Knowing the visibility for a flight in advance
 

Does anybody have any recommendation for the visibility forecast and ways how to decide on picking a day with as much less haze as possible? Are there any specialized forecasts one can consult? How do the pilots know?

For the UK the Met office issue a MesoScale for visibility covering the whole country. Very useful -

Met Office: Online services - customer login

Not sure the USA equivalent though.

It will depend on where the air is coming from as well as temperature and humidity. If you have light winds and high pressure you will usually have poor visibility, especially if there is a lot of industrial and traffic pollution (I expect that is often the case in LA). Winds from the sea are usually cleaner than from the land.

Often the best visibility is just after a cold front has passed through - stronger winds and lots of rain to clear the haze.

High humidity is bad for visibility as more water vapour is held in the air.

In the U.S., Try This
 

"With as much less haze".............?

For goodness sake - are you a pilot or what - interpret the met charts and you'll see when the haze is coming or clearing :ugh::ugh:

Calm down TC.
Possibly an "or what".

While forecasts can be useful, they are often wrong. The weather at any given point will be what you see out the window. :)