Shear is primetime for Tropical Development

[Anonymous]

This is even better conditions then Bret had. This has to be watched.

[skysummit]

Nothing but really good conditions ahead of out little system (as of right now). If it stays this way, someone may be in trouble next week.

[Anonymous]

The thing that worries me is that if this system strengthens like Bret, it may have a few days over the Gulf of Mexico to do so. If the shear stays low like that...right up to the coast, we will have a significant system impacting the Gulf Coast.

[skysummit]

Yea, and Bret wouldn't have been a woosie of a storm if he moved over the central Gulf.

[wxman57]

Beware those shear maps! They're only as good as the upper-level wind data that were fed into them. I've found that many of the models just don't have a clue what the upper-level winds are doing in the tropics in a lot of cases. Sometimes, for example, the GFS might show northeast winds in a part of the Caribbean where water vapor clearly shows a jet from the southwest. You just can't trust the models out there.

But you can trust your own eyes. Take a look at a long water vapor loop of the NW caribbean and you see TWO upper lows now. One is near the Isle of Pines/Youth, the other is over the southern Yucatan. I see indications of considerably more shear than the shear maps would suggest.

The wave axis is approaching the first upper low now, resulting in what I think is a temporary flare-up of squalls around Jamaica and west to the Cayman Islands. Water vapor loops indicate the wave axis is passing a "hot-spot" in the southeast quadrant of the upper low right now. Latest images suggest diminishing convection as the wave axis passes this hot spot. I'd expect thunderstorms to re-fire closer to Honduras/Nicaragua later today as the wave begins to interact with the 2nd upper low.

Here's a screenshot I just took. Still just a low-amplitude wave at the surface.

<img src="http://myweb.cableone.net/nolasue/carib5.gif">

[Dave C]

Water vapor also points out Wx man57 anaylasis
http://www.ssd.noaa.gov/PS/TROP/DATA/RT/WATL/WV/20.jpg
Upper lows show up nicely

[skysummit]

I'm not saying that this wave will blow up into a TS by this evening. I'm saying once it gets into the Gulf, it'll probably have a much better chance.

[Anonymous]

Yes indeed, as the Upper Level Lows go away, the outflow of the system could be dynamic given the upper level pattern.

[Derek Ortt]

the shear maps have 0 value, which is why we do not use them. The models are just awful at predicting UL winds (actually, they are good, often the exact opposite of what they predict happens)

[wxman57]

I'm not saying that this wave will blow up into a TS by this evening. I'm saying once it gets into the Gulf, it'll probably have a much better chance.

I definitely agree with that. Quesiton is, where? If the wave begins interacting with the upper low over the southern Yucatan tonight, then convection may begin concentrating farther southwest toard Honduras. From that point, movement would be northwestward across the southern BoC on Monday/Tuesday, very similar to where Bret formed. If that's the case, then not much time for development and only a threat to southern Mexico.

But if thunderstorms persist farther north, then development would be more likely in the SW Gulf rather than southern BoC. Development there could be a real problem.

Right now, I think the more southern solution is most likely.

[DROliver]

the shear maps have 0 value, which is why we do not use them. The models are just awful at predicting UL winds (actually, they are good, often the exact opposite of what they predict happens)

If shear maps have a 0 value then why do they issue them?

[loon]

I was wondering the same thing, but since Mets where saying it, I believe it. But I've always looked at those maps, and I thought they were snapshots of what shear was doing, and the "shear tendency" maps showed what the models expected to happen. I've just never heard the shear challenged and today two mets do...I guess I will stop looking at them, no use if its bad data. Besides, like I said, I thought it was snapshots, not model output...

cheers
loon

[skysummit]

I was going to ask the same question as Dr. Oliver, but I didn't want to seem like a smartass. But since it's already asked.....why do they issue them if it's no use?

[loon]

I see that the map in question was a tendency map, so maybe just those are worthless. My guess is the output is just a side effect of the model runs, so why not post it. Of course, if in the Met world they are known as completely worthless, I do wonder why you would keep issuing them.

[Derek Ortt]

the analysis maps are USUALLY good, though I have found many times where the GFS initial conditions just do not make sense.

The tendency forecast maps I have no clue at all as to why they are issued. They are based off of model forecasts which are more likely to be wrong than correct at the upper levels

[cajungal]

Our Meterologist Channel 4 New New Orleans, David Bernard, seemed a little concerned. He said we may have something tropical off the Louisiana coast by Wednesday. I will worry about it then. Right now, I just want to get through working this weekend. And enjoying the 4th off and hopefully going to the beach!

[skysummit]

Our Meterologist Channel 4 New New Orleans, David Bernard, seemed a little concerned. He said we may have something tropical off the Louisiana coast by Wednesday. I will worry about it then. Right now, I just want to get through working this weekend. And enjoying the 4th off and hopefully going to the beach!

I hear you cajungal! You know next Friday is David Bernard's last day in NOLA? He just may be sent off with a bang! I would be heading to the beach also, however, I just found out at the last minute yesterday that I'm on call this weekend I was looking so forward to this 3 day weekend too.

[Hurricaneman]

I think the ULL might be the only inhibitor

[tw861]

I'm not saying that this wave will blow up into a TS by this evening. I'm saying once it gets into the Gulf, it'll probably have a much better chance.

I definitely agree with that. Quesiton is, where? If the wave begins interacting with the upper low over the southern Yucatan tonight, then convection may begin concentrating farther southwest toard Honduras. From that point, movement would be northwestward across the southern BoC on Monday/Tuesday, very similar to where Bret formed. If that's the case, then not much time for development and only a threat to southern Mexico.

But if thunderstorms persist farther north, then development would be more likely in the SW Gulf rather than southern BoC. Development there could be a real problem.

Right now, I think the more southern solution is most likely.

No matter what happens it appears it will be further north than Bret. The little circulation that spawned Bret was further south and tracked over Honduras and into southern Mexico. Now does further north mean it still goes to Mexico I don't know but I'm betting somewhere between the middle Texas coast and the mouth of the Mississippi. Like it or not it does seem to be slowly getting better organized. Better rest up today and tommorow cause you might be busy next week.