Expert forecasts for 2021 North Atlantic Hurricane Season

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Expert forecasts for 2021 North Atlantic Hurricane Season

#1 Postby cycloneye » Thu Dec 10, 2020 12:34 pm

Here we go with the expert forecasts 2021 thread starting with TSR and CSU.

CSU

December 10 --- https://tropical.colostate.edu/Forecast/2020-12.pdf --- Outlook in general

April 8 --- https://tropical.colostate.edu/Forecast/2021-04.pdf --- 17/8/4

June 3 --- https://tropical.colostate.edu/Forecast/2021-06.pdf --- 18/8/4

July 8 --- https://tropical.colostate.edu/Forecast/2021-07.pdf --- Rest of season-15/8/4

August 5 --- https://tropical.colostate.edu/Forecast/2021-08.pdf --- Rest of season --- 13/7/3

August 19- https://tropical.colostate.edu/Forecast/2021-0819.pdf --- Near normal next two weeks - August 19-September 1

September 2- https://tropical.colostate.edu/Forecast/2021-0902.pdf --- Above normal next two weeks - September 2- 15

September 16 - https://tropical.colostate.edu/Forecast/2021-0916.pdf ---Normal next two weeks - September 16-29

September 30 - https://tropical.colostate.edu/Forecast/2021-0930.pdf --- Above normal next two weeks - September 30-October 13

October 14 - https://tropical.colostate.edu/Forecast/2021-1014.pdf --- Normal next two weeks - October 14-27

November 30 - https://tropical.colostate.edu/Forecast/2021-11.pdf --- Verification of season

TSR

December 9 --- http://www.tropicalstormrisk.com/docs/T ... ec2021.pdf --- 16/7/3

April 13 --- http://www.tropicalstormrisk.com/docs/T ... pr2021.pdf --- 17/8/3

May 27 --- https://www.tropicalstormrisk.com/docs/ ... on2021.pdf --- 18/9/4

July 6 --- http://tropicalstormrisk.com/docs/TSRAT ... ly2021.pdf --- 20/9/4

August 5 --- https://www.tropicalstormrisk.com/docs/ ... st2021.pdf --- Rest of season --- 18/7/3

NOAA May 20 --- https://www.noaa.gov/media-release/noaa ... ane-season --- 13-20

August 4--- https://www.cpc.ncep.noaa.gov/products/ ... cane.shtml --- 15-21


Crownweather Services --- https://crownweather.com/index.php/disc ... cy1uGDffYo --- 16/8/4 --- March 10

Joe Bastardi --- https://www.weatherbell.com/march-2021- ... on-outlook --- 16-22 named storms --- March 7

Accuweather --- https://www.accuweather.com/en/hurrican ... ESVAzERNOs --- 16-20 named storms --- March 31

University of Arizona --- https://has.arizona.edu/article/2021-hu ... xubin-zeng --- 18/8/4 --- April 13

The Weather Channel --- https://weather.com/storms/hurricane/ne ... il-twc-csu --- 18/8/3 --- April 15

--- https://weather.com/storms/hurricane/ne ... 21-may-twc --- 19/8/4 --- May 12

--- https://weather.com/storms/hurricane/vi ... date-is-in --- 19/8/3 --- July 22

UKMET --- https://www.metoffice.gov.uk/research/w ... lantic2021 --- 14/7/3 --- May 20

.

.

.
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season

#2 Postby cycloneye » Thu Dec 10, 2020 12:35 pm

Here are the possibilities.

1. AMO becomes very strong in 2021 and no El Niño occurs (resulting in a seasonal
average Accumulated Cyclone Energy (ACE) activity of ~ 170) – 25% chance.
2. AMO is above average and no El Niño occurs (ACE ~ 130) – 30% chance.
3. AMO is above average and El Niño develops (ACE ~ 80) – 15% chance.
4. AMO is below average and no El Niño occurs (ACE ~ 80) – 20% chance.
5. AMO is below average and El Niño develops (ACE ~ 50) – 10% chance.


Typically, seasons with the above-listed ACE values have TC activity as follows:
170 ACE – 14-17 named storms, 9-11 hurricanes, 4-5 major hurricanes
130 ACE – 12-15 named storms, 6-8 hurricanes, 2-3 major hurricanes
80 ACE – 8-11 named storms, 3-5 hurricanes, 1-2 major hurricanes
50 ACE – 5-7 named storms, 2-3 hurricanes, 0-1 major hurricane
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season

#3 Postby AnnularCane » Thu Dec 10, 2020 12:46 pm

Wait a sec, I thought the CSU didn't do December forecasts anymore. Or am I thinking of something else?
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season

#4 Postby ouragans » Thu Dec 10, 2020 2:37 pm

TSR was published yesterday

16 TS
7 H
3 IH
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season

#5 Postby CrazyC83 » Fri Dec 11, 2020 3:43 pm

If things don't change, 2021 could be another season of our worst nightmares. However, it's hard to imagine two consecutive insane seasons. Could 2006 be a potential analog for 2021? I think that will be thought of a lot.
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season

#6 Postby aspen » Fri Dec 11, 2020 3:52 pm

CrazyC83 wrote:If things don't change, 2021 could be another season of our worst nightmares. However, it's hard to imagine two consecutive insane seasons. Could 2006 be a potential analog for 2021? I think that will be thought of a lot.

We’ll need to see how fast the ENSO warms over the next 5-10 months. It’s going to warm at least somewhat, but we’re months away from the Spring Barrier, so we have essentially zero certainty as to what will have.

If we get a quickly warning ENSO, a 2006-like year is on the table. If we get an ENSO that barely warms and remains cool or neutral, another active season is likely.
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season

#7 Postby NorthieStangl » Sat Jan 09, 2021 7:04 pm

CrazyC83 wrote:If things don't change, 2021 could be another season of our worst nightmares. However, it's hard to imagine two consecutive insane seasons. Could 2006 be a potential analog for 2021? I think that will be thought of a lot.


That is a possibility, but the hyperactive 1995 season was followed by an active 1996, and an active 2004 was followed by 2005. Also, 2010 with 19 storms was followed by 2011 which also had 19 storms, which was followed by 2012 with, again, 19 storms.
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season

#8 Postby Category5Kaiju » Mon Jan 11, 2021 12:11 am

CrazyC83 wrote:If things don't change, 2021 could be another season of our worst nightmares. However, it's hard to imagine two consecutive insane seasons. Could 2006 be a potential analog for 2021? I think that will be thought of a lot.


So this topic is quite a bit talked about in the "2021 Indicators" thread, but 2006 may actually not be a good analog for 2021 because if you really think about it, 2005 had a weak La Nina that rapidly and easily became an El Nino in 2006 whereas 2020's La Nina is way more robust and moderate, with historical records showing that years with a moderate La Nina onset are rarely (if ever) followed by an El Nino the year right after. 2006 was mainly inactive because of the El Nino, and I think it would be safe to say that given historical data as well as some long-range forecasts from various models and professional meteorologists that we will likely be neutral at most this season, 2021 could very well be more active than 2006. In other words, just because 2020 went Greek like 2005 does not mean 2021 will necessarily be the same as 2006 and be a weak season.
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season

#9 Postby chaser1 » Mon Jan 11, 2021 1:12 am

This is the Expert Forecasts for 2021 North Atlantic thread, correct? Just wanted to make sure :wink:
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season

#10 Postby cycloneye » Fri Mar 05, 2021 9:43 am

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Re: Expert forecasts for 2021 North Atlantic Hurricane Season

#11 Postby chaser1 » Sat Mar 06, 2021 1:43 pm

Note to self: Resist ALL urges to "hock" my car or spend my anticipated Covid Relief check, to afford a Weatherbell/Bastardi advanced Client outlook perhaps suggesting another back to back hyperactive season and potentially another 14-20 named storm prediction for the upcoming '21 Hurricane Season?? Oh Joe..... the forthcoming sleepless nights I must now endure :cheesy:
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season: Crownweather Services is up

#12 Postby cycloneye » Wed Mar 10, 2021 7:05 pm

Crownweather Services is up with 16/8/4 and a repeat of 2017?

Image
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season: Crownweather Services is up

#13 Postby SFLcane » Wed Mar 10, 2021 7:35 pm

Shades of 2017... :eek:

cycloneye wrote:Crownweather Services is up with 16/8/4.

https://i.imgur.com/acy6hGg.png
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season: Crownweather Services is up

#14 Postby aspen » Wed Mar 10, 2021 8:05 pm

cycloneye wrote:Crownweather Services is up with 16/8/4 and a repeat of 2017?

https://i.imgur.com/acy6hGg.png

Hopefully the below-average forecast for the WCar holds. Central America really needs a break after Gamma, Delta, Zeta, Eta, and Iota all within 6 weeks.
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season: Crownweather Services is up

#15 Postby chaser1 » Wed Mar 10, 2021 10:10 pm

SFLcane wrote:Shades of 2017... :eek:

cycloneye wrote:Crownweather Services is up with 16/8/4.

https://i.imgur.com/acy6hGg.png


I think that's a reasonable consideration. I read all of Crownweather's season forecast and Rob didn't reference 2017 as one of his analogues but I think 2017 could potentially be one. The only area where I particularly disagree with is the thought that the W. Caribbean will be a barren wasteland ("dry" per long range projections). While long trackers may well track more NW, I don't think that'll preclude development in the W. Caribbean especially during climo periods during June and late September/October.
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season: Crownweather Services is up

#16 Postby crownweather » Thu Mar 11, 2021 11:06 am

cycloneye wrote:Crownweather Services is up with 16/8/4 and a repeat of 2017?

https://i.imgur.com/acy6hGg.png


THANK YOU for posting our forecast cyclone!! Really appreciate it as A LOT of work went into researching and writing it.

I came up with the following analog years for this upcoming season by comparing ocean water temps AND ONI data to past years. The analog years include 1899, 1950, 1956, 1996 (A STRONG ANALOG), 1999 and 2012 (ANOTHER STRONG ANALOG).

When you average those 7 analog years, you come up with 14 NS/8 H/4 MH & an ACE of 148.57.

Instead of using just precip anomaly maps, I also incorporated the 500 mb upper air guidance from the EURO and NMME, which actually shows a mean trough near the Great Lakes early in the season backing away into the northern Plains States by August and September. Makes me think that if there are any early season storms, they may head up the E Coast towards New England. By August and September, the tracks may be more clustered westward towards the NE Carib, Florida and the eastern Gulf. Also, the consensus in the guidance for a very dry Caribbean is why I chose to go below average activity in the WCarib. Although, truth be told, the analog set puts the Yucatan Peninsula and western Cuba at a medium to high risk.

One thing that I did notice in the data is that 1956 is a analog year, which was a very slow season, even though it started with La Nina conditions before the SPB. While I don't think we'll go full-blown El Nino by Summer and I think instead we should warm to neutral ENSO, that idea of a quick turnaround to El Nino is something I will be keeping in the back of my mind.

Finally, I did initially have 1954 and 1960 as analog years when I was first researching the data. I took those two years out as the ONI data indicated that 1954 started out with a weak El Nino and then cooled towards La Nina during the peak of the season. As for 1960, that year remained squarely neutral ENSO throughout the year.
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season

#17 Postby BadLarry95 » Thu Mar 11, 2021 3:23 pm

If these ~16 storms or so predictions come true, it will be only the second time this list has gotten past K. Infact this is the only list that’s never used R S T names

List 1 (Peter)
List 2 (Tomas)
List 3 (exhausted 2005... ζ)
List 4 (Tony)
List 5 (Tanya)
List 6 (exhausted 2020... ι)
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season: Crownweather Services is up

#18 Postby wxman57 » Sat Mar 13, 2021 10:46 am

aspen wrote:
cycloneye wrote:Crownweather Services is up with 16/8/4 and a repeat of 2017?

https://i.imgur.com/acy6hGg.png

Hopefully the below-average forecast for the WCar holds. Central America really needs a break after Gamma, Delta, Zeta, Eta, and Iota all within 6 weeks.


If I were to put any area as having less of a threat, it would be the eastern Caribbean from PR to Trinidad. It's very questionable as to whether the MDR will recover this year. It's been quite hostile for the past 3-4 seasons, leading to little in the way of significant storms in the deep tropics south of 18N. I would include the NW Caribbean and western Gulf as high-risk. Very little difference from 2020, with the exception of a La Nina not being as likely by peak season. My numbers indicate that it would be a good idea to add in "Q", "U", "X", "Y", and "Z". So many weak, short-lived storms are being named now that would not have been identified and named in the past. There were 15 last year that lasted less than 72 hrs. Watch out Gulf Coast and East Coast this season.
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season: Crownweather Services is up

#19 Postby aspen » Sat Mar 13, 2021 11:00 am

wxman57 wrote:
aspen wrote:
cycloneye wrote:Crownweather Services is up with 16/8/4 and a repeat of 2017?

https://i.imgur.com/acy6hGg.png

Hopefully the below-average forecast for the WCar holds. Central America really needs a break after Gamma, Delta, Zeta, Eta, and Iota all within 6 weeks.


If I were to put any area as having less of a threat, it would be the eastern Caribbean from PR to Trinidad. It's very questionable as to whether the MDR will recover this year. It's been quite hostile for the past 3-4 seasons, leading to little in the way of significant storms in the deep tropics south of 18N. I would include the NW Caribbean and western Gulf as high-risk. Very little difference from 2020, with the exception of a La Nina not being as likely by peak season. My numbers indicate that it would be a good idea to add in "Q", "U", "X", "Y", and "Z". So many weak, short-lived storms are being named now that would not have been identified and named in the past. There were 15 last year that lasted less than 72 hrs. Watch out Gulf Coast and East Coast this season.

Are there any indications as to what latitude the ITCZ will be for this year’s peak season? Or is it a “wait and see” kind of detail?
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Re: Expert forecasts for 2021 North Atlantic Hurricane Season: Crownweather Services is up

#20 Postby Shell Mound » Sat Mar 13, 2021 12:50 pm

wxman57 wrote:
aspen wrote:
cycloneye wrote:Crownweather Services is up with 16/8/4 and a repeat of 2017?

https://i.imgur.com/acy6hGg.png

Hopefully the below-average forecast for the WCar holds. Central America really needs a break after Gamma, Delta, Zeta, Eta, and Iota all within 6 weeks.


If I were to put any area as having less of a threat, it would be the eastern Caribbean from PR to Trinidad. It's very questionable as to whether the MDR will recover this year. It's been quite hostile for the past 3-4 seasons, leading to little in the way of significant storms in the deep tropics south of 18N.

By “significant,” I assume you mean major hurricanes. If so, then you are definitely correct, as 2018–20 has only seen MH Lorenzo (2019) in the MDR south of 18°N.
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