As always I am trying to be as accurate as possible when predicting snow amounts and conservative as possible when the storm is several days away. When dealing with a storm that has the potential this one does for the weekend you have to think worst case if you are planning to travel through the Tahoe area. This storm is the kind that can strand you and close down interstates, so please take it seriously. I know it seems hard to believe since it’s only Nov. 15th but this is a January storm in strength and cold.
Since storms like this aren’t that common I looked back through the records of the NWS reporting station that is on top of Squaw. You have to go back 8 years to find a big multi-day storm in November to 2002. Nov. 7th-10th that year 44 inches fell at the reporting station which is a good estimate for the entire Sierra crest. This storm will be in that ballpark. The last big November as whole was the year before that with 88 inches in the month. So far this November we are at 17″. So it’s looking like we may be in store for the biggest November storm in at least 8 years and biggest Nov. for snow in at least 9 years.
I am setting the comparison stage because we are now only 4 days away which means the margin of error is shrinking. The fact that the models are all in agreement and very consistent with the amounts means confidence is high. If anything the models underestimate the amounts of precip when dealing with a cold storm like this. This will not be like the other storms so far this year. This is all snow down below 5000 ft. with highs only in the 20′s for most of the storm which means high snow:water ratios and lots of instability.
The storm will move in on Friday with the initial cold front bringing a round of heavy snow. The snow should then lighten up on Saturday before the main low moves down the coast tapping Pacific moisture and brings another round of heavy snow Sunday and into Monday.
So let’s talk about potential snow totals. Instead of being conservative let’s look at lowest amounts and highest amounts possible based on the the latest model runs. Models are consistent on 2-3 inches of liquid over Tahoe for 2 days now, so that will be the basis for multiplying snow ratios. At lake lake level and in Truckee the temps will be 25-30 degrees. That is snow ratios of 12-15:1. I would say lowest end would be 18 inches with up to 3 feet possible. Above 7500 ft. the temps will only be 15-20 degrees which is snow ratios of 20-25:1. I would say that means lowest end 3 feet with up to 5 feet possible on top of the mountains. On the crest the potential is there to break 5 feet. We will even see several inches in Reno.
The devil is in the details as they say. We will have to see how much moisture this storm will be able to pull in off the ocean. The storm will last several days so we won’t know the totals until Tuesday. Just don’t be caught off guard by this storm. The last storm we had this big was last January.
It may be a gift to have this storm because with the AO and NAO going negative it is looking like December could be much more dry and mild than the last 2 months. That will however flip Jan – March when we’ll see lots of cold and snow. My prediction this winter is 125% of average snowfall for Tahoe, a little more than last year but much colder.
Stay tuned for the latest details on the weekend storm……….BA
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