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Thursday, October 19, 2017

The Significant Storm of the Season

The Seattle Times called it the onset of the "Big Dark", but those who know Northwest weather call it the "Big Normal".   Right on time we are enjoying the stimulating strong winds and heavy rain of a potent Pacific front.  And quite honestly, it feels good. 

Winds have gusted to 50-60 mph along the coast and over parts of Northwest Washington, and even here in Puget Sound we have had gusts above 40 mph at exposed locations (and 25-35 mph elsewhere).  The map of the max winds in the 24h ending 7 PM wed is shown below.


Strong winds, untested vegetation with summer growth, and trees with leaves have resulted in thousands of customers losing power around the area.   Here is the Seattle City Light outage map at 7 PM.  Puget Sound Energy has 36,000 customers in the dark.


As I write this blog, a very wet front is moving through the region, as shown by the 7 PM radar.

In fact, we are experiencing a modest atmospheric river that is bringing warm, moist subtropical air into the region (it was near 60F last time I looked).  A satellite image of the vertically integrated water vapor in the atmosphere shows the plume of moisture from the southwest, originating from north of Hawaii.  You can almost smell the pineapples.

The latest infrared satellite image clearly shows the juicy frontal zone clouds associated with the "river."  And potent instability clouds (the popcorn-looking clouds out in the Pacific) are ready to move in tomorrow


A strong front is embedded in the plume of moisture, something a trained eye can tell from the coastal Langley Hill radar image late in the afternoon (see below).  You see the corrugated pattern offshore, with orange/red colors?  That is a strong cold front with a narrow cold frontal rainbands.   These always reflect strong fronts. And that front is now moving across Seattle, with pouring rain and strong winds.  I have to admit, I love it.

Plenty more rain will fall during the next few days.  Here is the total for the 72 hr ending 5 AM on Monday.  5-10 inches over the western slopes of the Olympics and Washington Cascades.  Fire season is over. Our reservoirs will start to fill.  Our rivers will be refilled.  And the "Big Normal" is back..




from Cliff Mass Weather and Climate Blog http://ift.tt/2yxoLdK

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