The atmosphere contains an enormous amount of moisture that circulates around the globe, shown here in this imagery. However, not all of the moisture actually condenses into rain, sleet or snow, since the right balance of pressure and temperature is needed to create precipitation. The NOAA Global Forecast System weather model is used to predict the total precipitable water content of the atmosphere - the amount of water that could theoretically precipitate if the atmospheric conditions were ideal. Visible in this data imagery are the bands of moisture that encircle the equator, along with the atmospheric rivers that transport moisture from these areas to higher latitudes. The model updates every six hours and provides forecasts for 10 days (240 hours) out from the start time, in three-hour time increments.
California to get clobbered with wet atmospheric river.