The long-duration heatwave will continue for the coast and valleys through Thursday and through Friday for the lower deserts. Cooling will spread inland for Friday and Saturday, but high temperatures will remain around 5 degrees above average on Saturday. A low pressure system from the southwest on Sunday and north on Monday and Tuesday combined with tropical moisture will bring showers for late Saturday night through Sunday night with continuing chances for showers through Tuesday night.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, UPDATED AVIATION DISCUSSION,
(today through Friday), The long-duration heatwave will continue for the coast and valleys through Thursday and through Friday for the lower deserts. Inland areas will warm a few degrees today while the coast into the western San Diego County valleys cools a few degrees. There will be Moderate HeatRisk for the beaches and far inland valleys today with Major to locally Extreme HeatRisk for the rest of the coast and valleys. There will also be areas of Major HeatRisk in the lower deserts today.
Cooling at the beaches will begin to spread inland on Thursday with Moderate to locally Major HeatRisk for the coast and valleys with Major HeatRisk for the lower deserts. High temperatures on Friday will cool a few to around 5 degrees with high temperatures around 10 degrees above average. High temperatures will range from the upper 70s to mid 80s near the coast to the 90s for the Inland Empire with 102 to 106 for the lower deserts.
There could be some patchy low clouds and dense fog near the southern San Diego County coast early this morning with low clouds and locally dense fog over the coastal waters spreading locally inland along the coast for late tonight into Thursday morning with a little farther inland spread of the low clouds into coastal areas for late Thursday night into Friday morning as the marine layer slowly deepens.
(Saturday through Tuesday), The cooling trend will continue through Tuesday with high temperatures on Tuesday as much as 10 to 15 degrees below average for the mountains, deserts, and inland valleys. High temperatures for next Tuesday will be mostly in the 70s for the coast and valleys with the lower deserts in the lower to mid 80s.
A closed low pressure system will develop off the California coast on Thursday. This low pressure system will move toward the southeast and absorb the moisture from former Hurricane Rachel, then move northeastward into southern California and northern Baja bringing showers for late Saturday night through Sunday with another closed low pressure system from the north continuing chances for showers for Monday and Tuesday.
NBM chances for 0.10 inch or more of rainfall through Sunday night are 45 to 55 percent with chances for 0.50 inch or more ranging from 30 percent near the coast to 40 percent for the mountains. Chances for 1 inch or more of rainfall range from 15 percent near the coast to 25 to 35 percent for the mountains.
Through Tuesday night, NBM chances for 0.25 inch or more of rainfall ranges from 50 percent near the coast to 55 to 65 percent in the mountains. Chances for 1 inch or more of rainfall ranges from around 25 percent near the coast to 35 to locally 45 percent in the mountains. Chances for 2 inches or more of rainfall ranges from around 5 percent near the coast to 10 to 15 percent for the mountains. There could be a few inches of snowfall on the very highest mountain peaks above 9000 feet for Monday night and Tuesday as snow levels lower to 8000 to 8500 feet.
Onshore winds will strengthen for Sunday and Monday with southwest to west winds for Sunday afternoon through Monday morning gusting to 20 to 30 mph for the coastal waters to the valleys and to 35 to 45 mph for the mountains and deserts with gusts to 55 to 65 mph for the northern Coachella Valley below the San Gorgonio Pass.
071130z, Coast: Isolated and intermittent patches of low clouds and fog through 16Z. Any cigs would be around 500 feet MSL with vis 1- 5SM. Greater coverage of low clouds and fog more likely after 10Z Thursday. Bases would be 400-600 feet MSL and vis 1-6SM.
Otherwise, clear skies except for cumulus based around 10 kft over mountains 19-01Z.
No hazardous marine conditions are expected through Sunday. Stronger westerly winds develop late Sunday.
Increasing south swells will create surf of 3-5 feet with sets to 6 feet on south and southwest facing beaches through Friday, creating hazardous swimming conditions for inexperienced swimmers. This elevated surf will combine with high tides during the mornings and evenings to generate local coastal flooding and beach erosion. The Beach Hazards Statement and Coastal Flood Advisory contain the details.
Ca, Extreme Heat Warning until 8 PM PDT Thursday 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.
Beach Hazards Statement through Friday evening for Orange County Coastal Areas-San Diego County Coastal Areas.
Coastal Flood Advisory until 11 AM PDT Friday for Orange County Coastal Areas-San Diego County Coastal Areas.
Extreme Heat Warning from 10 AM this morning to 8 PM PDT Friday for Coachella Valley-San Diego County Deserts-San Gorgonio Pass near Banning.
PZ, None.
