2017 indicators: SST's / MSLP / SAL / Steering / Instability

[weathaguyry]

Part of me is surprised and part of me isn't.

I'm surprised at how quickly things have changed in just one month, and this just goes to show you that the indicators before May mean very little to almost nothing as just like we see here things can change on a dime!

What doesn't surprise me is that I felt the Euro was overdoing the higher pressures and lower precipitation. I mean we had our first Cat.5 in over nine years located in the extreme Southern Part of the Eastern Caribbean in October last year. This tells me that conditions and pressure had to have been quite favorable.

All in all something tells me(and has been) that this season could be a just as active or even more active than last.

Now the big question is where will the bulk of the storms track this year? Will we see an active Cape Verde season allowing storms to recurve instantly before affecting land, or will things wait to get going until further west just like in 2005 greatly enhancing the chances of land impacts?

My last question is when you say near normal Alyono does this mean slightly above normal pressures and slightly below normal precipitation or the opposite?

I think what was meant was that the EC has a huge bias when it comes to pressure forecasts, and the fact that it is showing near normal pressures is shocking, and may need to be closely watched for some very favorable conditions.

[Kazmit]

Keep in mind that last year was only active because of the PDO crash. Up until October, it was a below average season. So this year could very well be as active or even more active than last year, as you said. Just like you, this is what my gut feeling has been telling me.

[TheStormExpert]

:uarrow: Keep in mind that last year was only active because of the PDO crash. Up until October, it was a below average season. So this year could very well be as active or even more active than last year, as you said. Just like you, this is what my gut feeling has been telling me.

What exactly is the PDO, and why did it crash?

[Kingarabian]

:uarrow: Keep in mind that last year was only active because of the PDO crash. Up until October, it was a below average season. So this year could very well be as active or even more active than last year, as you said. Just like you, this is what my gut feeling has been telling me.

The PDO did crash, but what I think actually helped the Atlantic was the weak Nina that finally got going later on into the season. I doubt a Decadal variable can have its effects completely reversed simply due to a few anomalous months.

[RL3AO]

:uarrow: Keep in mind that last year was only active because of the PDO crash. Up until October, it was a below average season. So this year could very well be as active or even more active than last year, as you said. Just like you, this is what my gut feeling has been telling me.

That's quite the statement to make. It was ONLY active because the PDO index went negative for a few months?

[weathaguyry]

:uarrow: Keep in mind that last year was only active because of the PDO crash. Up until October, it was a below average season. So this year could very well be as active or even more active than last year, as you said. Just like you, this is what my gut feeling has been telling me.

That's quite the statement to make. It was ONLY active because the PDO index went negative for a few months?

If you think about it, we were only at 12/4/1 without Matthew, Nicole, and Otto

[TheStormExpert]

Interesting tweets from Levi Cowan.

 https://twitter.com/tropicaltidbits/status/861661057185656832




 https://twitter.com/tropicaltidbits/status/861661321854693376




 https://twitter.com/tropicaltidbits/status/861662011989643270

[Hammy]

:uarrow: Keep in mind that last year was only active because of the PDO crash. Up until October, it was a below average season. So this year could very well be as active or even more active than last year, as you said. Just like you, this is what my gut feeling has been telling me.

That's quite the statement to make. It was ONLY active because the PDO index went negative for a few months?

If you think about it, we were only at 12/4/1 without Matthew, Nicole, and Otto

The whole season counts, regardless of why it got active near the end, otherwise we have to go back and analyze every other season. 2001 was also below average prior to October, having had only 8/4/2 up to that point (and no hurricane landfalls.)

[Kazmit]

:uarrow: Keep in mind that last year was only active because of the PDO crash. Up until October, it was a below average season. So this year could very well be as active or even more active than last year, as you said. Just like you, this is what my gut feeling has been telling me.

That's quite the statement to make. It was ONLY active because the PDO index went negative for a few months?

Sorry for not clarifying. I am fully aware that last season wasn't active solely because of the PDO crash, as there are other variables involved.

[Ntxw]

PDO never went negative. It fell alongside exiting the big El Nino and moving into the weak La Nina.

[SFLcane]

Interesting developments today...

[Kingarabian]

Just to note: While the Euro is showing normal pressures over the MDR, the Euro's may forecast continues to show a moderate El Nino and it does not look anything close to a Modoki Nino. Interesting run indeed.

[NDG]

Meanwhile the deep tropical Atlantic continues to stay above average and what makes this +PDO interesting is how cold the SSTs along the NW North American Coast is which so far is not showing any signs of getting that classic +PDO signature.

[Ntxw]

Meanwhile the deep tropical Atlantic continues to stay above average and what makes this +PDO interesting is how cold the SSTs along the NW North American Coast is which so far is not showing any signs of getting that classic +PDO signature.

-PDO is all warm from Japan to the Gulf of Alaska, or 180 flip



Much more resembles left (warm phase) than right (cool phase)

Images courtesy of the source at JISAO

http://research.jisao.washington.edu/pdo/

[Kingarabian]

Not sure precisely how JISAO or NCDC calculate the PDO, but I recall the waters near Alaska and the NW America seaboard being above average during months of the Super Nino and the PDO would come in lower than it is now (compared with less warm waters near Alaska and NW America),

If you have too much warmth near Alaska and NW America, then those anomalies start creeping into the core and start reducing the warm horseshoe signature thus resulting in a not too positive PDO. The PDO being at +1.00 is nothing to sneer at and it'll continue the warm phase of the PDO for the rest of the year. I think the anomalies near Alaska and NW America could be a bit higher, and if they do then the PDO will start getting back to +2.00.

[NDG]

Not sure precisely how JISAO or NCDC calculate the PDO, but I recall the waters near Alaska and the NW America seaboard being above average during months of the Super Nino and the PDO would come in lower than it is now (compared with less warm waters near Alaska and NW America),

If you have too much warmth near Alaska and NW America, then those anomalies start creeping into the core and start reducing the warm horseshoe signature thus resulting in a not too positive PDO. The PDO being at +1.00 is nothing to sneer at and it'll continue the warm phase of the PDO for the rest of the year. I think the anomalies near Alaska and NW America could be a bit higher, and if they do then the PDO will start getting back to +2.00.

Yeap, the reason why last spring the PDO was at well above +2.0, had that classic horseshoe signature, which it does not have this spring so far.

[dexterlabio]

So am I getting this right, +PDO limits tropical activity in the Atlantic? I though it has something to do only with the Pacific?

[RL3AO]

So am I getting this right, +PDO limits tropical activity in the Atlantic? I though it has something to do only with the Pacific?

A +PDO favors stronger and more frequent El Ninos over a 20 to 30 year period. Although, sometimes I think some get a little carried away with the week to week trends of the PDO Index.

[Kingarabian]

So am I getting this right, +PDO limits tropical activity in the Atlantic? I though it has something to do only with the Pacific?

The jury is still out on the PDO and its impacts on the Atlantic hurricane season. Some seasons in the past had a warm PDO and a Nina and saw below average activity, while some seasons had a warm PDO and a Nina and saw above average activity. This season we'll have a warm PDO (no matter its shape or how it oscillates) and either warm Neutral/weak Nino. How it'll effect the
Atlantic hurricane season remains to be seen.

The PDO has a direct influence on ENSO. It can promote and aid a Nino when warm, and shut down emerging Nina's. When it's cool, it does the opposite.

[SFLcane]

 https://twitter.com/adriansweather/status/862008058205143040