Friday, July 17, 2015

Why won't a tropical storm EVER hit the Pacific Northwest?

By Cliff Mass July 16, 2015

Hurricane Dolores is prediction to move up Baja California  and reach the offshore waters west of San Diego by Tuesday AM (see graphic), but it will never reach us.

No tropical storm will ever reach our shores (as a tropical system that is).  The reason?  Because the eastern Pacific off our coast is too cold.

Hurricanes, Typhoons, and tropical storms in general require warm sea surface temperatures, specifically, above roughly 80F or 27 C. 

Here is a recent sea surface temperature analysis over the eastern Pacific.   The 27F contour is the at the boundary between yellow and yellow/green.  The hurricane will soon enter a region that is too cold for development....and the system should progressively weaken.    No tropical storm can even get close to us.

 The visible satellite image Thursday afternoon (see below) has a lot of interesting features, but none struck the eye like Hurricane Dolores moving up the Mexican coast (A).  There is also low clouds (stratocumulus/stratus) moving up the coast (B), clear skies where continental air is pushing offshore (D), and ship tracks, where particles from ship exhausts are producing lines of enhanced cloudiness (C).

Will things change under global warming?  No chance.   Remember this year has much warmer than normal water offshore and we are not even in the neighborhood.  Even more important is that our average sea surface temperature (around 50F) is roughly 30F colder than the minimum.  So it won't even be close- sea surface temperatures might become 5-10F warmer in a century---not anywhere close to 80F.

But the water temperatures around Hawaii are on the margin, so they will have to be watchful. 

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