Basic Forecasting Manual
Key Words.
Fetch-
Oceanography.
a.an area where ocean waves are being generated by the wind.
b.the length of such an area.
Offshore (as defined by NOAA)-
Waters beyond 5 nautical miles of the shore.
Nearshore-
Waters within 5 nautical miles of the shore.
Atmospheric Pressure-
1.the pressure exerted by the earth's atmosphere at any given point, being the product of the mass of the atmospheric column of the unit area above the given point and of the gravitational acceleration at the given point.
2.a value of standard or normal atmospheric pressure, equivalent to the pressure exerted by a column of mercury 29.92 in. (760 mm) high, or 1013 millibars (101.3 kilopascals).
Front-
A weather front is a boundary between two masses of air of different densities, and is the principal cause of significant weather.
Nautical Mile-
a unit of distance used chiefly in navigation, equal to 6080.20 feet (1853.25 meters) in the U.S.
Forecasting the Weather:
Always Remember: Wind direction is always where its coming from not where it is going. IE. A north wind is actually blowing winds toward the south
Understanding Highs and Lows:
in the northern hemisphere High pressures spins clockwise around a central point. (think hurricane but on a mini scale) and Low pressure spins counter clockwise
Pressure systems generally to move easterly at about a rate of 700 miles per day in the winter and 500 miles per day in the summer.
Generally speaking a low pressure system sitting over the Lower peninsula of Michigan is producing NE winds on superior. That said there are variations that can make it better or worse. Take for instance a few high pressure systems counteracting it, thats just one of many things that can stop it. Ideally that low would sit there for a day or 2 and move on leaving a lot of waves to come down from the top of lake superior. This is where fetch comes in. The more fetch the bigger and generally better the waves will be. the best conditions will be found once a low pressure has stopped blowing or moved out of town. This leaves all of the waves that were generated further up the lake to come strolling in when the lake is nice and glassy. I'm not going to get into how waves work but it is a very interesting topic and you can do some reading on it here: http://www.virtualnjshore.com/tbwaves.html
one more thing
Low pressure = snow storm
Why dosent the begining of a high pressure system work you ask?
well generally a high pressure system just lacks the wind needed to create waves. Low Pressure Brings the cool air in and High Pressure brings the cool air out.
Cold fronts are created by eastern moving mass of cold air hitting a mass of warm air the cold air rushes under the warm mass and can creates wind. Cold Fronts are denoted by points on a line where the point is pointing in the direction that the front is moving.
Southern winds are most common to the Great lakes.
Why is the winter so much better?
in the winter there is much more potential for low pressure. another leading role is friction. When the wind is colder it creates more friction with the water surface. Generally the best times to surf are when the air is much colder than the water.
for more info check out the wikipedia article on surface analysis.
Internet Forecasting:
the NOAA has made forecasting the Great Lakes easy and generally effective for us. if you check the offshore and see a NE20-25 kts for a day or longer you can bet if its winter there are waves.
here is a general synopsis of what I do when I check the internet.
Check the Offshore:
see if there are any winds at all on there if its reading 20-20+ kts Check the Maps
Checking Maps:
I usualy check the HPC surface analyses first to see what kind of weather is coming in and then check the RAP surface wind to see more specific winds.
If I see that there is wind coming the night before I go I look at a few things:
Checking the buoys .:
I will look at theiwindsurf site to see realtime updating of what winds are blowing what directions on the lake. then ill check buoys individually if I need too. I will then Check Sky Harbor to see the wind data near park point. If this is showing NE 20+kts for 12+ hours chances are that there will be waves at at least park point.
The morning before I go:
Check Sky Harbor and Cams:
Check Sky Harbor to see if the wind has run out. if it has dont give up just yet there is still a lot of potential. Next ill look at the cams most of the time I look at the LSMMA CAM as it has a good picture and it is very revealing in height and cleanness in comparison to the pier. its a good sign to see swell rolling through here(see pic below for an example) It is a general give away if there are waves breaking on the rocks to the left. Another thing to keep in mind, there is enough light shed from the pier to see waves breaking on those rocks at night.
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I hope this helps in your quest to as Jon K would say "harness some wave energy!"
There are many more sites linked to from this site and they can all give you just a little bit extra insight to the wave catching process. I encourage you to learn the weather and set up a routine for looking at the internet forecasting sites these two things will help you greatly in your search.
on a parting note. remember. GLCFS waves is not nearly as accurate as it should be.