I almost missed your post there...here's a little information.
As the name would indicate, EFAS exists to provide you with "timely" weather information relative to the enroute portion of your flight. One briefer is designated with this job, and often is monitoring a vast area. It is also the central location for pilot reports which provide valuable information that the weather reporting devices can't always detect. It Available on 122.0, from 5,000 to 17,500, 6am to 10pm local time. Often if you are not in a mountainous area, this service is available at lower altitudes. This is certainly something to consider if you are flying in the mountains and your planning involves a weather update enroute.
How to contact them:
Just with any communication, the format who you are, where you are and what you want is appropriate. EFAS is named "flight watch", attach the name of the local ARTCC on the front. Your initial call will just be a courtesy call.
IE...Oakland Flight Watch, N1234W, over Scaggs Island VOR
Give your position relative to the nearest VOR. Remember one person is monitoring a vast area, this easily identifies your position. Be patient when waiting for a response, the briefer may be talking to another pilot.
IE..Oakland Flight Watch, N1234W, C172/G, over Scaggs Island VOR, 3,000 ft, en-route to Ukiah, request en-route advisories.
Confirm where you are, and tell them your altitude and where you are headed. These advisories are tailored specifically for your flight after climb-out to your descent to landing. The briefer will provide any information relative to that including destination weather. This service is not intended to open or close flight plans, getting a full wx briefing, position reports, or getting random wx information. You will need to contact the local FSS station as indicated on your chart.
Probably the most important aspect of EFAS, is us as pilots. Being that weather is so dynamic, it is those that are in the air that have the most accurate information. We can confirm weather reports/forecasts as well as report the unforecast conditions. Flight Watch urges pilots to report good as well as bad weather.
This is a great service that the FSS provides so don't hesitate to use it. As well, when you are up there make sure to put aside some time to contact them with a pilot report. The rest of us considering a flight or already in the air sure appreciate the information.
Let us know how it goes,