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Category 3 Gonzalo Pounding Bermuda; Ana a Heavy Rainfall Threat for Hawaii

By: Dr. Jeff Masters, 3:10 PM GMT on October 17, 2014

The winds are rising and huge waves are pounding Bermuda as powerful Category 3 Hurricane Gonzalo closes in with sustained 125 mph winds. Gonzalo is gradually weakening, thanks to wind shear that has risen to a moderate 15 knots and Sea Surface Temperatures (SSTs) that have cooled to 28°C (82°F). However, Gonzalo is not weakening fast enough to spare Bermuda from a devastating strike by a major hurricane. Infrared and visible satellite loops on Friday morning showed that Gonzalo remained an impressive hurricane with a large area of intense heavy thunderstorms, good spiral banding, and solid upper-level outflow to the north. The appearance of the storm was somewhat ragged, with the storm stretched into an elliptical shape and the eye filled with clouds. But Friday morning data from the Hurricane Hunters during their 9 am EDT eye pass showed that Gonzalo remained a dangerous Category 3 hurricane with a central pressure of 947 mb and surface winds of 125 mph. With an eye 35 miles in diameter, Gonzalo's strongest eyewall winds were spread out over an area about 45 miles across.

Figure 1. Hurricane Gonzalo as seen from the International Space Station on October 16, 2014. Image credit: Alexander Gerst.

Figure 2. Gonzalo as seen by the Bermuda radar at 11:53 am EDT October 17, 2014. The eye was visible at the bottom of the image. Image credit: Bermuda Weather Service.

Forecast for Gonzalo
The 8 am Friday run of the SHIPS model predicts that wind shear will stay a moderate 10 - 20 knots through Friday night as Gonzalo approaches Bermuda, and SSTs will cool to 27°C (81°F.) These conditions should drive some modest weakening, but it is likely that Gonazalo will be a dangerous Category 2 or 3 storm with 100 - 115 mph winds at the time of its closest approach to Bermuda on Friday evening. The latest suite of model runs has the hurricane passing over or less than 30 miles to the west of the island, which would put Bermuda in the strong right-front quadrant of the storm, potentially bringing them the strongest winds of Gonzalo's eastern eyewall. However, late morning radar and visible satellite images show Gonzalo taking a course more directly at the island or slightly to the east, which means that the island would be more likely to get the weaker west side of the eyewall. Hurricane-force winds extend outwards about 60 miles from the center, so Bermuda is almost certain to see hurricane-force winds, though. In their 11 am EDT Friday Wind Probability Forecast, NHC gave Bermuda a 96% chance of sustained hurricane-force winds of 74+ mph. In their 12:30 pm AST advisory, the Bermuda Weather Service called for elevated locations on the island to see sustained winds of 105 - 125 mph (90 - 110 knots) gusting to 160 mph Friday evening. Seas were forecast to be 30 - 40 outside the reef, and 4 - 7 feet inside the reef.

Gonzalo is also a threat to Newfoundland, Canada. Although the hurricane will likely be declared post-tropical on Saturday, it will still have Category 1 strength winds when it makes its closest pass by Southeast Newfoundland, predicted to occur between 5 am - 8 am EDT Sunday by the 00Z Friday runs of the GFS and European models. In their 11 am EDT Friday Wind Probability Forecast, NHC gave Cape Race, Newfoundland a 64% chance of experiencing tropical storm-force winds, and a 5% chance of hurricane-force winds. Heavy rains from ex-Gonzalo are likely to be the main threat to Newfoundland.

Figure 3. Road washout at Bermuda International Airport from Category 3 Hurricane Fabian after it struck on September 5, 2003. Image credit: J.G. Howes.

Bermuda's hurricane history
Ten major hurricanes of Category 3 or stronger intensity have tracked within 75 miles of Bermuda in records dating to 1899. Two of these were Category 4 storms, the most recent of which occurred on September 13, 1948. The most recent Category 3 was Hurricane Fabian of 2003, the only hurricane to get its name retired exclusively because of its impact on the island of Bermuda. Fabian's eye passed just 14 miles (23 km) west of Bermuda on September 5, 2003 when the storm was a 120 mph (180 km/h) Category 3 hurricane. The eastern eyewall with the hurricane's strongest winds moved over the island, resulting in a direct hit; however, as the center did not move over the island, Fabian did not make landfall. According to the NHC final report, Fabian did $300 million in damage, making it the most expensive hurricane ever to hit the island. Fabian was also the first hurricane since 1926 to kill people on Bermuda; four people died when a storm surge swept over the causeway connecting the airport to the rest of the island, washing their car into the ocean. That causeway was replaced by a temporary bridge, which has remained to this day--and is of particular concern for Gonzalo's impact.

Bermuda links
Current conditions
Bermuda radar
Port of Bermuda webcam
Storm chaser Jim Edds is providing Twitter updates from Bermuda for Gonzalo

Video 1. Storm chaser Jim Edds was on Bermuda during Hurricane Fabian in 2003, and put together this 26-minute video on the experience. He is providing Twitter updates from Bermuda for Gonzalo, as well.

Strengthening Tropical Storm Ana a heavy rain threat to Hawaii
Tropical Storm Ana was at the verge of hurricane status again on Friday, with 70 mph winds. Satellite loops on Friday morning showed that Ana had its most impressive appearance yet, with a large area of heavy thunderstorms, plenty of low level spiral bands, and solid upper-level outflow to the north and east. Wind shear was light, 5 - 10 knots, and Sea Surface Temperatures (SSTs) warm, 27.4°C (81°F), which is about 1°F above average. The 8 am EDT Friday run of the SHIPS model predicted that wind shear would be light to moderate 5 - 20 knots, and ocean temperature would be warm, 27.5 - 28°C (81 - 82°F), through Saturday night. These conditions should allow Ana to slowly intensify until Saturday afternoon. Our top models for predicting hurricane tracks continue to trend farther to the west with their track for Ana, and now Kauai is the only main Hawaiian Island in the cone of uncertainty for a direct strike. In their 11 am EDT Friday Wind Probability Forecast, Central Pacific Hurricane Center (CPHC) gave Lilue on Kauai on a 32% chance of experiencing tropical storm-force winds, and a 1% chance of hurricane-force winds. Honolulu was given a 26% chance of experiencing tropical storm-force winds, and a 0% chance of hurricane-force winds. Even though it now appears that the islands will not experience major wind damage from Ana, heavy rains causing flash floods and mudslides are a major concern. Rainfall amounts of 8+ inches are possible on the Big Island, Oahu, and Kauai, according to the Friday morning runs of the GFDL and HWRF hurricane models.

Figure 4. Predicted rainfall for Ana from the GFDL model forecast made at 2 am EDT Friday October 17, 2014. The model predicted large areas of 8+ inches of rain would affect Oahu and the Big Island. Image credit: NOAA/GFDL.

Related posts
Climate Change May Increase the Number of Hawaiian Hurricanes, my August 6, 2014 post
Climatic Atlas of Tropical Cyclone Tracks over the Central North Pacific (2008)

Eastern Pacific tropical disturbance 92E a heavy rainfall threat to Mexico
In the Eastern Pacific, a well-organized area of disturbed weather (Invest 92E) was located about 150 miles south of tAcapulco, Mexico on Friday morning, and was headed north to northwest at about 5 - 10 mph. With light wind shear, warm SSTs near 29.5°C 85°F), and a moist atmosphere, this disturbance is likely to develop into a tropical depression this weekend. In their 8 am EDT Friday Tropical Weather Outlook, NHC gave 92E 2-day and 5-day odds of development of 70% and 80%, respectively. 92E is a threat to bring heavy rains to the Pacific coast of Mexico on Friday and continuing into the weekend. As of Friday morning, 92E's heavy rain had begun to push onshore, as seen on satellite loops and Acapulco radar.

Moisture from 92E may move northwards across Mexico into the southern Gulf of Mexico's Bay of Campeche by early next week, contributing to the formation of an area of low pressure that could bring heavy rains to Florida on Wednesday and Thursday, as predicted by the GFS and UKMET models.

Hurricane expert Steve Gregory has more on the tropics in a Friday morning post.

Jeff Masters


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.