Chance of Rain Increasing

The chances of rain are increasing a bit for Wednesday through Thursday. Rather than just showers developing over the mountains, the weak weather system aloft is starting to look a bit stronger.  As a quick demonstration of this, here is the rainfall forecast for Wednesday through Thursday morning that was made by the European model on Sunday.  Only gray shading (i.e. less than 0.10”) for the valleys. Other models showed even less than this. 



Now here is the same forecast made by the model today.  Notice that there’s more green shading (rainfall amounts above 0.10”) over a greater area, all the way down to Spokane and Moses Lake.  The rainfall predicted for the north Cascades is right where the two largest wildfires are located. 


The timing is still about the same. Showers and thunderstorms will form over the northern mountains by mid-afternoon Wednesday.  But instead of shutting down in the evening, the strength of the storm could keep them going all night in some areas. Thursday will be much cooler with continued chances of showers and thunderstorms. Again, they look more widespread over the northern counties than they did a couple of days ago. 

It’s worth noting that there’s a number of computer forecasts that disagree.  They keep all of the rain up by Colville and Republic. A few being rain as far south as Tri-Cities. So this is far from a slam dunk forecast.  Here’s a sampling of this forecasts that you can compare to the European forecast I showed you above.  





When we have all of this disagreement, we usually rely on the average, or blend, of all of the forecasts. This is what that looks like.



Here’s the blended forecast for Newport. The top graph is the probability of rain, and the bottom graph is the predicted amount of rain.


A couple of things to note. After this one weather event Wednesday and Thursday, there will be more chances for most of next week.  We’ll have to wait to see what the details will be. The predicted rainfall amounts at this point are encouraging, but I wouldn’t put much faith in a forecast that far out. 











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