Rainy, but No Flooding

December 4, 2012

As expected, a wet night and day today, but nothing extreme.  Notice we’ve seen less than 1″ of rain since midnight (so far) in the bulk of our viewing area.  Still, I sure got soaked downtown around 1pm during a downpour!

PLOT_Rain_Autoplot_Valley

Where do we go from here?  A nice day Wednesday by December standards.  Just partly cloudy with a chance of a shower here in the metro area.  Temps still around 50 too.

Thursday and Friday we’ll see some great snow in the Cascades, maybe 12-20″ during that period.  And snow levels drop down closer to 2,000′.

Of course that means cool showers here in the lowlands; high temps only in the 40s.

Beyond that, models are definitely not digging the cold upper trough for Friday and Saturday as much.  When a cold trough just continues moving east instead of digging sharply, it keeps the cold air farther north too.  In fact no 12z or 18z model output shows the possibility of snow sticking below 1,500′.  Most of them are just up in the usual 2500-3000′ range.  Translation?  Snow in the lowlands sure won’t happen later this week, and now it looks unlikely much below 2,000′

Beyond that?  More of the same setup mentioned in yesterday’s post.  Ridging just off the West Coast through the foreseeable future.  If the ridge moves slightly farther west (offshore), expect a surge of cold air and lower snow levels.  Right now I don’t see that in the next 7 days.  But stay tuned, at any time things could change.  I notice the 12z ECMWF and GFS ensembles both try to retrograde the big ridge around Day 12-15.   Not all the members show that, but it’s something to watch.

Chief Meteorologist Mark Nelsen


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