ATL: INVEST 92L - Discussion

[chaser1]

Please explain it it to me if I an misunderstanding something here. But with many 30+ kt SFMR & surface wind estimates (as well as multiple 35 kt+ measurements) & a clear center with plenty of convection near it, how is this not at the very least a TD? It doesn't matter how long the TC will still have before landfall, a TD designation should not be subjective based on impacts or the presence of prior advisories, but purely on whether a system matches the requirements and as far as I can see this one does. The NHC consists of experts in their field so I'm sure they're making the right call, I just don't fully understand it myself so if anyone could clarify.

Kevin, that's a very legit question. All of the points that you made are factors toward determining whether a TD or TS has in fact developed. The only reason that I think that 92L has not been designated as a TD is the lack of identified west winds at the surface. If I were correct that would explain NHC's possible perception of this system being an open (albeit very sharp) wave or trough of low pressure. On the other hand and to your point, NHC DID claim that a small well defined center of low pressure has developed. Well, what gives?? That statement suggests a "closed circulation" and clearly having some west wind component, right? So I see how that contradiction would cause you and others question the lack of any upgrade.

I'm still seeing a low level swirl that seems to be moving WNW to NW, while some level of westerly or northwestern mid to upper level shear clearly appears to be displacing any quasi CDO (or primary convection) off to the south. I don't know to what degree the slot of dry air over the Fla panhandle and eastern Georgia/Florida may be impacting this, but right now I certainly would have a hard time saying that 92L is looking like any well played Jinga game LOL.

All in all, I think better communication could have been applied here.

You both have hit on a lot of key points here, I think the main takeaway is it's a subjective process. The four main criteria for the NHC in designating a tropical cyclone is:

1. Must be a warm core system (check)
2. Must have a low-level circulation that is fully closed off (it did that this morning)
3. Must have surface winds of 35kt+ (recon confirmed)
4. Must have persistent convection (this is the subjective part for 92L, some will say it has sustained and fired convection over the past 24 hours, some may disagree)

All in all, I think the small footprint played a role in (1) the models not showing development and (2) one of the (subjective) reasons for the NHC not classifying this. I'm good with either option, but communication/transparency and consistency can definitely be improved upon.

Agreed. Two other points that could be added but until otherwise defined, would also prove to cause subjective tropical cyclone designations-

5) Strongest (35kt +) winds must be adjacent to some Quadrant of the center of circulation, as opposed to gradient related winds well removed from the center.
6) Establish "some" persistence of time frame where 35kt SURFACE winds are/ have been actually occurring. A CDO or banding feature may be very temporary as a result of diurnal cycle or temporarily overcoming of dry air, etc.

[Nimbus]

Southwestern Atlantic Ocean (AL92):
Satellite imagery and National Weather Service Doppler radar data
indicate that showers and thunderstorms associated with a
well-defined low pressure area centered about 80 miles
east-southeast of Brunswick, Georgia, continue to lack the necessary
organization for the low to be considered a tropical cyclone.
Recent Air Force Reserve reconnaissance aircraft data indicate that
winds to 35 mph are occurring in association with the low. Only a
small increase in the organization of the showers and thunderstorms
could result in the formation of a short-lived tropical depression
before it reaches the coast of northeastern Florida or Georgia
tonight, and interests there should monitor its progress. For more
information, refer to High Seas Forecasts issued by the National
Weather Service, as well as local forecasts issued by your local
National Weather Service Forecast Office.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 7 days...medium...60 percent.

So it looks like the next storm name might go to a gulf storm.

[jlauderdal]

It's nice to see a name not wasted for a change...although a naked swirl advisory for the GA coast would be nice:)

The Storm2k naked swirl advisory in effect for the northern Florida and southern Georgia coastline. Members in the area should immediately:

Ensure your car windows are rolled up. Secure any loose papers or mail in the yard. Get your naked swirl supplies in order (umbrella, candy, and popcorn). Conditions will begin to deteriorate decrease the temperature and bring a windy/cool evening to the area. Avoid Enjoy venturing outdoors and the subtle shift in wind regime.

It must be named, or else the internet is going to have a meltdown. Its good we have these smaller systems early to get all interests involved in the season and be ready when it matters. Even weak Alberto caused major issues, including deaths. We know there is real potential for this season.

[chaser1]

Decoupling. Will be a naked swirl by tonight when it moves ashore. Good call by NHC

But is this a tropical cyclone?

If I'm the NHC and want to make life a little easier for everyone-
A) Call it a Tropical Depression. Why? It is tropical and it is a cyclone
B) issue a PTC alert or warning at 24-48 hr for possible wind gusts to TS strength, heavy rains, dangerous high seas impacting marine interests, rip currents and possible coastal erosion.
C) continue to monitor disturbance for intensification and upgrade
D) once PTC has been issued, simply hand off local impact forecasting and warnings to local NWS (unless/until disturbance upgrade occurs).

[USTropics]

It's nice to see a name not wasted for a change...although a naked swirl advisory for the GA coast would be nice:)

The Storm2k naked swirl advisory in effect for the northern Florida and southern Georgia coastline. Members in the area should immediately:

Ensure your car windows are rolled up. Secure any loose papers or mail in the yard. Get your naked swirl supplies in order (umbrella, candy, and popcorn). Conditions will begin to deteriorate decrease the temperature and bring a windy/cool evening to the area. Avoid Enjoy venturing outdoors and the subtle shift in wind regime.

It must be named, or else the internet is going to have a meltdown. Its good we have these smaller systems early to get all interests involved in the season and be ready when it matters. Even weak Alberto caused major issues, including deaths. We know there is real potential for this season.

I knew we would need the Greek alphabet again soon, just not this soon.

All jokes aside, the threat for Alberto was real (historic drought + sudden increase in high precip for an area that has elevation is a real threat). There won't be much precipitation with 92L directly, the tropical moisture associated with the wave axis will enhance the PWAT for the next few days and increase afternoon thunderstorm activity for FL/GA (will welcome it here in Tally where the heat index is pushing 100+).

[chaser1]

It's nice to see a name not wasted for a change...although a naked swirl advisory for the GA coast would be nice:)

The Storm2k naked swirl advisory in effect for the northern Florida and southern Georgia coastline. Members in the area should immediately:

Ensure your car windows are rolled up. Secure any loose papers or mail in the yard. Get your naked swirl supplies in order (umbrella, candy, and popcorn). Conditions will begin to deteriorate decrease the temperature and bring a windy/cool evening to the area. Avoid Enjoy venturing outdoors and the subtle shift in wind regime.

Adding to Naked Swirl Advisory:

Those living south of the swirl should consider adjusting or turning off their yard irrigation in the event you actually experience some measurable rain.

[psyclone]

This system wants to go it's just not quite there...but to me it's just more evidence the basin is going to go boom later on. Let's enjoy the relative tranquility and chuckles while we can...we know what's most likely coming

[Jr0d]

I don't think it's necessary. Why have an advisory for at best a minimal storm over a small area when an afternoon thunderstorm can bring more intense winds?

If this was expected to strengthen up to landfall then sure it would be justified but a mostly naked swirl that appears to be struggling to keep convection firing is really not much of threat, with the exception of marine hazards. Also the rain impact will likely be minimal for a tropical system regardless of it becomes a depression or even storm before landfall.

Issuing unnecessary tropical storm warnings also runs the risk of complacency when less informed folks get minimal weather who are under the advisory and are more likely to ignore future advisories.

I've witnessed thunderstorms with over hurricane force winds....should we stop issuing hurricane warning? Yes, this is a marine hazard and PTC advisories could save a life at sea......MGC

There are multiple hazard warnings being issued where the marine hazards exist by the local NWS offices, i.e. rip currents statements, small craft advisory, ect. No need for tropical storm warnings as the winds simply are not sustained tropical force.

Clearly the NHC did not see strong enough evidence of sustained 35kt winds and I would even say giving this little swirl credit for sustained winds of 25kts would be generous, hence why it is not classified depression or PTC.

[Jr0d]

92L compared to Bertha, Danny, (and COUNTLESS others)??
That could be viewed & debated two different ways.
1) Compared to past named tropical storms like Danny & Bertha, 92L should be tagged as a TS (or at least a TD).
2) Danny, Bertha (and countless others) should never have been upgraded and classified as named storms to begin with.

This has been a recurring 2-3 decades old debate inside & outside of this forum and a "Sticky note" link to that discussion thread would be good for someone to bump here. If such a thread hasn't been created, "What Defines A Tropical Depression/Storm" might be really good to establish.

It could absolutely be tagged a depression.

While there have been SMFR data and radar suggesting winds around 30kts(35mph), that does not mean those are sustained winds.

While there are some rough seas, the beach erosion threat is minimal as even a modest cold front brings in much more wind and much higher seas. The wind speed and fetch is simply for strong and long enough to cause major surf/wave action.

The local NWS offices are doing a fine job of issuing pertinent advisories where hazards exist. No need to issue tropical storm warnings as it is unlikely this will bring tropical storm conditions to land.

[cycloneye]

 https://x.com/bnorcross/status/1804226689326600659

[Ubuntwo]

I don't think it's necessary. Why have an advisory for at best a minimal storm over a small area when an afternoon thunderstorm can bring more intense winds?

If this was expected to strengthen up to landfall then sure it would be justified but a mostly naked swirl that appears to be struggling to keep convection firing is really not much of threat, with the exception of marine hazards. Also the rain impact will likely be minimal for a tropical system regardless of it becomes a depression or even storm before landfall.

Issuing unnecessary tropical storm warnings also runs the risk of complacency when less informed folks get minimal weather who are under the advisory and are more likely to ignore future advisories.

I've witnessed thunderstorms with over hurricane force winds....should we stop issuing hurricane warning? Yes, this is a marine hazard and PTC advisories could save a life at sea......MGC

There are multiple hazard warnings being issued where the marine hazards exist by the local NWS offices, i.e. rip currents statements, small craft advisory, ect. No need for tropical storm warnings as the winds simply are not sustained tropical force.

Clearly the NHC did not see strong enough evidence of sustained 35kt winds and I would even say giving this little swirl credit for sustained winds of 25kts would be generous, hence why it is not classified depression or PTC.

The NHC established in the TWO that there is sufficient evidence of 30kt winds and a closed circulation. It is the lack of convective organization preventing a TD designation.

[LarryWx]

One band of showers came through here during the last hour or so. The rain wasn’t heavy and it didn’t last long. Interesting to see and comment on nevertheless.

[Hammy]

This system wants to go it's just not quite there...but to me it's just more evidence the basin is going to go boom later on. Let's enjoy the relative tranquility and chuckles while we can...we know what's most likely coming

The track is especially concerning, given the steering flow, when combined with the fact that both Alberto and the next system are also going to steer west (comparing with 2021, where three of the four systems by the end of June went northeast)

[AnnularCane]

It's nice to see a name not wasted for a change...although a naked swirl advisory for the GA coast would be nice:)

The Storm2k naked swirl advisory in effect for the northern Florida and southern Georgia coastline. Members in the area should immediately:

Ensure your car windows are rolled up. Secure any loose papers or mail in the yard. Get your naked swirl supplies in order (umbrella, candy, and popcorn). Conditions will begin to deteriorate decrease the temperature and bring a windy/cool evening to the area. Avoid Enjoy venturing outdoors and the subtle shift in wind regime.

You left out the most important part!

If your children are under 18, cover their eyes so that they don't see the naked swirl.

[cycloneye]

 https://x.com/AndyHazelton/status/1804236765064011835

[LarryWx]

The LLC per radar/satellite appears to have been moving close to due W instead of WNW the last couple of hours. It is ~40 miles E of FL/GA border.

[MGC]

Looks like landfall will be near St. Marts to Brunswick GA. Convection dried up so no longer a realistic threat to be classified. NHC rolled the dice and it came up a 7, front line winner!......MGC

[Sciencerocks]

[Sciencerocks]

 https://x.com/AndyHazelton/status/1804236765064011835

This and possibly the april east Atlantic system are two systems that I'll be watching the post season releases for early next year. I'd say both are equally deserving but this had full on recon showing 1. closed LLC and 2. winds near or above tropical storm force while the other didn't so much have the second one...

[cycloneye]

Reaching the coast shortly.