By Mike Godsey
Check out my mail from June 8 about 3rd. Ave. launch winds! Whining is fun but feedback improves forecasts! Feedback.

In the last decade, we have seen more days with WSW flow in the Hwy in 92 Gap and the nearby coast range area.

These winds, sometimes called “Evil Winds” can mess up the launch site winds. They also make our forecast for good channel winds frustrating.

(This recent blog talks about one of the causes of these southerly coast winds.)

This WSW flow, often called the “Evil Wind” at 3rd. Ave., is diffuse and turbulent since the gap is not at sea level and there are many canyons and buildings in its pathway towards the 3rd. Ave. launch.

The WNW pathway for the “Good Wind” to 3rd. Ave. is from the near sea level San Bruno Gap is low friction and primarily over water from the ocean to the Bay.

When the turbulent weak WSW flow just aloft hits the strong WNW surface wind, its impact on the 3rd. Ave. shore winds are highly variable and fast-changing.  But often, the “Evil Wind” pushes the WNW away from shore, leaving you with UP and Down lulls and shifts near shore.

With any hint of southerly ocean winds, things can change fast between our forecast time and your arrival at the parking lot.

Using sensors between Half Moon Bay and 3rd. Ave. 

to judge the likelihood of WSW “Evil Wind” at launch sites

We now have 18 Weatherflow Tempest consumer weather stations sited between Half Moon Bay and 3rd. Ave., as well as 6 Public Domain sensors and of course our Golf course and Channel ProNet stations.

We use all these in forecasting, but things often change fast

between the forecast time and your launch.

This infographic tells you how to use those sensors to get a better hint about what to expect at the launch sites as the “Good wind” and the “Evil wind” battle.

You can see some of these stations on and by zooming in on our wind map pages to judge the extent of WSW flow before making a long drive to 3rd. Ave. 

This last image shows a computer model of the battle between the “Good wind” and the “Evil wind”.

Notice how the battle line is right over the 3rd. Ave. launch sites.

This is the type of day described in the e-mails at the top of the page.