Enhanced MJO Set To Return Bringing Wet, Unsettled Start To May For UK

Written by on April 22, 2020 in Rest of Europe, United Kingdom & Ireland with 0 Comments

If you’ve read my latest articles and watched the videos then you’ll be well aware that our warm, wet winter was largely down to the warm ‘enhanced’ phases of the madden julian oscillation. The northward heat release fueled a highly active wintertime rossby wave train.

At the end of March, the MJO finally weakened into a suppressed state and we managed to pull out of our wet, unsettled rut as the MJO’s enhanced thunderstorm activity moved out of the western equatorial Pacific. This teleconnected to a slowing down of the trans Atlantic jet.

While the UK and a large swathe of Europe have been high and dry, it focus of disturbed, even stormy weather has been over Iberia and the Mediterranean as this visible satellite image clearly shows.

Credit: NASA

Unfortunately, our beautiful blocking high and day after day of clear blue sunny skies appear to be living on borrowed time. The models have our anticyclone deflating and retreating back south. Replaced by low pressure once again.

If you look at the GFS ensemble MJO forecast, the wave departs Africa and travels east over the Indian Ocean during April’s final week.

 

Credit: weather.com

If you look at the below charts, note the area of enhanced t-storm activity propagates across the Indian Ocean and returns to the maritime continent (Indonesia) while Africa and western Indian Ocean dries. In essence the MJO is heading back into an enhanced phase.

Credit: Michael Ventrice

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Another version.

Credit: Michael Ventrice

Of course seasonal adjustments must be taking into account but all in all, the models have a re-strengthening of the North Atlantic jet stream.

The below 250mb winds (jet stream) winds for yesterday shows a strong jet exiting Canada but weakens over the Atlantic. With a vast atmospheric boulder (stationary planetary wave) parked over the UK, one arm of the jet can be seen diving into Iberia bringing wet and windy weather here and the other arm rerouted north into Scandinavia.

As we end April and begin May, the below 250mb wind (jet stream level) charts shows the return of a more prominent, zonal jet, forcing the southward displacement of the high. Atlantic low pressure shall return to the corridor between Iceland and Scotland.

Now

Credit: Tropical Tidbits

240 hours

Credit: Tropical Tidbits

276 hours

Credit: Tropical Tidbits

The GFS precip/surface charts

36 hours

Credit: Tropical Tidbits

120 hours

Credit: Tropical Tidbits

156 hours

Credit: Tropical Tidbits

186 hours

Credit: Tropical Tidbits

Goodbye high, hello again low!

Credit: Tropical Tidbits

Credit: Tropical Tidbits

Expect to see a regime of wet and blustery one day followed by drier, sunnier and warmer the next. I suspect this shall take us into at least the first 10 days of May.

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