Tuesday 3 September 2019

What you need to know! Four potential tropical depressions forming in the Atlantic and the Gulf as Hurricane Dorian becomes a multi record-breaker

As we head into September and we hit the peak of the Atlantic hurricane season, Catastrophic Hurricane Dorian has slowed to a crawl over Grand Bahama Island overnight. Credit NOAA

While Hurricane Dorian Dorian's forward speed has slowed to a virtual stall near Grand Bahama Island. The eyewall has now been pummeling the island for more than 24 straight hours – since Sunday night. Unfortunately, that means the northwestern Bahamas – particularly Grand Bahama Island – are taking an extended pummeling from destructive winds and catastrophic storm-surge flooding. The National Hurricane Center is issuing advisories on Hurricane Dorian, located just north of western Grand Bahama Island.

Recent satellite-derived surface winds indicate that the low-pressure area located a few hundred miles west of the Cabo Verde Islands is becoming better defined (extreme right on the map above). Associated thunderstorm activity has been increasing and showing signs of organization, and a tropical depression is expected to form later today while the system moves generally northwestward across the eastern tropical Atlantic Ocean. * Formation chance through 48 hours...high...90 per cent. * Formation chance through 5 days...high...90 per cent.

Showers and thunderstorms associated with a large low pressure system located over the west-central Gulf of Mexico about 200 miles east-northeast of Tampico, Mexico, is showing signs of organization extreme left of the map above). Environmental conditions are conducive for a tropical depression to form during the next day or so while the low moves slowly westward or west-southwestward toward Mexico. Interests along the northeastern coast of Mexico should monitor the progress of this system. NOAA reconnaissance aircraft is scheduled to investigate the disturbance this afternoon, if necessary. * Formation chance through 48 hours...high...80 per cent. * Formation chance through 5 days...high...80 per cent.

A trough of low pressure, located several hundred miles south-southeast of Bermuda, is producing disorganized showers and thunderstorms (middle of the map above). Some gradual development of the disturbance is possible during the next couple of days. Afterwards, upper-level winds are forecast to become less favourable for tropical cyclone formation. Interests in Bermuda should monitor the progress of this disturbance. * Formation chance through 48 hours...low...30 per cent. * Formation chance through 5 days...low...30 per cent. Forecaster Stewart

A tropical wave is forecast to emerge over the far eastern tropical Atlantic between Africa and the Cabo Verde Islands in a few days. Environmental conditions are forecast to be conducive for development, and a tropical depression is likely to form late this week or over the weekend while the system moves westward to west-northwestward. * Formation chance through 48 hours...low...near 0 per cent. * Formation chance through 5 days...medium...60 per cent.

Credit NOAA

As Hurricane Dorian begins it's slow march up the US Southeast coast today after delivering one last punishing blow over the storm-fatigued northwest Bahamas. Hurricane watches have been extended northward to include the entire Georgia coast and South Carolina's Lowcountry. Outer rainbands have already moved ashore in South Florida, where winds over 40 mph have been clocked in a few locations near the coast, including at Opa Locka Airport near Miami. Dorian's intensity has backed off a bit from Sunday's peak and is now a Category 3. Regardless, Dorian will remain a formidable hurricane over the next several days, according to Weather Underground.

Hurricane Dorian smashes records

It’s the strongest storm on record to occur east of Florida in the Atlantic and so far north. After striking the northern Bahamas, it matched the 1935 Labor Day hurricane for the strongest winds of any storm making landfall. These are just a few of the incredible feats Dorian has already accomplished, and more may be ahead, reports the Washington Post.

Strongest landfall winds (tie): Hurricane Dorian’s 185 mph (160 knots) sustained wind at landfall on Great Abaco in the northwest Bahamas this afternoon tied for the strongest winds at landfall on record in the Atlantic Ocean. The only other storm with wind speeds that high at landfall is the similarly timed Labor Day hurricane of 1935. Dorian may have produced gusts as high as 220 mph.

Strongest storm on record for the Bahamas. This may go without saying given the bullets above, but it’s worth repeating — and zooming in on the hardest-hit places in the northwest parts of the island nation. Before Dorian, its worst storm was the 1932 Bahamas hurricane, which passed by with 160 mph winds as a Category 5. Hurricane Andrew in 1992 also passed just south of Dorian’s Bahamian landfall zone but wasn’t nearly as strong as Dorian.

Strongest storm on record east of Florida and north of the Caribbean: Whether your metric of strength is wind speed or low pressure (the lower the pressure, the stronger the storm), Dorian places first for the most intense in this zone.

Gaining strength at record speed: Dorian underwent what’s known as rapid intensification between both Friday and Saturday and Saturday and Sunday. Rapid intensification refers to an increase in wind speeds of at least 35 mph in 24 hours. Dorian entered rare air for this metric, too. In a space of just nine hours on Sunday, its peak winds increased from about 150 mph (130 knots) to 185 mph (160 knots) — a rate of intensification never before observed for a storm this strong.

First time with four consecutive years featuring Category 5s in the Atlantic: 2019 became the fourth straight year with a Category 5 in the Atlantic, the longest such streak on record. Dorian became the fifth Category 5 hurricane to form in the past four years in the Atlantic following Matthew (2016), Irma (2017), Maria (2017) and Michael (2018). No matter how you count it, the overall trend in such powerhouse storms is upward.

Astronaut Christine Koch of the International Space Station captured this image of Hurricane Dorian outside the ISS windows the morning of Sep. 02, 2019. Credit: NASA

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