Wednesday, July 27, 2011

High Pressure Ridge Main Factor For Where Don Will Go

Tropical Storm Don will continue his west-northwestward jog through the Gulf of Mexico over the next 36 to 48 hours. While there is a high certainty he will make landfall along the Texas coast, the answers aren't as clear as to where along the coast that will be.
The steering currents, or the wind direction, is the overriding factor as to where tropical systems will end up going. Just like wind aiding along a sailboat, the winds in the mid levels of the atmosphere will ultimately decide where Don will go in the days ahead.

The main steering current will be our large dome of hot, high pressure. It is expected to strengthen and move towards the Southeast United States. With that clockwise flow around the ridge, Don will continue his northwestward trek through the Gulf.

The tricky part comes in how strong will the ridge become and where exactly will it be positioned. If it is slightly weaker or farther away than models indicate, then Don could take a northward jog, meaning the upper Texas coast is in line to see a direct landfall Friday evening. However, if the high pressure ridge is as strong as the models make it out to be, then Don will probably end up making landfall somewhere around Corpus Christi or far South Texas.

Our rain chances on Friday will be soley dependent upon Don's position. Because he is not a broad system, the rain bands will be confined to areas in and near the low pressure center. So while we typically don't welcome tropical storms to the state, this time around is different. After all, we've been saying all along that a tropical system is what we need to help alleviate the ongoing extreme drought.