ADT estimates for all Atlantic tropical cyclones this season

[kevin]

So ADT data has been posted on this forum quite a few times, especially this year. I thought it would be interesting to compare the ADT data to the actual intensity that all storms have had this season. It might be a good way to get some more insight in 1) how ADT works and what it's weaknesses/strengths are and 2) which storms are more likely to get post-season upgrades or downgrades. Here below is the data of all storms of this season. I got the ADT data from (http://tropic.ssec.wisc.edu/real-time/adt/archive2020/) and I pasted the highest CI# (current intensity) estimate with the corresponding MSLP and VMAX estimate in mbar and kts. I also show the category on the Saffir-Simpson scale. The figure also shows the true peak intensity as by NHC advisories. The final columns show the difference in MSLP and VMAX between ADT and the official data (it's ADT value - official value). Thus, a negative value in the MSLP difference means that ADT estimated the storm to be weaker and a positive value in the VMAX difference means that ADT estimated the storm to have lower winds. Since this can be a bit confusing I also added color coding where green means that ADT estimated the storm to be stronger than the official data and red means that the official advisories are stronger than the ADT estimates. The very final column shows whether ADT has a different peak intensity on the Saffir-Simpson scale than the NHC data. I tried to copy everything as good as I could from the ADT website, but please notify me if there are any mistakes.

One interesting observation is that the ADT website shows significantly lower MSLP's for the first storms this season. Even though Wikipedia mentions that a T-number of 3.0 only corresponds to ~1000 mbar, the ADT website seems to show significantly deeper systems for a CI# of 3.0. Could anyone explain why this is the case?

[kevin]

Some interesting observations:

*As already mentioned a few of the early season storms have way deeper pressure estimates with ADT (Bertha, Cristobal, Dolly). Isaias and Josephine also have way lower MSLP estimates with ADT.
*According to ADT Cristobal was even briefly a cat 1 hurricane.
*On the other hand ADT does not support cat 1 strength for both Marco and Nana.
*ADT goes completely bonkers with Sally, showing a 110 kt cat 3. It also blew up Teddy way more with a 130 kt cat 4 instead of 120 kts.
*ADT puts Zeta as a cat 3, but on the other hand it doesn't support a cat 3 for Epsilon.
*And as a we all know ADT went crazy with Eta and indeed estimated a cat 5.
*If we would only follow ADT, 2020 would actually have 1 hurricane less, but it would gain 2 major hurricanes, which brings the total to 30/12/8.
*TD10 does not get a TS upgrade if you would only follow ADT.

I think from this we can learn some of ADT's weaknesses. For example, recon inside Epsilon clearly measured a cat 3 even though recon is 10 kts below cat 3 strength, perhaps showing a bias to underestimate high latitude systems late in the season. On the other hand quite a few peak season storms like Paulette, Sally and Teddy seem to be overestimated by ADT. Unfortunately this sample size is too small to draw large conclusions. It would be amazing if such a comparison database would exist for a lot of seasons so we can perhaps more clearly notice the bias of ADT for certain time periods or regions, but I'm not aware of one.

[RL3AO]

One interesting observation is that the ADT website shows significantly lower MSLP's for the first storms this season. Even though Wikipedia mentions that a T-number of 3.0 only corresponds to ~1000 mbar, the ADT website seems to show significantly deeper systems for a CI# of 3.0. Could anyone explain why this is the case?

A lot of research has been done since Dvorak first developed his technique. The latest versions of these techniques include the research from Courtney-Knaff-Zehr (usually called CKZ) which did a lot of work on the wind/pressure relationships in tropical cyclones. ADT incorporates this to include a background pressure that the cyclone is in. That's why a 3.0 under a background ridge in August will have a higher ADT pressure than a 3.0 at the base of a trough in the mid-Atlantic in October.

The Dvorak Technique isn't perfect. It's just usually the best thing available when it comes to analyzing higher end TCs when recon isn't available. Most of the time it does a pretty good job.

[underthwx]

In the spirit of learning...may I ask, in a nutshell, what ADT is?...

[RL3AO]

In the spirit of learning...may I ask, in a nutshell, what ADT is?...

The Dvorak Technique was developed by Vernon Dvorak in the 1970s to estimate the intensity of TCs based solely on satellite appearance. The Univ. of Wisconsin has since developed the Advanced Dvorak Technique (ADT) which build on what Dvorak developed.

[underthwx]

In the spirit of learning...may I ask, in a nutshell, what ADT is?...

The Dvorak Technique was developed by Vernon Dvorak in the 1970s to estimate the intensity of TCs based solely on satellite appearance. The Univ. of Wisconsin has since developed the Advanced Dvorak Technique (ADT) which build on what Dvorak developed.

Oh ok!.... thank you very much...