Surface conditions measured by TAO buoy network seem to show a definite general warming trend throughout the Pacific. This is in contrast to satellite measurements, and the SST indexes reported by BOM, which suggest that temps have been close to flat or slow drop since about October. TAO can certainly have some issues with coverage, and whether the buoys happen to be in the cool or warm part of eddies when the eddies occur, but I wouldn't think that this could cause such a difference over that long a time period. Westerlies anomalies have likely been in the far west outside the region currently covered by TAO and have pushed further east to near the dateline just in the last few days to be picked up by the TAO network.
These westerlies seem to have created a very strong warm kelvin wave. TAO now shows temps above 4 degrees near the dateline. This compares with temps peaking a bit above 5 degrees west of the dateline during the kelvin wave that set up the 97/98 el nino.
Satellite measurements seem to support a significant warming near the dateline. The classic process for a big kelvin wave is warming near the dateline due to the direct impact of the westerlies, followed by warming in the far east in about two months time when the kelvin wave crosses. Currently the temp gradient in the far west is still favorable with warmest temps furthest west, but this has eased. One thing to watch for in the next few weeks is whether or not the current westerly period is able to reverse this temp gradient - if that happens then that would make further westerly activity more likely, whereas if the gradient stays in the current favorable direction it makes it a lot less likely.
MJO continues to be very slow moving, although it looks like it may move into the western hemisphere (Amercia/Africa) in the next couple weeks, or at least go very weak. Models still do not want to see any MJO action in the Indian for the next month. Eg BOM forecast below. If so that would be two months without the MJO in the la nina favorable Indian or Australian sectors. How long would this need to go for before we start thinking this is not just an unusual MJO cycle, but a larger scale shift?
There has been a change in the general atmoshperic pattern associated with this MJO movement. Before the MJO convection was centered across the Indian and also north of Australia, although areas of weakly enhanced convection remained in central tropical Pacific. The equatorial dry reigon pushed a long way west which is a very good sign for Australian precipitation patterns reflecting solid trade winds pushing moisture towards Australia with minimal interruption by tropical systems to our east. Although there was some weak enhanced cloudiness north of NZ.
For the last month the focus of enhanced convection has shifted significantly east to be now north of Australia and in the far west Pacific. The Indian has been very quiet for this period.
At the same time there has been a lot more activity north of NZ, and there is no longer a path for the equatorial trades to reach the Australian region without first being interrupted by tropical activity in the far west Pacific. There is also more cloudiness in the north Pacific. However this region is now pushing into winter in that region and cloudiness can reflect upper trough activity a lot more than it does deep convection. SLP patterns doe show low pressure anomalies in that region though.
A significant warming of the entire Pacific seems all but guaranteed for the next few months. How long will this current shift of tropical activity further east last for? Will there be a new trade wind surge when the MJO finally emerges from its current movement?