Monday, August 20, 2012

80% Chance of Development Next 24-48 hrs!

In the last outlook we pointed out the main reason as to why this was going to be slow developing. Nothing has really changed with that particular reason and it is quite clear when one looks at the water vapor image above.
Before we go on we want to address a couple questions that we have gotten on this system.

Question # 1? What track will this take? This was actually addressed in the outlook last night as to which direction it would be moving over the next 5 days. We do not go beyond 5 days because things become more uncertain and you end up putting more guess work into it then actual forecasting.

Question #2 Will this effect the East Coast? Well, this is relatively simple at this time to answer and that is that until a center of circulation develops ..No track is going to be set in stone. Folks it is important to understand that there is no center of circulation and that means that Hurricane models , which initialize with a COC ..are already starting off on a false foundation..

Question #3 Will this become a Category 3 or greater hurricane? This was based off a few runs of the GFS (Global forecasting system model).. If any one "bites" into those runs when there is not a COC even developed then they are simply forecasting something they want to see happen or occur. 

This is something we will NEVER do and it does not have any part in forecasting!

So with those questions out of the way ..lets once again look at the present case scenario or the atmosphere that is having an influence on this Tropical Wave as it is trying to develop..

The atmosphere surrounding the system is a lot more important when the system is developing then what track its going to take. Why? Because if the atmosphere is to hostile it may NOT develop.
So lets start off by looking at the shear. While there is an anticyclone across the system there is still an area of shear at 10-20 knots across the system as well. Now if this was a already developed system this would not be that bad of news for the system but because it is developing ..it helps to filter dry air into the mid level vortex ..especially if there is any dry air around and water vapor shows the dry air (above) and the image below shows the dry air as well..
So now, we have an added concern from last nights update for development of this system and that is that besides the dry air we now have shear across the system.  So we have the shear helping to increase dry air into the vortex as it is trying to develop.. Not a winning combination. Does it get any better?
This is the shear tendency map and the purpose of this map is to show where shear is increasing and shear is decreasing and as is evident there is a wall of shear increasing to its west in its very pathway.
So .. we have increasing shear
We have dry air 
We have 10-20 knots of shear present...

These are all hinderences to a developing tropical cyclone.  Convergence and divergence tonight are fairly decent with the system at the time of this writing..


However, and this probably has to do with the dry air and the shear when we look at the actual vorticity we see that it has become stretched out and elongated which suggests that it has decoupled.

When one looks at the steering currents one pretty much gets the idea of a west to perhaps even west southwest movement due to the very strong subtropical ridge of high pressure to the north of the system. This may be why we are seeing the system become more decoupled... it may try to reform further south..

And surely enough you can see that the guidance does take this on a basically due west track towards the Lesser Antilles...

Now in review we have L
1. Dry air intrusion
2. Wind shear 10-20 knots
3. Increasing shear to the west of the tropical wave
4. Stretched out and decoupled vortexes...
5. And last but not least would be its fast motion speed..

All these things suggest that the environment is not conducive for fast strengthening and we will continue to see a slowly intensifying system. It is quite possible that this gets to the Lesser Antilles and it is not much more organized then what it is now...

We will say the only way this effects the east coast is if there becomes a weakness in the ridge and the system is able to feel out that weakness..Other wise ..this should keep heading due west with perhaps a touch of south of due west...

Update in another 24 hrs.... Keeping it real and down to Earth!

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