Return a callable function for computing nowcasts blending into an NWP forecast.
the linear blending of a nowcast method with other data (e.g. NWP data).
the salient blending of a nowcast method with other data (e.g. NWP data) described in [HCLK15]. The blending is based on intensities and forecast times. The blended product preserves pixel intensities with time if they are strong enough based on their ranked salience.