Atlantic Jet Stream To Go From Summer To Autumn Strength Next Week

Late July is generally considered the peak of summer with the subtropical ridge strongest and furthest north flooding the majority of the mid latitudes in warmth. At the pole, cold is shrunk and so the jet stream is typically weak and further north.

Recent weeks has seen that typically weak jet but it’s position north varies and a lot can be determined by temperature anomaly. The last couple of decades has seen wetter summers due to the warm phase of the AMO. Warm and cold water often influences the strength and position of the jet stream and like recent summers (except June/July 2013/2014), the warmer than normal Atlantic has enhanced the SUBTROPICAL jet which has pumped a lot of moisture in over the UK. Colder waters associated with the cold phase of the AMO tends to supress the subtropical jet further south and therefore we see less summer rainfall in the UK.

Recent weeks has seen a weak jet positioned just north of Scotland with fairly weak lows dominating and providing a very changeable weather for Ireland and UK. The Azores high has been quite strong and therefore it’s been warmer than average over Iberia.

The models are all over a stronger and further south trans Atlantic jet next week as the pressure and thermal gradient increases going from a typical summer strength between 50-70 kts to 130 kts. A wavy jet at this strength means lows are likely to be deeper and therefore we may find windier, wetter and cooler times for the UK and NW Europe.

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As you can see from the ECMWF jet stream charts below, we go from a 50-70kt jet blowing over the UK from the NW today to a roaring 130kt westerly jet later next week.

Credit: AccuWeather Pro

Credit: AccuWeather Pro

Credit: AccuWeather Pro

Credit: AccuWeather Pro

Credit: AccuWeather Pro

Credit: AccuWeather Pro

Credit: AccuWeather Pro

Credit: AccuWeather Pro

Credit: AccuWeather Pro

Credit: AccuWeather Pro

Credit: AccuWeather Pro

Credit: AccuWeather Pro

GFS

Credit: Netweather.tv

Credit: Netweather.tv

See this morning’s video.

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