Tahoe Weather Discussion.com

It wouldn’t be hard to do with the winter we have had so far. If we can pick up more than 60-70 inches we would beat out any other month so far this season. We got our first big dump but now we have finished off January and will start February on a dry note. I do see several things occuring that could mean we have a decent month.

Currently we have a flat ridge off the coast keeping the storms just to our North. We have a chance for a flake the next three days as three storms come onshore into the Pacific NW brushing us on the Southern edge. I wouldn’t expect much of anything. After that the ridge builds in over the West keeping us dry and mild for another week. That gets us to the 8th of February which is the beginning of the second week.

Now most of you know I am one of the few forecasters that will write about weather out more than 10 days. That is because the accuracy beyond that is not good. Also, a lot of the forecasts are based on oscillations that don’t always match up 1 for 1 with what happens. But hey you know that, there are enough jokes out there about how wrong weathermen can be even on 5 day forecasts.

In my long-range forecasts I specifically look at the things that have been known to be associated with increased liklihood of snowfall for our area. In doing so the forecasts have been wrong but sometimes we get an early jump on the development of a snowy pattern. When we are in dry spells we really have no choice because. We can’t just sit here and say, “oh well it will snow again someday I’m sure,” we need to be looking forward optomistically at when we will see the snow begin to fall. Or at least I need to or I’ll go crazy which is what created this blog in the first place.

Let’s take a look at what may be lurking for the month of February. We are walking into positive PNA and negative AO & NAO territory. (I keep getting emails about a glossary for the terms and acronyms but as I have said previously I won’t have time to add anything like that until next season. For now you will have to Google the terms and there are lots of sites that explain them.) Those phases of the teleconnections tend to be associated with an amplified trough in the East and ridge in the West. Doesn’t sound good but we can still get storms.

What we look for in this pattern is for the jet stream to come underneath the ridge in to the West Coast. There is a weakened subtropical jet stream during La Nina so not much help there for undercutting the ridge. We need the ridging to be in the North Pacific to force the polar jet stream underneath, or something to strenghten the subtropical jet stream like the MJO. The MJO is a tropical wave of convection that circles the globe along the equator and when it moves through the Pacific (phase 6 & 7) the subtropical jet stream can tap the energy strengthening the jet and sending it towards the West Coast. We picked up 100 inches last December from this type of scenario.

Now as you can see on the right sidbar the forecast of the MJO on the GFS model is for it to get quite strong and moves East through the Pacific into phase 7. You can also see what happened the last time it was in its current phase 6, it weakened and looped back around. That has happened a few times, most likely because of the cold La Nina water along the equator has weakened the convection. The forecast is for it to continue and strengthen so we’ll have to watch to see if it can make it this time. La Nina is beginning its fade which will continue through spring and it looks like we could have an El Nino next season.

I pulled some images off the GFS model and CFS long-range model today which shows what could be the progression of the ridging for February. The ideal setup with the teleconnections cards we have been dealt currently would be for the ridge to build up over Alaska into Western Canada opening the storm door underneath. This is what started the pattern change 2 weeks ago that resulted in the big snows last week. The ridge that time shifted into the Bering Sea and then Siberia bringing the trough back to Alaska and the ridge to the West Coast this week.

Here is the pattern we have to start this week.  The high heights (ridging) is in orange and low heights (troughing) in blue.  You can see the flat ridge off the coast and trough over Alaska and down into Western Canada where the snow will fall in feet this week.

Now as we get to the end of the week and into next weekend the ridge begins to build in over the West.  Then amplifies North into Western Canada.  Looks like it could be game over for everyone up the West Coast for at least a few days.

Then week 2 the ridge continues to build North towards Alaska.  Underneath now there is the beginning of an opening for storms to come underneath into CA.  Both the Euro and GFS forecast models have been hinting at storms beginning to push into CA starting around the 8th

Then by 2 weeks from today the forecast looks like this.  The ridge is up over Alaska and Western Canada and the storm door is open underneath.

Here is what today’s 0z GFS showed for the 13th.  Now this just verifies a trend we can’t look at a storm this far out.  You can see it has high pressure over Alaska and Canada.

All this could change of course but looking at everything on the table this forecast would make sense.  If the MJO can work its magic we could have a fire hose, but the risk of high snow levels is there.

Now I’m going to get really crazy and use the CFS long-range model to show you its forecast for weeks 3 & 4.  Week 3 shows the ridge still over Alaska and Western Canada.

And week 4 still there over there in the North Pacific.

If this pattern were to verify for the month it would be a wet month the latter 2/3rds and the hope would be a white month as well.  More to come…BA

That’s not a good thing. You can see up on the top bar we are now back in positive territory again. That tends to be associated with West Coast ridging. If you click on it you can see it better but you can see that it was negative in November when we had storms, and then positive until going negative the past week when we had storms again.  This was the case last season as well as the Positive PNA showed up for the 6 week dry spell in Jan before going negative again in mid-February.

We can get storms with a +PNA pattern if the ridge is positioned far enough North to allow storms to cut underneath.  The storms do tend to be mild though with higher snow levels. The models suggest this could happen the 2nd week of February. Until then we look to be dry with maybe a quick dusting Sunday night or Tuesday night as storms brush by to the North.  The MJO forecast on the right sidebar does look interesting but it hasn’t made it to phase 7 without falling apart in a long time.

This is becoming a drought year and if we keep down this road it may become the driest moderate La Nina with a cold PDO season we have ever had. Those seasons normally average out to average snowfall which is why I forecasted that for the season in the Fall. We are doing better than the driest year on record however. Here is a look at the current snowpack analaysis.  You can see the pink line for this current year is ahead of the driest year of 76-77.  We are just a little behind last season in green, ha.

Don’t forget that from mid-February on last season we picked up 500 inches.  When we have these dry spells I am not just saying oh well I’ll just check back in a week. I don’t post everyday because there are only so many ways to say no snow for 2 weeks, but I am working just as hard as ever trying to find something positive in the pattern that can get us back on track with the snow.

As most of you know I am not a meteorologist. I switched majors halfway through school after a trip to some third world countries including Madagascar made me want to study Economics. Now as an accountant by day and snow obsessed weather hobbyist by night I like to call myself a snowcaster. I have spent my time over the years focusing in on one thing with the weather and that is being able to forecast when big snows will come (specifically to Tahoe). I will mis-state things sometimes but overall my goal isn’t to write a term paper here, it’s to write an easy to understand discussion on what I have found during my research of when we might see snow again.

I have had the privilige since starting to this blog to talk with and gain insights from lots of meteorologists around the country. I am excited now to be teaming up with one who is just as snow obsessed as I am and has written a similar blog in Colorado called Coloradopowderforecast.com.  He is meteorologist Joes Gratz and he has started a new site called opensnow.com.  This site will bring together meteorologists and snow forecasters from each ski region to write a daily brief blog on the upcoming snow chances.  It also has a snowfall forecast by day for the resorts in each area.

I will be updating the snowfall forecasts for the Lake Tahoe resorts and writing a short blog on the upcoming snow chances for Tahoe in the CA section.  I believe this site will compliment my long discussions with more a more condensed “when is it going to snow next in 60 seconds or less”  plus added bonus of a quick look at potential snowfall at each resort for the coming week.  It will also allow me to have the resource of several meteorogists to discuss the weather patterns with and to bounce ideas off of.

I hope that you will all visit the new site if you don’t already.  I will continue to do my long-winded rants and long-range forecasts and theories on this site as always.  I hope to setup some icons linking between the sites for quicker access.  The lack of snow has allowed a little more time for setting this up, but I am dying for the next big dumps.  I will be the first to let you know when there is something on the horizon.  Stay tuned….BA