Tuesday Tropical Update

Hurricane Earl continues its’ west-northwest track as a category 4 storm with 135mph winds. The trend of edging the forecast track slightly west with each new forecast model continues.

The key to how close Earl comes to the Mid Atlantic coast lies in an upper level disturbance moving in from the Midwest.

The graphic above is one computer model’s upper air forecast for Friday morning. Earl’s position off the mouth of the Chesapeake Bay is obvious. The dip in the “height lines” and the alignment of the wind barbs over Minnesota, Wisconsin, Iowa and Illinois delineates the disturbance. The circulation around the disturbance near the Great Lakes will eventually push Earl eastward but this disturbance is apparently slowing down and that is why forecasts are calling for Earl to move a little closer to the East Coast.

Computer models also forecast what radar echoes will look like at a given time.

This computer radar simulation is for Friday morning. Earl is producing rain along the Mid Atlantic coast. The Midwest disturbance is generating rain in the upper Midwest and Canada. Rainfall related to Fiona is shown from the island of Hispaniola northward.

The late Tuesday morning forecast track for Earl is below.

This track places the core of Earl off the DELMARVA coast. At this point Earls is still forecast to be a major storm with 130 mph winds, gusting to 160 mph. Tropical Storm force winds would most likely be the rule along near the Mid Atlantic coastline if this forecast turns out to be correct. Dangerous surf conditions, gusty winds and perhaps some precipitation from outer rain bands will be the most likely effects from the storm as seen at this time. The storm is still a couple of days away and changes in the forecast track and impact on the Mid Atlantic region are possible.

The image below is the midday Tuesday satellite image.

Hurricane Earl is the large storm north of the Caribbean Island of Hispaniola. Close behind is Tropical Storm Fiona. Farther east is a tropical wave off the East African coast that has some potential for development into a tropical cyclone. On the edge of the image there are two additional disturbances over Africa heading for the Atlantic.

Fiona continues to have a tough time becoming well organized, perhaps because of its’ proximity to Earl.

Computer models forecast Fiona to turn northward  and pass closer to Bermuda as a tropical storm by the end of the weekend. Fiona’s earlier turn north is being influenced by the same Midwest disturbance that will likely prevent Earl from moving inland along the U.S. East Coast.

These storms and any new ones coming off the African continent are traveling in a rich environment for tropical cyclones.

Water temperatures over the central and western Atlantic are very warm. The orange and red shades indicate sea surface temperatures in the low to mid 80s. These temperatures are slow to change so the next few weeks hold a lot of potential for any storms that move over these waters. The other controlling influence is upper level winds and these change from day to day so the guessing game continues.

Check out the latest on the tropics on our web site  http://www.wbaltv.com/hurricanes/index.html

You can also watch Tom, Tony, Sandra and me this week for live updates during WBAL-TV 11 newscasts.

John Collins