Re: [Paddlewise] Mexican expedition crosses by kayak the Sea of Cortes in Baja.

On Wed, Apr 23, 2008 at 12:35 PM, Rafael en prodigy <
silidriel_at_prodigy.net.mx> wrote:

>
> The weather predictions through Weather Channel and Mexican official navy
> and electrical utility were not good enough to really show what was going
> on
> locally. We had better luck with


I spent considerable time (several years, actually) in the Sea of Cortez on
a sailboat along with what was then dozens (probably hundreds, now) of
others in the cruising fleet. There is a very reliable weather reporting and
forecasting system in place but it all takes place on the 40-meter amateur
radio band. It used to be 7235 LSB at about 8am but it's probably something
else by now.

>From about November through April the weather in the Sea of Cortez tends to
be fine except for occasional bursts of northerly winds which typically last
for 1 to 3 days and then relapse into the fine weather again. In about 1980
we finally figured out what causes them and how to predict them.

The Sea of Cortez lies between two mountain ranges; a significant cordillera
to the west on the Baja peninsula and then the Sierra Madre to the east
(although farther from the coastline than the western mountains). The Gulf
Northers are a typical thermal low fed by a cool high pressure. The high
pressure is typically located in the eastern California and Nevada and
Arizona deserts north of the Sea. Thermal warming causes a low pressure area
in the Sea of Cortez and the cool dense air north flows down from the
deserts a funneling between the mountain ranges into the low pressure;
creating blustery northerly winds of up to 40kts (but typically more like 25
to 30). These winds have hundreds of miles of fetch so the seaway they raise
can be significant. The winds die completely at the tip of the Baja
Peninsula even when they are blowing heavily only ten miles north.

These winds can be predicted if you pay attention to the AM radio weather
reports for the CA, NV and AZ areas. If they are having cool, sunny days
then expect northerly winds. If it's raining then you'll have fine clear and
warm (well relatively warm, anyway) weather in the Sea.

A gulf norther can create heavy going for even 40-foot sailing yachts;
especially if they are trying to go north.


Craig
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