Understanding Your Marine Forecast
Understanding Your Marine Forecast
by Capt. Brant McMullan
Every fisherman must consider the weather before making final plans to fish offshore. There is no escaping the reality of wind driven seas and the discomfort it brings and thus we seek to find the most favorable sea conditions on which to enjoy your fishing day. The resource most of us fishermen use is the NOAA marine forecast, however the trick is in knowing and fully understanding what you are reading and knowing when to read between the lines and when to apply a filter on some of the information. Here is how I read and interpret the information.
The first thing that absolutely kills me is their prediction of the sea height. As far as your fishing comfort goes, that is the THE most inaccurate, misleading and unuseable information you can use. The wave heights they predict are severely tainted as they typically include swell heights as well, which are really of no consequence to your fishing. The truth is that the wind is the key. A 10-15kt wind means 2-3 foot seas. A 15-20kt winds means 3-5 foot seas. 20-25 knots means 4-6+ foot seas. And variable wind, that is the holy grail as it means near flat calm seas. Now, if you read the marine forecast and it says winds 10-15 knots and seas 3-5 feet, there must be something wrong. Consider the weather the day before this forecast. Maybe it was rougher and thus the reason they are calling 3-5 feet is from some of the residual swell left over from the previous day. You read 3-5 feet and decide not to go fishing but it is truly a 2-3 foot day and a perfect day to be on the water. NOAA factors the predicted swell height into their seas forecast and that is what throws off the scale. The sea height will be overstated if the seas are in a decreasing state- ie. it was rougher the day before. Once the weather stabilizes and is constant for a couple of days and the swells lay down, the sea forecast will be more accurate. Final example is before or after a hurricane. The storm is throwing a big swell and that is predicted in the marine forecast. I’ve seen 10kt winds and 10-12 foot seas forecast before. The ocean can be a slick as glass with a long rolling swell, which is quite acceptable for fishing comfortably; not the menacing 10-12 foot forecasted. Keep this in mind, read the wind and not the seas, I promise you’ll get to go fishing more.
The other part of the forecast that I see misread is the difference between the nearshore marine forecast and the offshore marine forecast. The nearshore covers out to 20 miles and the offshore covers from 20 to 250 miles. 250 miles offshore is half way to the Flemish Cap, and there is a lot of weather that occurs between there and here. For fishermen, the majority of the time we stay inside of 20 miles, but when we venture offshore of that, you can’t let the offshore forecast scare you off. Truthfully, the nearshore forecast is much more relevant than the offshore forecast, even if you are traveling as far as the Gulf Stream. The offshore forecast is often filled with doom and despair of giant seas and heavy winds, when in reality those conditions may be far from where you’ll be fishing. The way I analyze the forecast is to read the nearshore and then I also read the offshore. I accept 75% of the nearshore and then pepper in 25%of the offshore to create my prediction for fishing offshore of 40+ miles. If its 10-15 nearshore and 15-20 offshore, I can expect to see winds around 15 knots and thus seas of around 3-4 feet.
The last resource to use is the data buoy off of Frying Pan Shoals. This is a key resource, particularly if you are going to be fishing 40+ miles offshore. Certainly the current wind conditions are important, but just as important is the data buoys last 12 hour history. You can compare what the wind has actually been blowing as relates to the forecast and in particular, you look at the trend of the wind. You want to see whether it is stable, increasing or decreasing. The optimal circumstance has the forecast decreasing and the data buoy corroborates that ie. Forecast= tonight winds 15-20kts decreasing to 10-15kts. Tomorrow winds 10-15kts. You plan to go fishing, but that AM before you go, you look at the Frying Pan buoy and it shows the winds overnight ranging from 15-17kts most of the night, but for the last 2 or 3 hour they’ve been consistently decreasing and are now at 13-15kts. It may still be a little choppy, but the data is consistent with the forecast and thus you can safely assume it will be a nice day as the winds should continue to decrease.
It seems like a lot to absorb, but the jist of what I’ve said above is not to take the forecast at full face value and use all the information you have to make a better prediction. Consider what conditions have been, what they currently are and what they are predicted to be and mesh that into a formula that will have you fishing comfortably and I’m sure, fishing more often.
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