Monday evening weather forecast – Sep 20
Significant warming will continue through Wednesday due to weak offshore winds with hottest conditions across the inland valleys. Winds will turn back onshore for most areas by Thursday as a weak low pressure area drops into California. There will be a slight chance of showers by Friday and Saturday.
Monday is a smoky day with temperatures running 4-12 degrees warmer than yesterday depending on the amount of northeast winds.
The main impact from this weak Santa Ana will be continued heating into the valleys Tuesday. Low clouds have been hanging over the coastal waters west of the Channel Islands and expect they will hug the coastline late Monday night for most of the South Coast and start to push around the corner along the Central Coast by morning. Skies could remain somewhat smoky until Wednesday morning. Weak offshore flow remains in place through early Wednesday.
Temperature trends remain every bit as warm and perhaps warmer in a few locations still experiencing mild overnight temperatures due to the downsloping winds. Coastal areas will likely experience a stronger afternoon seabreeze as the pressure gradients begin to transition to onshore. This will likely result in a deeper marine layer for Thursday morning along with a cooling trend for the entire region as heights drop. Low pressure will be rapidly dropping southward through Nevada on Thursday with the air mass becoming unstable over the southern Sierra Nevada mountains in the afternoon. Some debris clouds could push into our area Thursday night if/when any thunderstorm activity falls apart as winds aloft carry leftover moisture to the south.
Low pressure drops into central California late Thursday, then moves out south of the channel islands on Friday. This will rapidly cool us down and brings a slight chance of thunderstorms.
