Tuesday evening forecast – Sep 7
High pressure will keep very warm temperatures over the area through the week and likely through the weekend. The marine layer will remain shallow with night through morning low clouds likely remaining over coastal areas. There will be a slight chance of monsoonal thunderstorms over the eastern mountains and desert on Thursday.
The trends over the next few days will generally be warming with increasing moisture aloft. Models have been consistent showing weakening onshore flow through about Friday so most areas will see a degree or two of warm up each of the next couple days, then not much change after that. Still overall a warm week with highs 5-15 degrees above normal, the biggest anomalies being in the mountains and interior areas. A heat advisory is in place for the mountains and interior valleys through Friday at 8PM as temperatures climb into the triple digits.
The increasing monsoon moisture along with additional instability will raise thunderstorm chances each of the next couple days in the eastern mountains, Thursday being the highest, though still overall pretty small. It will also increase humidities and afternoon cloud cover, helping to lower the ambient air temperatures there but adding to the stickiness factor.
Once the high pressure ridge shifts back into the rockies later Friday there will be minimal changes to the weather into early next week. Highs will remain 5-10 degrees above normal overall and the marine layer should remain confined mainly to coastal areas. Monsoon moisture is expected to decrease over the weekend eliminating any potential for interior thunderstorms. Perhaps a more significant impact could be a possible increase in southerly swells at some point from the next tropical system that is rapidly developing just off the coast of Mexico.
