Strong Tropical Wave WSW of CV Islands (INVEST 94L is up)

[AJC3]

At H240, the location of the 12Z ECM's H85 wave axis is nearly identical to the 18Z GFS position of it's H85 trough axis /low. Both have it extending NNE or NE from about 100-150 miles N of Hispanola. There's nothing overly detrimental in the H25 wind fields that I can see. MRH in the MDR seems OK. This has mildly piqued my attention, even for July. We'll see if the 00Z runs hold serve.

[tarheelprogrammer]

GFS is a little different this run. Let us see what it does. Looks to be forming east of 18z run.

[RL3AO]

Noticeably slower this run.

[TheAustinMan]

Noticeably slower this run.

I believe the difference is that the previous runs had a pocket of convection being sheared west and being the incubator for a developing low. On this run it appears the pouch has remained intact, giving the appearance of slower motion.

[RL3AO]

Looks like one organized area of vorticity vs two separate ones last run.

[Kingarabian]

12z Euro Parallel similar to the 12z Euro. Very weak low pressure, open wave.

[Siker]

00z CMC now develops this.

[Kingarabian]

00z GFS more in line with the Euro now - little to no development.

[cycloneye]

At least the 00z Euro sees it.

[NDG]

A zoomed in look of the Euro on its 120 hr forecast. Closed low pressure.

[NDG]

I wouldn't doubt if the the NHC starts mentioning this TW again in their TWO with the GFS not being the only model anymore.

[cycloneye]

8 AM TWO: 0%-20%

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Sat Jul 1 2017

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

1. A tropical wave located about 400 miles southwest of the Cabo
Verde Islands is producing an area of disorganized showers and
thunderstorms. Environmental conditions are expected to be
conducive for gradual development during the next several days
while the disturbance moves westward at 10 to 15 mph.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...20 percent.

Forecaster Stewart

[OuterBanker]

Yes, we have a yellow X. Is there any rule of when it becomes an invest? I.E. is there a certain percentage like the red X? Just curious.

[tolakram]

I'm a bit surprised that people are looking at intensity forecasts, MSLP maps, rather than vorticity. If the models were any good at judging intensity the NHC intensity forecasts would be much better.

Looks like most of the models have a decent vorticity signature developing over the next few days.

I'd also like to remind folks that if you make a post bashing a model, any model, rather than providing something constructive you can expect your post to be removed. Let's please try and keep the conversation constructive. Thanks.

[ouragans]

Yes, we have a yellow X. Is there any rule of when it becomes an invest? I.E. is there a certain percentage like the red X? Just curious.

Generally it becomes an Invest when the NHC marks it at 20% at 48 hrs

[cycloneye]

@MJVentrice
Definitely looks like there's going to be an attempt!

 https://twitter.com/MJVentrice/status/881123001542070272




@EricBlake12
Ah the bulls have come out?

 https://twitter.com/EricBlake12/status/881123094374567936

[OuterBanker]

Yes, we have a yellow X. Is there any rule of when it becomes an invest? I.E. is there a certain percentage like the red X? Just curious.

Generally it becomes an Invest when the NHC marks it at 20% at 48 hrs

Thanks ouragans. Surprisingly low threshold.

[cycloneye]

Loop:

http://rammb.cira.colostate.edu/ramsdis ... display=12

[GCANE]

When this is forecast to get to the islands this time next week, the key interaction will be the UL Low / Trough to its north.

It will be running into higher Theta-E air; aka increasing instability which should fire off and maintain convection.

It looks like it'll be another tug-o-war event with shear trying to keep a lid on TC development; yet the shear and unstable air will fire off short-term MCS's which could push away the PV.

I think we'll have a lot to talk about next weekend.

[wxman57]

Yes, we have a yellow X. Is there any rule of when it becomes an invest? I.E. is there a certain percentage like the red X? Just curious.

Generally it becomes an Invest when the NHC marks it at 20% at 48 hrs

Thanks ouragans. Surprisingly low threshold.

I talked with the NHC forecasters at the last National Hurricane Conference in New Orleans. There really isn't any hard and fast rule about declaring an invest. They can declare an invest at any time for any reason. They may be occasionally doing some internal testing and declare an invest on a disturbance with little or no chance of development. Mostly, they declare an invest just because they want to view the model guidance, which may be independent of development chances. Such a declaration does not automatically infer greater development potential.

That said, its satellite representation is pretty poor this morning. The TPW loop shows a fair bit of moisture centered around 11N/30W. Perhaps a little rotation. It's on the leading edge of a fairly significant SAL outbreak. Development chances don't look good at all for the next 3-4 days. Beyond then, maybe - after it passes the NE Caribbean.