NHC article on evaluation of PTC designation

[Teban54]

On Wednesday, NHC released an evaluation of the Potential Tropical Cyclone designation, which has been in use in both the Atlantic and EPac since 2017:

https://noaanhc.wordpress.com/2023/06/1 ... dvisories/

Interesting tidbits:

• Of the 30 PTCs in the two basins, only three failed to develop into a tropical cyclone (Ten 2017, Seventeen-E 2019, Four 2022)
• Even though there's no requirement for 2-day and 5-day formation chances for starting PTC advisories, in practice, all advisories so far had at least 70% 2-day chance when designated PTC, with most over 80%
• 20% of PTCs were already at tropical storm intensity for the first advisory
• There have been 5 hurricane watches issued for systems that are still PTCs
• Most PTCs take around 20 hours for genesis, but Alex and Bonnie 2022 took 57 and 88 hours, respectively
• The PTC designation provides an average of 21 hours of extra lead time for issuing watches and warnings, compared to if PTC did not exist (Isaias had 36 hours of extra lead time)

[wxman57]

I see that for 9 of the 27 Atlantic storms with PTC advisories, development occurred within 6 hrs. Not much additional warning. That included Harvey's redevelopment in the BoC after crossing the Yucatan. We never stopped advisories on Harvey after it was downgraded in the central Caribbean, as it was expected to redevelop after moving into the BoC and SW Gulf in 3-4 days.

[weeniepatrol]

I see that for 9 of the 27 Atlantic storms with PTC advisories, development occurred within 6 hrs. Not much additional warning. That included Harvey's redevelopment in the BoC after crossing the Yucatan. We never stopped advisories on Harvey after it was downgraded in the central Caribbean, as it was expected to redevelop after moving into the BoC and SW Gulf in 3-4 days.

Good point. I suppose it’s better than nothing, for sure, but clearly still room for improvement