Posts Tagged ‘NAO’

Warmer Weather Makes a Brief Return

Tuesday, November 25th, 2008

Although this week is starting off on the cool side, temperatures will being to find their way back to normal by late in the week. In fact temperatures will be about 4 degrees warmer than last year in Berlin before going back to cooler than normal temps. The chart below shows the temperature trends starting last week and the 2 week forecast for some of the major cities in Europe. In the temperature fields, dark blue represents much colder, light blue is cooler, gray is similar, orange is warmer, and red is much warmer. For the precipitation column, dark green is much wetter, light green is wetter, gray is similar, yellow is drier and orange is much drier. 

 
 
As we enter December, cooler weather will begin to dominate much of the continent which is expected for a negative NAO. As forecasted, the NAO is trending more negative and is forecast to go greatly negative for the end of November before starting to head toward zero through the first half of December.

Wind Energy Output Down in Germany

Thursday, November 13th, 2008

The North Atlantic Oscillation (NAO) is one of the most highly correlated teleconnection indices used in forecasting temperatures in Europe and the Eastern United States.  It is the anomalies of the polar low typically centered over Iceland and the sup-tropical low usually in the area of the Azores.  Positive values indicate stronger than normal pressure anomalies while a negative NAO is the opposite. Although the NAO is present in summer months it is predominantly used in the winter when it has the most impact on the northern hemisphere jet-stream. 

Although we’re not in true winter just yet, the NAO index will play a large role in European weather. In the short term (3-7 days) a positive NAO is forecast, with the strong pressure gradients we anticipate stronger winds across the Northern North Sea. It is still too early to tell if the strong winds will be enough to disrupt oil production in the region. Winds are forecast to be up to 45 knots with high seas in some areas of the North Sea for the middle of next week.  Unfortunately for the wind farms in Germany, the winds have been fairly calm as of late and wind farm output has dropped to around 3,000MW from a peak of close to 15,000 MW on Tuesday. 
 
In the mid-range of the models (around 10-14 days) the NAO is forecast to go more negative bringing cooler temperatures to North Europe. This should also bring some increased winds to mainland Europe, although the winds will not be anything near what the North Sea is forecast to experience. 

Demand Will Peak Late in the Week

Monday, November 10th, 2008

Heating demand will rise as the week progresses, until it peaks on Friday. A cold front, presently situated in northern Europe, will slowly make its way southwest bringing with it cooler temperatures and rain. Following the passage of this system, winds will begin to calm and temperatures will start to rise a bit. Coal prices could see a slight rebound due to the lower energy output from the wind farms. Heating demand across much of the continent will decrease at least for the short term.

The NAO is currently weak negative and is forecast to become almost neutral over the next 5-7 days. There is good model agreement in the short term but after day 7 the model starts to diverge. November has been pretty much neutral NAO to this point and the next 2 weeks will determine where the monthly value will fall. 
 
As a side note, if you frequent this site and would like a certain geographic region covered that has not been covered (and is in the EU) please leave a comment or e-mail me at dodonnell@wxtrends.com and I will make an effort to include it more thoroughly in future posts. 

Warmer Weather in Store for Most of Continent

Thursday, October 30th, 2008

Over the next week or so much of the continent will experience a significant warming. Parts of southwestern Germany will see temperatures in the low single digits tomorrow and possibly warming to the teens late next week. There will be some rainy periods in the mix with southern France and north western Italy having rain falling most of the week. 

 
The American GFS model is trending towards a negative NAO in the coming weeks which could change some November outlooks and even some winter outlooks as the November NAO can be a precursor to winter weather. It also has an influence on wind magnitude in central Europe. Winds will be out of the east at 6-14 knots until Wednesday, at that time winds will diminish a bit. Wind energy production will be at its peak early in the week. 
 
Below are the minimum temperatures for the EU through 11th November 2008.
 
 
 

 

 

Warm Temperatures Hurt Heating Demand

Friday, October 10th, 2008
Tropical activity is still non-existent right now but there are some areas of investigation. The most prominent is still in the middle of the Atlantic and any threat to the production region is low. Historically, storm development this time of year is confined to the western Caribbean and the Gulf of Mexico. 
 
As expected, NAO values are beginning to trend neutral and should go positive shortly. A positive NAO typically leads to a warm dry weather in much of southern Europe while the UK and Scandinavia are typically warm and wet. Its impact is most relevant in the winter months as the Icelandic low and Bermuda high help direct storms into northern Europe. 
 
NAO through Oct. 10
 
 
Temperatures this weekend, and even into next week, will be well above normal for much of the continent. Berlin, Paris, and Madrid will all have high temperatures 2-4 C above normal. Heating demand will suffer as the temperatures rise. A frontal system will be coming in from the Atlantic bringing with is some rain into Spain as well as some potential thunderstorms. Also with this approaching system, strong winds will be observed throughout southern Spain.