Set to music of Dire Straits: “I want my NPH”
by Mike Godsey, mike at iwindsurf.com
The Gorge and the Bay Area are going through a unseasonal wet weak wind period. Normally after a cloudy period like this a burst of wind returns as the North Pacific High slams back to the west coast to reclaim its summer turf.
But today and tomorrow a combo of a slow moving storm off the West coast and a tropical storm off Baja and an upper high over the mid west have the North Pacific High lurking way out in the pacific NW of Hawaii.
This leaves the Bay Area and the Gorge without the high pressure needed to drive their thermal winds.
So first study the graphic here to get oriented then study the model video of the North Pacific High wobbling around today and Wednesday.
First find the main body of the North Pacific High and note the NW winds on its eastern side. Those winds should be hitting the California coast this time of year.
Now notice the huge wintry type storm west of the Gorge ands its counter-clockwise spinning winds. This surface low, along with the shortwave upper trough ≈ 18,000 ft. feet have pushed the North Pacific High far from the west coast.
Normally a storm like this moves quickly to the East and the North Pacific High slides up to the west coast and the winds ramp up fast. But this storm is moving very slowly due to an upper level high pressure in the middle of the USA. In addition there is a tropical storm you can see west of Baja that is blocking part of the NPH. So the North Pacific High is being squeezed between the 2 storms so it can not rush back to the west coast. Hence we see weak winds today and tomorrow.
Now look carefully at the last frame of the animation.
See the sliver of the North Pacific High break off from the main body and snake its way towards the west coast. See it stack a few isobars (representing the pressure gradient) along the California coast. That will bring a bit of NW wind to the Bay Area and Thursday afternoon.
Normally the main body would arrive the next day bringing big winds to the Gorge and the S. F, Bay Area. But remember that upper level high pressure I mentioned in the middle of the USA? The models have it moving over the S. F. Bay Area and the Gorge by Thursday bringing on a heat wave which would weaken any wind.
Let’s hope the models are wrong about that heat wave since we are way overdue for some strong summer wind.
Of course weather savvy Southern California kiters and sailors are praying for the upper level high pressure since it will bring solid winds to the coast.