Break through update, then what?
Some models are continuing to advertise the break through of westerlies on the west coast with the PSD ensemble showing a distinct shift toward probability of above normal precipitation in the California region in week 2 (Feb 10-16). Tropical convection is now established over the west Pacific and continues to be active over the Indian Ocean. The tendency for convective forcing to be further west should continue to effect the North Pacific circulation with more retrogression of features. This could eventually (beyond week 2) lead to weakened westerlies in midlatitudes and a return to a trough along the US west coast, especially if a new MJO develops over the Indian Ocean.
Klaus Weickmann and Ed Berry