Friday, October 24, 2014

An Update on Windy Weekend and Hurricane Ana

The Inland Northwest will see some interesting weather over the next 4 days.  First, we have a strong Pacific storm moving through the area this weekend, then the potential for remnants of Hurricane Ana.  First, let's update the forecast for the weekend wind.

The satellite shows a beautiful storm off the West Coast.  The warm front of this storm is the cloud band stretching from Washington into Montana.  The cold front is the cloud band that extends from western Washington southward off the California coast.  The warm front is bringing us rain this evening.  It will lift northward into BC.  Then we'll have a dry start to Saturday, before the cold front brings more rain Saturday afternoon/evening. 

Infrared Satellite at 730pm PDT 24 Oct 2014
Here's the UW WRF forecast of wind gusts as the low approaches the coast.

The dark blue colors along the southern Oregon coast are gusts around 60 kts (70 mph).  There's already a high wind warning out for that area.

As the low moves onshore and eastward across the US/Canadian border, winds will increase Saturday night over the Inland Northwest.  The cold front should move over the Cascades around midnight, and reach the Panhandle before sunrise.  That's when the winds will be strongest.  Below is the forecast for 5 am Sunday:

The green shading in southeast Washington is 35 kts (40 mph).  There's a bulls-eye of 60 kts over the Blue Mountains.

But this computer forecast looks too conservative.  The pattern of a deep low passing just to our north is a common pattern for high winds here.  Actually, the perfect pattern for really strong winds is where the low tracks just a little farther to the north.

So for the area from Spokane/Cd'A down to Lewiston and over to Tri Cities, expect wind gusts to 50 mph Saturday night into Sunday morning.

Then our attention turns to Hurricane Ana, churning northwest of Hawaii.

IR Satellite image 830pm PDT 25 Oct 2014

Here's the GFS forecast Friday evening.  The little white circle with the yellow shading is Ana.

GFS forecast of SLP (white lines) and precipitation (shading) for 11pm 25 Oct 2014

By Saturday afternoon, the Pacific low has picked up Ana and is moving her remnants to the north.

GFS forecast of SLP (white lines) and precipitation (shading) for 5pm 26 Oct 2014
24 hours later, the low is moving into the Gulf of Alaska towards the Canadian coast.

GFS forecast of SLP (white lines) and precipitation (shading) for 5pm 27 Oct 2014
And finally by Tuesday morning, the rain has reached the Inland Northwest.

GFS forecast of SLP (white lines) and precipitation (shading) for 5am 28 Oct 2014
Here's the track forecast from the Central Pacific Hurricane Center in Hawaii:

We can't remember ever seeing a situation quite like this.

So on Tuesday morning, as the rain falls on your windshield as you drive to work, you can thank Hurricane Ana for providing some of the moisture to the Inland Northwest.  

Once again, by the time this reaches the Pacific Northwest, it will not be a tropical storm, just the moisture remnants of it.  Still, it's kinda neat to think that our rain came in part from a Hurricane.

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