Dolly And Bertha Satellite Pictures

As of Tuesday morning it is apparent that Dolly has the potential to cause some problems along the Gulf coast of south Texas and Mexico. The storm continues to strengthen and is headed in the general direction of Brownsville.

The picture above is NOAA visible satellite imagery from early Tuesday morning. Check out our Hurricane Tracker page for the latest information on Dolly……. http://www.wbaltv.com/hurricanes/index.html

While on the subject of hurricanes I wanted to show you a different type of satellite image. Infrared sensors on weather satellites record sea surface temperatures(SST) and provide forecasters vital information on the environment tropical weather systems will be moving into. Water temperature is an important factor in the development of hurricanes.

The satellite image below is from Monday, July 21. It is color coded and shows SSTs over the Atlantic, Caribbean and Gulf of Mexico.

First, look at the western Gulf of Mexico. The color coding shows that the water temperatures are running around 27-30 degrees celsius(80-86 degrees fahrenheit). This is a perfect water temperature environment for hurricane development and is one of the factors taken into account in developing a forecast for Dolly. Notice that the temperatures cool slightly right along the Texas/Mexico coast.

Perhaps the most interesting feature displayed on this satellite image is the water temperature in the Atlantic Ocean just east of Bermuda. The island is the white speck just north of the 30th parallel and west of longitude 60. Just east of the island the satellite image shows a band of SST values of 23-25 degrees celsius(around 75 degrees fahrenheit). This north/south band of cooler water is positioned exactly along the track that Bertha took earlier in July. Bertha slowed down as it approached Bermuda and moved slowly northward as it passed just east of the island. This strip of cooler water is the result of Bertha’s churning of the ocean and bringing cooler water to the surface. The churning effect very likely played a role in weakening Bertha as it approached Bermuda. A loop of the satellite images showing the upwelling of this cooler water can be found at http://www.ssd.noaa.gov/PS/TROP/DATA/RT/sst-atl-loop.html

Satellite images like these are a beautiful demonstration of the interaction of the ocean and the atmosphere. It is a complex process and one that makes forecasting weather in the near or long term a challenge and, at times, less than perfect.

John Collins

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