2019 CPAC Season

[cycloneye]

Looks like this basin will be more active than normal.

















 https://twitter.com/NOAAComms/status/1131312752021127169

[Kingarabian]

Yeah water temps are extra toasty near Hawaii so far due to what looks to be a combination of a more positive PDO and a +PMM trying to reestablish itsef. It's only the 3rd week of May and they already can support a hurricane track towards the islands, be it from the south or east. Waters that are immediately south/south west of the islands are 27-28C and east of the islands they are 26C.

Hope the great Hawaiian shear is a permanent feature this season.

[Kingarabian]

Well no doubt that waters can easily support a high end major hurricane strike on the islands this year. Let's hope the subtropical ridge remains a permanent feature and shear remains high.

[Kingarabian]

Very worrying that Joe Bastardi, for the past couple months or so, is sounding the alarm for a strong Hawaii impact this year.

[cycloneye]

Kingarabian, and the alarm from JB is even more louder now.

 https://twitter.com/BigJoeBastardi/status/1137764693555257344

[CyclonicFury]

It's likely we'll see multiple hurricanes approaching Hawaii. The big question, as always, is if they reach Hawaii intact or do they get sheared apart like they have recently?

[TheStormExpert]

It seems each season since 2014 that the hurricane threat towards Hawaii has been steadily increasing each season, when will it stop? This season looks to have the highest threat yet, of course both wind shear and steering currents will be the determining factors as to whether or not Hawaii gets hit as has been the case the last few seasons.

But Joe B. sounding the alarm is quite concerning considering he is usually just concerned for the U.S. East Coast each and every year.

[Cyclenall]

Isn't the great Hawaiian shear belt a permanent feature in general? Has there ever been a period during hurricane season with it absent? Its usually the unexpected that bites.

[Kingarabian]

Isn't the great Hawaiian shear belt a permanent feature in general? Has there ever been a period during hurricane season with it absent? Its usually the unexpected that bites.

Typically strong shear, strong high pressure north of Hawaii, and cool SST's are what keep Hawaii so safe from TC's.

While the shear is very helpful in negating a lot of Hawaii threats, the Sub Tropical Ridge also usually holds quite firm and keeps systems from gaining too much latitude. Prior to 2014, SST's near Hawaii were usually too cool which does not allow systems to remain strong near Hawaii.

But since 2014, SST's in the vicinity of the main Hawaiian islands have been anomalously warm to the point where we're seeing a lot of major hurricanes maintain their strength very close to the islands. Fortunately when the ridge allows for a track that would allow a system to make landfall over any of the islands, shear is strong, and when shear is low, the STR is holding firm and does not allow for a track towards the islands.

[Kingarabian]

 https://twitter.com/BenNollWeather/status/1138913479358763008

[NotSparta]

https://twitter.com/BenNollWeather/status/1138913479358763008

Wow, Hawaii under the gun again

Been a bad few yrs, hope you guys don't get threatened again

[Cyclenall]

Isn't the great Hawaiian shear belt a permanent feature in general? Has there ever been a period during hurricane season with it absent? Its usually the unexpected that bites.

Typically strong shear, strong high pressure north of Hawaii, and cool SST's are what keep Hawaii so safe from TC's.

While the shear is very helpful in negating a lot of Hawaii threats, the Sub Tropical Ridge also usually holds quite firm and keeps systems from gaining too much latitude. Prior to 2014, SST's near were usually too cool which does not allow systems to remain strong near Hawaii.

But since 2014, SST's in the vicinity of the main Hawaiian islands have been anomalously warm to the point where we're seeing a lot of major hurricanes maintain their strength very close to the islands. Fortunately when the ridge allows for a track that would allow a system to make landfall over any of the islands, shear is strong, and when shear is low, the STR is holding firm and does not allow for a track towards the islands.

In that case then I don't know why there would be any concern as the shear belt is permanent or you have something that blocks TCs from getting close. Perhaps its flooding related concerns?

I think the geography of the Big Island itself creates a type of wind shear that prevents intense hurricane landfalls directly on it. The Western Regional Climate Center showed no hurricane-strength winds on any Hawaii Islands with the exception of Kauai documented.

[Chris90]

Isn't the great Hawaiian shear belt a permanent feature in general? Has there ever been a period during hurricane season with it absent? Its usually the unexpected that bites.

Typically strong shear, strong high pressure north of Hawaii, and cool SST's are what keep Hawaii so safe from TC's.

While the shear is very helpful in negating a lot of Hawaii threats, the Sub Tropical Ridge also usually holds quite firm and keeps systems from gaining too much latitude. Prior to 2014, SST's near were usually too cool which does not allow systems to remain strong near Hawaii.

But since 2014, SST's in the vicinity of the main Hawaiian islands have been anomalously warm to the point where we're seeing a lot of major hurricanes maintain their strength very close to the islands. Fortunately when the ridge allows for a track that would allow a system to make landfall over any of the islands, shear is strong, and when shear is low, the STR is holding firm and does not allow for a track towards the islands.

In that case then I don't know why there would be any concern as the shear belt is permanent or you have something that blocks TCs from getting close. Perhaps its flooding related concerns?

I think the geography of the Big Island itself creates a type of wind shear that prevents intense hurricane landfalls directly on it. The Western Regional Climate Center showed no hurricane-strength winds on any Hawaii Islands with the exception of Kauai documented.

I think the concern, especially for this year, is a combo of factors. 1. The past few years have had some strong hurricanes threaten Hawaii, they seem to be getting closer and more frequent. Combine this with the fact that some long-term climate predictions show the CPAC becoming more favorable and producing higher ACE values. The kind of activity we've seen the past few years could add some credence to these theories.
2. Model runs dealing with the next few months show higher rates of potential tropical activity for the CPAC/Hawaii indicating the potential for a pretty active season there.
3. 1992 has been mentioned as a possible analog numerous times by a few different people, and of course, 1992 brought Iniki.

I think there's just some indicators that this season might be more active than the average season and it's something to monitor, especially for those in Hawaii. I think it's important to raise awareness on the possibilities for the season, especially because Hawaii doesn't experience significant tropical cyclones with frequency.

[Kingarabian]

Isn't the great Hawaiian shear belt a permanent feature in general? Has there ever been a period during hurricane season with it absent? Its usually the unexpected that bites.

Typically strong shear, strong high pressure north of Hawaii, and cool SST's are what keep Hawaii so safe from TC's.

While the shear is very helpful in negating a lot of Hawaii threats, the Sub Tropical Ridge also usually holds quite firm and keeps systems from gaining too much latitude. Prior to 2014, SST's near were usually too cool which does not allow systems to remain strong near Hawaii.

But since 2014, SST's in the vicinity of the main Hawaiian islands have been anomalously warm to the point where we're seeing a lot of major hurricanes maintain their strength very close to the islands. Fortunately when the ridge allows for a track that would allow a system to make landfall over any of the islands, shear is strong, and when shear is low, the STR is holding firm and does not allow for a track towards the islands.

In that case then I don't know why there would be any concern as the shear belt is permanent or you have something that blocks TCs from getting close. Perhaps its flooding related concerns?

I think the geography of the Big Island itself creates a type of wind shear that prevents intense hurricane landfalls directly on it. The Western Regional Climate Center showed no hurricane-strength winds on any Hawaii Islands with the exception of Kauai documented.

Thats true. Thats why there hasn't been a major hurricane landfall since Iniki 1992. However since 2014 something changed. We've seen two abnormal hits (thankfilly weak) coming from the east which is almost unheard of. Not counting the amount of Cat1+ hurricanes flirting with landfalls, coming within 50-100NM of the isalnds.

So the problem is that its becoming more frequent. We saw what happened to Peurto Rico in 2017 which I believe is more hurricane ready than Hawaii. Hawaii's infrastructure is terrible snd thats without counting the amount of ocean side houses that will be wiped out. I think a direct hurricane impact on any of the Islands will be pretty catastrophic.

[NotSparta]

Eric Webb pointing out how anomalously warm (& warming) the CPAC is, unfortunately right around Hawaii

 https://twitter.com/webberweather/status/1142152151248056321

[Kingarabian]

Eric Webb pointing out how anomalously warm (& warming) the CPAC is, unfortunately right around Hawaii

https://twitter.com/webberweather/status/1142152151248056321

Yeah just saw that.

This sub=tweet is even more alarming:
 https://twitter.com/webberweather/status/1142157554937683968




I'm not sure if the same rule applies here but I read before that warmer SST's = less shear. Which would be a big reason why Hawaii since 2014 has been under the gun quite often.

[NotSparta]

Eric Webb pointing out how anomalously warm (& warming) the CPAC is, unfortunately right around Hawaii

https://twitter.com/webberweather/status/1142152151248056321

Yeah just saw that.

This sub=tweet is even more alarming:
https://twitter.com/webberweather/status/1142157554937683968

I'm not sure if the same rule applies here but I read before that warmer SST's = less shear. Which would be a big reason why Hawaii since 2014 has been under the gun quite often.

Yes that's exactly it. The higher SSTs excite more convection, which leads to a more anticyclonic look at the upper levels which typically reduces shear

[Chris90]

I'm going to make a little prediction and say that the CPAC generates more ACE than the EPAC this year. With the way the SST pattern has been setting up, and the fact the EPAC has been taking so long to wake up, I think there's a decent chance the CPAC wins the ACE majority this year.

I did look at some other prolific years, and if I'm reading the chart I looked at correctly, it looks like the CPAC did generate more ACE than the EPAC back in '94. It looks like the EPAC generated 78 units that year, while the CPAC generated 107 units.
I also looked at '92, but I couldn't find an ACE breakdown between the CPAC/EPAC for that year, just the total of 295 between the two. 2015 and 2018 are also two years with a lot of CPAC ACE, but the EPAC still manages to beat it out both times.

[Kingarabian]

I'm going to make a little prediction and say that the CPAC generates more ACE than the EPAC this year. With the way the SST pattern has been setting up, and the fact the EPAC has been taking so long to wake up, I think there's a decent chance the CPAC wins the ACE majority this year.

I did look at some other prolific years, and if I'm reading the chart I looked at correctly, it looks like the CPAC did generate more ACE than the EPAC back in '94. It looks like the EPAC generated 78 units that year, while the CPAC generated 107 units.
I also looked at '92, but I couldn't find an ACE breakdown between the CPAC/EPAC for that year, just the total of 295 between the two. 2015 and 2018 are also two years with a lot of CPAC ACE, but the EPAC still manages to beat it out both times.

Yup this would be the season if it were to happen.

[Kingarabian]

Prime example of how TC development is being pushed west with all these low pressure areas moving into the CPAC.



CPAC conditions generally start to become favorable in late July and last throughout ASO.