ATL: HERMINE - Post-Tropical - Discussion

[ScottNAtlanta]

In my experience what has happened to date is usually a good indication of what is to come. Long track waves that wait to develop (Earl) have been a trend, but I also see the MJO is strongly in phase 7 and forecast to move to weak phase 8 (or inside the circle where it doesnt play much of a role). Since we have also seen a lot of sinking air ahead of this I'm not sure why or what has changed significantly to allow this to develop. Sometimes taking off the "model hat" and just looking at whats there is better than chasing models...just sayin

[TheStormExpert]

Convection sustaining and expanding.

[Hurricaneman]

Convection sustaining and expanding.

I can see this becoming a tropical cyclone before 50W based on the way it looks and its connection to the ITCZ

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[TheStormExpert]

I can see this becoming a tropical cyclone before 50W based on the way it looks and its connection to the ITCZ

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the National Hurricane Center and National Weather Service

The sooner it becomes a tropical cyclone the sooner it disconnects from the ITCZ, meaning it may still have to contend with SAL.

[tolakram]

SAL isn't too bad and Fiona has cut a pretty good swath right through it.

[tarheelprogrammer]

I can see this becoming a tropical cyclone before 50W based on the way it looks and its connection to the ITCZ

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the National Hurricane Center and National Weather Service

The sooner it becomes a tropical cyclone the sooner it disconnects from the ITCZ, meaning it may still have to contend with SAL.

Also, the sooner it disconnects the more likely it goes OTS correct?

[tolakram]

Also, the sooner it disconnects the more likely it goes OTS correct?

Connected or disconnected is not something that would determine steering. Steering is determined by the strength of the system and the steering currents.

[TropicalAnalystwx13]

99L has the potential to be a long-tracked cyclone in a few days. Shear is expected to remain low, the environment is plenty moist thanks to Fiona, and ocean temperatures will only increase. The Euro appears to have some superficial elongation of 99L's vorticity behind 48-96hr, hence why it does not develop the system. Every other conventional model shows formation, and I definitely think this will be one to watch.

[Aric Dunn]

Very quickly organizing. especially in the low to mid levels. at the surface the ITCZ is starting to buckle which will take some time to close of a circ. still another 24 hours or so till its close to a TC

[Nimbus]

Those thunderstorms at sunset should help focus the LLC, has to be some serious inflow being drawn in when they burst like that. Southern forecast track isn't particularly a calming element given that it is getting too late in the season for a strong wave to track harmlessly all the way to the Pacific.

[gatorcane]

Looking good indeed, wide loop shot below as it comes into view on the far bottom-right:

[Blown Away]

A stretch, but maybe the beginning of a broad LLC?? IMO, if this system develops over the next few days it's going to be tough to clear the islands.

[Kazmit]

Looking better than Fiona did as an invest, and conditions are far more favorable. Looks like a long lived one and I see this crossing the Windwards near St. Vincent, and then strengthening in the West Caribbean. It's still too early to tell, but it could be a possible threat to the Gulf Coast and/or Mexico.

[Spirit29]

I start school again on August 29th. I'm not superstitious or anything but the late-bloomer of a season people are now predicting has me concerned.

Dumb question - if Fiona recurved because it strengthened and organized quickly, why wouldn't this invest follow suit as it seems to be doing the same thing?

[Kingarabian]

It has 25kts-30kts of shear waiting for it to the southwest...

[tolakram]

I start school again on August 29th. I'm not superstitious or anything but the late-bloomer of a season people are now predicting has me concerned.

Dumb question - if Fiona recurved because it strengthened and organized quickly, why wouldn't this invest follow suit as it seems to be doing the same thing?

Steering currents are constantly changing. Strength of storm plus steering currents at various levels in the atmosphere determine where a storm might go. Weak generally moves west, stronger will depend on any ridging in the atlantic. A ridge will keep the storm moving west, a break in the ridge will allow it to move north.

[NDG]

It has 25kts-30kts of shear waiting for it to the southwest...

Is all easterly UL winds, if the TW picks up significant forward speed towards the west, which the GFS shows it approaching the windward Island by Wednesday morning, traveling west at an average speed of 15 mph, it cancels out a lot of that UL easterly shear.
18Z SHIPS shows shear to be well under 15 knots over the next 5 days as it travels westward.

Code: Select all

SHEAR (KT)        14     8     8    11    12     7     9     6     9    12     5     9     8

[p1nheadlarry]

Convection sustaining and expanding.

I can see this becoming a tropical cyclone before 50W based on the way it looks and its connection to the ITCZ

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the National Hurricane Center and National Weather Service

The bands to the north, it looks better than Fiona has at times. Don't even get me started on Colin.

[Nimbus]

Probably not close enough to Fiona to experience any Fujiwara effect but often times the lead storm leaves a weakness that can set up the following storm for a recurve.

No models showing that scenario, so probably expect a weak and west wave for a few days.

[tarheelprogrammer]

Much stronger at 138 Hours on 18z GFS.

12z:


18z: