Madden-Julian Oscillation pulse and tropical cyclone activity in January


Hi all! Bit of an introduction first: my name is Ben and I’m a meteorologist at NIWA in Auckland. I specialize in sub-seasonal and seasonal forecasting and regularly produce NIWA’s 3-month outlooks, contribute to NIWA’s Island Climate Update, and leverage seasonal forecast datasets to create bespoke climate products, like maps. I look forward to sharing my knowledge in this space and engaging with the Pacific meteorological and hydrological community.

I just wanted to pass along the latest Madden-Julian Oscillation (MJO) update from the ECMWF model. A pulse (of cloud and rainfall) is expected to push across the Pacific as we head into January. This may be associated with an enhanced risk for tropical cyclone activity, so it is probably a good time to review your plans in case one does form.

We are already seeing some activity from this pulse in the Indian Ocean and former Tropical Cyclone Owen has re-generated in the Gulf of Carpentaria.

If you’re not already, you can follow along for updates on our Facebook page and Twitter page.




Hi Ben

Thanks very much for this post. What do the yellow lines and shading represent in this figure? Sorry - I’m not familiar with this product.



Hi Andrew, great question.

The yellow lines refer to the 51 individual members that make up the ECMWF ensemble. The thicker green line refers to the ensemble mean and the most likely trajectory of the MJO. The dark grey and light gray plumes that sit underneath the lines show the 25/75th percentile and help to communicate uncertainty (e.g. a wider dark grey plume would imply large ensemble spread or uncertainty).

The MJO can also be tracked by looking at outgoing longwave radiation, such as the 7-day image available here:

The purple shades to the south of India indicate enhanced cloud cover and rainfall.


Hi all,

Ben here, just checking back in. As discussed earlier, the Madden Julian Oscillation pulse has navigated into the Maritime Continent and is moving toward the Western Pacific.

We have seen Tropical Cyclone Penny form near Far North Queensland in recent days and another persistently disturbed area north of Fiji, which FijiMet expects will become a tropical cyclone in the coming days.

The active regime may linger for another 7 to 10 days before another active period emerges later in the month.



Infrared satellite 2320 UTC 2 Jan 2019 shows two active regions of convection in the Southwest Pacific