Tropical Depression Five

[WxWatcher007]

We have homebrew potential in the Gulf as an area of low pressure has formed in the northern part of the region and is producing persistent disorganized convection. 

The NHC has taken note, and the odds of development have gradually risen to 30%. 

The key inhibitor here is time, although the guidance has pointed to a more modest development signal, this is likely to be onshore near the Texas/LA border in 48-72 hours. Generally speaking, however, the conditions do seem to be favorable with very warm SSTs (not thinking about OHC needed to sustain a strong system given proximity to land and timing) in the northern Gulf. 

There is dry air to its north, and that could also be an inhibiting factor, but so far that hasn't prevented consistent convection, which has been deep at times. The more consistent deep convection can be, the more likely we see eventual pressure falls and the tightening of the low pressure. However, should dry air make an intrusion it could disrupt any progress toward organization into a TC. 

Importantly, shear is low in the basin. In fact, it's basically the only place in the Atlantic that has a large enough area of low shear to have a meaningfully large enough window for development. That's consistent with my peak season forecast, but we'll see if it leads to another short lived TC here.

Shear may be kept at bay, but the signal is a bit mixed on whether we see some southerly shear eventually develop. Overall, I think this is a legitimate homebrew opportunity for a weak tropical storm that would impact the northern Gulf coast in a couple of days. I think there's a good chance 97L has slightly increased odds and is an orange for the 2pm outlook. 

Northern Gulf of America (AL97):
Showers and thunderstorms associated with an area of low pressure 
located about 125 miles south of the coast of southeastern Louisiana 
have become more concentrated. However, current surface observations 
indicate that the system has not yet strengthened. Slow development 
of this system is possible during the next couple of days as it 
drifts westward to west-northwestward across the northern Gulf. 
Interests along the Louisiana and Upper Texas coasts should monitor 
the progress of this system.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 7 days...low...30 percent.

$$
Forecaster Beven

 

[GaWx]

12Z UKMET doesn’t quite designate this as a TD but it does have 25 knot winds just offshore LA Mon night and landfall Tue AM near TX/LA border. Lowest SLP only gets down to 1011 mb fwiw.

[GaWx]

12z Euro: looks like a TD that comes ashore near LA/TX border midday Tue.

[WxWatcher007]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Sun Aug 30 2026

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

Northern Gulf of America (AL97):
A low pressure area is located over the northern Gulf of America 
about 125 mils south of the coast of southeastern Louisiana.  
Satellite imagery and recent satellite wind data indicate that this 
system has become better organized since yesterday.  Additional 
development is possible as the low moves slowly west-northwestward, 
and a short-lived tropical depression or tropical storm could form 
before the system reaches the Upper Texas or southwestern Louisiana 
coasts Tuesday or Tuesday night. Interests along the Louisiana and 
Upper Texas coasts should monitor the progress of this system. 
Regardless of development, locally heavy rainfall is possible over 
portions of the Upper Texas or southwestern Louisiana coasts during 
the next couple of days.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 7 days...low...50 percent.

 

[WxWatcher007]

This one has legs 

[NorthArlington101]

This one has legs 

Twitter folks like it a lot. Pretty surprised that this doesn’t have a PTC designation. Not sure what else it would be for other than to use it for a potential storm developing that will be surely impacting land which needs a sexier name than “97L” to grab media attention.

[Scott747]

1 hour ago, WxWatcher007 said:

This one has legs 

Slow season is getting to you I see....

[Scott747]

13 minutes ago, NorthArlington101 said:

Twitter folks like it a lot. Pretty surprised that this doesn’t have a PTC designation. Not sure what else it would be for other than to use it for a potential storm developing that will be surely impacting land which needs a sexier name than “97L” to grab media attention.

NHC is still old school and likes the 10 pm news cycle on a Sunday night so I'd be surprised if they didn't designate a PTC or even straight to depression at 10.

Weekday and this might have been a PTC at 5, although it still seemed a little early this afternoon with the lack of storms around the center.

 

[NavarreDon]

I’ve learned to trust the crew at the NHC about jumping the gun. That said I’m not calling for it, but all the visuals & ascat passes say that they could issue a special for PTC. Nice diurnal blow up starting now.


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[Scott747]

19 minutes ago, NavarreDon said:

I’ve learned to trust the crew at the NHC about jumping the gun. That said I’m not calling for it, but all the visuals & ascat passes say that they could issue a special for PTC. Nice diurnal blow up starting now.


.

Doubt they would do a special for a PTC. Could get a hint that one is coming with the update at 7 and going red.

[NavarreDon]

Doubt they would do a special for a PTC. Could get a hint that one is coming with the update at 7 and going red.

That makes sense, what are the possibilities of going straight to TD at some point.

[Scott747]

8 minutes ago, NavarreDon said:

That makes sense, what are the possibilities of going straight to TD at some point.

This close to land and landfall? Pretty high. Just need a few reliable obs. Does appear there is a good circulation but most of the day it had no real convective activity around it. I'd still guess without recon in there they will go PTC first and full upgrade in the morning unless it goes bonkers tonight.

[NavarreDon]

This close to land and landfall? Pretty high. Just need a few reliable obs. Does appear there is a good circulation but most of the day it had no real convective activity around it. I'd still guess without recon in there they will go PTC first and full upgrade in the morning unless it goes bonkers tonight.

Nice call on the cherry, 70% on the 7pm CDT outlook.


.

[Scott747]

4 minutes ago, NavarreDon said:

Nice call on the cherry, 70% on the 7pm CDT outlook.


.

Outlook does imply they may bypass a PTC and go straight to a TS watch/warning at 10 or 5. Makes sense with the blowup this evening and better model support.

Looks to be on track between High Island and Cameron for the watch/warning. Might extend down to Galveston.

[WxWatcher007]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Sun Aug 30 2026

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

Northern Gulf of America (AL97):
An area of low pressure located over the northern Gulf of America, 
about 125 miles south of the coast of southeastern Louisiana, 
continues to become better defined, and the associated shower and 
thunderstorm activity is gradually increasing. Continued gradual 
development is expected as the low moves slowly west-northwestward, 
and a short-lived tropical depression or tropical storm is likely to 
form before the system reaches the Upper Texas or southwestern 
Louisiana coasts on Tuesday or Tuesday night. 

Interests along the southwest Louisiana and Upper Texas coasts 
should monitor the progress of this system, as tropical storm 
watches or warnings could be required for portions of the area later 
tonight or Monday morning. Regardless of development, this system is 
expected to bring locally heavy rainfall to portions of the Upper 
Texas and southwestern Louisiana coasts during the next several 
days. An Air Force Reserve reconnaissance aircraft is scheduled to 
investigate the low-pressure area on Monday morning.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 7 days...high...70 percent.

 

[WxWatcher007]

Looks like it's a TD already, but I could see the NHC waiting until recon arrives to confirm. A PTC designation at 11pm works just fine. The main takeaway for me with the image below is the convection continuing to fire even as we fade into DMIN. I wish it were in radar range, but I'd guess there's a tightening center in there. It helps a lot to have weak shear in the area. 

[vortex95]

The convection is still strongly pulsing, and NHC likes to wait to see more persistent and coherent convection or decent circular banding before declaring a TC, which is a good mode IMHO. Quickly waxing/waning convection is a sign of dry air or shear, and pulsing the convection results in cool outflow boundaries that interfere w/ the organization of the LLCC.

It is also a very small system, and small systems are more susceptible to environmental factors.  In this case, lots of dry air just to the N that can get entrained easily.  Looking at the 00z SHIPS output for 97L here, you can see the 700-500 RH is quite low. (below 50%).
https://hurricanes.ral.ucar.edu/realtime/plots/northatlantic/2026/al972026/stext/26083100AL9726_ships.txt
 

[WxWatcher007]

30 minutes ago, vortex95 said:

The convection is still strongly pulsing, and NHC likes to wait to see more persistent and coherent convection or decent circular banding before declaring a TC, which is a good mode IMHO. Quickly waxing/waning convection is a sign of dry air or shear, and pulsing the convection results in cool outflow boundaries that interfere w/ the organization of the LLCC.

It is also a very small system, and small systems are more susceptible to environmental factors.  In this case, lots of dry air just to the N that can get entrained easily.  Looking at the 00z SHIPS output for 97L here, you can see the 700-500 RH is quite low. (below 50%).
https://hurricanes.ral.ucar.edu/realtime/plots/northatlantic/2026/al972026/stext/26083100AL9726_ships.txt
 

Yeah, that’s all true. It makes sense to wait until there’s either another overnight cycle of observations or for recon to confirm. The PTC designation was designed for these scenarios and raising the proverbial alarm tomorrow isn’t a bad call if the ceiling continues to be limited. 

[Windspeed]

The HAFS suites like closing this off and bring a tropical storm into East Texas. As is typical with NGOM genesis, placement and timing remain critical. How fast can a tight vorticity develop? A small system like this has an intertwined advantage and several disadvantages. The main disadvantage is time. We're only looking at a small window of 24-36 hours here. The other is the environmental factor with marginal relative humidity over the adjacent landmass at present combined with dry airmass in the mid-levels countering any rapidly forming convective envelope. This could delay organization by landfall. In most cases, a small system should struggle as mid-level steering flow will mix in that airmass. But small systems can develop faster if the environmental factor is limited. Being so small is also an advantage if rapid development of intense mesoscale convection does occur and can persist. The immediate envelope moistens and persistent convection results in the formation of a small vortex under negligible shear. A large circulation would still be susceptible to pulling in the dry air. Negligible shear prevents dry mid-level airmass from advecting into a small vortex against the mid-level steering flow. SSTs are very high, so this system could outperform the TC models and SHIPs parameters if the organization gets going today. Regardless, I do like this getting named by landfall, and I'm going to be a bit bullish with this one. I like a better than a weak TS (40-50 kts) and perhaps even a moderate to strong TS (50-60 kts) by landfall. Too bullish? Yes, it's a tiny system. But I think convection will blossom today and shield off any dry air entrainment. I'll favor any small system moving over high SSTs with negligible shear with at least marginal supporting environmental factors to outperform versus a broad system when time is the biggest factor. Fortunately, time should limit anything stronger.

[vortex95]

5 hours ago, WxWatcher007 said:

Yeah, that’s all true. It makes sense to wait until there’s either another overnight cycle of observations or for recon to confirm. The PTC designation was designed for these scenarios and raising the proverbial alarm tomorrow isn’t a bad call if the ceiling continues to be limited. 

I think they are holding off on PTC b/c it is not clear it will be a TS before landfall.  They do not want to put up TS warnings due to this uncertainty b/c of the impact alone warnings have.   It puts things different level from a EM standpoint and business/commerce.

97L looks better on sat and radar as I type this.  Will they declare it a TD or do PTC by 5am?
 

[vortex95]

Also, 97L is *tiny*.  In fact, it is not that much larger in convective coverage now than smallest TC on record -- Macro in Oct 2008 in the Bay of Campeche.  I attached a current WV of 97L and image of Marco.

The small size is a product of how unfavorable conditions are in the Atlantic overall for TCs.  Yes, in the Gulf, the shear is low (unlike the MDR) but mid-level dry air is an issue.  Nary any other convection in anywhere near 97L!

[WxWatcher007]

Everything on satellite would suggest this is a TC this morning, and a ship observation of a westerly wind near the center would suggest this is a closed low. Recon will confirm I guess. Given its size and more symmetrical convective appearance this morning, I don’t think dry air has been too impactful yet. It may have a higher ceiling as @Windspeed suggests, but we’ll see what recon finds. 

[WxWatcher007]

Recon heading into the invest now. It's a short flight so we're going to know soon if this is a TC. Will wait for more data before doing much analysis but no surprise that there's a westerly wind in there. 

First light over our invest. 

[Windspeed]

Recon heading into the invest now. It's a short flight so we're going to know soon if this is a TC. Will wait for more data before doing much analysis but no surprise that there's a westerly wind in there. 

First light over our invest. 

No surprise. The MCS appears to be drilling down at that location with a very small vmax underway. We may have a depression. We'll see what the NHC does. I imagine they would at least go with a PTC at 11AM/10AM CT.

[NorthHillsWx]

24 minutes ago, WxWatcher007 said:

Recon heading into the invest now. It's a short flight so we're going to know soon if this is a TC. Will wait for more data before doing much analysis but no surprise that there's a westerly wind in there. 

First light over our invest. 

A light breeze based on that pass 

[WxWatcher007]

3 minutes ago, NorthHillsWx said:

A light breeze based on that pass 

We've gotten names for less  

I kid, I kid...

[NorthHillsWx]

Looks pretty broad/open on south side. That mid level feature looks more impressive than what’s under the hood. This is why NHC waits for solid data before designating systems even close to land. Could see PTC at 11 tho 

[WxWatcher007]

1 minute ago, NorthHillsWx said:

Looks pretty broad/open on south side. That mid level feature looks more impressive than what’s under the hood. This is why NHC waits for solid data before designating systems even close to land. Could see PTC at 11 tho 

Yep. We see this plenty of times--satellite looks good but when recon gets in there it's still a bit of a mess. This one is on its way to being a TC, but probably not quite there/borderline. Interested in what they find on the eastern flank & in that possible center. 

[WxWatcher007]

PTC 5 initial advisory coming at 11am. 

[NorthHillsWx]

3 minutes ago, WxWatcher007 said:

PTC 5 initial advisory coming at 11am. 

Good call for NHC. Center is too broad at this time for a classification and plane hasn’t found any winds over 20 mph but the organization trend warrants PTC. Not far off but also not there yet