ATL: Ex INVEST 99L - Discussion

[LadyBug72]

It's been a while since I've seen this, but oftentimes, waves that come off the West African coast at low latitudes, i.e., 99L, often hitch a ride on the ITCZ, get further west, then break away and go solo to further develop in the Western Caribbean or Gulf of Mexico! I'm thinking that's what might happen here...ST

That's what Ike did, correct?

Ike started further north and was pretty far north of the Caribbean before it began to move to the west south west then west going through Cuba. Ike's track was pretty unusual because you don't really see hurricanes get into the GOM if they start as far north as Ike did. A good example of a low riding wave that was able to get all the way into the GOM due to being weak is Harvey. Harvey was able to strengthen into a TS in the far Eastern Caribbean for a couple of days before it weakened back into an open wave.

Thank you!

[StormTracker]

It's been a while since I've seen this, but oftentimes, waves that come off the West African coast at low latitudes, i.e., 99L, often hitch a ride on the ITCZ, get further west, then break away and go solo to further develop in the Western Caribbean or Gulf of Mexico! I'm thinking that's what might happen here...ST

That's what Ike did, correct?

"Ike started further north and was pretty far north of the Caribbean before it began to move to the west south west then west going through Cuba. Ike's track was pretty unusual because you don't really see hurricanes get into the GOM if they start as far north as Ike did. A good example of a low riding wave that was able to get all the way into the GOM due to being weak is Harvey. Harvey was able to strengthen into a TS in the far Eastern Caribbean for a couple of days before it weakened back into an open wave."

What IcyTundra said!
I can't remember what storms did, but it's been a while...

[Stratton23]

Another new burst of deeper convection around the “ center” 99L is really putting up a fight , this could be a sleeper

[cycloneye]

Eastern Tropical Atlantic (AL99):
Showers and thunderstorms associated with a tropical wave located
several hundred miles west-southwest of the Cabo Verde Islands have
become better organized this evening. However, earlier
satellite-derived surface wind data showed that the system does not
have a well-defined center. Environmental conditions appear
marginally favorable for additional development over the next day or
so while the system moves generally westward at 10 to 15 mph, and a
short-lived tropical depression could form. In a couple of days,
environmental conditions are expected to become unfavorable for
further development.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 7 days...medium...50 percent.

[AnnularCane]

It's been a while since I've seen this, but oftentimes, waves that come off the West African coast at low latitudes, i.e., 99L, often hitch a ride on the ITCZ, get further west, then break away and go solo to further develop in the Western Caribbean or Gulf of Mexico! I'm thinking that's what might happen here...ST

You never know, this is the at-least-somewhat notorious 99L after all.

[Stratton23]

99L’s structure has been improving over the last few hours, I already think this is a TS

[AnnularCane]

Wasn't there an invest once that went straight from maybe 30% to a TS?

[cycloneye]

AL, 99, 2025082200, , BEST, 0, 102N, 371W, 30, 1010, DB

[StormWeather]

Wasn't there an invest once that went straight from maybe 30% to a TS?

That was Tropical Storm Bertha in 2020.

[abajan]

AL, 99, 2025082200, , BEST, 0, 102N, 371W, 30, 1010, DB

To me, the last four records (starting at 6Z) in AL99's Best Track file seem to show a WSW track instead of a W one. But I could be wrong. When you get a chance, could you please post the graphic showing the Best Track plots?

EDIT: Actually, never mind. I found it at https://cyclonicwx.com/.
I could've sworn I bookmarked that website last year. Anyway, I've bookmarked it now.

[skillz305]

Spaghettis getting interesting on 99L

[Hurricaneman]

Spaghettis getting interesting on 99L

Yep, this may not dissipate before the Caribbean and could end up being more than predicted for the lesser Antilles than the global models are indicating

[zzzh]

 https://x.com/oz4caster/status/1958722830431904131


I agree here, those 'northeasterlies' make zero sense to me.

[chaser1]

99L’s structure has been improving over the last few hours, I already think this is a TS

Could be. I'd be more apt to agree with you then accept that this were simply a sharp wave axis lacking even weak westerly surface winds. If this were in the GOM, we'd have PTC advisories flying.

[Kingarabian]

Still hasn't poofed yet. Models are messing up with this one so far.

[zhukm29]

 https://x.com/AndyHazelton/status/1958688120611688852

[zhukm29]

Webb also seems to believe this is already a TC. Even if we disregard the ASCAT data, the microwave passes over 99L as well as its behavior these last few days provide further support for TC designation. Multiple ASCAT passes throughout the past few days have shown wind barbs above 34kt so it should jump straight to TS as well in my opinion.

 https://x.com/webberweather/status/1958715637607653565

[AJC3]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Fri Aug 22 2025

Central Tropical Atlantic (AL99):
Showers and thunderstorms associated with a tropical wave located
about a thousand miles west-southwest of the Cabo Verde Islands
remain well organized. This system could become a tropical
depression at any time, but the latest satellite-derived wind data
indicate that the system does not have a well-defined circulation
center. The system is expected to move into a less conducive
environment later today through Saturday, but could reach a slightly
more favorable environment again late this weekend into early next
week as it moves westward at 10 to 15 mph over the central tropical
Atlantic and approaches the Lesser Antilles.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 7 days...medium...60 percent.

[Sciencerocks]

[HurricaneRyan]

How is this not named already?