The tropical air mass of former Hurricane Marie that has brought this hot humid heat wave to the area this week will transition over the weekend with a trough of low pressure bringing drier southwest flow aloft and onshore lower level flow. High temperatures will not be quite as hot today for the coast into the western valleys with the cooling then spreading inland for Friday through Sunday with not much change for early next week. There is still a slight chance of showers and thunderstorms for the mountains for this afternoon.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, UPDATED AVIATION DISCUSSION,
(today through Saturday), It was a very warm start on Wednesday with low temperatures for coast and valleys mostly in the 70s to mid 80s. High temperatures on Wednesday of 105 to 110 were widespread for inland coastal areas into the western valleys. There was less coverage of thunderstorms on Wednesday with the strongest recorded thunderstorms wind gust to 50 mph at Pauma Creek in the Pauma Valley in San Diego County at 1:40 PM.
As of 3 AM early this morning, temperatures are still in the very warm 70s to mid 80s for the coast and valleys, but are a few to around 5 degrees cooler than 24 hours ago for coastal areas into the western valleys. High temperatures will not be quite as hot for coastal areas into the western valleys today, but still with areas of Major to Extreme HeatRisk for inland coastal areas into the western valleys. High temperatures for today will range from 80s at the beaches to the upper 90s to 108 for the Inland Empire with the lower deserts 110 to 114. High temperatures for the mountains and deserts will be a few degrees warmer than Wednesday.
Cooling will spread inland across all of southwestern California on Friday with the cooling continuing through the weekend. By Saturday, moderate or greater HeatRisk will be mostly confined to the lower deserts. High temperatures on Saturday will range from the mid 70s to lower 80s near the coast to the upper 80s to mid 90s for the Inland Empire with 104 to 108 for the lower deserts. Low temperatures early Saturday morning will be mostly in the 60s and lower 70s for the coast and valleys.
(Sunday through Wednesday), A low pressure system moving inland through the western states will maintain drier southwest flow aloft. High temperatures on Sunday will be as much as 4 to 8 degrees below average for the Inland Empire. High temperatures on Sunday will range from the mid to upper 70s near the coast to the mid to upper 80s for the Inland Empire with 100 to 104 for the lower deserts. Low temperatures will be mostly in the 50s for the inland valleys with the coast into the western valley in the 60s. Patchy night and morning coastal low clouds will spread into the far western valleys at times.
101130z, VFR conditions expected across the region through this evening, with SCT-BKN clouds between 10-20 kft. ISO SHRA/TSRA over mountains 19-00Z, with CB clouds based 8-12 kft MSL and tops rising to 30 kft. Localized gusty winds and heavy rain in and near any TSRA. Areas of coastal low clouds and fog will gradually increase after 07Z Friday, with cigs most likely 11-16Z Friday in vcnty KSAN. Bases would be around 800-1000 feet MSL, with vis 3-5SM over higher coastal terrain.
No hazardous marine conditions are expected through Monday.
Ca, Extreme Heat Warning until 8 PM PDT 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.
Heat Advisory until 8 PM PDT this evening for Riverside County Mountains-San Diego County Mountains.
Extreme Heat Warning until 8 PM PDT Friday for Coachella Valley- San Diego County Deserts-San Gorgonio Pass near Banning.
PZ, None.
