Another pacific storm will come onshore this evening and start working its way into the Great Basin Saturday.

This is a large system and a piece is going to go north and combine with a large longwave trough full of very cold air reaching from the east coast of the US to British Columbia.

Another piece will go south, which will be the part of the system that begins to affect Sunday morning.

Late Sunday and  Monday the northern trough will drop south pushing colder air into our area and flow will change from the SW to Northerly/Northwesterly shutting off the precipitation to most areas except those that prefer NNW flow.

Notice in the above map the tightly packed blue “thickness lines” in southern Canada (Ontario) those 492 and 498 lines have very cold air and indicate that the dreaded polar vortex may center itself in the midwest with cold air filtering down covering much of the country by mid-month. We will see.

Here are the liquid precip amounts that models were predicting on their 5 am model runs Friday morning.

Euro

GFS

Last the NAM short term mesoscale model, I throw this in the mix because it is really highlighting the NNW flow at the end of the storm and you can see how that affects the totals in the areas that favor north and northwest flow.

I am not at the point where I favor one model over the other with this storm, I hope tomorrow will shed a little more light on all of these variables.

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