Its been a while since a cold trough moved through the sierra from the Eastern Pacific. This time, there was no split and this time a pair of Vort maxes following the main trof axis passage, brought unstable air and snow showers today.  This will continue for a time tonight as the flow becomes more WNW and some of the shower north of the bay area, possibly swings into our area tonight.  This is all great news for the Mammoth Mt Ski Area with storm totals now 8 to 12 inches! That’s a big deal this winter!  Temperatures will moderate upward into early next week with lots of high clouds and lighter winds at the surface. Highs will climb into the low 50s by Sunday or Monday. Lows will move back into the 20s from the current single digits and teens.

Reflecting on the Late Fall and winter so far, the global pattern across the north hemisphere has been dominated by meridional Flow (North-South) since December.  This is likely to continue through at least part of February as the QBO remains in its negative phase and of moderate strength. The MJO is becoming very strong and will strengthen further as it moves into the Western Pacific and toward the Dateline about week 3.   SEE: 


This may repeat the pattern we had last December with strong ridging developing over the far Eastern Pacific/west coast in the coming weeks with dryer than normal weather continuing. The East Coast will get hammered again with Arctic Air. I’ll be following the progress of the pattern change which will remain in its warm phase in the east until phase 7 of the Rimm, provides the open door for the Arctic Highway for the East and extensive ridging for the West again.

Just as a note; I have noticed that the effects of the MJO, with relation to modulating the East Asian Jet, frequently behaves differently during winters when the QBO is in its “positive phase” contrary to what we have today.  There is often more Zonal Flow across the western hemisphere which tends to foster more successful undercutting’s of the west coast ridge and more successful central west coast extensions of EAJ and resulting Atmospheric Rivers. It is not to say that they are impossible, but more improbable.  With the current set up of the QBO, currently in its Easterly Phase or negative phase, meridional flow dominates, which combined with the current weak to moderate La Nina, may be the stronger force working against the MJO’s modulating effect upon the westerlies in phase 7-8-1.  If you click on the link above, you will notice that the MJO strengthens and then makes a run for Phase 8.  Watch the models toward that time period, and see how they want to amplify, then retrograde the west coast ridge. I bet that there will be models runs with the westerlies showing undercutting into the west coast. Keep your heart on this as there are strong forces working against any undercutting reaching the central west coast through mid February. The Pacific NW may benefit with “AR’s” during weeks 2 and possibly 3.

Opine: Looking at how strong the trades are getting again, and if they keep up current strength at this pace, we may be in for a protracted La Nina period, that goes well into the Summer.  The good thing to remember, is the QBO will eventually flip back to positive later this year and that is likely to bring winter back to the central west coast with more generous amounts of precipitation next year.

Just to Add:

For those who are interested in the QBO, here is a link that gives an easier explanation as compared to the abstracts written by actual scientist’s. I think that you will all agree that after going through all the analog’s in the various links associated with the link below, the screaming message is that there is a very strong bias for drier and warmer winters in California with the QBO in its negative phase during weak La Nina’s such as the one were are currently in.


The Dweeber……….:-)