The National Weather Service forecast for Los Angeles currently includes this paragraph in the long-range forecast. "Long-range" in this case is from next Sunday to next Wednesday. They're talking about a ridge of high pressure that will be keeping us dry through the weekend…
The ridge pushes back westward over the east Pacific Sunday as a weak inside slider moves through Nevada, at the same time a weak retrograding cut off low rumbles through northern Mexico just to the south of California. The upper low may spin some high clouds over L.A. County Sunday and Monday so partly cloudy skies are likely there. Skies should clear by Tuesday and then remain clear. Maximum temperatures will cool each day Sunday through Tuesday as heights slowly fall and offshore flow slowly relaxes. A return to ridging Wednesday (remember 4 days ago when the models showed a large rain storm for this time period? This morning's lesson…never trust a day 9 forecast) along with offshore flow will kick off a warming trend.
I'll translate: The ridge will leave us on Sunday but any storms will miss us, though we may get some high (and therefore, rainless) clouds Sunday and Monday. By Wednesday, another ridge of high pressure should build in, keeping us dry.
A few days ago, the nine-day forecast had a different and wet scenario and the meteorologist who wrote this forecast is reminding us how unreliable a forecast that far ahead can be. Back when I was involved with that industry/science (that's a long story), I spoke to guys at the N.W.S. who were not happy that they were expected to always issue a ten-day forecast. Sometimes, they could predict with great confidence. Other times, they could not but it was still demanded of them, to some extent for competitive reasons. Almost all the commercial weather services offer 15-day and even 30-day forecasts that almost never have any value…but people still pay for them.
I often quote the great journalist Jack Germond who said, "The trouble with the news business is that we're not paid to say 'I don't know' even when we don't know." That applies to the weatherfolks, as well.