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Gray-Wolf

Atlantic hurricane season/invest thread

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Tropical Storm Fabio is due to intensify into Hurricane status in the next 48 hours.

 

The Pacific is really churning them out!

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Starting to get more rumbles in the Atlantic now even if none of it is forecast for significant development. 

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So from nowhere there are two areas to watch. 1. South of Bermuda which has a 50% chance of development and then a Cape Verde system. Only yesterday this had a 20% chance of developing, today that is now 70%.

looks a well organised feature which is due to become a tropical depression before encountering less favourable conditions. 

Its a bit surprising this one as ocean temps are generally lower this season, but the system is well south where the SST are nearer normal. 

Hopefully it will just bring lots of rain for the leeward islands to ease the drought here.

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7 hours ago, Cleeve Hill said:

So from nowhere there are two areas to watch. 1. South of Bermuda which has a 50% chance of development and then a Cape Verde system. Only yesterday this had a 20% chance of developing, today that is now 70%.

looks a well organised feature which is due to become a tropical depression before encountering less favourable conditions. 

Its a bit surprising this one as ocean temps are generally lower this season, but the system is well south where the SST are nearer normal. 

Hopefully it will just bring lots of rain for the leeward islands to ease the drought here.

I notice you are in Antigua you lucky thing! What takes you there?

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95L may still have a hard time developing as the atmosphere is forecast to become less conducive however it's good to see robust wave activity this early. 

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17 hours ago, Lauren said:

I notice you are in Antigua you lucky thing! What takes you there?

I'm senior insurance underwriting mgr for a leading property & casualty insurer in the Caribbean. Trust me it's not as boring as it may sound. 3 year contract. After Irma and Maria last year the Caribbean needs a quiet year. 

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As i stated a few weeks ago when i postulated that we see low major hurricane numbers but high overall storms forming, June saw lower than average pressure across most of the tropical Atlantic east of the Carribean suggesting that we won't have problems getting Cape Verde systems forming. The question is both how much impact the -SST's have and also how much shear a developing Nino will impart in the Gulf and Carribean. 

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MJO - LIKELY INFLUENCE ON HURRICANE SEASON THROUGH JULY 2018?

The current phase of the MJO is the latest teleconnection likely to be currently influencing this hurricane season. Research presented by Phil Klotzbach at the AMS 33rd Conference on “Hurricanes and Tropical Meteorology” held in Florida in April 2018 shows a strong correlation between the different phases of the MJO and hurricane activity:

The Madden-Julian oscillation (MJO) has been documented in a variety of prior studies to significantly impact Atlantic hurricane activity through modulations in atmospheric conditions including vertical wind shear, mid-level moisture, vertical motion and surface pressure.

We find that US hurricane landfalls are more likely in MJO phases 1-4 (MJO enhanced convection is centered over Africa, the Indian Ocean, or the western portion of the Maritime Continent) and is less likely when the MJO is in phases 5-8 (MJO enhanced convection is centered over the eastern portion of the Maritime Continent, the western Pacific or the Western Hemisphere).

Here's the link to the presentation. The following two charts from the presentation clearly show the impact on activity. (There are many other charts shown in this excellent presentation including maps of where storms form, subsequent landfall and damage caused by phase). 

357188738_HurricanesbyMJOPhaseKlotzbach2015.thumb.jpg.d76e1ee65388367b05903c27c5f24023.jpg1255228068_Hurricane_CycloneLandfallbyMJOPhaseKlotzbach2015.thumb.jpg.c83e3581fe84dae312665d49a58a0bc7.jpg

The latest Wheeler-Hendon phase plot forecasts from ECMF for 17th to 31st July shows MJO activity in the ‘lower activity’ Phases 5 to 6 over the coming 2 weeks:

1213858232_MJOPhasePlot15Julyto31JulyECMF.thumb.gif.d830705fa5fbd3f459332024e73b3f1f.gif

And Michael Ventrice has just tweeted:

“After a swift start to the 2018 Atlantic Hurricane Season, things have quieted down. It's not coincidental that this lull in activity is timed with the passage of the convectively suppressed phase of the Madden Julian Oscillation across the Atlantic Basin.

1679529557_Ventricetweethurricane17July2018.thumb.jpg.c0615675c7e57df2a1e975d6c0fc6344.jpg

https://twitter.com/MJVentrice/status/1019258434397659139

 

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Very interesting! It does indeed seem to have died down whereas the Pacific has kicked off again.

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On 18/07/2018 at 09:26, Lauren said:

Very interesting! It does indeed seem to have died down whereas the Pacific has kicked off again.

What I'm finding interesting is the developing hurricane season seems to be acting as if ENSO has already transitioned from La Nina to El Nino, yet the latest multi-model forecasts suggest it's not until late summer/early autumn that a weak El Nino develops:

1165001238_ENSOModelPredictionsatJuly2018.thumb.jpg.676746f6cee2e3c496e241f984349a3d.jpg

"Climate model ensemble average calls for borderline weak El Nino conditions for peak of Atlantic hurricane season (August-October), with potential for weak to moderate El Nino during the winter of 2018/19."  Philip Klotzbach. https://twitter.com/philklotzbach/status/1020023751264690178

Phil Klotzbach is a Research Scientist in the Department of Atmospheric Science at Colorado State University specialising in hurricanes, so his interest in ENSO here is related to its impact on the hurricane season. This research paper shows why ENSO state is very relevant:

Impacts of El Niño and La Niña on the hurricane season.
El Niño favors stronger hurricane activity in the central and eastern Pacific basins and suppresses it in the Atlantic basin. Conversely, La Niña suppresses hurricane activity in the central and eastern Pacific basins and enhances it in the Atlantic basin. These impacts are primarily caused by changes in the vertical wind shear, which refers to the change in wind speed and direction between roughly 5,000-35,000 ft. above the ground. Strong vertical wind shear can rip a developing hurricane apart, or even prevent it from forming.

https://www.climate.gov/news-features/blogs/enso/impacts-el-niño-and-la-niña-hurricane-season

237247875_ElNinohurricaneimpact.thumb.jpg.714566c230aab9d7ffc9468ba8096a87.jpg

 

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59 minutes ago, Blessed Weather said:

What I'm finding interesting is the developing hurricane season seems to be acting as if ENSO has already transitioned from La Nina to El Nino, yet the latest multi-model forecasts suggest it's not until late summer/early autumn that a weak El Nino develops:

1165001238_ENSOModelPredictionsatJuly2018.thumb.jpg.676746f6cee2e3c496e241f984349a3d.jpg

"Climate model ensemble average calls for borderline weak El Nino conditions for peak of Atlantic hurricane season (August-October), with potential for weak to moderate El Nino during the winter of 2018/19."  Philip Klotzbach. https://twitter.com/philklotzbach/status/1020023751264690178

Phil Klotzbach is a Research Scientist in the Department of Atmospheric Science at Colorado State University specialising in hurricanes, so his interest in ENSO here is related to its impact on the hurricane season. This research paper shows why ENSO state is very relevant:

Impacts of El Niño and La Niña on the hurricane season.
El Niño favors stronger hurricane activity in the central and eastern Pacific basins and suppresses it in the Atlantic basin. Conversely, La Niña suppresses hurricane activity in the central and eastern Pacific basins and enhances it in the Atlantic basin. These impacts are primarily caused by changes in the vertical wind shear, which refers to the change in wind speed and direction between roughly 5,000-35,000 ft. above the ground. Strong vertical wind shear can rip a developing hurricane apart, or even prevent it from forming.

https://www.climate.gov/news-features/blogs/enso/impacts-el-niño-and-la-niña-hurricane-season

237247875_ElNinohurricaneimpact.thumb.jpg.714566c230aab9d7ffc9468ba8096a87.jpg

 

It's the horse shoe effect.

Extremely low GLAAM as you see with a -PDO/-ENSO can also at times contribute to low Atlantic SST's. In our case we saw an extremely positive NAO period (not uncommon in Nina events) which cooled the tropical Atlantic during the spring. 

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Interestingly the MDR is continuing to cool, rather than warm up.

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Excellent tweet from Ben Noll:

"The late-July SST anomaly pattern in the tropical Atlantic during 2018 is the complete opposite of 2005, which was the most active Atlantic hurricane season on record. The difference is striking."

July 2005 878426228_SSTAnom26July2005.thumb.jpg.bba28b7f324a555139b2cfc360a23849.jpg July 2018 63935751_SSTAnom26July2018.thumb.jpg.519a08acb45189c330bb63b5fc8f4cbe.jpg

https://twitter.com/BenNollWeather/status/1023188777198530560

 

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On the flipside, the Pacific is churning them out.

I think the Carribean would be happy if this was a quiet season considering how battered they've been of late.

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On 28/07/2018 at 16:18, Blessed Weather said:

Excellent tweet from Ben Noll:

"The late-July SST anomaly pattern in the tropical Atlantic during 2018 is the complete opposite of 2005, which was the most active Atlantic hurricane season on record. The difference is striking."

July 2005 878426228_SSTAnom26July2005.thumb.jpg.bba28b7f324a555139b2cfc360a23849.jpg July 2018 63935751_SSTAnom26July2018.thumb.jpg.519a08acb45189c330bb63b5fc8f4cbe.jpg

https://twitter.com/BenNollWeather/status/1023188777198530560

 

Interesting that where the SST's are quite high there's a marked increase in activity off the coast of West Africa on the ITCZ.

itcz.jpg

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On 28/07/2018 at 17:47, Lauren said:

On the flipside, the Pacific is churning them out.

I think the Carribean would be happy if this was a quiet season considering how battered they've been of late.

Quiet is no guarantee of no impact.

1961 produced only 11 systems but one those was Hurricane Carla, one of the strongest systems at impact on record. 

2004 did not see it's first system until late July, then it went guns blazing. 

In our case we have most -AMO value for June since 2002. It will be more notable if it persists into September with not a single -AMO year since 1998 (that one of course produced Hurricane Mitch, until Wilma, the strongest storm on record. 

.........

I do believe the season will see below average ACE but it's still likely that we'll see a major hurricane or two. 

Edited by summer blizzard

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10 hours ago, summer blizzard said:

Quiet is no guarantee of no impact.

1961 produced only 11 systems but one those was Hurricane Carla, one of the strongest systems at impact on record. 

2004 did not see it's first system until late July, then it went guns blazing. 

In our case we have most -AMO value for June since 2002. It will be more notable if it persists into September with not a single -AMO year since 1998 (that one of course produced Hurricane Mitch, until Wilma, the strongest storm on record. 

.........

I do believe the season will see below average ACE but it's still likely that we'll see a major hurricane or two. 

Oh certainly. Season doesn't really kick off until this  month. Just saying that I think the Caribbean and East Coast would be grateful for a below average season.

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Maybe most of this season's activity will be initiated in the Gulf of Mexico, at the SSTs there are quite warm.

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The EPAC is ridiculous right now!

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With the latest Colorado State University (CSU) forecast for the Atlantic season going for 12 named storms, 5 hurricanes and now only 1 major hurricane (cat 3 or stronger), Phil Klotzbach has provided some interesting analysis showing that in every "one major only" season since 1950, each of those hurricanes made continental USA landfall.

114159673_Klotzbachtweetoneonlyhurricaneseasons.thumb.jpg.29b139cb617dc61ed962a79bc97d8826.jpg

CSU update: https://source.colostate.edu/csu-team-continues-to-predict-below-average-2018-atlantic-hurricane-season/
Klotzbach tweet: https://twitter.com/philklotzbach/status/1027933953993269249

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