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Sunday, January 15, 2012

Prepare For Major Changes

Starting today, prepare for major changes in our weather pattern. Tonight a cold front will be coming through the area. It will snow some in the Sierra, but probably not much. It will bring very cold air that will plunge low temperatures on Monday night into the single digits. This is just the first of a 4 part wave to hit the area. When all is said and done, expect 5-10 inches of liquid precip in the Sierra.

The 2nd wave comes through on Thursday. There are some concerns about snow levels with this system. Right now the NWS is predicting the majority of the precip will be rain under 9,000 feet, especially just south of here. That could make it down to 8,000 feet and we will monitor as this 2nd wave approaches. Here is what GFS thinks for Thursday late morning:

Late Thursday Morning 1/19

The third and biggest wave is set to come in Friday afternoon and last through Saturday. This system also is raising some concerns about snow levels. Here is the GFS look for Late Friday:

Late Friday 1/20

This system will tap into very moist air from the tropics and has the potential of dumping a tremendous amount of moisture in a very short period of time.

The 4th wave comes in Tuesday and it too looks like a warm, wet storm. Here is the GFS look at this storm:

Tuesday 1/24

Having said all this, here is what the EC see's insofar as total precip by Wednesday 1/25:


As you can see, the Northwestern half of Lake Tahoe is in the 5+ inch zone. The leeward valley's of Reno and Carson look to be in the 2-4 inch range. If these storms shift just a hair south then this could be a major event.

Finally, looking well ahead, this is the EC forecast for precip by the 2nd week in February:


There is still a big swath of 10+ inch moisture just to the west of us. All of Tahoe is in the 6-8 inch range.

Discussion
The biggest risk to this not being a great event are the snow levels of these warm, wet storms. The worst case scenario, which I do not believe is likely, would be for this entire event to be rain above 9,000 feet. That would almost surely wipe out all the man made snow and probably cause some very minor flash flooding. The best case scenario would be for snow levels to drop to 7,000 or below for the entire event. In that case we could expect 4-8 feet of snow by the middle of  next week. The likely scenario, is somewhere between the best and worst case scenarios. That likely scenario is where I will be concentrating my efforts in the coming days.

Stay Tuned ...

1 comment:

  1. Thanks for your blog! I'm curious, what is your source for the GFS images? Thanks.

    ReplyDelete