Above is a shot of a 180+ km Asian Jet coming across the Pacific for Tuesday January 21st. Notice how it doesn’t make it past 160W latitude as it weakens. This is effectively pressing the ridge right on top of us sending California into a heat wave! Highs will be up to 76F this week, with 80’s in L.A.
We are going to have an inversion set up above 6,500′ through Friday at least. Highs in the mid 50’s for the Sierra valleys and 40’s at the 10,000′ level, with overnight lows remaining above freezing on the mountains. So much for the really good winter conditions we are currently experiencing, looks like we are going to watch our minuscule snow pack erode for the next two weeks.
There really were no teleconnections to support a break through of the westerlies. There was no tropical forcing in the equatorial Pacific, and the Madden-Julian Oscillation has been inactive or extremely weak all season.
Here is the most current index of the MJO. It finally appears to briefly become active again in the next week. http://www.bom.gov.au/climate/mjo/.
Hope to go into detail later, but it looks like the MJO becomes active in space phase seven, which is leading to “signs of retrogression” and a possible break through of the Asian Jet to the west coast. Normally a strong MJO moving through space phase 7 would create an Atmospheric River event for the Pacific coast. The MJO doesn’t stay in its active phase for very long however and appears weak, but it may be ONE of the possible causes signaling the retrogression of the ridge which is showing up in ALL of the models for the end of the month.
The most current run of the ECMWF control has come in with a major break through of the westerlies straight into central California for the end of the month. This is the first run with this solution so we will have to at least give it a few days. The possibility that the EPO (ridge) retrogrades in time for an inside slider before months end is another possible solution. Is there still hope for January? Looks like a definite pattern change is coming for the beginning of February! It’s always darkest before the dawn..