score:11
The road.is site provides a list of road and weather condition definitions.
"No passage" means that it is literally forbidden to drive there. Even if you have a truck that can, otherwise, deal with conditions. This may include roads that are closed for non-weather related issues.
"Impassable" however means that a road is closed due to weather (snow typically).
The map you cite has current conditions. Roads may be closed at any time if there is bad weather. Main roads are usually cleared within hours or (at worst) days. Again, it depends on the weather.
However, mountain tracks (any road whose designation starts with an 'F') tend to only be cleared in the spring. Most of the roads currently (November) marked impassible, will likely remain impassible until spring. Some may not open until next June.