La Nina and Tropical Storms – Wully Davidson

La Nina has  officially been declared. This is the cool counterpart of El Nino, which is a warming of the eastern tropical Pacific. La Ninas usually have a small global cooling effect, and the magnitude of this is dependent on whether the La Nina is classed as weak, moderate or strong. La Ninas usually last for a minimum of 5 months. The regional climatic effects around the globe include  reduced rainfall in east Africa. During the strong 2010-11 event, between 50,000 and 100,000 people in Somalia and neighbouring countries died of famine. It would have been far worse in the past, without international aid.

‘In August, La Niña conditions were present, with below-average sea surface temperatures (SSTs) extending across the central and eastern equatorial Pacific Ocean (Fig. 1). In the last week, all Niño indices were negative, with the Niño-3.4 index at -0.9ºC and the Niño-1+2 and Niño-3 indices cooler than -1.0ºC (Fig. 2). Equatorial subsurface temperature anomalies averaged across 180°-100°W were negative (Fig. 3), with the largest departures observed in the east-central Pacific from the surface to 200m depth (Fig. 4). Atmospheric circulation anomalies over the tropical Pacific were also generally consistent with La Niña, despite sub-seasonal variability during the month. The low-level and upper-level winds were near average for the month as a whole, but enhanced low-level easterly winds were prominent across the equatorial Pacific Ocean during early and late August. Tropical convection remained suppressed over the western and central Pacific, and was near average over Indonesia (Fig. 5). Both the Southern Oscillation and Equatorial Southern Oscillation indices were positive. Overall, the coupled ocean-atmosphere system was consistent with La Niña conditions.’

10 September, 2020

Tropical Storm Sally

Tropical storm Sally has just formed over Florida, and is currently just about to enter the Gulf of Mexico. It has sustained winds of 40 mph, and is predicted by the National Hurricane Center to make landfall near New Orleans on Tuesday as a low end 80 mph category 1 hurricane. That would cause power outages and some structural damage, but nothing to write home about.

However, the NHC admits that there is ‘some uncertainty’ about the intensity, and many observers on the tropical weather forum I visit are suggesting that it could rapidly intensify up to a major hurricane category 3. There doesn’t seem to be any of the usual environmental factors that would hinder development, such as dry air, wind shear, low sea surface temperatures etc.

The NHC have a social responsibility not to cause unnecessary panic, but if Sally does rapidly intensify to a major, there won’t be much time for warnings to evacuate. Tropical storms have intensified to catastrophic category 4/5 hurricanes in less than 3 days in the past. Hopefully, Sally will do as the NHC predicts.

12 September, 2020

Record Simultaneous Named Storms

We’ve been warned for many years that global warming would result in more, and stronger tropical cyclones. Yesterday, there were five named storms in the Atlantic, equalling the record for simultaneous named storms. One of them has since dissipated, but there’s another system emerging from Africa to replace it. Sally will be making landfall near Mobile, Alabama tonight, as a category 1 hurricane. Tropical storm Vicky is the latest addition to the family – only the second time that ‘V’ has been used. Since we’re only 5 days past the peak of the Atlantic hurricane season, it’s almost certain that the National Hurricane Center will soon be using Greek alphabet names for the storms, only the second time they’ve had to do this.

At the start of the season, the Azores/Bermuda high pressure ridge was strong, and pushing storms west, threatening land. Now, it has weakened, and storms forming in the eastern Atlantic appear to be meandering harmlessly out to sea. A few may turn up on UK shores as ‘remnants’. The ridge could become strong again, and October has produced some monsters in the past. What we’re witnessing now is exactly what scientists predicted decades ago, and it’s only going to get worse.

15 September, 2020

Hurricane Sally has just made landfall (10 am) on the Alabama – Florida border, as a category 2 storm, with 105 mph sustained winds. It’s moving inland at a very slow 3 mph, which means it’ll hang around longer than most landfalling hurricanes, and cause more damage than would normally be expected for a 105 mph storm. The National Hurricane Center has warned of ‘historic and catastrophic’ flooding, due to the huge amount of rainfall. Pensacola, Florida, is getting the worst of it.

16 September, 2020

5 October, 2020 – Currently 2 Named Storms in Caribbean

There are currently two named storms in the Caribbean. Gamma is a 45 mph tropical storm, which is expected to dissipate after it makes landfall in the Yucatan peninsula of Mexico in a day or so. Delta is a tropical storm south of Jamaica. The National Hurricane Center estimates Delta’s winds at 60 mph, but it looks as if it might have started to rapidly intensify since the last advisory 4 hours ago. It’s predicted to make landfall on Friday, somewhere between the Texas/Louisiana border and the westernmost part of the Florida panhandle, as a 100 mph category 2 hurricane, similar to Sally, which landed in Alabama at 105 mph, just three weeks ago. It’ll be dreadful if it lands in the same spot.

The NHC is often very conservative with its long range intensity forecasts, and the tropical weather nerds on the Wunderground forum are thinking this could be a very dangerous major hurricane. The current apparent bout of intensification, inferred from satellite loops, supports this.

This is the 25th named storm of the season, and there’s a good chance that 2020 could end up beating the 2005 record of 28 storms. Hopefully, Delta won’t turn out to be the equivalent of that year’s hurricane Katrina. New Orleans is currently in the centre of the cone, but that’ll probably change in the days ahead.

You can follow the NHC advisories and view (almost) real time satellite loops of Delta’s progress here

To view the satellite pics, click ‘data & tools’, then ‘satellite imagery’, then ‘animated GIF’ for either the Caribbean or Gulf of Mexico.

6 October, 2020

Hurricane Delta – 10 October, 2020

NHC now has Delta as a 110 mph category 2 hurricane, and predicts it will strike the city of Cancun (pop. 750,000), in Mexico, as a 130 mph category 3 major hurricane tomorrow. Will weaken slightly afterwards before regaining strength to a 130 mph storm. However, conditions in the northern Gulf of Mexico aren’t particularly supportive, so the landfall prediction in Louisiana is still 100 mph. They are excellent with track predictions, but not so much with intensity, tending to underestimate, rather than overestimate.

Hurricane Delta has become the 10th named storm to make landfall in the US this year, breaking a record that has stood since 1916. It came ashore as a 100 mph category 2 hurricane in a sparsely populated salt marsh region of Louisiana, almost exactly where hurricane Laura made landfall in August.

Hurricane Epsilon – 24 October, 2020

This is a warning from the site, concerning the transition of hurricane Epsilon to a powerful extratropical storm, hitting the UK on Tuesday. They were spot on with their prediction of the severe squally weather we got this morning. It didn’t last long, but I can’t remember seeing such intense sheets of rain.

“There is another, more concerning feature of interest after this weekend’s North Atlantic depression is over. The currently ongoing hurricane Epsilon in the northwestern Atlantic will undergo an extratropical transition and head towards Europe.

Global models are hinting a very powerful extratropical cyclone could form on Monday and head towards the UK and Ireland on Tuesday. Major waves and destructive hurricane-winds will be possible.

We are closely monitoring the evolution of the North Atlantic activity and will keep you updated in the coming days – stay tuned!”

Edit: Epsilon’s remnant now expected to head north to the Faroe Islands. UK will still get a lot of rain from the trailing rain bands and very heavy sea conditions.

Tropical Storm Zelta

Arctic Ocean sea ice coverage for the date is at a record low by a huge margin.  Click for larger image.

60,000 people are being evacuated from the Irvine area of Orange county, California, as the Silverado fire continues to grow.

26 October, 2020 – Tropical Storm Zelta

Tropical storm Zeta is heading for the north east of Yucatan, Mexico, and is expected to arrive as a 75 mph category 1 hurricane early tomorrow. It’ll be the third time this month that a tropical storm or hurricane has made landfall there. Currently predicted to make landfall near New Orleans early Tuesday as an 80 mph hurricane, but long range intensity forecasts are notoriously unreliable, and more often than not, too conservative. Zeta is the furthest into the Greek alphabet on record, and may not be the last named storm of the season.

31 October , 2020 – Super Typhoon Goni

Super typhoon Goni is currently headed for the Philippines as a catastrophic 180 mph storm, equivalent to an Atlantic category 5 hurricane. It’s the strongest storm of 2020, and will make landfall in a few hours. The Philippines is the most storm battered country on the planet. In 2013, super typhoon Haiyan hit with 190 mph winds, killing around 8,000 people and making millions homeless. Haiyan was the strongest typhoon/hurricane ever to make landfall, equaled by typhoon Meranti in 2016, which made landfall with the same intensity on a small outlying Philippines island.

Tropical Storm Eta – 1 November, 2021

Tropical storm Eta has formed in the Caribbean, and ties the record of 28 named Atlantic storms in a season, set in 2005. It currently has winds of 65 mph, and is predicted to be a high end category 2 hurricane with 110 mph winds when it makes landfall in Nicaragua on Tuesday morning.

Thereafter, it becomes a slow moving system, as it meanders north into Honduras. That’s very bad news, as Honduras and neighbouring countries are mountainous, and the longer it sits over the mountains, the more rain will be funneled down the steep sided valleys, potentially causing disastrous flash flooding.

That was what happened in 1998, when hurricane Mitch stalled over the region, dropping 6 feet of rain, and causing upwards of 11,000 deaths. Mitch was the deadliest hurricane since the ‘Great Hurricane’ of 1780. Eta won’t be nearly as bad, but it will be bad.

Edit 3 pm Monday: Eta now already a 110 mph hurricane, and predicted by the NHC to be a category 4 major hurricane with 140 mph winds at landfall in Nicaragua at 1 pm tomorrow.

Sub-Tropical Storm Theta 10 November, 2021

Subtropical storm Theta has become the 29th named storm of the Atlantic hurricane season, beating the record of 28 storms, set in 2005. It’s currently a few hundred miles west of the Canary islands, and has winds of 70 mph, just below the 74 mph threshold for a category 1 hurricane. Current track would take it to Portugal, but that could change. In 2018, Portugal was hit by ex-hurricane Leslie, with 70 mph winds at landfall. This was the strongest storm to hit Portugal since 1842.

Hurricane Eta exited central America, went over Cuba, then turned west, causing extensive flooding in Florida, and is now a 60 mph tropical storm in the Gulf of Mexico. It’s expected to weaken as it slowly edges north to make its final landfall between Florida and Louisiana. But, it’s 2020, so don’t rule anything out. November sees an average of 1 named Atlantic system, but there’s currently a third one brewing in the eastern Caribbean, which could become Iota at the end of the week.

The times they are a changin’.

November 16, 2020 – Some Extreme Hurricane Season

This is some extreme hurricane season. Two weeks ago, hurricane Eta hit Nicaragua as a major category 4, and caused devastating flooding throughout central America. Now, 145 mph hurricane Iota is poised to make landfall in the same place tomorrow morning as a 155 mph category 5 storm. It’s the first time there have been two majors in November in the Atlantic region, and these are high end majors. Iota is a record 31st storm of the season, and will be the strongest ever recorded in November.

The region has been afflicted by a multi year drought, which has resulted in ‘caravans’ of refugees travelling through Mexico in a largely vain attempt to resettle in the US. I’ve read that the news of Iota’s impending arrival is the last straw for many, and that there is about to be a major surge of migrants making the dangerous trip through Mexico. We’ve been warned for many years that climate change would result in millions of environmental refugees, and we’re now seeing the reality.

The Devastating Atlantic Hurricane Season 2020

The devastating 2020 Atlantic hurricane season officially ended on November 30, and set an incredible amount of new records. Dr. Jeff Masters does an excellent summary in his article here:

There were 30 named storms, the most ever recorded, 13 hurricanes (second highest), and 6 majors (second highest). There was a record number of rapidly intensifying storms (10), which has been a noticeable trend in recent years, and is probably global warming related. A record number made landfall in the US (12). Thankfully, many of the strongest ones landed in sparsely populated salt marsh areas, so the damage was a lot less than might have been expected.

Sadly, that wasn’t the case in Central America, which was hit by two very late season major hurricanes. Hurricane Iota was the latest cat 5 on record making landfall in Nicaragua, just after hurricane Eta hit the same area. Damage from both storms has been estimated at $10 billion dollars in Honduras, or 40% of GDP, equivalent to 22 years of economic development.


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