Atlantic hurricane season 2018

[Cyclone Tracy]

After a non existent start due to cooler sea surface temps, the Atlantic hurricane factory off west Africa is starting to fire up and it's looking ominous as a conveyor belt of Tropical depressions commence moving west.

[Nev]

Not sure what you mean by 'a non existent start'?

The Atlantic hurricane season, which runs from June 1 to November 30, actually began early with a named subtropical storm in May, followed by another 6 named tropical storms so far (1-minute mean-winds above 34 knots), 2 of which reached hurricane status in July (1-minute mean-winds above 64 knots). And of the 2 current Atlantic tropical storms (aka tropical cyclones), Gordon may reach hurricane status as it makes landfall around southern Mississippi in about 36 hrs time.

An average hurricane season produces 12 named storms, of which 6 become hurricanes, including 3 major hurricanes.

[Cyclone Tracy]

Not sure what you mean by 'a non existent start'?

The Atlantic hurricane season, which runs from June 1 to November 30, actually began early with a named subtropical storm in May, followed by another 6 named tropical storms so far (1-minute mean-winds above 34 knots), 2 of which reached hurricane status in July (1-minute mean-winds above 64 knots). And of the 2 current Atlantic tropical storms (aka tropical cyclones), Gordon may reach hurricane status as it makes landfall around southern Mississippi in about 36 hrs time.

An average hurricane season produces 12 named storms, of which 6 become hurricanes, including 3 major hurricanes.

Accumulated cyclone energy (ACE), a calculation method used by meteorologists to combine duration and strength of tropical cyclones is currently at its lowest level (18.1) in the Atlantic basin since the 2013. For the first time since 2013, not one Hurricane formed in the Atlantic basin in August. Enough said ...but that is now changing, hence the new subject.

[Cyclone Tracy]

TS Gordon has just registered 44 knot surface winds and 1004 hPa on the last Hurricane Hunter (mission 03) dropsonde observation. The storm is currently having issues with unfavourable wind shear, stalling further development. More favourable SST’s over 30 to 31c in the next 12 hours, with a neutral wind shear environment could see a more robust structure develop and give Gordon a chance of the first Hurricane to cross the U.S mainland for 2018.

TS Florence has gained some strength over the last 24 hours but there remains much uncertainty past 120 hours at this stage. UK, EC (control) and ICON are tracking a hurricane past 120 hours towards the U.S mainland along a strong subtropical ridge but the big U.S models think otherwise for the moment.

[Cyclone Tracy]

TS Gordon currently not quite a hurricane status and is a messy asymmetrical storm with the heavy weather raking the Alabama coast, Mississippi will be next as he closes in on land over the next 6 hours. NOAA still projecting a Hurricane level system on crossing.

Florence is now a hurricane and tracking along the subtropical ridge in the middle of the Atlantic.

[Cyclone Tracy]

TS Gordon now on approach to the coast near Mississippi (10am NZT). Just under Hurricane intensity currently (Would be a cat 1 bordering cat 2 for South Pacific scale)

[Nev]

TS Gordon now on approach to the coast near Mississippi (10am NZT). Just under Hurricane intensity currently (Would be a cat 1 bordering cat 2 for South Pacific scale)

Hmm… NHC's 60 kt 1-minute mean-winds at 2100z equals about 53 kt 10-minute mean-winds, which is easily a Cat 2 TC on the BoM/Fiji scale.

[Cyclone Tracy]

TS Gordon now on approach to the coast near Mississippi (10am NZT). Just under Hurricane intensity currently (Would be a cat 1 bordering cat 2 for South Pacific scale)

Hmm… NHC's 60 kt 1-minute mean-winds at 2100z equals about 53 kt 10-minute mean-winds, which is easily a Cat 2 TC on the BoM/Fiji scale.

I've been watching the Stepped Frequency Microwave Radiometer (SFMR) and wind has yet to register over 51 knots on the last take for NOAA.

Storm now has a better structure as it's closing in on the land.

[Cyclone Tracy]

Northern side land obs now coming into the game. Watching for the last 15 min, the highest 1 min sustained wind speed I'm finding is only 41 knots at the moment. Same Ob had a gust of 61 knots.

[Cyclone Tracy]

Highest 10m wind ob I can spot has registered 58 knots 1 min speed. An ob at 36m has registered 59 knots but would be ruled out by NOAA I assume due to the non standard height.


Unless Gordon's backend fires up, he goes down in history as a Tropical storm and not a Hurricane.... with lots of flooding.

[Cyclone Tracy]

meanwhile out in the Atlantic, Florence becomes a cat 2 Hurricane and develops a robust eyewall. Only fish should be concerned at this stage of its life

[Cyclone Tracy]

An Atlantic hurricane parade is starting to take shape.

Hurricane Florence is now a major Hurricane and Cat 3, defying models and forecasters with her ability to strengthen in 20 to 25 knot shear. Longer term, ensembles are split on the strength of the subtropical ridge and the position of the omega block over North America. EC control currently showing a direct impact on the U.S mainland with no exit door to the North but it’s still too early to take serious.

[Cyclone Tracy]

Defying the climatological swath of major hurricane tracks, Florence is now a Cat 4 well NE of normal. Cooler SST's and unfavourable wind shear has incredibly made no difference to intensification.... NOAA hurricane forecast from 24 hours ago is currently 45 knots out !!

For what it is worth, models are still projecting Florence to ease back in the next 2 days....then it's a whole different ball game with favourable shear and SST in her path.

[Cyclone Tracy]

Florence was ripped apart by wind shear in the last 24 hours, downgrading her from a cat 4 to a storm. Re-intensification will commence again over the next 24 hours with favourable conditions ahead. Still massive differences past 2 days across all models. Interestingly, the UKM (which has been the world best in the last 12 months at picking the strength of the subtropical ridges) has an alarming westerly track towards the U.S. Odds of a major Hurricane hitting the U.S are starting to shorten.

[Cyclone Tracy]

Tropical Atlantic is now starting to erupt with 3 named storms and 2 disturbances. TS Florence is now very close to hurricane status again (2pm NZT) with newly named storms Isaac and Helene now moving westward along the subtropical ridge in the eastern Atlantic.

TS Florence has ingested a lot of dry air in the last 48 hours, which has commenced flushing out. Deep convection is now being spotted on the southern side of her centre. Short term, she will again become a Hurricane, medium term the east coast of the U.S is now in her sights.

[Cyclone Tracy]

Florence has re-formed back to a hurricane status. A new thread has now been created for Hurricane Florence.

https://www.weatherforum.nz/phpBB3/view ... 66#p176866

[Cyclone Tracy]

Officially now 3 Hurricanes in the Atlantic as of 3pm NZT with Isaac just being upgraded. All are category 1's but Florence is now very close to becoming a Category 2. The flow on affects for Isaac and Helene will depend on Florence's behaviour along with the high pressure ridge to the north.

[Cyclone Tracy]

It's becoming a full house.

> Florence for the SE U.S coast
> Isaac into the Caribbean
> Helene will swallow a TD, then ride the ridge and become an XTC. One to watch for Ireland and the U.K
> New storm potential for the Gulf of Mexico within 72 hours

[Cyclone Tracy]

I can't recall seeing anything like this for the Atlantic basin.

Welcome to Sub-TS Joyce, making it now 4 named systems. 5 simultaneously would be a record in the Atlantic basin from what I can gather. The one in the Gulf of Mexico is now a 70% chance of being upgraded to a TS.

[Cyclone Tracy]

A quieter few weeks since the early September hurricane parade but the EC ensemble is starting to show a 50% chance of a tropical storm developing in the Gulf of Mexico late next week. SST's in the Gulf of Mexico are currently between 28 to 30c.

Now it's October, any tropical depression, storm or hurricane that moves towards the U.S can have significant mid latitude impacts, with colder air interacting from the north. Snow Hurricanes like Hurricane Sandy and the great snow Hurricane of 1804, can be an atmospheric flow on effect on a system with tropical origins from October onwards.

[Cyclone Tracy]

The Central American Gyre has given birth to a small low level circulation centre currently spinning around 25 knots. Gulf of Mexico U.S states will now be watching with interest as a favourable SST and wind shear environment lay ahead for the circulation along with a high pressure ridge east of the U.S.

[Cyclone Tracy]

Tropical Storm Michael has been born overnight. He may each Cat 1 Hurricane status within 24 hours.

He is starting to look like being a major Hurricane that attacks the Florida panhandle by mid to late week. Sea surface temperature is near or above 30c in the gulf....

[Cyclone Tracy]

TS Michael has dropped 11 hPa in the last 2 hours based on the current recon flight mission. That type of sudden fall generally indicates a rapid intensification hurricane scenario is underway. Overall today, Michael has now dropped 21 hPa in the last 12 hours.

Edit > New thread for Hurricane Michael has now been created.

https://www.weatherforum.nz/phpBB3/view ... 75#p177227