ATL: ERIN - Tropical Depression - Discussion

[wxman57]

I'm just not seeing any increase in organization yet. Surface obs all along the SE FL Peninsula are all out of the ENE to E. There were SW winds earlier. Models all indicate that the low pressure area will be inland along the FL coast for most of the next 24 hours. GFS, which I don't believe, has it over Ft. Myers Sunday morning.I think it may be classified on Sunday morning, assuming it's offshore.

[northjaxpro]

Should be TD4 by as early as Saturday night IMO.

Don't forget Invest 99L. I think that is already a TD and could become a TS designation too as early aa tomorrow.

I initially thought 99L would get named Dorian before 98L., but 98L has organized much quicker than I had anticipated, probably like most others.

98L and 99L will both be named.imo by the end of the weekend for sure!

[GCANE]

Hmm, pretty good pressure drop at Long Key

[GCANE]

Multi-Sat about an hour ago

[Patrick99]

so from that graphic, it "made landfall" at extreme southern Biscayne Bay, or extreme Upper Keys, depending how you want to look at it

Cloudy here at mainland Miami, but has barely rained.

[SFLcane]

Thought it wasn’t going over FL... Based on that multi/sat I would not be suprised if the gfs ends up right and it moves into the gulf and up into Fort Myers area.

[boca]

Here at my work in Boca Raton the sun is out and no rain and a gust of wind of 13 mph.

[Aric Dunn]

Seabreeze's kicked in. surface obs are all wacky. gonna have to wait couple hours.

[wxman57]

so from that graphic, it "made landfall" at extreme southern Biscayne Bay, or extreme Upper Keys, depending how you want to look at it

Cloudy here at mainland Miami, but has barely rained.

Don't assume that the winds on that graphic are from observations. We've been having a running discussion on the tstorms email list about the "multi platform" winds. The key word is "multi". Lacking observations, I believe the winds are filled in using winds from models. Surface obs across southern Florida look nothing like that wind field.

[GCANE]

Lots of UL Outflow: north, west, and east over Key Largo.
Could be the sign of the development of an anticyclone.
If this moves west and gets SW of the UL trough, would be a great setup for possible rapid intensification.

[Aric Dunn]

No real sign of the flow changing. main energy is moving inland soon and across florida into gulf. piece of energy is probably going to break off to the NE by Sunday. a lot of things to watch and see what plays out.

[GCANE]

Here's the real scoop on Multi-Sat Analysis

http://rammb.cira.colostate.edu/product ... p#MPSATWND

[GCANE]

Unfortunately, this may be the only obs you can get in the Glades

[boca]

Here's the real scoop on Multi-Sat Analysis

http://rammb.cira.colostate.edu/product ... p#MPSATWND

Do you have the cliff note version of that.

[Evil Jeremy]

TD is a very loose designation, without any hard scientific point to call it a TD. We only know the point above which it is a TS if there is a closed circulation.

IMO, and this occurred to me with TD3, but the "pre-tropical cyclone" designation could/should eliminate the need for a TD classification. If a system is out in the open waters, simply classify it as a TS when you can make the determination. If it's close to land, use Pre-cyclone until you're ready to name the system.

I know there's probably a meteorological necessity for the Tropical Depression designation, but it feels more redundant now than ever.

[Hammy]

TD is a very loose designation, without any hard scientific point to call it a TD. We only know the point above which it is a TS if there is a closed circulation.

IMO, and this occurred to me with TD3, but the "pre-tropical cyclone" designation could/should eliminate the need for a TD classification. If a system is out in the open waters, simply classify it as a TS when you can make the determination. If it's close to land, use Pre-cyclone until you're ready to name the system.

I know there's probably a meteorological necessity for the Tropical Depression designation, but it feels more redundant now than ever.

I believe the reason for the "pre-tropical" designation is to issue warnings for systems that are expected to develop, but fail to meet the organizational criteria (lack of closed circulation, too little convection, elongated center etc). If something is organized enough than it's a tropical cyclone.

[Aric Dunn]

TD is a very loose designation, without any hard scientific point to call it a TD. We only know the point above which it is a TS if there is a closed circulation.

IMO, and this occurred to me with TD3, but the "pre-tropical cyclone" designation could/should eliminate the need for a TD classification. If a system is out in the open waters, simply classify it as a TS when you can make the determination. If it's close to land, use Pre-cyclone until you're ready to name the system.

I know there's probably a meteorological necessity for the Tropical Depression designation, but it feels more redundant now than ever.

The issue is about accurate data. and the battle will always continue..

If something is a warm core system with a closed circ and convection.. it needs to be included in the year end data, period... designated TD/TS , TC. or whatever is not really important.

Sure be strict about giving it a name.. but the difference between warm-core, cold-core and hybrid are well defined thermodynamically.

So if it is closed and producing convection that is consistent with a warm-core then it needs to be included in the data.. simple as that.


anyway back to 98L. Looks like it is being tugged around and disrupted a little from the localized pressure drops and sea breezes. presently seems like its over northern Key largo.

[wxman57]

Here's the real scoop on Multi-Sat Analysis

http://rammb.cira.colostate.edu/product ... p#MPSATWND

Do you have the cliff note version of that.

Bottom line - don't assume those multi-spectrum winds bear any resemblance to surface winds. They may be using a 700mb pattern and reducing the winds to the surface, which isn't a good idea for such a weak system.

[Aric Dunn]

somewhere around northern Key Largo at the moment.. land heating jumbled things up. disregard the observation east od miami it has been stuck like that since last night..

[TheAustinMan]

The primary utility in the Multiplatform Satellite Surface Wind Analysis is to diagnose the strength of the wind field, and not to identify a closed circulation. It has more use for stronger systems from which hurricane-force radii can be derived. The main reason the winds seem to always be cyclonic and closed on that product is because for storms without recon, the dominant input is a simulated wind field based on the motion and strength of the system that automatically assumes cyclonic flow aloft, which is then adjusted to the surface according to friction. In fact, the product has four inputs, and none of those are direct surface observations.