Shear 'o Rama

[MWatkins]

Looks like the system is getting impacted by increasing vertical shear.

http://www.ssd.noaa.gov/PS/TROP/DATA/RT/WATL/WV/20.jpg

The ULL to the north appears to be stretching the cloud pattern from the SW to the NE with time...nosing off thunderstorm activity to the NE. The models have been under-doing the forward speed of the wave...so the system may have run into the shear faster than forecast by the intensity guidance.

If there will be any development...it hinges on what happens aloft in the next 48 hours.

To borrow an old Seinfeld movie title....

Prognosis Negative.

MW

[Matthew5]

Your right! Now I'm going to feel sick

[whereverwx]

ah! poor system! well at least i cared for it! ill miss that poor guy!

[Derecho]

The ULL is clearly moving NW while the wave moves barely N of W.

They'll eventually get farther apart with time.

[ATS]

The ETA progs indicate the ULL will for the most part remain put over the next 36 hours, therefore meaning the track of the wave will be critical to how much interaction there is between it and the upper level low.

Once the wave enters the Caribbean, it will be sheared apart as the upper level easterly flow (and corresponding vertical shear) increases over the region in response to the intensifying upper-level anticyclone that will center it's self over the Bahamas. You can see that very clearly at 200mb.

Chances for development in my estimation are low.

It had the chance today to do so when the interaction between it and the upper low north of the islands was a positive--acting as a ventilation mechanism for the system, with no SAL being entrained into the wave, and weak vertical shear. It's problem all along has been the fast forward motion.

[ATS]

MWatkins, you noted the stretching of the clouds. This would suggest the system is becoming more linear in nature, which is confirmed on the latest IR and WV imagery.

[The Dark Knight]

it survived the islands overnight.... now it gets interesting.....

[rbaker]

correct in that it stayed alive overnight, which alot of these systems do. And it may do the same thing this afternoon and tonight. I don't think the shear from the upper low well north is having that much of an affect. In fact a 15 kt shear is not that much of shear as compared to 30 to 60 mph shear.
Climitology tells us that no system has every developed in this area to a ts since 1886 between 1886 and now. However, there are always first times, but my sense tells me wait till over by the w. caribbean. And by the way, I wouldn't count out the gom yet, even though right now stong westerlies over northern gulf coast, and dry air intruding into western gulf. This could eventually spin up a subtropical low in the middle or eastern gom later, pressures low right now and you have convergence in there with persistance in convection. Watch this area for next few days.

[HURAKAN]

Someone said:

"THERE IS ALWAYS ONE ULL TO BOTHER EVERY TROPICAL WAVE"

And that's is true, every time we have a potential tropical wave that looks good for development, one ULL get in its way and makes the life of the tropical wave a misery. Remember last year Claudette how she had to fight to stay alive because of the ULL that was in front of her. Another example is Fay in 2002, was impossible to develop further because a ULL to its west was causing shear. And many other cases.

[vbhoutex]

As the trough moves out, expect a cut off low to be left behind over/near SE TX/SW LA. Where it goes from there and conditions(currently not particularly favorable) when it happens will, of course, be critical in whether we have something to watch.

[rbaker]

vbhoutex, I saw in my local weather discussion that a trough/cut off low would be in the ne gom, not off of tx. I also saw, where broad low pressure would be left in eastern gom. I located on w coast of fla.

[vbhoutex]

vbhoutex, I saw in my local weather discussion that a trough/cut off low would be in the ne gom, not off of tx. I also saw, where broad low pressure would be left in eastern gom. I located on w coast of fla.

I saw the same in mine(meaning what I posted), unless I misread it, which is possible since it was late.

Either way, with a system such as this one we would expect a cut-off to form. Where it forms and where it goes are, of course key in what may happen with it.

[yoda]

Hey David, what's up with the GGEM, ECMWF, and Canadian models this morning? They all seem to want to take this low, make it become tropical, and have it go around/affect the East Coast. This is very interesting. If you want to believe the Candaian model, it has a hurricane off the Delmarva Coast early next week! Wouldn't that be fun, IF it were to ever happen, which is like 0% chance.

[vbhoutex]

Yoda, I haven't had and won't have time this am to take a look at the models past what I've seen posted here. I find it interesting. The ULL to the N is definitely affecting the wave right now. How long that will continue remains to be seen. I did post yesterday that it appeared to me that the wave might be splitting and I still see some indications of that. If that is the case then the East coast scenario becomes more of a "possiblility"(as opposed to probability). Interaction with the trough, among other factors would determine if this scenario develops and how far(I doubt the strength they are showing). Basically, yes the scenario is possible, but if I had to put numbers on it right now I would put them around 35/65 for it happening.

As far as how fun it would be?? This board would go crazy if that happens. It would be something to really sink our teeth into and try our prediction/forecasting skills that would hopefully not affect anyone in an adverse way.

[vbhoutex]

Referencing back to the cut-off low scenario, I am cutting and pasting this from the US Weather Watch forum.

I know this isn't tropical, so no point posting it there. But what's with the wind off the coast?

https://www.fnmoc.navy.mil/CGI/scat_hir ... 0_-100.gif

This was posted by GalvestonDuck. Definite turning in the few clouds noted over the West GOM. Is it anything?? Time will tell.

[rbaker]

looking at latest wv loop, indeed there does look like there is a spin ull spin off tx and la. like vbhoutex said in their last post on the board. Of course still a mid latitude system.