The models are finally catching on to the movement of the MJO. If you look at the progress of the MJO on the sidebar you can see that it is holding strong and moving fairly quickly into the Western Pacific. This area of convection and storminess normally has a large impact on the jetstream and our weather within a week or two after entering the Pacific, especially during La Nina. The first couple model runs this morning show a series of storms crashing into the Pacific NW and then into Northern CA starting around the weekend of the 23rd.

There is some weather that will happen before that. The ridge is currently building in and warming us up for the rest of the week. Truckee will hit the 70′s over the next couple of days. This will last through the weekend until the next storm approaches for next Monday. This storm will be cut-off from the jetstream like the last one and will slide over CA and into Nevada. The difference is that it doesn’t seem to have much moisture and won’t get stuck over us for 6 days this time. The biggest impact should just be cooling and a chance of showers the beginning of next week.

The following weekend is when the pattern shift should begin and we see storms begin to move into the Pacific NW. The jetstream would then lower even more bringing storms into Northern CA. We will have to continue to monitor the MJO and this pattern change over the next week to see if it holds.

Beyond that there will be a lot of cold air building in Canada that will want to try and come down from the North in November. What would be perfect would be snow that last week of October and then cold the first week of November to make snow. It is way too early to bet on this series of storms, but it is a good sign that the models are catching onto the pattern over the Pacific. Stay tuned for more updates……..

Looking at the La Nina discussion from Monday all sections have cooled and section 3 is now at -2.1. The ONI 3 month average is now at -1.0, so we now have moderate La Nina conditions in the Pacific. All forecast models point at us being in a strong La Nina by December and January. Our go to winter of 73-74, which was the only other strong La Nina coming off a mod/strong El Nino, is looking like the right analog right now. That was a 500 inch Donner Summit winter, 125% of average, which is what we had last winter. The difference would be all that snow will come in a shorter span and be mostly done by March where last year a lot fell in April and May. That means bigger storms this winter.

The other 3 strong La Nina winters featured: 88-89 coming off a weak El Nino and brought 450 inches, 55-56 coming off a mild La Nina and brought 600 inches, and 75-76 coming off a weak La Nina and brought below average snowfall. 75-76 the storm track stayed just to our North all winter. 88-89 was the all time snowfall record set at Mt. Baker with 1,140 inches that season, and it was the 24 hour snowfall record for Donner Summit on Feb. 3rd with 52 inches in 24 hours.

Something interesting to note is that the MEI readings, which measure a combination of air pressures, air temps, water temps, and a few other variables in the ENSO region of the Pacific along , are at there lowest levels right now since the 55-56 season. If that had an affect on that big snowfall year we may need to keep that in mind. Based on all that history I come up with a less than 25% chance of a below average snowfall year. I know some people are saying below average but I like using all that comparitive analysis on history and lining it up with today as an idea of what the winter may be like here in the Sierra. Let’s score it at the end of the winter….. BA

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