High pressure will strengthen this weekend and linger into next week. This will bring a heat wave lasting several days for areas west of the mountains. Gusty Santa Ana winds will continue through the weekend as well before weakening on Monday. The peak of the heat will be this weekend, but daytime high temperatures 10 to 15 degrees above normal will likely continue through the middle of next week for areas west of the mountains.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
, UPDATED AVIATION DISCUSSION,
This morning, Temperatures are generally higher than at this time yesterday with some inland valley locations as much as 10 to 15 degrees higher. Several locations broke or tied the maximum temperature records for Oct 2nd. See our Record Event Report. Skies are clear but overnight low temperatures will likely remain above normal west of the mtns due to the gusty offshore winds and humidities in the 30-40 percent range.
High pressure aloft and moderate to locally strong offshore flow will cause the heat to peak this weekend, with daytime high temperatures 15-25 degrees above normal for the inland valleys and coastal areas. Daytime high temperatures will reach the upper 90s to low triple-digits within a mile or two of the beaches in spite of there being a weak sea breeze. The high pressure aloft will keep the marine layer very shallow and the offshore flow will keep any low clouds or fog from moving onshore.
The offshore flow weakens on Monday and we could see some minor relief at the immediate coast by Tuesday. The lower temperatures will slowly spread inland through the middle of next week but the high pressure aloft will persist. As a result, daytime high temperatures will remain in the upper 90s to low triple-digits for the inland valleys through next Thursday. A return of marine layer low clouds/fog to the coastal areas seems unlikely before Wed night/Thu morning.
Beyond next Thursday, Forecast details remain quite uncertain, however a slim majority of ensemble members across model platforms shows the high pressure ridge weakening in response to a trough of low pressure approaching from the northwest. The forecast reflects this with a trend toward noticeably lower temperatures beginning next Friday, although high temperatures on Friday will still be as much a 15 degrees above normal in the western portions of the inland valleys.
030940z, 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 12Z, then weak onshore W/NW sea breeze prevails after 19Z. Local areas of low lvl wind shear possible (mostly between 12-18Z) with easterly winds 10-20 kt above ~1500 ft MSL.
Inland Valleys/Foothills/Mountains: East winds over west-facing foothills, inland valleys and in parts of the Inland Empire will be locally elevated this morning over the western slopes in the mountains. Stronger east winds expand to return throughout inland areas after 15Z into the afternoon. MOD UDDFS with wind gusts 30-45 kts. East winds become more isolated again after 01Z Sun.
Otherwise, Clear skies through the TAF period.
No hazardous marine conditions are expected through Wednesday.
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 this morning to 6 PM PDT this evening 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.
