Two Strong Fronts Are Approaching

For those those worried about dry conditions, additional relief is on the way.

Two strong fronts are approaching for this weekend.

The first arrives Saturday morning and it is interesting to watch it get modulated and weakened by our mountains..  Let me show the the 3-h precipitation predicted by the UW model.

For the period ending 8 AM Saturday, you can see the front making landfall, with the precipitation just reaching Puget Sound.


Three hours later is has reached the Cascades, with the mountains locally enhancing rainfall.

 But then dramatic change in the frontal rain is evident (2 PM shown): as the front descends the eastern side of the Cascades, the downslope flow greatly weakens the front and its associated rainfall.

And by 5 PM the frontal rain has reached the Rockies, where it is enhanced .  Note the residual showers on the western slopes of the Olympics and Cascades well behind the front.  Quite typical.

 The total precipitation for the entire frontal passage (through Sunday at 5 AM) shows the overall story, with up to around an inch in the Cascades, nearly nothing on the lower eastern slopes of the Cascades and modest amounts over the Rockies.   Classic.


And then we do it all again, late Sunday and Monday morning (see precipitation forecast for 2 AM Monday).


With these two fronts, April rainfall will have recovered to be in striking distance of normal. 

The first front will have a sharp wind shift and decent winds, particularly over the coast and Northwest Washington--the UW/Seattle Windwatch guidance shows the story at 6AM Saturday, with some gusts above 40 mph.
Enjoy the fronts....and Sunday looks like the best day to get out...or at least as out as you can be these days.

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