By Mountain Mama \ January 17 2012 \ 6 Comments
So, here is what I ended my last blog with:
There has been a persistent high pressure blocking the whole western US. It spells dry. Basically, it is like a boulder in a stream. When water or small rocks hit the boulder, they can't knock it down, so they go over the boulder. The high pressure is the same...the storms go up and over until finally a big "boulder" comes along and knocks the persistent boulder out of the way. Well, it has finally been knocked down and it will open the door for moisture to finally hit the west.
Starting with the jet stream, we look at the pattern as a whole. It is what drives the storms across the country. This winter, there has been a dominant High Pressure which blocks a lot of storms from rolling into the west. The high has sat over California-which is common in the summer- and driven storms away from basically the whole western US. In keeping an eye on computer models, in which all of us in Meteorology do, you look for trends. When checking things out from day to do you look for continuity. Day after day, no change until last week I noticed the models starting to break down the high starting the 18th. So, I continued to watch to make sure the idea stuck. Sure enough, the trend continued. "Breaking down the high" means the jets stream was shifting. Finally, the change is here. Now, this is hard to look at, but first locate Utah in the picture. Note the black line that extends from Utah back to northern California. That black line is heading straight west, not up north, not somewhere else. This is a look at the upper air winds, which steer our storms, and it is coming from the west. This is valid for Thursday morning. Now, look at the moisture, there is a lot of green. So what. Well, you're scratching your head, but all this adds to the pattern change and adds to Utah getting snow. Bottom line, the high is gone and the zonal flow is here. We like that, we need that.
Bottom line, when this flow sets up, it will bring consistent moisture into the area. What does this mean? Winter Storm Warnings for the mountains. 1 foot to 3 feet plus! It looks to be a series of storms that run together. The storm cycle begins Wednesday (I know lots of squigly lines) and will cycle through the weekend. It will be heavy from Wednesday through Friday with the 1'-3' amounts. A slight break on Friday night into early Saturday morning. Then snow with heavy and light cycles through Sunday evening where there could possibly be a little lake effect into Monday morning. Possible to catch our breath by Tuesday. Beyond that, well looks like things will get active later in the weekend once again. A little far out to look. But as I mentioned above...it's all about watching the trends.
Bottom line: Storminess from Wednesday through at least Monday. Possible: 12"- yes; 24" - some areas; 36"-48"-not out of the question!!
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