ATL: INVEST 91L - Discussion

[cycloneye]

AL, 91, 2021080312, , BEST, 0, 129N, 237W, 20, 1011, LO, 0, , 0, 0, 0, 0, 1014, 120, 30, 0, 0, L, 0, , 0, 0, INVEST, S, 0, , 0, 0, 0, 0, genesis-num, 017, SPAWNINVEST, al782021 to al912021,

https://ftp.nhc.noaa.gov/atcf/aid_public/

[MarioProtVI]

This seems to be doing exactly what 10L did last year: pinching off into a small low from the broader trough and quickly spinup into a short-lived TD/TS near Cape Verde. ASCAT and satellite shows the circulation is slowly getting better defined with the latest burst. 18z TWO probably 30/30 or 40/40 with the usual “if trends continue, a short-lived tropical depression may form before moving into unfavorable conditions”.

[wxman57]

Looks like a small eddy that will soon dissipate. Very common with waves moving off the coast of Africa.

[HurricaneEnzo]

It's running out of warm enough water real fast. As soon as it hits the Cabo Verde Islands it will be in 25C waters. I don't think it has enough time.

[InfernoFlameCat]

Looks like a small eddy that will soon dissipate. Very common with waves moving off the coast of Africa.

It will have to immediately strengthen or otherwise pull a wave and turn into this small disturbance. Does look like an eddy though. Love the analogy.

[Hypercane_Kyle]

I'd put the odds for this one near zero. We're getting towards the time of the year where conditions are more favorable, but not quite there yet.

[HurricaneEnzo]

Also appears to be a couple of small areas of rotation. Looks like it is barfing out an eddy right now. Not very organized + cold water coming = nada.

[Nimbus]

If it gathers a center with convection a little further south near the ITCZ as it moves west it might have a small chance later.
The tail end of the cold front off the west coast of Florida has a small chance but they didn't declare an invest for that yet.

[Sciencerocks]

[abajan]

So, the 5-day formation chance decreased from 20% to 10%, but it's now an invest. Interesting.
I guess we can reasonably expect that percentage to go back up shortly.

[abajan]

5-day formation chance still at 10%:

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Tue Aug 3 2021

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

A small area of low pressure with some associated showers and
thunderstorms is located about 100 miles south of Praia in the Cabo
Verde Islands. Significant development of this system is not
expected during the next day or two due to unfavorable upper-level
winds and marginally warm waters. The low is forecast to move
northward or north-northwestward through Thursday before the system
moves over cool waters, ending development chances. Locally heavy
rainfall and gusty winds are possible over portions of the Cabo
Verde Islands through Wednesday.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...low...10 percent.

A tropical wave is forecast to move off the west coast of Africa by
late Thursday. This system has the potential for slow development
over the far eastern Atlantic through the weekend while it moves
westward at about 15 mph.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...20 percent.

$$
Forecaster Blake

[AutoPenalti]

https://imagizer.imageshack.com/img922/5070/OpqQK7.gif

I believe it's an invest because of proximity to land.

[wxman57]

So, the 5-day formation chance decreased from 20% to 10%, but it's now an invest. Interesting.
I guess we can reasonably expect that percentage to go back up shortly.

The NHC declaring any area an "invest" has nothing to do with development potential (or proximity to land). They just want to run models on it to see what they say. You should not infer that the NHC thinks something is a development threat just because an invest is initiated. I expect development chances to drop to zero after Stewart gets off shift at the NHC.

[AutoPenalti]

So, the 5-day formation chance decreased from 20% to 10%, but it's now an invest. Interesting.
I guess we can reasonably expect that percentage to go back up shortly.

The NHC declaring any area an "invest" has nothing to do with development potential (or proximity to land). They just want to run models on it to see what they say. You should not infer that the NHC thinks something is a development threat just because an invest is initiated. I expect development chances to drop to zero after Stewart gets off shift at the NHC.

Couldn't they just run models without an Invest designation?

[cycloneye]

A small area of low pressure with some associated showers and
thunderstorms is located about 100 miles south of Praia in the Cabo
Verde Islands. Significant development of this system is not
expected during the next day or two due to unfavorable upper-level
winds and marginally warm waters. The low is forecast to move
northward or north-northwestward through Thursday before the system
moves over cool waters, ending development chances. Locally heavy
rainfall and gusty winds are possible over portions of the Cabo
Verde Islands through Wednesday.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...low...10 percent.

[gatorcane]

If this somehow gets to a depression or name storm status, which it shouldn’t, it would just inflate the numbers considering something this minor was not tracked or counted decades ago.

[HurricaneEnzo]

So, the 5-day formation chance decreased from 20% to 10%, but it's now an invest. Interesting.
I guess we can reasonably expect that percentage to go back up shortly.

Guess they just don't want to be rusty when the switch flips lol. Or they needed something to do with the lull in activity. They had been going just about non-stop since last season before we hit this drought the last few weeks. It must have gotten boring.

[NotSparta]

If this somehow gets to a depression or name storm status, which it shouldn’t, it would just inflate the numbers considering something this minor was not tracked or counted decades ago.

What's the point of having new and better technology if we don't use it?

[wxman57]

So, the 5-day formation chance decreased from 20% to 10%, but it's now an invest. Interesting.
I guess we can reasonably expect that percentage to go back up shortly.

The NHC declaring any area an "invest" has nothing to do with development potential (or proximity to land). They just want to run models on it to see what they say. You should not infer that the NHC thinks something is a development threat just because an invest is initiated. I expect development chances to drop to zero after Stewart gets off shift at the NHC.

Couldn't they just run models without an Invest designation?

No, it's a requirement that model running requires them to define an invest point.

[kevin]

If this somehow gets to a depression or name storm status, which it shouldn’t, it would just inflate the numbers considering something this minor was not tracked or counted decades ago.

What's the point of having new and better technology if we don't use it?

Exactly. It's not the fault of current technology that not all storms could be tracked in the past. While I can understand the annoyance of some people that compared to older seasons the more recent ones seem 'inflated' due to better technology, I don't think we should just ignore these small storms because of that. Just because our technology was insufficient in the past to track some of the storms doesn't mean we should just keep ignoring them now that we can actually detect them. That would mean artificially skewing data to 'what feels right', which is definitely not something I would ever advocate for in any field of science. If it's a TS then it's a TS and the fact that storm tracking and detecting technology was worse in the past shouldn't have anything to do with that. Of course we should keep these things in mind when analyzing and comparing data from seasons in different time periods. Just a general comment btw, not specifically about 91L and its chances of becoming a TD/TS.