Warmer and drier Sunday through Tuesday with periods of moderate gusty Santa Ana winds. A low pressure system from the southwest will likely bring a return of precipitation for Wednesday through next weekend, though exact timing and precipitation amounts are still uncertain.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
Evening update, Cumulus that developed today has since cleared out. Surface pressure gradients have begun to trend offshore, and weak to locally moderate northeast winds are forecast to develop overnight, mainly below the wind prone passes and canyons where gusts will be around 35 mph. In the wind-sheltered valleys, patchy shallow fog may develop may develop once again. Winds have trended slightly stronger for Sunday night through Tuesday morning with peak gusts around 60 mph. Given this, a High Wind Watch was issued early this afternoon for the San Bernardino Mountains, Inland Empire, San Gorgonio Pass, Santa Ana Mountains, and San Diego County Mountains and Valleys. Wind advisories may be needed for additional areas should this forecast hold.
Previous discussion, Dry and warmer conditions are expected for Sunday through Tuesday as high pressure builds over the west coast and a positively- tilted trough extends to the southwest over SoCal with a closed upper low forming to our southwest. Offshore flow develops on Sunday and persists through Tuesday as a sfc high moves into the Great Basin. The offshore flow gets some upper level support on Mon and Tue with northeast winds aloft. The offshore flow will likely be strongest on Tuesday, producing gusty Santa Ana winds in the mtns and lower elevations west of the mtns. Northeast to east winds gusting 35-45 mph will be possible in the favored locations. Tuesday will also be the warmest day, with high temps in the 70s west of the mtns and most areas seeing temps near or above seasonal averages. Coastal and valley areas could be as much as 7 degrees above average while the mtns and deserts will be near or just a few degrees above.
Chances for rain and mountain snow will return for Wed through next Sat as a low pressure system moves in from the Gulf of Alaska, causing the closed low to our southwest to become an open wave as it is drawn into the mean westerly flow over the Southwest US. Forecast details are still uncertain due to differences in model solutions but it's likely that we will see periods of showers between Wed and next Sat. The timing is also in question but preliminary estimates are for totals of 1"-1.5" in the coastal areas and valleys, 1"-3" in the mtns, 0.3"-0.6" in the high deserts and 0.15"-0.30" in the low deserts. The snow level will remain above 8,000 ft through Friday before lowering to around 6,500 ft on Sat.
280600z, VFR condition are expected through the TAF period with FEW- SCT high cirrus AOA 25,000ft. North-northeasterly offshore winds pick up after 12z Sunday, gradually strengthening Sunday afternoon/evening. Wind gusts of 25-30kts expected for the coastal slopes of the mountains and mountain passes from 12-18z, spreading below mountain passes and into the inland valleys after 18z. While gusts may not surface at terminals like KONT or KSBD until late Sunday night or Monday, gusty northerly winds below Cajon pass could produce crosswinds on approach/takeoff within the Inland Empire Sunday afternoon. Gusts strengthen to 35-45 kts for the coastal mountain slopes and passes after 00z Monday with mod up/downdrafts expected. Strong offshore winds prevail into Monday evening.
No hazardous marine weather conditions expected through Friday.
Ca, High Wind Watch from Sunday evening through Tuesday afternoon for 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 Watch from late Sunday night through Tuesday afternoon for San Diego County Mountains-San Diego County Valleys.
PZ, None.
