Does the NAO have only affect Eastern US weather?

Answer 1

Good question. I looked up a couple maps to show the temperature and precipitation effects of the NAO. It seems it can effect the western US as well.

Temp: http://www.cpc.noaa.gov/data/teledoc/nao_tmap.shtml
Precip: http://www.cpc.noaa.gov/data/teledoc/nao_pmap.shtml

Answer 2

The answer is both yes and no. What the North Atlantic Oscillation does is either block low pressure systems or allow an easy exit for low pressure systems out of the eastern United States. So what the NAO really is reporting is whether or not you have a blocking high out in the Atlantic. But the NAO is itself a grouping of weather systems which themselves produce weather, effecting Greenland, Iceland, and possibly even Great Britain.

Here's the short of it:

Reporting the NAO is for the benefit of forecasting in the eastern United States and Canada, but the components of the NAO produce weather themselves.

Answer 3

Yeah. When the NAO is negative, air from canada is rushed down into the united states and if your within that negative NAO, your tempertures will be much colder then when the NAO was positive. If the NAO is positive, that means the temperatures are pleasant. An example of that is the Northeast (NY,DE,NJ,MA) experience a warm spell in the winter which means their NAO was possible (cold air gets trapped from a certain location)

Answer 4

This is a very good question and of course is related to other similar phenomeno as the ENSO.The NAO is the dominant mode of winter climate variability in the North Atlantic region ranging from central North America to Europe and much into Northern Asia. The NAO is a large scale "seesaw" in atmospheric mass between the subtropical high of mid latititudes and the polar low. The corresponding index, either positive or negative, varies from year to year, but also exhibits a tendency to remain in one phase for intervals lasting several years.

For example, the Positive NAO index phase shows a stronger than usual subtropical high pressure center and a deeper than normal Icelandic low. The increased pressure difference results in more and stronger winter storms crossing the Atlantic Ocean on a more northerly track. This results in warm and wet winters in Europe and in cold and dry winters in northern Canada and Greenland.The eastern US experiences mild and wet winter conditions.

On the other hand, the negative NAO index phase shows a weak subtropical high and a weak Icelandic low. The reduced pressure gradient results in fewer and weaker winter storms crossing on a more west-east pathway. They bring moist air into the Mediterranean and cold air to northern Europe The US east coast experiences more cold air outbreaks and hence snowy weather conditions. Greenland, however, will have milder winter temperatures.