Significantly cooler today as a low pressure system moves inland to the north. This system will also bring stronger and gusty west winds through this evening in the mountains and deserts. Gusts of 35 to 45 mph are likely in the wind-prone areas. Dry conditions will likely continue throughout the rest of the week, but then there could be a slight chance of precipitation later this weekend into next week.
For extreme southwestern California including Orange, San Diego, western Riverside and southwestern San Bernardino counties,
A low pressure system moving inland to our north has brought a return of onshore flow and marine layer low clouds/fog to the coastal areas and valleys. The strengthening onshore flow is producing gusty westerly winds, mainly in the mountain passes and on adjacent desert slopes. Wind gusts of 35-45 mph are expected through this evening in the wind-favored locations before the winds weaken on Tuesday. Today will be significantly cooler than recent days, with high temperatures in the 60s to low 70s in the coastal areas and high deserts, the 70s in the inland valleys, the 50s to 60s in the mountains and the 80s to near 90 in the low deserts. These temperatures are still near or a little above seasonal averages, especially in the low deserts where it could be as much as 10-13 degrees above seasonal averages.
Numerical model solutions remain in good agreement through Thursday with respect to the synoptic pattern. As the low pressure system moves into the Rockies and a weak transient ridge of high pressure moves over SoCal, temperatures will rebound somewhat on Tue and Wed, mainly in the inland valleys where high temperatures will reach the upper 70s. Continuing onshore flow will maintain a marine layer presence, with low clouds and fog in the coastal areas and inland valleys during the nights and mornings.
Another low pressure system moving inland to our north on Thursday will bring another brief round of gusty west winds to the mtns and deserts, mainly on Thursday. It will also bring a deepening of the marine layer, possibly enough to produce patchy drizzle west of the mtns Thursday morning. Temperatures will dip again for Thursday and Friday, returning to near seasonal averages and even a little below seasonal averages in portions of the mtns and high deserts.
Beyond Friday, numerical model solutions diverge significantly but the medium-range deterministic models are all in agreement with the upper trough deepening to the southwest, forming a closed upper low near or a little south of SoCal by Saturday. A majority of ensemble members now show a similar solution so forecast confidence is improving. This pattern is likely to bring a warming trend as offshore flow develops, with northeast flow aloft.
030540z. Coast, Patchy low clouds have moved in over southern portions of the San Diego county coast. Patchy low clouds with bases around 1,000-3,000 ft MSL will continue to develop at the coast and in portions of the valleys into the early morning hours. Vis restrictions of 1-3SM in BR on higher terrain. Low clouds will clear 17-19Z. Patchy low clouds will redevelop after 06Z Wednesday with bases expected 500-1500 ft MSL.
Otherwise, VFR with predominantly clear skies. Areas of gusty northwest winds 25-35 knots in the mountains and deserts through 08Z. Mod up/downdrafts in lee of ridges. Locally reduced vis in BLDU in deserts.
Gusty northwest winds are beginning to ease and will continue to decrease overnight. Northwest winds may increase again Wednesday afternoon/evening into Thursday. Winds in the outer waters will start to increase Wednesday, spreading closer to the coast by Thursday afternoon. Peak wind gusts of 20-25 kt expected.
Ca, None. PZ, None.
