High pressure will intensify into the weekend and linger into next week. This will bring a long-duration heat wave for areas west of the mountains. Increased Santa Ana winds will also occur today through the weekend as well. The peak of the heat will be this weekend, but confidence is still low on how long the heat lasts into the end of next week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, UPDATED AVIATION DISCUSSION,
The thin marine layer gave it one last try this morning, with foggy conditions within 5 miles of the coastline. High pressure aloft will subtly strengthen into the weekend, causing the marine layer to thin even further with mainly clear skies going forward each night. Clockwise flow around the high pressure system to our northwest has allowed Santa Ana winds to move into the area. We have already gusted over 50 mph in some spots this morning across the San Diego County Mountains. Locally gusty conditions will continue this afternoon and overnight, before strengthening further late Saturday morning and afternoon. Model guidance shows a fairly good chance (60- 65%) chance of far inland valley locations like Ramona gust to 35 MPH. Since this wind will be mainly easterly, the strongest winds will once again be across the San Diego Co mts and inland valleys, as well as the Inland Empire. Winds become weaker by Sunday in these areas with gusts closer to 20-25 MPH. Gusty winds and lower relative humidity each day will lead to elevated to near-critical fire weather conditions, so make sure to do your part that leads to one less spark!
The main story will be the heat wave that is expected for areas west of the mountains. Much warmer weather is already occurring today with highs 10-15 degrees warmer than yesterday. The area of high pressure over the Desert Southwest will not move very much, with slight fluctuations in intensity. This, combined with increased Santa Ana winds on Saturday, will most make this day to be the hottest day of the event. Those within about 10 miles or more of the coast have a 60-90% chance of seeing triple digit heat on Saturday, similar chances on Sunday. Always a tricky forecast with an offshore winds pattern, where locations that do see an elevated east or northeast winds will be hotter than those who do not. The same will go for overnight temperatures as light offshore winds and a warm air mass will keep lower temperatures well into the 70s for areas west of the mountains. Other locations across the mountains and deserts will still see highs 5 to 10 degrees above normal.
The area of high pressure may weaken slightly by the first half of next week, but changes in temperatures will be rather minimal. Multiple days of the heat will lead to high heat risk west of the mountains, so make sure to be in areas of A/C and check on those without effective cooling. Models hint at the high becoming weaker by the end of next week, but just how weak it becomes is still uncertain. The forecast still has an outlook of temperatures above normal, but please keep up with the latest forecast for additional details.
022345z, Coast/western valleys: Mostly clear skies expected through the period. East winds with gusts up to 25 kts near Camp Pendleton and southern Orange County after 14z Sat, then weak onshore W/NW sea breeze prevails after 21z.
Inland Valleys/Foothills/Mountains: East winds over west-facing foothills, inland valleys and in parts of the Inland Empire, gusting to 30 kts, to diminish this evening, staying locally elevated overnight over the western slopes in the mountains. Stronger east winds expand back throughout inland areas after 15Z Saturday into the afternoon. MOD UDDFS with wind gusts 30-45 kts.
Otherwise, Clear skies through the TAF period.
No hazardous marine conditions are expected through Tuesday.
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.
Wind Advisory from 6 AM to 6 PM PDT Saturday for Orange County Inland Areas-Riverside County Mountains-San Bernardino and Riverside County Valleys-The Inland Empire-San Diego County Mountains-San Diego County Valleys-San Gorgonio Pass near Banning-Santa Ana Mountains and Foothills.
PZ, None.
