Ken Clark

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Continued Rain-free or Big Rainstorm(s) Southwest Late Week?

January 21, 2013; 2:18 PM ET

A huge ridge of high pressure has made weather forecasting very clear cut and relatively easy for well over a week now. It looks like the models are trying to make up for that by late this week into early next week.

In this edition, I will be showing some of the model data that I have been faced with today in making forecasts across California and the rest of the Southwest for the weekend into early next week. After seeing the differences, it may give you an idea of why there are a few less hairs on top of my head.

Not that the forecast had not possessed challenges before then. In the shorter term, we have two weather systems that will be affecting the weather. First, a satellite picture of the West and Pacific.

It is fairly easy to see the two weather features, a storm in the eastern Pacific west of the Northwest and an upper-level low in the low latitudes at about 15N and 137W. The northern system is heading east to southeast and will bring some rain into the coastal Northwest and northern California Wednesday into Wednesday night. That feature will pick up the southern low and start it moving toward California. If it were just the northern feature, it would not bring rain any farther south than the northern third of California before it moved off to the east. However, you can see that the southern low has a lot of clouds and moisture with it. Both the GFS and European models take this low and approach it toward southern and south-central Californian Friday, passing through Friday night into Saturday. However, the GFS is virtually precipitation-free with it while the European brings ½ to 1 inch of rain for the southern half of the state west of the deserts. What are my thoughts? I find it hard to believe this southern low with all the moisture it has moves through without any rain at all like the GFS has. In fact I could see how there might be a shower or sprinkle as early as Thursday. I am not as confident about rain amounts. So for now I think there is the possibility for a few showers at the least and maybe more Friday into Saturday.

However, our problems don't stop here. From Sunday through Tuesday, the GFS and European are playing very different tunes, a difference sort of like classical music to hard-core rap. Nothing close to the same. Below I am just going to give you the 500 mb maps Sunday, Monday and Tuesday mornings. It should be pretty obvious that the GFS is saying dry and the European is saying very wet. Here I find it much more difficult to play favorites. The European has been out performing the GFS operational model in many cases this winter in North America. Therefore I am slightly leaning to a wetter solution, just not yet the deluge the European is bringing right now. Even though the European has been better that does not mean it cannot go off the rails this time. There is plenty of time to see how things change with time as we go through the next few days.

The first map under each section is the GFS and the second is the European.

12Z Sunday:

12Z Monday:

12Z Tuesday:

The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com

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Ken Clark
Ken Clark's Western U.S. weather blog tackles daily weather events with commentary from one of the most experienced and trusted Western U.S. weather experts.