Expert Forecasts for the 2024 North Atlantic Hurricane Season: NOAA up on May 23rd at 10 AM EDT

[Ptarmigan]

Here's the full forecast from UPENN. Apparently it's based off a statistical model, which explains why it is so insanely high.
https://web.sas.upenn.edu/mannresearchg ... hurricane/

University of Pennsylvania EES scientists Dr. Michael E. Mann and Shannon Christiansen, and Penn State ESSC alumnus Dr. Michael Kozar have released their seasonal prediction for the 2024 North Atlantic hurricane season, which officially starts on 1 June and runs through 30 November.

The prediction is for 33.1 +/- 5.8 total named tropical cyclones, which corresponds to a range between 27 and 39 storms, with a best estimate of 33 named storms. This prediction was made using the statistical model of Kozar et al. (2012, see PDF here). This statistical model builds upon the past work of Sabbatelli and Mann (2007, see PDF here) by considering a larger number of climate predictors and including corrections for the historical undercount of events (see footnotes).

The assumptions behind this forecast are (a) the persistence of current North Atlantic Main Development Region (MDR) sea surface temperature (SST) anomalies (+1.9°C in April 2024 from NOAA’s Coral Reef Watch) throughout the 2024 hurricane season, (b) development of a moderate La Nina (Niño3.4 anomaly of -0.5°C) conditions in the equatorial Pacific in late Boreal summer and fall 2024 (ENSO forecasts here; we used mid-April 2023), and (c) climatological mean conditions for the North Atlantic Oscillation in Fall/Winter 2023-2024.

If neutral ENSO conditions (Niño3.4 anomaly of 0.0°C) take shape later in 2024, then the prediction will be lower: 30.5 +/- 5.5 storms (range of 25 – 36 storms, with a best guess of 31).

Using an alternative model that uses “relative” MDR SST (MDR SST with the average tropical mean SST subtracted) in place of MDR SST yields a lower prediction (19.9 +/- 4.5 total named storms). This alternative model also includes positive ENSO conditions.

Interesting that almost all of the previous best guess forecasts were either pretty close to actual numbers or too low of a forecast. Exceptions were 2009, 2010, 2013 and 2016, but even these the forecast numbers were only 3-4 named storms too high.

Just to put things into perspective, 39 named storms would tie 1964's WPAC for the world record.

If there were 39 named storms, we would be close to running out of supplemental names. There are 21 supplemental names. The 2024 name and supplemental name list have a total of 42. I wonder what happens.

[NotSparta]

Interesting that almost all of the previous best guess forecasts were either pretty close to actual numbers or too low of a forecast. Exceptions were 2009, 2010, 2013 and 2016, but even these the forecast numbers were only 3-4 named storms too high.

Just to put things into perspective, 39 named storms would tie 1964's WPAC for the world record.

If there were 39 named storms, we would be close to running out of supplemental names. There are 21 supplemental names. The 2024 name and supplemental name list have a total of 42. I wonder what happens.

Greek letters after we run out of supplemental names:

[Category5Kaiju]

To be fair, if we ever got to 39 NSs in the Atlantic (or god forbid exceed 42 lol), then I think the most plausible and reasonable scenario would be that the NHC decides to designate the 6 naming lists as independent of year and use them on a rolling basis like we do in the WPAC and Australian basins.

Clearly, if that happens then what would be the purpose of having a “supplemental” list? If the Atlantic somehow shocks us all and demonstrates it can be even more active than the most active basin on the planet?

[chaser1]

If/when this happens, we simply begin using ALL the names of NHC employees. 'Course, if they're not all that onboard with the idea..... then lets just get jiggy with it and start naming tropical cyclones after all of our country's past presidents or perhaps past Pope's (well, the latter might result in a bit of an Italian flair to the season LOL)

[ouragans]

INSMET (Cuba) published today their forecast

20 TS
11 H

 https://twitter.com/cnp_insmet_cuba/status/1787893204114628906

[Nuno]

To be fair, if we ever got to 39 NSs in the Atlantic (or god forbid exceed 42 lol), then I think the most plausible and reasonable scenario would be that the NHC decides to designate the 6 naming lists as independent of year and use them on a rolling basis like we do in the WPAC and Australian basins.

Clearly, if that happens then what would be the purpose of having a “supplemental” list? If the Atlantic somehow shocks us all and demonstrates it can be even more active than the most active basin on the planet?

I have long been a proponent of this. The current protocol of starting at letter "A" was started due to the usage of the Joint Army/Navy radiotelephony spelling alphabet, yet as any S2k lurker or weather enthusiast by now is well aware, the "I" storm curse is merely just peak season lining up at that part of the alphabet every year. Instead of having to "worry" (I use that term lightly lol) about the alphabet running out and the auxiliary lists, we really should just adopt the rolling-list method.

[Category5Kaiju]

To be fair, if we ever got to 39 NSs in the Atlantic (or god forbid exceed 42 lol), then I think the most plausible and reasonable scenario would be that the NHC decides to designate the 6 naming lists as independent of year and use them on a rolling basis like we do in the WPAC and Australian basins.

Clearly, if that happens then what would be the purpose of having a “supplemental” list? If the Atlantic somehow shocks us all and demonstrates it can be even more active than the most active basin on the planet?

I have long been a proponent of this. The current protocol of starting at letter "A" was started due to the usage of the Joint Army/Navy radiotelephony spelling alphabet, yet as any S2k lurker or weather enthusiast by now is well aware, the "I" storm curse is merely just peak season lining up at that part of the alphabet every year. Instead of having to "worry" (I use that term lightly lol) about the alphabet running out and the auxiliary lists, we really should just adopt the rolling-list method.

I agree. I mean don't get me wrong I fully understand why the Atlantic uses an alphabetical order list of names (it's easy to keep track of storm number, we've been doing this for nearly 70 years, etc.), but also the rolling list of names guarantees that you will never run out of names no matter how freakish of a season you have, and it also would definitely alleviate the I curse.

[wwizard]

To be fair, if we ever got to 39 NSs in the Atlantic (or god forbid exceed 42 lol), then I think the most plausible and reasonable scenario would be that the NHC decides to designate the 6 naming lists as independent of year and use them on a rolling basis like we do in the WPAC and Australian basins.

Clearly, if that happens then what would be the purpose of having a “supplemental” list? If the Atlantic somehow shocks us all and demonstrates it can be even more active than the most active basin on the planet?

You could add Q, U, X, Y, Z and rotate them with I where each letter is on the list once every 6 years. Example, next year there's no I storm on the list and instead there's a Q name. 2026, replace Q with U and so on. The next time I appears would be 2030.

[cycloneye]

NOAA will release their outlook on may 23 at 10 AM EDT.

 https://twitter.com/NOAAComms/status/1790034605300490342

[Category5Kaiju]

I'm expecting a NS range that goes into the 20s, a H range that goes into the 10s, and a MH range that includes 6 and 7 as possibilities.

[Hurricane2022]

I'm expecting a NS range that goes into the 20s, a H range that goes into the 10s, and a MH range that includes 6 and 7 as possibilities.

19 - 25 Tropical Storms
8 - 13 Hurricanes
3 - 6 Major Hurricanes
90% chances of above-normal activity
10% chances of near-normal activity

[Beef Stew]

NOAA’s forecast will be interesting; I think it will be something along the lines of:

15-22 NS
7-12 H
4-6 M

75% Above Normal
15% Near Normal
10% Below Normal

[StPeteMike]

NOAA’s forecast will be interesting; I think it will be something along the lines of:

15-22 NS
7-12 H
4-6 M

75% Above Normal
15% Near Normal
10% Below Normal

Seems in the ballpark of what we should expect from NOAA next week. Unsure what the highest forecast for named storms is from NOAA, but I think we will see one of the highest forecast from NOAA we have seen yet.

[Beef Stew]

NOAA’s forecast will be interesting; I think it will be something along the lines of:

15-22 NS
7-12 H
4-6 M

75% Above Normal
15% Near Normal
10% Below Normal

Seems in the ballpark of what we should expect from NOAA next week. Unsure what the highest forecast for named storms is from NOAA, but I think we will see one of the highest forecast from NOAA we have seen yet.

I think 2010 holds the record for their most aggressive forecast? It had an upper limit of 23 storms if I remember correctly. Someone (maybe Larry?) made a post in the past diving into the history of NOAA’s most bullish forecasts (and their verification scores); I think the top three were along the lines of 2006, 2010, and 2022.

[LarryWx]

NOAA’s forecast will be interesting; I think it will be something along the lines of:

15-22 NS
7-12 H
4-6 M

75% Above Normal
15% Near Normal
10% Below Normal

Seems in the ballpark of what we should expect from NOAA next week. Unsure what the highest forecast for named storms is from NOAA, but I think we will see one of the highest forecast from NOAA we have seen yet.

I think 2010 holds the record for their most aggressive forecast? It had an upper limit of 23 storms if I remember correctly. Someone (maybe Larry?) made a post in the past diving into the history of NOAA’s most bullish forecasts (and their verification scores); I think the top three were along the lines of 2006, 2010, and 2022.

My post was about CSU’s as opposed to NOAA’s most bullish forecasts.

[skyline385]

NOAA’s forecast will be interesting; I think it will be something along the lines of:

15-22 NS
7-12 H
4-6 M

75% Above Normal
15% Near Normal
10% Below Normal

Seems in the ballpark of what we should expect from NOAA next week. Unsure what the highest forecast for named storms is from NOAA, but I think we will see one of the highest forecast from NOAA we have seen yet.

I think 2010 holds the record for their most aggressive forecast? It had an upper limit of 23 storms if I remember correctly. Someone (maybe Larry?) made a post in the past diving into the history of NOAA’s most bullish forecasts (and their verification scores); I think the top three were along the lines of 2006, 2010, and 2022.

Just fyi, all of NHC/NOAA forecasts can be found here

https://www.cpc.ncep.noaa.gov/products/ ... hive.shtml

2010 was indeed the highest for a May forecast at 14-23 NS, then 2022 with 14-21 NS and finally 2013 (the dreaded year for mets ) with 13-20 NS.