Analyzing The “Dry January”

Okay, let’s get the current ski conditions out of the way first. Truth be told the changes are incremental this week. Our warmest weather peaked on Wednesday with colder temperatures and more wind becoming prevalent the last two days and into the weekend. At the risk of sounding like a broken record, or repetitious calls from a telemarketer, the groomed slopes are king right now. That is until they aren’t.

They all start the day in excellent condition, but depending of factors like traffic, sun exposure and wind, some hold up better than others. Eventually many of the groomed slopes lose their stripes and become a slick icy surface. Over the last week, the places that have been the slickest have been the steeper sections of Alpine Bowl and Wolverine Bowl, Werner’s Schuss, Yellow Trail and Dance Floor. These are all high traffic trails that get scraped pretty quickly. All runs on Scott, Lakeview and Sherwood will start out slick until they soften. Sherwood Run will likely get more traffic than it can handle, meaning as the snow softens it immediately gets scraped back down.

There are just a few off piste areas of the mountain left that are ungroomed and not very icy. You may or may not find them. I hesitate to mention any specific areas as being “okay” as they will then become as icy as everything else. Let the glare off the ice be your guide. Also, not much of the Sherwood off piste terrain has defrosted or consolidated this week.

Looking at the coming three day weekend, the “free” parking reservations are not sold out yet, indicating that it may be less crowded. That said, probably 95% of all visitors will be utilizing the groomed slopes, so it will seem extra busy. Additionally, Palisades Tahoe (including Alpine Meadows) has announced a $99 ticket special for the weekend. These special rate tickets are being sold as a fundraiser for Los Angeles fire victims. That’s a good thing. The $99 tickets are available to Base Pass holders that are restricted this weekend and for an afternoon ticket for non-pass holders. This could encourage more people to show up. That’s a bad thing given the limited terrain.

Debunking The Dry January Myths

One thing I have heard consistently on the hill and around town is that having a dry month of January is a normal thing around Tahoe. Locals have a name for this idea, “Juneuary.” Obviously it has not felt like June at all this month, as it has been exceptionally cold and exceptionally windy. But it definitely has been dry. So far during January, we have only seen one storm bringing about 8-10 inches to the base at Alpine Meadows two weeks ago.

There’s a few other crazy ideas out there that try to simplify the weather patterns we see in mid-winter. So I sat down with a copy of the official snowfall stats for Alpine Meadows from 1970 until this season. It’s a lot of data. Let’s start with one particular number and that is the average snowfall during the month of January, as measured at the base of Roundhouse weather station. The 54 year average is 71.4 inches of snowfall.

• 29 of 54 years have had less than average snowfall during January, which is 54% of the time. This is not all of the time, nor most of the time.
• 18 of 54 years have had less that 50% of average snowfall during January. That means that 33% of those 54 years have been very dry. That is a reasonable explanation for why we really remember those dry months.
• Often people suggest that a dry January is nearly always followed by a snowy February. Sadly, it has only happened 10 times out of 54 years where a dry January was followed by a snowier than average February.
• Another suggestion I have heard was that winters that start early with a lot of snow in November become drier than average. That “truism” has only happened in 7 years of the last 54 years on record.
• While the average snowfall in January is 71.4 inches, the range is huge. The lowest recorded January was 1 inch and the highest was 235 inches. There is hardly a normal distribution of the numbers, they vary wildly.

The reason things are hardly predictable is that “average snowfall” in the Sierra, or rainfall in other parts of the state, is not a number you can count on. Most of the higher level meteorologists will tell you that California is a “boom or bust” state. Most of our rain and snowfall comes from big atmospheric river events. I have spent years telling you that atmospheric rivers are very difficult to predict because a small movement of the jet stream north or south can mean everything. That means our “average” is really kind of a false target. We get big swings between seasons and during seasons and average is really not as meaningful as one would think.

The reality is that we really have not seen a true AR event during this ski season. We have been in a zonal flow a few times, but nothing with the potential for huge snowfall has appeared. Again, the Snowfall Tracker page at the official Palisades Tahoe site is broken and no storm totals are available for this season. But my best guess is that our biggest storm has only been around 18 inches of snow or so.

Although NOAA did say that we are officially in a “La Niña” over the next few months, there is no guarantee that means anything as there are so many different teleconnections at work. The fact that Cletus at your local ski rental shop told you that means “big snow is on the way” is not likely a true statement.

Will It Snow?

The closest thing we have to a Magic 8 ball when it comes to forecasting Tahoe weather is the PNA index. We have been in a positive PNA state, or ridging in the Pacific, since the last week of November. Looking at the PNA index forecast now, we have seen a couple of days in a row of a negative PNA, or a trough in the Pacific. This is an important feature that could lead to a stormier period. Today that looks like 10+ days out, still in Fantasyland.

That said, another simple indicator of what could happen is the 8-14 day outlook. Here’s the one for precipitation.

Don’t panic as the grey looks scary. It’s not a brown shade. “Near normal” is far better than what we have seen. I am a bit concerned that this pattern above looks like an inside slider pattern, not a typical storm pattern. But seeing the precipitation outlook with no brown “drier than average’ is encouraging.

Temperatures staying in the near normal to a slightly better chance of below average is a good thing. Our snow pack is getting very thin in south facing areas and we don’t want to lose those parts of the mountain.

The models are showing only 8-10 inches of snow, still out in Fantasyland around day 13, so no miracles are in sight. Just go skiing, or don’t. See you out there.