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

[RL3AO]

@EricBlake12
Eric Blake Retweeted Michael Ventrice
If that strong convection sets up over Africa w/subsidence near 180- watch out! Historically that's an active August Atlantic TC pattern

That would be an unsettling large scale pattern by mid-August.

[SFLcane]

 https://twitter.com/mjventrice/status/891269364548329473

[gatorcane]

something to consider since there is a distinct global depression in TC activity

is the heat distribution between the tropics and the poles more equal the normal? If so, that will have a major suppression on TCs as a TCs function is to redistribute heat from the tropics to the poles. This is not my area of expertise so I will have to defer to others on this question

But plenty of warmer than normal SSTs in the tropics this year.

[gatorcane]

https://twitter.com/mjventrice/status/891269364548329473

This overall pattern of stronger Western Atlantic ridging goes back to 2015. Here in South Florida just like the last two summers, the east wind pattern has dominated with all the afternoon storms pushed well inland. Finally we see a pattern change this week but the ridge looks to build back. We have gotten lucky here from not taking a direct hit from something significant from the east so far with such a pattern. Seems like there has been always something to prevent that from happening from either a ULL that shows up just in time (2016 Hermine when it was an invest in the Bahamas - Euro had a hurricane into South Florida), to the ridge not being quite strong enough (Matthew), or above normal shear in place (2015 super El Niño)

[TheStormExpert]

Michael Lowry says 2003 and 2005 featured more Saharan dust when compared to seasons like 2013 and 2014.

 https://twitter.com/MichaelRLowry/status/890994740019245056

[Ntxw]

something to consider since there is a distinct global depression in TC activity

is the heat distribution between the tropics and the poles more equal the normal? If so, that will have a major suppression on TCs as a TCs function is to redistribute heat from the tropics to the poles. This is not my area of expertise so I will have to defer to others on this question

But plenty of warmer than normal SSTs in the tropics this year.

I think his concern was more towards the possible expansion of the Hadley Cell or likewise. If the subtropics and extra-tropics going pole-ward is also warm if that distorts the need for heat distribution via TC activity globally.

[Ntxw]

Michael Lowry says 2003 and 2005 featured more Saharan dust when compared to seasons like 2013 and 2014.

It is probably a good stepping stone for research, but the dust alone is not the full cause. I'd be interested in more research on the mid level warm/dry layer that accompany the dust. The dust itself likely doesn't prohibit convection, but rather the cap induced by the warm air layer. That's why we call it SAL (saharan air layer) and not just African dust

[AutoPenalti]

So much for "Season cancelled"

[Hammy]

Atlantic still dry, but lots of turning and starting to remind me of the large dry 'tumbleweed' waves I remember seeing frequently in the first half of 1998-2000.

[gatorcane]

pretty big dent in the SAL with the large wave rolling off Africa and the one further west the NHC has marked. Getting closer to that time of year the SAL slowly starts to lose its grip.

[Alyono]

Michael Lowry says 2003 and 2005 featured more Saharan dust when compared to seasons like 2013 and 2014.

It is probably a good stepping stone for research, but the dust alone is not the full cause. I'd be interested in more research on the mid level warm/dry layer that accompany the dust. The dust itself likely doesn't prohibit convection, but rather the cap induced by the warm air layer. That's why we call it SAL (saharan air layer) and not just African dust

2005 did not have the strong wind shear that is usually associated with the SAL. The waves were moving SLOWLY, meaning that there was not the strong low level easterly jet. Also, I believe the SAL product mainly picks up drier air. I THINK I read somewhere that the dry air in 2005 was more from the North Atlantic and not so much the Sahara. That would explain the weaker than normal wave activity that year

[Hammy]

Not to sound alarmist or start another impatient season cancel string of comments, but as some mets here have expressed doubt concerning the global conditions, combined with the models showing little to nothing as far as tropical waves (which I started noticing last night), what are the thoughts of some of the mets and other more knowledgeable posters on this--are we potentially headed towards something along similar lines to 2013? Or are there other clearer atmospheric forces at work here? What are the implications on the rest of the season? My confidence in this year being active are starting to slide at the moment.

[CFLHurricane]

Not to sound alarmist or start another impatient season cancel string of comments, but as some mets here have expressed doubt concerning the global conditions, combined with the models showing little to nothing as far as tropical waves (which I started noticing last night), what are the thoughts of some of the mets and other more knowledgeable posters on this--are we potentially headed towards something along similar lines to 2013? Or are there other clearer atmospheric forces at work here? What are the implications on the rest of the season? My confidence in this year being active are starting to slide at the moment.

To answer your questions: No.

[wxmann_91]

Michael Lowry says 2003 and 2005 featured more Saharan dust when compared to seasons like 2013 and 2014.

So I personally would tend to agree that SAL is a little bit overrated when it comes to modulating seasonal activity. SAL will always be there. Personally I think the biggest factors last several years have been a) positioning of TUTTs, b) large scale ascent or lack thereof across the basin, c) instability. Given a plentiful supply of AEW's, a favorable combination of those factors can overcome the so-called "dry air" which will always be widespread under the Azores subtropical high.

[chaser1]

Not to sound alarmist or start another impatient season cancel string of comments, but as some mets here have expressed doubt concerning the global conditions, combined with the models showing little to nothing as far as tropical waves (which I started noticing last night), what are the thoughts of some of the mets and other more knowledgeable posters on this--are we potentially headed towards something along similar lines to 2013? Or are there other clearer atmospheric forces at work here? What are the implications on the rest of the season? My confidence in this year being active are starting to slide at the moment.

To answer your questions: No.

Just thought I'd piggy-back on that and perhaps expand on it as well:

"No" and "very busy"

[SFLcane]

Not to sound alarmist or start another impatient season cancel string of comments, but as some mets here have expressed doubt concerning the global conditions, combined with the models showing little to nothing as far as tropical waves (which I started noticing last night), what are the thoughts of some of the mets and other more knowledgeable posters on this--are we potentially headed towards something along similar lines to 2013? Or are there other clearer atmospheric forces at work here? What are the implications on the rest of the season? My confidence in this year being active are starting to slide at the moment.

I thought the season was over? I don't see anything close to 2013 Iam expecting a rather active season with multiple threats to the US.

[weathaguyry]

Not to sound alarmist or start another impatient season cancel string of comments, but as some mets here have expressed doubt concerning the global conditions, combined with the models showing little to nothing as far as tropical waves (which I started noticing last night), what are the thoughts of some of the mets and other more knowledgeable posters on this--are we potentially headed towards something along similar lines to 2013? Or are there other clearer atmospheric forces at work here? What are the implications on the rest of the season? My confidence in this year being active are starting to slide at the moment.

I thought the season was over? I don't see anything close to 2013 Iam expecting a rather active season with multiple threats to the US.

It is still July after all, and we are not supposed to see activity too active right now, if it is August 15th and we are dealing with these same conditions, then we will know that there are factors working against climatology in play

[tolakram]

I don't get the concern with the waves.

http://tropic.ssec.wisc.edu/real-time/europe/movies/m7irn/m7irn_loop.html

GFS long term accuracy not that good, but I suppose this could all dry up.

[tarheelprogrammer]

My biggest question is why are the waves not developing some? SAL is out there, but it is no where near where it was a few weeks ago. Shear does not appear to be a problem in the MDR? Will we ever see another MDR, long tracking season again? Long range models not showing much dry air, and shear. It seems the waves just get weaker out of the blue.

[Ntxw]

My biggest question is why are the waves not developing some? SAL is out there, but it is no where near where it was a few weeks ago. Shear does not appear to be a problem in the MDR? Will we ever see another MDR, long tracking season again? Long range models not showing much dry air, and shear. It seems the waves just get weaker out of the blue.

Ambient pressures are still relatively high from the strong Azores/bermuda high thus the background was favoring sinking air. Some of that will quell once full passage of CCKW and natural weakening of the high with climo. Mid August or later is still the best shot for improvement, as said before it doesn't flip 180 overnight and takes time.