HOPE FOR MID-SEPTEMBER RAIN? PERHAPS….

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As you know we like to share early information on trends in weather that may help in long range planning here in the North Bay. Especially with the current severe drought and fire conditions across the region, this information is among the most important we can share.

We always do so with a caution that long range forecasts are very often unreliable. But it is important to note that this unreliability goes both ways; dry forecasts can turn wet as easily as wet forecasts can fizzle into dry ones.

With that in mind, the various weather models are hinting that September may bring some early rain to Northern California. We’ve reported this previously, but there is a bit more consistency now that September is upon us.

First, the Canadian Ensemble forecast (averaging of more than a dozen model runs) definitely sees something going on. (Image 1)

Another, more detailed look at the Ensemble forecast. A tenth to half inch of rain across Northern California. (Image 2)

Now, not all models see rain arriving this early. Here is the European version of the same thing. (Image 3)

Digging further, we find that the American GFS model’s ensemble forecast (again, an average of lots of model runs), brings more hopeful news by mid-month. (Image 4)

It is important to note that there has been some consistency among models in the overall pattern, i.e. a weak La Nina year with average rains or better this fall. Here are the Canadian and Euro. (Images 5 and 6)

Very often in weak La Nina years, seasonal patterns like the Madden Julian Oscillation (thunderstorm patterns in the Pacific) can have more influence on West Coast rain. That may well be the case this winter. We’ll just have to wait and see.

For now though, there are as many reasons to be hopeful as not. Let’s cross our fingers that some early showers come our way and help to tamp down a very dangerous fire season!