Category 2 Earl Heads for Cape Cod

Hi, Dr. Rob Carver with your early-morning blog update. Earl is starting to pass the Outer Banks, all tropical warnings south of Cape Lookout, NC have been discontinued, and the hurricane watch for North Carolina has been canceled. Looking at our METAR history page, it is apparent the low pressure center of Earl is now moving away from Cape Hatteras.

As of 500AM EDT, Earl is still a Category 2 storm with sustained winds of 105 mph. From the advisory, Earl is located at 35.3 N, 74.0 W, 85 miles east of Cape Hatteras, NC and 465 miles south-southwest of Nantucket, MA. On average, Earl is currently moving north-northeast at 20 mph. The minimum central pressure is now 955 mb. Data from TRMM (Fig. 1) and WSR-88D radar data (Fig. 2) show that Earl's eye is large and poorly-defined.


Fig. 1 Estimated rainfall-rate of Earl from TRMM taken at 2AM EDT 3 September 2010. Image courtesy of the Naval Research Lab


Fig. 2 Reflectivity image of Earl taken at 5am 3 September 2010. Doppler velocity scan showing the large-scale rotation of the storm.

Even though Earl's winds are declining, he still covers a very large area. Hurricane force winds extend 70 miles from the storm center and tropical storm force winds can be found 205 miles away. 12 foot seas extend at least 220 nmi from the center in all directions and may reach out to 420 nmi in the southeast quadrant of the storm. The most recent wind field analysis (930PM EDT) shows that the winds associated with Earl are weakening. Earl's integrated kinetic energy is 74 TJ, with a wind impact of 2.5 out of 6 and a storm surge impact of 4.3 out of 6.

Track/Intensity Forecast

NHC has not altered their track forecast for this update. Now that Earl has been captured by the trough, it will accelerate off to the northeast towards Nova Scotia. At the same time, shear from the trough and cooler surface waters continue to weaken Earl. This forecast weakening calls for Earl to be a category 1 storm when he passes Cape Cod this afternoon and when he makes landfall in Nova Scotia tomorrow.

Earl will pass by the mouth of the Chesapeake Bay later this morning, bringing tropical storm force winds to much of the Mid-Atlantic coast. Tropical storm force winds will arrive in coastal New England this afternoon, and hurricane force winds will arrive later this evening. You can track Earl's progress up the East Coast with our storm-centered radar animation.

Winds Forecast
NHC puts out a very useful wind probability forecast. Nantucket, MA looks to be the place most likely effected by Earl today, there is a 97% chance of TS force winds. Boston, Hyannis, and Providence, RI have a greater than 50% chance of tropical storm force winds today.

Current Watches and Warnings
Hurricane warnings are valid for the coast from Cape Lookout, NC to the NC/VA border and for eastern MA from Westport to Hull. Hurricane watches are in effect for Nova Scotia from Medway Harbour to Digby. Tropical storm warnings and watches cover parts of the Atlantic coast from the NC/VA border to Nova Scotia

For the latest information on watches and warnings for Earl in the US, visit our Tropical Alerts page. For people interested in watches and warnings for New Brunswick and Nova Scotia, visit Environment Canada's watches and warnings page.

Impacts
The threats from Earl have not changed significantly since my previous posting.

The primary threats from Earl are going to be surf, wind, and storm surge. The wind threat is going to be greatest in eastern MA since the passage of Earl is expected to bring hurricane force winds to Nantucket. Eastern Long Island will have the greatest winds outside of MA, with estimated winds of 30-40 mph, with gusts to 55 mph. This is expected to bring down trees and cause trouble for older mobile homes. People elsewhere along the Mid-Atlantic and New England coasts should expect weak tropical storm force winds (less than 35 mph).

For storm surge, 1-2 feet are expected along the NJ coast, with 3 feet possible in some locations. Eastern Long Island may have 2-4 feet surges along the Long Island Sound and Petonic and Gardines Bay. The Boston NWS office is not concerned about storm surge, but they note 20-25 foot seas are possible off Nantucket.

Since Earl is going to be moving quickly, flooding from rain should be confined to poor drainage areas and urban area street flooding.

For more localized info, check out the NWS Hurricane Local Statements or our severe weather page.

What to do
It's time to batten down the hatches. People living in New England have less than 12 hours to finish their preparations. Be sure to listen to local media for statements from emergency management agencies and the local NWS office.

Next update
Dr. Jeff Masters will have an update later this morning.