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Category 3 Earl Continues Moving Towards the East Coast

By: Dr. Jeff Masters, 4:13 AM GMT on September 01, 2010

Hi, Dr. Rob Carver with your evening blog update. It's a busy night in the tropics with Hurricane Earl and Tropical Storm Fiona in the Atlantic, and 3 named storms in the western Pacific. Tonight, though, we'll focus on Earl.

As of 11PM EDT, Earl is still a Category 4 storm with sustained winds of 130 mph and gusts of 160 mph. From the advisory, Earl is located at 23.0 N, 69.9 W, 910 miles south-southeast of Cape Hatteras, NC. On average, Earl is currently moving towards the northwest at 14 mph. Remember, large storms are known for having wobbly tracks. Aircraft observations and microwave imagery (Fig. 1) indicate that the eyewall is reforming.

Fig. 1 Estimated rain-rate of Earl taken at 2332Z 31 Aug 2010. Image courtesy of the Naval Research Lab

Earl is passing near buoy 41046 and is generating some large waves as shown by Figure 1.

Fig. 2Plot of wave heights observed at buoy 41046. Data courtesy of the National Data Buoy Center

Earl is a large storm. Hurricane force winds extend 90 miles from the storm center and tropical storm force winds can be found 200 miles away. This means Earl will have an impact on areas well away from the center's track

Track Forecast
NHC has not really altered their track forecast for this update. Thanks to the subtropical high, Earl will continue a slight turn to the right as it moves around the subtropical high. Then when a trough in the jet stream comes out on Thursday, Earl will accelerate quickly to the northeast. The timing of the trough's arrival will determine Earl's impact on the East Coast. The current forecast still holds that Earl's center will stay out to sea, and I don't see any reason to disagree. Most of the computer model guidance supports this forecast (except for NOGAPS and NGFDL, and they have Earl only crossing the Outer Banks). It is worth noting that the ECMWF global model (the best global model) does bring Earl close to the Outer Banks. Earl will make his closest approach to the Outer Banks sometime early Friday morning.

Winds Forecast
Earl's size and track will likely produce tropical-storm force winds somewhere along the East Coast this weekend. From the wind probability product issued by NHC, Cape Hatteras has a 63% chance of tropical-storm force winds sometime this weekend. There is a wide swath of 30% chance of TS winds from Virginia north towards Maine. New York City has a 20% chance of TS winds, and Nantucket, MA has a 50% chance.

When Earl hooks on to the trough and starts accelerating to the northeast, it will start transitioning from a tropical system to an extratropical low. This means it will start weakening.

Current Watches
As of 1045PM EDT, a hurricane watch is in effect for the coastal US from Surf City, NC to the NC/VA border. Remember, this means tropical-storm force winds are expected within 48 hours. A tropical storm warning has been issued for the Turks and Caicos islands. A tropical storm watch is also in effect from Cape Fear to Surf City and for the southeastern Bahama islands. For the latest information on watches and warnings for Earl, visit our Tropical Alerts page.

It's too early to be specific. That said, the local NWS office in Morehead City, NC thinks that with the combination of tides and winds, a storm surge of 4 feet is possible along the Outer Banks with moderate coastal flooding possible. They also think rip currents are a likely threat at the beaches.

What to do
People living in areas covered by the hurricane watch should start following their hurricane preparation plans now. You have less than 48 hours to complete your preparations. Be sure to listen to local media for statements from emergency management agencies and the local NWS. If you live in areas prone to flooding, evacuate to a hurricane shelter or a place outside evacuation zones. If an evacuation order is given, please follow it.

People living from Virginia to New England should monitor the progress of Earl and think about their hurricane preparations.

Fiona stayed too close to big brother Earl and is paying the price. Outflow from Earl is expected to create shear, transforming Fiona into an open trough. It's forecast to dissipate in 2-3 days.

Earl has weakened to a category 3 storm with maximum winds of 125 mph. NHC has extended the hurricane watch from the NC/VA border to Parramore island. The track forecast has shifted a bit to the west, so the chance of tropical-storm force winds in the New England area has gone up. For example, Eastport ME has a greater than 50% chance of tropical storm force winds now. For more cities, take a look at the wind probabilities product. Intensity forecast is relatively unchanged.

Fiona is starting to build a little more space between herself and Earl. If this keeps up, Fiona might have a shot at survival. This is worth keeping an eye on.

Next update
Dr. Jeff Masters will have an update Wednesday morning.


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.