April 8, 2017

Effect of a Cold Front as Seen From Space


We've seen the impact of a strong cold front up close, but this is how coastal Louisiana is affected as a whole.

Cold fronts are a weather phenomena anglers put up with fall to spring. They can bring heavy rains, cold temperatures and, worst of all, strong winds from the north and west.

This change in conditions can radically alter the marsh by dropping water levels and wiping the sky clean of cloud cover. If and when the water gets low enough, waves created by wind will roll on the bottom, stirring up silt and organic detritus.

Knowledge Bomb

This is how the water gets dirty and the chief reason a west wind is the bane of inshore anglers in Louisiana. 

It's important to note the water only turns to "chocolate milk" when it gets significantly low. Otherwise it wouldn't get dirty at all.

The Gulf of Mexico is a good example of this because the depths are too great for waves to roll across the bottom.

Remember not all cold fronts are created equal. Some are more potent than others and this can be seen in the degree of temperature drops and wind changes.

Effect of a Cold Front as Seen From Space

MODIS Today is a mapping tool hosted by the Space Science and Engineering Center at the University of Wisconsin.

The imagery is compiled from advanced sensors flying aboard NASA's Earth Observing System. Every day, two satellites (Terra and Aqua) make passes over the United States and take pictures.

If the sky is clear (like after a cold front) then we have an unobstructed view of the marsh.

There are three resolutions available:

  • 2000 meters per pixel
  • 1000 meters per pixel
  • 250 meters per pixel

You want to use 250m to get the best resolution. While you can't zoom in super close, you can still get a good overview of the marsh and determine where clean water is.


The pictures below are thumbnails. Click on them to see the actual photo.

They are all 4MB to 5MB so they may take a little longer to load depending on your connection.

You can also click here to see the wind speed and direction recorded at the Shell Beach Buoy in Lake Borgne. 

April 4th, 2017

This is the day before the cold front hit. Winds were light and variable all day. It was a pretty day to go fishing!

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April 5th, 2017

This is the day the cold front hit Louisiana.

Click to Enlarge

April 6th, 2017

The day after the cold front. Compare to April 4th and you can already see some distinct changes in water clarity. If you're lost as to what good/bad water clarity is, then use the Mississippi River as a reference for "dirty" water and the Gulf of Mexico for clean water.

Also, on this day we had northwest winds gusting to nearly 40 knots! That is guaranteed to hose the marsh!

Click to Enlarge

April 7th, 2017

Click to Enlarge

April 8th, 2017

On April 8th the wind has laid down and the water is beginning to clean up.

How is this important to us as inshore anglers?

The effect of a cold front as seen from space shows us where water stays clean and water does not.

The Mississippi River Gulf Outlet has largely remained unaffected. You can tell by how dark it is.

If I were going fishing that's the first place I would hit up, so long as the wind was not blowing down its middle.

We also see where clean water goes once water levels drop significantly. Look at Lake Pontchartrain to understand what I am talking about.

You can see the clean water dumping out of Bayous Lacombe, Cane, Bonfouca, etc. That water is being pulled across the northern shoreline.

It may be worth looking there to see how clean it is and if fish are there or not.

If so, you will have learned something that puts you ahead of the power curve!

Captain Devin

About the Author

Devin is a former fishing guide and lifelong inshore angler. He founded Louisiana Fishing Blog in 2012 to share his ideas as a charter captain and still writes in it today. Since then he's created a fishing university — LAFB Elite — where he teaches inshore anglers how to safely navigate Louisiana's coast and catch more fish.

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