Tropical Storm Gonzalo swept into the Caribbean on Monday, gaining strength as it heads toward the U.S. and British Virgin Islands and parts of Puerto Rico. (The Washington Post)


Tropical storm Gonzalo, positioned in the northern Leeward Islands (very close to Antigua), is on a collision course with U.S. and British Virgin Islands. It will also make a close pass to eastern Puerto Rico.

Packing sustained winds to 65 mph, Gonzalo is likely to dump 4-8 inches of rain, with isolated amounts of 8-12 inches, and produce dangerous surf and damaging wind gusts along its path.

The intensifying storm has prompted tropical storm warnings and hurricane watches for Puerto Rico and the U.S. Virgin Islands while the British Virgin Islands are under a hurricane warning.

(National Hurricane Center)

As of Monday morning, Gonzalo shows a developing eye, and has rain bands wrapping around mostly on the east side.  Tropical storm force winds are affecting Antigua and will shortly move into the remaining islands in the northern Leeward Islands.  Antigua reported a sustained wind of 67 mph this morning with a gust to 88 mph, according to the National Hurricane Center.

Satellite and radar data suggest that the storm should quickly reach hurricane intensity. The National Hurricane Center predicts Gonzalo will achieve this milestone tonight or Tuesday, coinciding with its closest approach to eastern Puerto Rico.

Gonzalo’s exact track will determine how severe the conditions are across Puerto Rico.  Its eye is expected to remain offshore, but the storm’s outer bands could still lash the island, with the worst impacts on the east coast.

Long radar loop of Tropical Storm Gonzalo near the Leeward Islands. (images from Meteo France, loop from University of Miami)

Given favorable environmental conditions, by mid-week, Gonzalo could become the season’s second major hurricane (category 3 or higher) in the Atlantic.

Beyond that, a strong mid-latitude low pressure area will steer Gonzalo northward, and perhaps bring it near Bermuda over the weekend (unfortunately, Bermuda was just hit by Tropical Storm Fay this past weekend too).

Enhanced infrared satellite image of Gonzalo from 9:15am EDT. (NOAA)

Gonzalo formed from a a tropical wave located east of the Lesser Antilles Sunday afternoon. Assuming its maximum sustained winds reach 74 mph, it will become the season’s sixth hurricane, but the first to actually occur in the tropics… the previous five (Arthur, Bertha, Cristobal, Edouard, and Fay) hurricanes all resided in the subtropics!

It is rare to get a storm passing through this area so late in the season. There have been just seven known tropical cyclones to pass within 100 miles of Gonzalo’s position during October since 1851 that were also hurricanes at some point.  The most recent was Noel in 2007 and the most analogous to Gonzalo’s forecast track is a Category 4 1939 hurricane (it’s the one that passed just east of Bermuda in the map below).

Tracks of the previous seven known tropical cyclones that passed within 100 miles of Gonzalo’s position during October and were hurricanes at some point. (NOAA)

Using a common metric for gauging seasonal activity, ACE (Accumulated Cyclone Energy), the 2014 Atlantic season is now at 45 percent of an average season for this date.  We have had 7 named storms, 5 hurricanes, and 1 major hurricane… the average for October 13 is  10 named storms, 5 hurricanes, and 2 major hurricanes (using 1981-2010 as the period of record).

In the graph below, the average daily ACE values are shown in purple shading, and 2014’s daily ACE values (as of this morning) are shown with yellow bars.  On any given day, it is relatively easy to exceed the average for that date.

Daily ACE values for the 1981-2010 average (purple) and 2014 (yellow).

Elsewhere, Tropical Storm Fay, after battering Bermuda, is racing eastward into the north-central Atlantic tropical cyclone graveyard and will become an extratropical cyclone later today.

Tropical Storm Fay struck the southeast coast of Bermuda on Sunday and strengthened into a hurricane with heavy rain and strong winds. (The Washington Post)


(Jason Samenow contributed to this post.)