ATL: BERTHA - Post-Tropical - Discussion

[abajan]

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT WED JUL 30 2014

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

Showers and thunderstorms associated with an area of low pressure
located about 1150 miles east of the southern Windward Islands
remain limited. This system continues to show signs of
organization, however, and the low could develop into a tropical
depression later today or tomorrow while it moves generally
west-northwestward near 15 mph. Interests in the Lesser Antilles
should monitor the progress of this system.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...70 percent.

$$
Forecaster Pasch

With the current state of 93L, how can this be? 70%??

[tropicwatch]

I think it has a lot to do with the solid rotation it has and light shear. It should be able to develop under these condition IMO.

[blp]

I think it has a lot to do with the solid rotation it has and light shear. It should be able to develop under these condition IMO.

I agree, it does have good spin. The models are still suppporting this at least until the islands. It will be going over higher SST temperatures. Weak TS is probably are far as it gets.

[wxman57]

With the current state of 93L, how can this be? 70%??

Think about it. The NHC's primary goal is public safety. We have a strong disturbance approaching a populated region. Which would promote public safety more - keeping the threat level up or reducing it? What if it suddenly developed as it moved into the Caribbean and lives were lost because the NHC indicated a decreasing risk? It's not just about coming up with as accurate an estimate of chance of development as possible, it's about public safety. I'm sure that the NHC forecasters realize that the chances of any significant development are decreasing. They just want the public to stay alert as it approaches.

[OuterBanker]

I lie somewhere between Star Trek and Mony Python.

Most of me says "It's dead Jim."
Yet some of me is waving saying "I'm not dead yet."

[Rail Dawg]

The spin itself is going to generate this into a TD. Enough inertia will get it through any weak spots and a solid flare of convection will kick this thing up.

The cyclonic rotation in and of itself provides a lifting mechanism.

I'm with NHC on this.

[caribsue]

wxman57.... thank you for that .... this coming from someone who lives in Barbados.

[gatorcane]

Saved image below...clearly struggling but still has a tight circulation and some new convection popping near the center. NHC states its showing signs of organization...movement looks due west to me...needs to starting gaining some latitude soon for the models to verify:

[Frank2]

Think about it. The NHC's primary goal is public safety. We have a strong disturbance approaching a populated region. Which would promote public safety more - keeping the threat level up or reducing it? What if it suddenly developed as it moved into the Caribbean and lives were lost because the NHC indicated a decreasing risk? It's not just about coming up with as accurate an estimate of chance of development as possible, it's about public safety. I'm sure that the NHC forecasters realize that the chances of any significant development are decreasing. They just want the public to stay alert as it approaches.

True, almost always better to err on the side of caution - better to risk making a few posters grumpy that to endanger thousands of coastal residents : )

P.S. The system does seem to have outflow that it did not have yesterday...

[tropicwatch]

Still has not gone north of the magic 10 yet:)

[tropicwatch]

A little off topic but the wave behind 93L has good rotation too.

http://earth.nullschool.net/#current/wi ... 8,2.08,572

[tolakram]

Vis loop: http://wwwghcc.msfc.nasa.gov/cgi-bin/get-goes?satellite=GOES-E%20HURRICANE&lat=8&lon=-45&info=vis&zoom=1&width=1024&height=768&type=Animation&quality=92&palette=ir1.pal&map=none&numframes=5

[Sanibel]

I don't think I've ever seen dry air take down a forming system so badly.

[Fego]

Imo is a mix of the great expectation and our memory playing games .

[abajan]

With the current state of 93L, how can this be? 70%??

Think about it. The NHC's primary goal is public safety. We have a strong disturbance approaching a populated region. Which would promote public safety more - keeping the threat level up or reducing it? What if it suddenly developed as it moved into the Caribbean and lives were lost because the NHC indicated a decreasing risk? It's not just about coming up with as accurate an estimate of chance of development as possible, it's about public safety. I'm sure that the NHC forecasters realize that the chances of any significant development are decreasing. They just want the public to stay alert as it approaches.

Sorry but I don't agree. I know I'm going to get lots of backlash for this but I think they should simply state what they truly feel the percentages for development are. Maybe they could include a disclaimer that the percentages are not set in stone and that things could quickly change.

Nevertheless, thanks for your reply.

[blp]

Saved image below...clearly struggling but still has a tight circulation and some new convection popping near the center. NHC states its showing signs of organization...movement looks due west to me...needs to starting gaining some latitude soon for the models to verify:

http://i57.tinypic.com/osg4kn.jpg[/img]

Good point, I posted a similar thought earlier in the models thread where it seems to me that 50W is the point where most models start the WNW movement. It will be interesting later on tonight when it get close will that change happen otherwise the models will be off.

[SFLcane]

Just can't see this disturbance doing much of anything in an environment like this.

[Hyperstorm]

Folks, remember that the GFS (Yes, the same model that has been persistently calling for development) predicted that today was going to be a very hostile day for this disturbance. It is verifying. According to the GFS, a stronger burst of development will begin tomorrow and Friday. It looks like the GFS is seeing the interaction of this disturbance with the upper-level system NE of the islands as something positive that would initiate a good burst of convection. If the system still keeps its circulation, the burst of convection would classify it.

I don't see this system moving straight west into the Caribbean, regardless of development. Remember, not every system that remains a tropical wave/low moves straight west. Bursts of convection would cause it to be impacted more by the upper-levels...and if the interaction with the upper-low starting tomorrow is an indicator for a growing burst of convection, this system is going to be pulled NW.

This post is NOT AN OFFICIAL FORECAST and should not be used as such. It is just the opinion of the poster and may or may not be backed by sound meteorological data. It is NOT endorsed by any professional institution including storm2k.org. For Official Information please refer to the NHC and NWS products.

[cycloneye]

The squadron is still going with the missions beginning on Thursday. See the missions at the 93L Recon Thread

[Alyono]

I'd say development chances are cratering now.

May be close to 25%... and that is probably being generous