The National Hurricane Center expects Arthur to make landfall as a Category 2 hurricane on the morning of July 4, with peak winds around 105 mph. The Post's Jason Samenow gives an updated forecast for the holiday weekend. (Tom LeGro and Jason Samenow/The Washington Post)

11:00 a.m. update: Arthur is continuing to intensify with maximum sustained winds now 90 mph, as of the 11 a.m. National Hurricane Center (NHC) update. Significantly, NHC now expects Arthur to make landfall as a Category 2 hurricane, with peak winds around 105 mph Friday morning (around 8 a.m.)

Original post, from 9:47 a.m.: Arthur was upgraded to the season’s first hurricane at 5 a.m. EDT today, and has begun the turn toward the northeast that will take it very near the Outer Banks late tonight.   The intensifying storm poses multiple hazards for the North Carolina coastline including a 3-5 foot (or more) storm surge, several inches of rain and strong tropical storm to even hurricane force winds.

Enhanced infrared satellite image of Hurricane Arthur at 7:15am EDT. (NASA)

Tropical weather dashboard
System type: Category 1 Hurricane, Arthur
Intensity: 90 mph, 981 mb (updated 11 a.m. EDT)
Location: 95 miles southeast of Charleston, SC
Intensification potential: Medium (confidence: medium)
Landfall potential: High (confidence: high)
Days from possible landfall: 0.5-1
Zones to watch for possible landfall: North Carolina (confidence: high)
Will if affect VA/MD/DE beaches? Yes, during day on Friday (confidence: high)
Will it affect D.C.? Not directly, but cold front with enhanced t-storms today (confidence: medium-high

Intense rainbands already have or are affecting most of the South Carolina coast and some of the southern North Carolina coast. Much of coastal North Carolina is under a hurricane warning. Northern South Carolina and southeast Virginia, around Virginia Beach, are under tropical storm warnings. Farther inland, flash flood watches extend from Virginia up to Maine (more related to a cold front passing through infusing some tropical moisture, rather than Arthur itself).

Latest Southeast radar image, courtesy National Weather Service.

Coastal areas will see water levels rise throughout the day as the storm surge builds.  The worst storm surge will be in far eastern North Carolina, with some areas from Wilmington to Cape Hatteras perhaps reaching 4-6 feet above normal. If you live anywhere along the coast from South Carolina up into the Northeast, you should visit NHC’s zoomable storm surge inundation maps.

Don’t forget — you don’t need to live directly on the coastline to experience storm surge: it works its way up into bays, rivers, inlets, and canals.

Storm surge forecast for a portion of the North Carolina coast. (NOAA)

Arthur has still not deviated much from the forecast track or intensity.  It will make its closest approach (or landfall) right around the 1-3 a.m. July 4 timeframe near Cape Lookout and Cape Hatteras, NC as a Category 1 (or possibly Category 2) hurricane.  After that, it will continue moving to the northeast, away from the Mid-Atlantic states.  The track forecasts from various computer models are packed tightly together, signifying high confidence in the storm’s course.

Model tracks for Arthur. The National Hurricane Center official forecast is the thick red line.

The forecast for various cities up and down the coast has changed little since yesterday.

The Outer Banks are still forecast to bear the brunt of the storm. The other areas that will be impacted – but not as severely as the Outer Banks – include:

* Coastal South Carolina, today into tonight
* Around Virginia Beach, tonight into midday Friday
* Eastern New England, Friday afternoon through early Saturday

These areas may experience tropical storm conditions with wind gusts to 30-60 mph, 1-3 inches of rain, and beach erosion.

The Delmarva and New Jersey beaches may well experience a period of wind and rain early Friday into Friday afternoon, but should not anticipate true tropical storm conditions.

The entire coastline along the eastern seaboard should expect high seas and the potential for dangerous rip currents into Saturday.

A buoy located about 45 miles southeast of Charleston SC (#41004) has been experiencing 15-foot waves with wind gusts to 40 mph. Another buoy to keep an eye on tonight is Diamond Shoals (#41025) which is located about 16 miles off of Cape Hatteras.

Aside from buoys, we also have routine land-based surface observations and multiple radars to closely monitor the storm’s progress.  Several aircraft will once again be flying into and over the hurricane to acquire data on its exact intensity and environment.

Resource: Long radar loops available that continuously add new frames.

Of course, if you’re in eastern N.C., you’re no stranger to hurricane encounters.  Though it ranks behind south Florida, it’s comparable to eastern Louisiana for most-hit section of the U.S coastline by hurricanes.  The last few to affect the Outer Banks area are Irene (2011), Ophelia (2005), Alex (2004), Isabel (2003), and Floyd (1999).

Hurricane strike density map, by county, using 1900-2010 data. (NOAA)

Arthur is the earliest first hurricane in the Atlantic basin since 2010 (Alex). Before that, you have to go back to 1995 to find an earlier one (Allison).  Incidentally, both 2010 and 1995 were extremely active seasons.  The last hurricane to make landfall on the U.S. was Isaac in August of 2012… it hit eastern Louisiana at Category 1 intensity.

The latest for D.C.: There will be minimal impact from Arthur on the area.  However, a cold front moving through today and this evening will bring periods of heavy rain and potentially severe thunderstorms.  That will end late tonight, and Independence Day will be clearing, drying, and breezy, but beautiful by evening!  Our friends further up the coast in New England won’t be so fortunate. Stay tuned for additional updates on the severe weather/flood risk in forthcoming posts.

A couple videos:

1) What Arthur looked like from the International Space Station yesterday:

Astronauts on board the International Space Station got a dramatic view of Hurricane Arthur off Cape Canaveral, Florida Wednesday. (NASA)


2) North Carolina prepares: