More of the same for today and tomorrow… Pattern change slowly starts to take place starting Monday with snow possible by the end of the week.
Inversions still in place for the next two days. We have three distinct systems to talk about, each one giving us a better chance for snow.
The first system is another backdoor slider, similar to the one we had on Thursday. On Monday, it will be dropping down the continental divide and bringing light snow and cold air to our east. For us, it’ll just bring some clouds, breezes and slightly cooler air. However, this will likely be enough to at least help the air quality.
The next system of note is the one that will be doing most of the damage to the ridge. This system is timing for Wednesday. As mentioned yesterday, and still the case today, it looks like the ridge will significantly weaken the system and push most of its energy north of the area. This is very common for the first storm breaking through a ridge. We might be able to get an inch or two out of it in the high elevations, but at this time it looks minimal.
Finally, the third system to affect the area will have a much better chance at actually bringing us snow. This system is timing for Friday/Friday night. While it’s still too early to know exactly how strong the system will be, it does appear that we’ll get at least some accumulating snow from it.
The other victory with all this is that we will finally be rid of the inversions later this week. As we head further toward Spring and the sun angles get higher, it becomes more difficult for inversions to form. Hopefully this is the last strong inversion event we’ll see this season.
There is absolutely no agreement in the long range so it’s pointless to discuss it. I will say this, however — it appears as if the MJO is strengthening and so is the Pacific jet. I’d be surprised if we saw anymore 10+-day periods of totally dry weather from here on out. We will of course still see periods of ridging, but the overall pattern should get more progressive with troughs moving in with greater ease.
The PNA teleconnection correlates very closely with ridging/troughing in the West. Here is a look at the past 15 days or so of the PNA (blue line) along with the forecast for the PNA (black dots):
Notice the beginning of the graph the PNA dipped negative for about 5 days. This correlates almost perfectly with the 5 days of storms we saw earlier this month. The positive portion from about January 13 on is our current dry spell. You can see that the PNA is now forecasted to drop negative by February 1. What we need is for this PNA pattern to stay negative which should mean consistent troughing over the west. This is just another way we can see that the large-scale pattern is changing. It also helps forecasters like myself put more confidence in a pattern change.
For Tahoe readers who have desperately been searching for good news — the latest model runs have looked much better for you with the third system mentioned above. This will move through Thursday/Thursday night in your area. Very good news which goes far beyond skiing as you hope to avoid a dangerous drought.