue through Christmas Day with additional rainfall mostly one-quarter inch or less, though locally one-half to one inch on the coastal slopes to the west of the Cajon Pass.
Another round of more widespread showers is expected to move southward across the area for Thursday night and Friday, though with some differences in timing and amounts. For Orange and southwestern San Bernardino Counties for Thursday night and Friday, rainfall could range from 0.5 to 1 inch near the coast to 1.5 to 2.5 inches in the mountains with locally greater amounts. Amounts will decrease from north to south with amounts across far southern San Diego County around one-third inch. For the high desert, 0.25 to 0.50 inch is expected with one-tenth inch or less for the lower deserts.
The snow level will rise above 9000 feet early this morning, fall to around 6500 to 7000 feet for late tonight through Thursday, rise to around 7500 feet for late Thursday night, then fall to around 5000 feet for the weekend.
231000z, BKN-OVC regionwide with several cloud layers based 2000- 5000 ft MSL. Sct -SHRA moving northeast across the region, bringing local bases 2000-3000 ft MSL and vis 3-6 SM. South to southeast winds strengthen this morning, with frequent gusts 20-35 kt for coastal/valley sites and 40-55 kt over the mtns into parts of the high desert through today. Mod to strong up/downdrafts over and near higher terrain.
The main band of precipitation moves into northeast Orange Co/Inland Empire after 17Z or so, then northeast San Diego Co after 20Z. This will bring moderate to heavy precipitation with vis reductions 1-3 SM and cigs locally as low as 500-700 ft MSL. Embedded thunderstorms with lightning, heavy rain, and erratic winds are also possible through the region today. Widespread precipitation will give way to sct SHRA after about 06Z, and winds will gradually decrease. Cigs will continue to vary freq through the period with a variety of cloud layers 1000-5000 ft.
Winds will continue to increase this morning to gale force, with wind gusts upwards of 35 kts. This will bring steep combined seas of 6-9 feet. Periods of moderate to heavy rain today will lead to areas of poor visibility and thunderstorms will be possible over the open waters. Some of these may contain small hail, gusty winds, and a waterspout or two will be possible. Winds diminish slightly late today, but winds and seas will remain hazardous to small craft through early Thursday morning.
South to southwest winds strengthen slightly again late Thursday into early Friday, with gusts possibly exceeding 20 kts. Winds then turn northwest and gradually decrease late Friday into Saturday.
Strengthening south winds today will lead to elevated surf 5 to 8 feet with sets to 9 feet, highest for south-facing beaches. This will lead to hazardous swimming conditions. Minor tidal overflow for south-facing beaches is also possible from a combination of winds and elevated surf today, especially during high tide this morning. Additionally, there is a slight chance for thunderstorms, which would bring dangerous lightning.
Winds diminish along with surf late today, but more breezy winds along with large fresh swell will lead to surf building again Friday- Saturday, especially for west-facing beaches. A Surf Advisory is in effect from tonight to Saturday afternoon.
Ca, High Surf Advisory until 11 AM PST Saturday for Orange County Coastal Areas-San Diego County Coastal Areas.
Wind Advisory until 10 PM PST this evening for Orange County Coastal Areas-Orange County Inland Areas-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Coastal Areas-San Diego County Valleys-Santa Ana Mountains and Foothills.
Flood Watch through late tonight for San Diego County Coastal Areas-San Diego County Deserts-San Diego County Mountains- San Diego County Valleys.
Flood Watch through this evening for Apple and Lucerne Valleys- Coachella Valley-Orange County Coastal Areas-Orange County Inland Areas-Riverside County Mountains-San Bernardino County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire-San Gorgonio Pass near Banning- Santa Ana Mountains and Foothills.
High Wind Warning until 3 PM PST Thursday for Apple and Lucerne Valleys-San Bernardino County Mountains.
PZ, Gale Warning until 4 PM PST this afternoon for Coastal Waters from San Mateo Point to the Mexican Border and out to 10 nm- Waters from San Mateo Point to the Mexican Border Extending 10 to 60 nm out including San Clemente Island.
Small Craft Advisory from 4 PM this afternoon to 4 AM PST Thursday for Coastal Waters from San Mateo Point to the Mexican Border and out to 10 nm-Waters from San Mateo Point to the Mexican Border Extending 10 to 60 nm out including San Clemente Island.
