Tropical storm Arthur forms, forecast to become hurricane on ride up East Coast July 2-5

July 1, 2014

Visible satellite image of tropical storm Arthur as of 10:30 a.m. EDT. The surface center is marked with a red X. (UM/RSMAS)

The first tropical storm of the 2014 Atlantic hurricane season has formed off the east coast of Florida, and will pester much of the U.S. East Coast between now and the July 4 holiday weekend. Named Arthur, it is the latest first tropical storm (in any given season) to form in the Atlantic since  2004.

The first tropical storm of the 2014 hurricane season will visit the East Coast between now and the July 4 holiday weekend. The Post's Jason Samenow explains where and when it will hit, and whether you'll need to change your weekend plans. (Tom LeGro and Jason Samenow/The Washington Post)

Arthur is forecast to crawl up the Southeast coast over the next two days, slowly strengthening. The National Hurricane Center predicts Arthur will then reach category 1 hurricane early Friday, July 4, when it lifts north from the North Carolina Outer Banks to offshore the Delmarva Peninsula.

At present, the storm is stalled just 70 miles east of Vero Beach, Fla. and about 70 miles north of Freeport, Bahamas.  Thus far, its development has been slow. But conditions are favorable for slow strengthening and multiple aircraft flying into the storm today will monitor changes in intensity.


Tropical weather dashboard

Track forecast for Tropical Storm Arthur (National Hurricane Center)
Track forecast for Tropical Storm Arthur ; click to enlarge (National Hurricane Center)

System type: Tropical Storm
Intensity: 40 mph, 1007 mb (updated 11 a.m. EDT)
Location: 95 miles southeast of Cape Canaveral, Fla.
Intensification potential: High (confidence: high)
Landfall potential: Medium (confidence: medium)
Days from possible landfall: 2.5 – 3
Zones to watch for possible landfall: North Carolina (confidence:medium)
Will if affect VA/MD/DE beaches? Possible skirt (confidence: medium)
Will it affect D.C.? Indirectly (enhanced rain possible Thursday, confidence: medium)


For the moment, Arthur’s coastal impacts are minimal. The heavy rain and thunderstorms remain displaced to the south of the storm’s center, and during the day today, only the occasional rainband is expected to affect coastal areas of the eastern Florida peninsula.

A tropical storm watch is in effect from Fort Pierce to Flagler Beach in eastern Florida. A recent analysis of surface wind and pressure from the RAP model also shows a very lopsided system: the “business end” is all over open ocean with minimal winds and rain affecting coastal Florida.


Surface wind and pressure from the 8am RAP model analysis. (UM/RSMAS)

Track forecasts from the usual suite of models are in excellent agreement now, giving high confidence to its future course.  After meandering for another day, it should finally make a steady move to the north and then northeast Wednesday afternoon, while intensifying.

Five-day track forecasts from various models. (Clark Evans, UWM)
Five-day track forecasts from various models. (Clark Evans, UWM)

During the day on Thursday we can expect a strong tropical storm off the South Carolina coast, then a possible landfall as a minimal hurricane early Friday morning near the Outer Banks of North Carolina.  From there, it remains offshore, cruising by the Mid-Atlantic area and Delmarva peninsula during the day on Friday.

Forecast rainfall totals from Tuesday morning through Sunday morning. (NOAA/WPC)
Forecast rainfall totals from Tuesday morning through Sunday morning. (NOAA/WPC)

The bulk of the rain from this system will remain offshore through Friday, with the exception of coastal areas of FL, GA, SC, NC and possibly the Delmarva – depending on the storm’s exact track.  The North Carolina Outer Banks are most vulnerable to hazards from this storm and are likely to contend with heavy rain, tropical storm-force winds and some coastal flooding Thursday night into Friday morning.

While locations further inland (towards the I-95 corridor) are unlikely to be directly impacted by the storm, a cold front sweeping through the eastern U.S. may draw in some of the storm’s tropical moisture. Much of the East Coast will experience a wet week ahead at times, with the Southeast’s rain coming mostly in the next two days and the Northeast’s more on Wednesday through Friday.  The forecast totals over the next five days (through Sunday morning) are shown in the map to the right.

In Washington, D.C., enhanced rainfall and thunderstorms are possible Thursday into Thursday night, possibly lingering into Friday morning, mainly in areas east of the city. By Friday afternoon, the region should be drying out.

Rain and possibly some gusty winds would most impact the Delmarva and Virginia/Maryland/ Delaware beaches  late Thursday through Friday afternoon, if it tracks close enough to the coast.

Depending on exactly how far offshore the storm is by Friday evening, it looks like the greatest likelihood of a fireworks spoiler is going to be coastal regions of New Jersey up into northern New England.

A map showing the probabilities of locations experiencing tropical storm force winds over the next five days is available at the National Hurricane Center. Gusty winds will almost certainly be confined to coastal areas with the possible exception of eastern North Carolina where some stronger wind gusts could work into the interior some.

All beaches up and down the East Coast will experience higher surf and enhanced rip tide risks this week, especially Thursday through Saturday.

Stay tuned to the CWG for updates on Arthur as well as any impacts it may have on the area.

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Jason Samenow · July 1, 2014