ATL: Ex-Tropical Storm FIONA - Discussion

[jinftl]

Generally, the further west a system develops in the atlantic, the less likely it will recurve out to sea and be a 'fish'. Not an absolute rule, but as a rule of thumb systems that develop further west are the ones to watch. Perhaps a pro can comment, but I believe it has to do with stronger, more organized systems being more influenced by the sharp upper atmosphere troughs and ridges, while weaker systems are more steered by low-level flow, which is generally west or wnw in direction.

Katrina came off of the coast of africa as a weak wave and didn't become a tropical depression until she was over the Bahamas!!!

I am beginning to think it will never become a depression
what does anytone else think

[senorpepr]

Can someone explain how this isnt a Tropical Depression? IMO it's been a Tropical Depression for at least the past 24 hours.

As long as microwave imagery suggests it's still a broad low/wave, it will not be upgraded to a depression.

hey senor! So good to see you! What are your reasoned thoughts on both Earl and this invest?

Hey there... I haven't really looked too much down the road, although both appear to make a northward curve near or just before the islands. Essentially, I'm looking at NHC's Earl forecast--or maybe a bit westward--and 97 having a similar track. The problem is waiting for 97L to develop. It's not quite there yet. Looking at the latest ASCAT pass, I'm not expecting it to be upgraded any time real soon. (Maybe later tonight or tomorrow, but we'll see when the new forecasters get on shift) The latest visible shots don't get my hopes up either...

[Migle]

I am beginning to think it will never become a depression
what does anytone else think

It already is a Tropical Depression, NHC just doesn't want to name it for some reason.

Please explain why you think it's a tropical depression? Based on the data that's available, it appears to be a very broad low, if not a wave. Looking at the microwave imagery, I agree with it NOT being a depression.

I haven't seen a microwave image lately, but I going off of the satellite image and it has some convection. It looks better than TD5 did, you don't think?

[AdamFirst]

As I mentioned in the earl thread, maybe the repeated gfs solution of earl eating 97L isn't that farfetched, especially how it still remains highly disorganized. Earl is slowing down and 97L is just trucking along.

[senorpepr]

I haven't seen a microwave image lately, but I going off of the satellite image and it has some convection. It looks better than TD5 did, you don't think?

To me, with each visible image that comes it, it look worse and worse--losing convection, opening up.

Here's a recent ASCAT pass... not looking too hot for a depression... but rather a vigorous wave/broad tropical low

[Migle]

Could it be getting sheared by Earl, senor?

[jinftl]

Update this morning from Dr. Jeff Masters on 97L:

The tropical wave (Invest 97L) now midway between Africa and the Lesser Antilles Islands has developed a well-defined surface circulation, and appears destined to develop into a tropical storm and follow the path of Danielle and Earl. Satellite loops show the surface circulation clearly, but also reveal that there is not enough heavy thunderstorm activity associated with 97L for it to be called a tropical depression. The storm is experiencing low wind shear of 5 - 10 knots, is over warm 28°C waters, and is battling a region of dry air associated with the Saharan Air Layer (SAL) to its northwest. The latest SHIPS model forecast calls for shear to stay in the low range, 5 - 10 knots, through Wednesday, and this should allow 97L to organize into a tropical depression today or Monday.

The storm will follow a track very similar to Danielle and Earl westward towards the Lesser Antilles Islands, and the storm should arrive near the northern Lesser Antilles Wednesday or Thursday. A more northwesterly path is likely for 97L as it approaches the Lesser Antilles, as the storm follows a break in the high pressure ridge steering it, created by Danielle and Earl. It currently appears that the Northern Lesser Antilles Islands may be at risk of at close brush or direct hit by 97L. If 97L moves relatively quickly, arriving at the Lesser Antilles on Wednesday, it is likely to be a weaker system, since it will have less time over water, and will be closer to big brother Earl. Earl is likely to be a large and powerful hurricane at that time, and the clockwise upper level outflow from Earl will bring strong upper-level northerly winds to the Lesser Antilles, creating high wind shear for 97L.

However, if 97L moves relatively slowly, and arrives in the Lesser Antilles on Thursday, Earl will be farther away, the wind shear will be lessened, and 97L will have had enough time over water to potentially be a hurricane. Depending upon how fast they have 97L moving, the computer models have a wide variety of solutions for 97L, ranging from a making it a Category 1 hurricane five days from now (GFDL model) to a weak tropical storm five days from now (several models.) History suggests that a storm in 97L's current location has a 25% chance of making landfall on the U.S. East Coast. NHC is giving 97L a 80% chance of developing into a tropical depression by Tuesday.
http://www.wunderground.com/blog/JeffMa ... rynum=1591

[jlauderdal]

I am beginning to think it will never become a depression
what does anytone else think

i think your impatient, give it time, it will be classified when the NHC gets good and ready

[HURAKAN]

It will develop. Remember that Earl also struggled in this area.

[fci]

It is interesting how much longer 97L is taking to develop compared to Danielle and Earl. Especially considering that it has had a very high percentage for a couple of days now.

Interesting to figure out the correlation between the three storms and the effect that they have had with the development of 97L

[Stephanie]

Cooler waters perhaps due to the churning of the other storms?

[HURAKAN]

Unofficial track

[somethingfunny]

Is it moving too quickly to organize at this point? IIRC Earl already had an established circulation when he got caught in the 20+mph steering flow, and only developed very slowly. At times I think 97L has been very close to being a depression but perhaps the NHC doesn't want to alarm the islands at this point because moving at this speed it could easily open up into a wave again by the next advisory.

[gatorcane]

Okay 12z gfs curves it away from the united states. Clearly the ecmwf and the gfs see different synoptic setups in the long-range. I have to say I would probably lean more towards the gfs at this point wth a greater than not chance this misses at least the se united states and probably the united states all together. Main reason is that the great lakes trough is starting to dig and 97l is very likely going to catch Earl. Earl is very likely to become a large and powerful hurricane that takes up a lot of the western Atlantic. Should leave a nice weakness behind as it merges with the trough.

I still think the ecmwf will start shifting east away from a se united states hit. May take a couple of days for it to completely shift though.

[Ivanhater]

Okay 12z gfs curves it away from the united states. Clearly the ecmwf and the gfs see different synoptic setups in the long-range. I have to say I would probably lean more towards the gfs at this point wth a greater than not chance this misses at least the se united states and probably the united states all together.

I still think the ecmwf will start shifting east away from a se united states hit.

I don't think it is a good idea to lean toward the model that has been absolutely horrible with the evolution of 97L. I'll start paying attention to the GFS when it actually sees "Fiona" as it's own entity. Most of the Pro mets out in the weather world blogs are laughing at the GFS right now.

[ROCK]

Okay 12z gfs curves it away from the united states. Clearly the ecmwf and the gfs see different synoptic setups in the long-range. I have to say I would probably lean more towards the gfs at this point wth a greater than not chance this misses at least the se united states and probably the united states all together. Main reason is that the great lakes trough is starting to dig and 97l is very likely going to catch Earl. Earl is very likely to become a large and powerful hurricane that takes up a lot of the western Atlantic. Should leave a nice weakness behind as it merges with the trough.

I still think the ecmwf will start shifting east away from a se united states hit. May take a couple of days for it to completely shift though.

I disagree.....the GFS has been horrible this year...I dont even look at for surface reflections anymore. rather upper air synopics....Dee was a large and powerful hurricane and so far its weakness is not as pronounced as model had progged....if anything as long as 97L keeps its distance / fails to organize I can see this getting into the caribbean....or the GOM....

[supercane]

Latest microwave imagery:

[Portastorm]

The ECMWF has consistently outscored the GFS in 5-day and 6-day forecasting errors (or lack thereof).

I'm just sayin' ...

[Vortmax1]

Most of the Pro mets out in the weather world blogs are laughing at the GFS right now.

Thank you for that Ivanhater.
I can't believe what has happened to the GFS since they started messing with it.
It is the first one I throw out lately.
I think the ECM is on to something and only further runs will tell.

[ronjon]

Okay 12z gfs curves it away from the united states. Clearly the ecmwf and the gfs see different synoptic setups in the long-range. I have to say I would probably lean more towards the gfs at this point wth a greater than not chance this misses at least the se united states and probably the united states all together. Main reason is that the great lakes trough is starting to dig and 97l is very likely going to catch Earl. Earl is very likely to become a large and powerful hurricane that takes up a lot of the western Atlantic. Should leave a nice weakness behind as it merges with the trough.

I still think the ecmwf will start shifting east away from a se united states hit.

Sounds like you'll live or die with the GFS. I wouldn't pin a 7-10 day forecast on the results of one model - particularly one that is often poor in the long range such as GFS is. The ECM and its ensembles have a much better track record with synoptics in long range forecasting - just glance at almost any HPC discussion and you can see that they rely heavily on the ECM ensemble runs. In addition, the ECM/CMC has been trending more west and south with each run not swinging wildly back and forth. You may be right, whos to say at this time frame but the ECM is a better performing model in the long term.