ATL: FIONA - Post-Tropical - Discussion

[cycloneye]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT TUE AUG 16 2016

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

An area of cloudiness and thunderstorms associated with a tropical
wave centered about 600 miles west-southwest of the Cabo Verde
Islands is beginning to show some signs of organization.
Environmental conditions appear to be favorable for additional
development, and a tropical depression could form on Wednesday.
This system is expected to move toward the west-northwest and then
northwest over the open waters of the central Atlantic during the
next several days.
* Formation chance through 48 hours...high...80 percent
* Formation chance through 5 days...high...90 percent

$$
Forecaster Avila

[cycloneye]

Latest microwave looks like is organizing.

[chaser1]

Sure seems that this should remain shallow enough to gain less latitude in the near term. Of course it may well begin to start popping more convection and it might not take too much to deepen enough to start getting pulled by the deeper layer flow. Sure seems as if the models want to recurve it though; that or... maybe Ninel has simply willed 98L as an sacrificial offering to the "re-curve gods"

[Gustywind]

000
AXNT20 KNHC 161721
TWDAT

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
205 PM EDT TUE AUG 16 2016



...SPECIAL FEATURES...

A tropical wave is over the Eastern Atlantic about 500 nm
southwest of the Cabo Verde Islands with axis from 14N31W to
06N31W. A 1008 mb low is embedded on the wave axis near 10N31W.
Scattered moderate convection is from 09N-13N between 29W-35W.
The wave is in a moist environment with a noticeable 700 mb
signature. Environmental conditions are expected to be conducive
for development during the next few days, and a tropical
depression is likely to form while the system moves
northwestward toward the central tropical Atlantic. Latest
Tropical Weather Outlook gives this system a high chance of
tropical development within the next 48 hours.

[NDG]

12z Euro is trending weaker and more westward.

[wxman57]

Looks like it's already a TD, to me. The only question is when the NHC will decide to initiate advisories. Their text in the outlooks indicates they've decided to start advisories tomorrow. The fish will be happy...

[gatorcane]

I'd say that is a pretty big west shift with the ECMWF. Yes it is weakening towards the end but could it find better conditions down the road?

[znel52]

Looking nice on floater imagery.

http://rammb.cira.colostate.edu/ramsdis ... display=12

[gatorcane]

should have turned NW 24 hours ago

It seems to be gaining some latitude now albeit slowly but nothing like what the models had it doing looking at their runs just 24 hours ago. Latest Euro is out and it has significantly shifted to the west though it shows the system degenerating into a wave after about a week.

[Hammy]

Looks like it's already a TD, to me. The only question is when the NHC will decide to initiate advisories. Their text in the outlooks indicates they've decided to start advisories tomorrow. The fish will be happy...

My guess is they're waiting for the convection to pick up a bit, it seems pretty shallow at the moment.

[NDG]

It sure looks like it has gained significant organization during the day, close to a TD if not already.

[wxman57]

Looks like it's already a TD, to me. The only question is when the NHC will decide to initiate advisories. Their text in the outlooks indicates they've decided to start advisories tomorrow. The fish will be happy...

My guess is they're waiting for the convection to pick up a bit, it seems pretty shallow at the moment.

I agree there's no reason to be in too much of a hurry to initiate advisories on a system like this. What's the point (with the possible exception of shipping interests)?

[cycloneye]

18z Best Track:

Location: 11.3°N 32.6°W
Maximum Winds: 25 kt Gusts: N/A
Minimum Central Pressure: 1008 mb
Environmental Pressure: 1012 mb
Radius of Circulation: 160 NM
Radius of Maximum Wind: 80 NM

[LarryWx]

18z Best Track:

Location: 11.3°N 32.6°W
Maximum Winds: 25 kt Gusts: N/A
Minimum Central Pressure: 1008 mb
Environmental Pressure: 1012 mb
Radius of Circulation: 160 NM
Radius of Maximum Wind: 80 NM

So, being now at 11.3N, this has gained 2 degrees latitude since it bottomed near 9N yesterday.

[abajan]

Looks like it's already a TD, to me. ...

Going by the last few frames of the visible loop, I agree:

[StormHunter72]

Looks like it's already a TD, to me. ...

Going by the last few frames of the visible loop, I agree:

http://i.imgur.com/Ovqu7sy.gif

It has the look.

[cycloneye]

 https://twitter.com/JMGarciaRivera/status/765631514990305282

[Nimbus]

I'm curious to see how 98l does once it starts to move away from the moisture down in the ITCZ.
They don't seem to have the ridge weakness nailed down just yet but typically a track recurving out that 1020 mb line at the end of the animation would be expected if there is a depression or TD north of 20 degrees latitude.

[gatorcane]

Convection on the increase, we should see "Fiona" soon enough:

http://rammb.cira.colostate.edu/ramsdis ... display=12

[gatorcane]

18Z guidance, tracking still a little left of the model guidance envelope. The ECMWF track (not shown) is way to the left of these models but also shows a weaker cyclone: