Weather Underground – October 2, 2015
Hurricane Joaquin, an extremely dangerous Category 4 storm, remains parked over the central Bahamas producing hurricane-force winds, storm surge flooding and torrential rain.
Dozens are trapped in their homes in the central Bahamas, with authorities unable to reach them. All schools have been closed in The Bahamas.
(MORE: Bahamas Latest News/Impacts)
The odds of the U.S. mainland seeing its first landfalling hurricane in 15 months are now very low as the forecast track continues to trend farther to the east. The storm could pass close to the southeast New England coast, and a close pass to Bermuda cannot be ruled out.
The Latest
- The official forecast path for the center of Joaquin no longer includes the U.S. East Coast.
- At 11 a.m. EDT Friday, the eye of Hurricane Joaquin was centered about 5 miles south of Rum Cay in the central Bahamas.
- Maximum sustained winds remain around 130 mph, making Joaquin a Category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale.
- Hurricane warnings remain in effect for a large part of the Bahamas. Tropical storm warnings are up for the Turks and Caicos Islands and eastern Cuba.
- Hurricane-force wind gusts have been reported on a few of the islands in the central Bahamas, but most weather observation sites near the eye of Joaquin are no longer reporting data.
- Joaquin underwent rapid intensification from a tropical storm to a Category 4 hurricane in less than 36 hours, and may fluctuate in intensity Friday before a slow weakening begins this weekend.
- This system has made the anticipated turn toward the north, though its forward motion remains very slow (only 3 mph).
- Joaquin’s northward motion will accelerate by Saturday as it finally departs the Bahamas.
- Dangerous coastal and inland flooding is still expected for several states along the U.S. East Coast through the weekend despite the low likelihood of Joaquin making landfall.
- For now, Joaquin is expected to pass sufficiently west of Bermuda Sunday to limit any direct impacts.
Hurricane Joaquin Information
Joaquin Blasting the Central Bahamas
It has now been an over 24-hour siege of Joaquin’s eyewall, the ring of extreme winds surrounding the eye itself, hammering Acklins, Crooked Island, Mayaguana and uninhabited Samana Cay in the central Bahamas. The eyewall also continues to pummel Rum Cay, San Salvador and Long Island.
Flooding from storm surge and torrential rainfall has been documented on Long Island and Acklins. A Weather Underground personal weather station at Pitts Town, Crooked Island, reported winds up to 84 mph before it stopped reporting.
Unfortunately, this Category 4 hurricane will spend another day near the storm-battered central Bahamas, before finally accelerating away Saturday. A catastrophic situation may be unfolding there with such a prolonged period of intense hurricane conditions.
(MORE: Expert Analysis | Hurricane Central)
Current Satellite and Winds
Watches and warnings are in effect for parts of three countries – the Bahamas, Cuba, and the Turks and Caicos Islands (a British Overseas Territory). Here are the details as of 8 a.m. EDT:
- A hurricane warning remains in effect for parts of the central, northwestern and southeastern Bahamas including the Abacos, Berry Islands, Eleuthera, Grand Bahama Island, New Providence, The Acklins, Crooked Island and Mayaguana. This includes both Nassau and Freeport.
- A hurricane watch remains in effect for Bimini and Andros Island.
- A tropical storm warning continues for Andros Island and the rest of the southeastern Bahamas not in the hurricane warning, including the Turks and Caicos Islands, as well as parts of eastern Cuba.
Hurricane Joaquin: Watches and Warnings
Joaquin is in the process of making its sharp right turn and heading north, but it’s already too late for that turn to spare the Bahamas from dangerous impacts.
Potential impacts for any islands the eyewall of Joaquin touches include:
- Catastrophic wind damage: Even well-built homes may lose their roofs and experience failure of one or more exterior walls. Most trees will be snapped and many uprooted. Given the small size of the islands, the electrical grid will likely experience a complete blackout and may be partially or completely destroyed. Recovery may take weeks or months.
- Dangerous storm surge and waves: In areas where the wind blows toward shore, water levels may rise 6 to 12 feet above normal tide levels, flooding areas, especially near the immediate shore. Extremely high waves from the open ocean may then damage or destroy any structures flooded by seawater.
- Extreme rainfall: Rainfall totals up to 25 inches are possible, leading to potentially life-threatening flash flooding. Storm surge and the generally low elevations of the islands will greatly limit the ability of rainwater to run off into the ocean, further aggravating the situation.
The northwestern Bahamas, including Nassau and Freeport, are not likely to encounter Joaquin’s dangerous core – but we can’t completely rule out at a period of hurricane conditions Friday.
Rapid Intensification
An Air Force Reserve Hurricane Hunter reconnaissance aircraft flying through Hurricane Joaquin Thursday morning found estimated surface winds of 117 knots, or roughly 135 mph, in the southwestern eyewall’s deep thunderstorms.
At one point between Wednesday morning and Thursday evening, Joaquin saw a pressure drop of 57 millibars in about 39 hours, going from a strong tropical storm to a Category 4 hurricane in the process.
Colorado State University tropical meteorologist Dr. Phil Klotzbach said Joaquin was the first Category 4 hurricane to track through The Bahamas in October since 1866. Joaquin’s minimum central pressure of 931 millibars Thursday was also the lowest observed in an Atlantic Basin hurricane since September 2010, when Hurricane Igor bottomed out at 924 millibars.
As virtually all intense tropical cyclones do, Joaquin appeared to be in an eyewall replacement cycle, a process during which a second, outer eyewall forms, chokes off inflow to the old, inner eyewall, then contracts inward. During these cycles, fluctuations in intensity can be expected.
Visible Satellite
Hurricane Joaquin remains intense as wind shear – harmful to the intensification of tropical cyclones – has lessened substantially from a few days ago. However, this wind shear will increase once again as Joaquin moves north this weekend, finally inducing a gradual weakening.
Forecast Track Becoming Clearer
A complicated atmospheric pattern makes its future track – including any potential landfall on the U.S. East Coast – still a challenge to forecast, but a bit clearer than earlier this week.
Residents along the East Coast of the U.S. should still pay close attention to the forecast now through this weekend, though the threat is much lower from Joaquin itself than it appeared earlier this week.
(MORE: Dangerous Flooding, High Winds Likely for East Coast Regardless of Joaquin
Aware Threat Index
Computer forecast models – and the meteorologists who use them for guidance – have grappled with a complex interaction between Joaquin, a cold front near the East Coast, the remnants of Tropical Storm Ida, a strong bubble of high pressure aloft over the North Atlantic Ocean, and a strong area of low pressure aloft digging into the southeastern U.S.
Over the last few days, those computer forecasts have put out a bewildering range of future track scenarios, though mostly in two main camps – one favoring a U.S. landfall, and the other favoring a decisive northeastward path over the open waters of the western Atlantic.
Ensemble Forecast Model Tracks
On Thursday, computer models moved closer to a consensus, as models formerly bullish on a U.S. landfall began pulling their forecast paths east, favoring tracks closer to the Atlantic seaboard or even entirely offshore. By Friday morning, the overwhelming majority of reliable track models kept the center of Joaquin away from the U.S. East Coast.
That model consensus is reflected in the forecast track accompanying the National Hurricane Center’s 11 a.m. advisory.
(MAP: Track Hurricane Joaquin with our New Interactive Storm Tracker)
Projected Path
While the official forecast cone has shifted east of the mainland U.S., it’s important to note that the NHC cone is only designed to encompass about two-thirds of the typical range of possibilities, so as not to overwarn areas at relatively low risk. It is too early to completely write off a track closer to the East Coast, even though it now appears rather unlikely.
Data from NOAA Gulfstream aircraft surveillance missions and extra balloon soundings launched from National Weather Service offices on the mainland may have contributed to the eastward shift in some of the model guidance.
(MORE: 3 Reasons Hurricane Joaquin Has Been So Difficult to Forecast)
Regardless of the ultimate outcome of Joaquin’s path, portions of the East Coast states will still see multiple impacts from the evolving large-scale weather pattern, including flooding rainfall, coastal flooding, high surf, beach erosion, and gusty winds. These threats will extend well inland from the Atlantic coast.
(MORE: Dangerous Flooding, High Winds Likely for East Coast
The eastward shift in the forecast also means that Bermuda is at an increased risk of at least peripheral impacts from Joaquin. Watches or warnings may be issued for Bermuda on Friday. Portions of Atlantic Canada may end up dealing with Joaquin early next week.