ATL: INVEST 95L - Discussion

[cycloneye]

Up to 40%/60%

A small area of low pressure, located several hundred miles
west-southwest of the Cabo Verde Islands, is producing an area of
disorganized showers and thunderstorms over the central tropical
Atlantic. Although there is dry air located to the north of
the system, favorable upper-level winds are expected to allow for
gradual development during the next several days. This system
could become a tropical depression early next week, as it moves
westward across the tropical Atlantic.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 7 days...medium...60 percent.

[tolakram]

Looks like center is almost exposed, if there is a well defined center.

SLIDER: https://rammb-slider.cira.colostate.edu ... aw_width=6

[Blown Away]

[url]https://i.postimg.cc/gk3fP60s/F47105-BE-2-EE8-456-A-9217-796-D70357-EDF.jpg [/url]

Looking at this decent structure, the models are all mostly depicting a big undefined mess which might happen, but for now IMO the models are off.

I agree that it's satellite presentation looks quite impressive especially when you look at its transition from 24 hours ago, but I just dont think we have near enough to go on beyond what best track was seeing as a weak 1014 low. There's nothing to see at the surface that would validate how tilted or whether any LLC may even be closed at all. Heck, given near center arcing outfow boundries, the center could well be filling (or at least transitory). Btw, ICON, GFS, CMC, & NavGem were all depicting a weak 1013/1014 low in yesterday's 24 hr forecast. I think its appearance is primarily 850mb and higher up

Agree it’s weak and tilted, but there was a clear weak LLC yesterday and no reason to think it isn’t still there, albeit weak.

[Sciencerocks]

 https://twitter.com/AlanSevere/status/1682445129104121856

[GCANE]

Just to keep things in perspective


 https://twitter.com/BenNollWeather/status/1681737608504778753

[chaser1]

Looks like center is almost exposed, if there is a well defined center.

SLIDER: https://rammb-slider.cira.colostate.edu ... aw_width=6

Yep, thats what i see. 'Course, that could just spin off and with this new convective bursting further west, an already shallow system could well develop a new COC underneath. As an aside, that fast approaching easterly surge will likely help moisten up the broarder environment around the disturbance, but it might also impact an additional component of easterly shear in the next day or two as well. 95L might not have developed enough of a robust vertical core to withstand that.

[gatorcane]

I'd be interested in hearing why you think this. Environment looks favorable over the next 3–days or so other than the possibility of dry air intrusions. SSTs are warm (much warmer than normal) and shear looks relatively weak over this period. Considering recent convective trends, I'd argue global models aren't resolving this compact structure well. If convection can persist throughout today, I like this system's chances for genesis. It's a big "if" for now.

I agree with WxMan57. Conditions will only get worse as it moves west especially once in the Caribbean as shear really increases due to a strengthening El Niño. All of the global models are showing this. Atlantic SSTs are running above normal but the EPAC is running way above normal and so should the shear across the Caribbean this season.

I'm sorry, but this is just not accurate. For example, SHIPS, which uses GFS conditions, shows shear remaining below 10 kt throughout the next 120 hours, which is quite favorable: https://ftp.nhc.noaa.gov/atcf/stext/230 ... _ships.txt . Perhaps conditions in the Caribbean are less favorable, but this system will have a sizable window over the next five days or so.

To clarify, the shear will increase once near the Caribbean and especially in the Caribbean. The bottom-line is the system doesn’t look to have much of a future and very likely won’t become anything significant, just a small swirl of clouds which might become a short-lived depression. As you pointed out the dry air is the main issue. Shear should be the issue down the road.

[Sciencerocks]

[tolakram]

loop: https://www.star.nesdis.noaa.gov/GOES/sector_band.php?sat=G16&sector=taw&band=GEOCOLOR&length=24

[cycloneye]

AL, 95, 2023072118, , BEST, 0, 118N, 399W, 25, 1012, LO

[Blown Away]

AL, 95, 2023072118, , BEST, 0, 118N, 399W, 25, 1012, LO

Convection popping over that position. A little N of 12z.

[Iceresistance]

It's already developing upper-level outflow.

Like, seriously, 2022 all over again with Invests having good outflow before being named?


https://s12.gifyu.com/images/SWJjg.png

[zzzh]

[ScottNAtlanta]

https://i.imgur.com/TcqlVag.png

loop: https://www.star.nesdis.noaa.gov/GOES/sector_band.php?sat=G16&sector=taw&band=GEOCOLOR&length=24

That offset center is getting pulled under that big blowup of convection

[wxman57]

It doesn't appear to have much of a future. Wind shear will increase as it nears or enters the Caribbean. Will probably move into Central America in a week as a wave. Might be classified as a depression at some point east of the Caribbean.

Regardless of your downplaying, the Lesser Antilles are in the path before it gets into the hostile Caribbean and will thus be affected by a tropical entity of unknown strength. Nobody knows how strong or weak it will be then. A TS is a distinct possibility.

Just made our first forecast tack. Takes it very near Barbados Tuesday morning as a 35kt TS, enters Caribbean just south of St. Lucia around noon Tuesday as a 30-35kt system, weakening due to shear. Dissipates in central Caribbean Wednesday near 14N/71W. Moves into Central America Friday as a wave. It's going to be a VERY small system. Any fluctuation in environmental shear could result in rapid changes in intensity up or down. No impacts across U.S. or British Virgin Islands or Luis in PR.

[cycloneye]

Looking good.

[zzzh]

LLCC is in the northeast of the convection.

[Blown Away]

:uarrow: LLCC is in the northeast of the convection.

Continues W with no S component and N of 12z models.

[BobHarlem]

95L in perspective, still really tiny, and with circular convection.

[Ivanhater]

Code Red

MIATWOAT ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Fri Jul 21 2023

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

Active Systems:
The National Hurricane Center is issuing advisories on Tropical
Storm Don, located over the central Atlantic.

1. Central Tropical Atlantic (AL95):
A small area of low pressure located roughly midway between the Cabo
Verde Islands and the Lesser Antilles continues to produce
disorganized showers and thunderstorms. Although environmental
conditions are only marginally conducive, slow development is
expected and this system will likely become a tropical depression
early next week while it moves westward across the tropical
Atlantic.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 7 days...high...70 percent.

Forecaster Cangialosi/Roberts