Misa/Why are long-term forecasts so difficult?

 

 Reference from: Winter weather: How to make it more predictableposted
 By Philip Ball on May 20, 2014

Although the UK was alerted months in advance severe condition of the winter, it never materialized, the East Coast being unusually bitter. The UK’s Met Office stressed the poor forecast and insists the difficulty to accurately predict forecast months or years beforehand because of many factors involved that can be discussed in detail in their five-day forecasts. The weather prediction is so sensitive that it can be changed totally and bring completely different outcome by tiny causes. We may response with “A fat lot of good”, yet there is an optimistic possibility to improve the system, focusing on European and North American winter climate, which are precisely predictable months in advance.

It is absolutely helpful that we can anticipate the weather of next week. It enormously benefits to from children to seniors, farmers, commuters, and even companies which have to handle the business depending on the weather. Nevertheless, the law of physics has established a limit on how far beforehand the forecast can be anticipate, as it is mathematically impossible to predict in detail such as local weather forecast in more than 10 days away. However, some aspects of weather such as average temperature, and ocean circulation. Not perfectly accurate as the current forecasts are, the systems and technology in Western Europe, satellite observations and computer modelling has come a long way; for example, five-day predicting weather is demonstrably more accurate than the three-day forecast in the late 1980s. The Met Office have therefore optimistic eyes on winter forecasting in the North Atlantic area, where the atmosphere is not tightly related to ocean circulation so they cannot rely on medium-range forecasting.

The North Atlantic Oscillation is a difference in air pressure which takes a role to decide the strength of the westerly jet stream and tracks of Atlantic storms, depending on the deference between low-pressure over Iceland and high-pressure around Azores, which is the most important seasonal factor for North Atlantic climate. The size of difference has been back and forth every few years irregularly. Though it’s similar to El Nino, which is closely related to fluctuation of sea-surface temperature and more predictable, NAO is different in that it is almost unpredictable. The causes of erratic NAO have not been proven, but it seems that it linked to the state of Arctic sea ice and two-year cycle in the winds of the tropical lower stratosphere. When the model gains the information of those things, NAO will be well predictable, which helps us prevent from dismal catastrophes and also provide useful and crucial date for wind energy plan and setting fuel-pricing policies.

I think if we can get accurate forecasts months in advance, it helps greatly our life; it is enormously beneficial to not only agriculture but also area of producing power sustainably. Tons of money has drawn into floods resulting from severe weather. It is the time for making energy efficiently, cultivating products stably prospecting the total harvest, and saving lives from sudden disaster. I hope to get more accurate weather forecast down the line.