1/N One last weak gasp of the wet season as the westerlies make a show across the North Pacific... Next weekend a breakdown & removal of the long-standing Rex Block in the NE Pacific will lead to more weak closed/cut-off lows meandering towards the SW US. #CAwx

2/N The ridge associated with the Rex Block has been persistently blocking the west coast from consolidated upper level jet support & this has been the case all winter until this upcoming weekend. A sign that a pattern change is ahead... #CAwx #CAstorms

3/N As this ridge begins to build again over the course of this week, the East Asian Jet will give one more try & reconsolidate across the N. Pacific. It’s with this chance that a modest looking area of baroclinicity will move beneath the ridge towards the west coast... #CAwx

4/N Referring back to the first graphic in the thread... It’s important to note the continual splitting of EA jet stream with the polar front jet moving poleward (north) & the subtropical jet amplifying across the subtropics towards N. America (below 30N). Why do I mention this?

5/N Persistence in the seasonal-scale is still present as this pattern change develops, the same area of low pressure that helps create the expected weaker closed/cut-off lows could be carried around the ridge to meet with them off our coast... #CAwx #CAwater

6/N Not only that, but with the poleward movement of the Polar Front Jet & the branch of the subtropical jet amplifying zonal even further overhead California, signs show this pattern may not be so reserved for the Pacific SW which has become the unfortunate case since March.