Update: Friday’s Atmospheric River Fading

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Things can change pretty quickly in the spring.

For the last few days, forecast trends have shown weakening in the expected atmospheric river event for Friday.   In fact, the storm is now losing much of it’s tropical moisture feed, and the latest model runs are forecasting this system to produce only moderate rain amounts across the North Bay on Friday into early Saturday.

For now, the system still qualifies as a borderline AR event, due to the moisture plume it continues to push eastward toward the Pacific Coast.  Here’s what it looks like out in the Pacific.

Yes, the incoming storm still looks fairly impressive, but you might also notice how quickly it’s moving.  A strong mid level jet stream is pushing it along so quickly that it’s rapidly losing its subtropical moisture connection.  What that means for us is a less moist, fast moving system.  And that means less rain will come our way than most models, just a day or two ago, were forecasting.

Current expectations are for just a half inch of rain Friday and early Saturday in Santa Rosa, Rohnert Park and Sebastopol, with up to an inch and a half in wetter locations in the North Bay.

Looking further ahead, Sunday should have sun breaks and slight warming.  However, the storm track will stay active just to our north through midweek, giving us clouds at times and cool weather through midweek.

And next weekend?  Yes, April will apparently not give up without a fight.  It looks like a cool trough may drop down the coast, possibly giving us a wet weekend of the 13th.  You can see the long range forecasts show a cool, showery pattern over the Western U.S.  Stay tuned for more on that.

 

 

 

 

 

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