2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
Yellow Evan wrote:Category5Kaiju wrote:toad strangler wrote:I think many get a skewed vision looking at the blue colors of anomaly maps LOL!. Look at actual SST's and you see it's pretty darn warm and just a hair off normal in most of the MDR. There are pro's out there talking about these supposedly cool SST's so I'm not discounting it fully but I won't be buying a seat on that bus just yet.
http://i.ibb.co/4pFQ7RD/SST2.gif
http://i.ibb.co/9Wybtc5/SST.png
Yeah I agree; in fact I could be mistaken of course but I wonder when the last year was when during peak season we had a La Nina (so an EPAC with the majority of it with cooler than average sst anomalies) but also an Atlantic with most of the basin experincing below average sst anomalies? I feel like you have to look back into the -AMO 1970s-1990s era for the last time something like this happened?
1974 is the classic season with this setup. Ofc we have an epic ASW pattern right now when the 70s had a very dry Africa so I would expect very different outcomes.
Ah yes, 1974; the only recorded year at least in more recent times when the WPAC, EPAC, and Atlantic all failed to produce a Cat 5 equivalent storm!
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
I know many dont know what is the Atlantic Niño so here is a detailed explanation about it and how it influences TC activity especially in the MDR.
https://cpaess.ucar.edu/sites/default/f ... tation.pdf
https://cpaess.ucar.edu/sites/default/f ... tation.pdf
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
Just to put season cancel season to bed early, I read through one of the seasonal threads from 2013 and one of the big things was the MDR was dry and stable even into August. Now, on July 12, even with suppressive MJO and CCKW regimes right now the ITCZ convection definitely seems pretty active still. No suppression issues here


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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
I think looking at raw MDR SSTs is very misleading. The ITCZ is much farther south this year than last year, meaning tropical waves are going to develop in warmer waters. Therefore, while the MDR might be slightly cooler than last year, waves are developing in warmer waters.
Last edited by AlphaToOmega on Mon Jul 12, 2021 10:38 am, edited 1 time in total.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
AlphaToOmega wrote:I think looking at raw MDR SSTs is very misleading. The ITCZ is much further south this year than last year, meaning tropical waves are going to develop in warmer waters. Therefore, while the MDR might be slightly cooler than last year, waves are developing in warmer waters.
Correct. This further suggests greater concern for regions at further west longitudes then during years where it is common to see a few or perhaps a majority of storm tracks recurving between 40-60W. As deadly as 2005 was, look at the number of tropical storms that formed east of 60W. In addition to overall conditions being conducive for development, there is no doubt that SST's in the Central Atlantic MDR (as well as the sub-tropics) offered an assist toward earlier development. This in turn (fortunately) allowed a few storms to recurve early as a result of their quick development. Naturally, strength and location of the Atlantic ridge along with the location of N. Atlantic troughing played a role as well. Bottom line though is that assuming overall favorable background state conditions, any somewhat deficient SST's (or other inhibiting condition) that may exist in the East Atlantic is apt to result in strong tropical waves to develop further west. What happens thereafter is of course dependent on steering or any disruptive conditions from 50W and points west from there.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
NotSparta wrote:Just to put season cancel season to bed early, I read through one of the seasonal threads from 2013 and one of the big things was the MDR was dry and stable even into August. Now, on July 12, even with suppressive MJO and CCKW regimes right now the ITCZ convection definitely seems pretty active still. No suppression issues here
https://i.imgur.com/g7RoEdv.jpg
Also while I know past seasons are past seasons and that there is no such things as having two identical hurricane seasons, the "season cancel" posts imho are very premature and unfortunately likely not going to pan out this year because of what I think to be a very simple but compelling observation (at least given historic trends): the only recorded seasons that did feature a July MDR hurricane are 1926, 1933, 1961, 1996, 2005, and 2020 (with 2021 now being the seventh season with such event). Those 6 seasons unanimously went on to be hyperactive years, with 1933, the only year out of those years that featured an earlier MDR hurricane than 2021, going on to becoming the season with the most ACE as well as a very high impact year. Oh yeah, did bizarre 2013 feature a July MDR hurricane? Nope, it only got its first in September.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
Category5Kaiju wrote:NotSparta wrote:Just to put season cancel season to bed early, I read through one of the seasonal threads from 2013 and one of the big things was the MDR was dry and stable even into August. Now, on July 12, even with suppressive MJO and CCKW regimes right now the ITCZ convection definitely seems pretty active still. No suppression issues here
https://i.imgur.com/g7RoEdv.jpg
Also while I know past seasons are past seasons and that there is no such things as having two identical hurricane seasons, the "season cancel" posts imho are very premature and unfortunately likely not going to pan out this year because of what I think to be a very simple but compelling observation (at least given historic trends): the only recorded seasons that did feature a July MDR hurricane are 1926, 1933, 1961, 1996, 2005, and 2020 (with 2021 now being the seventh season with such event). Those 6 seasons unanimously went on to be hyperactive years, with 1933, the only year out of those years that featured an earlier MDR hurricane than 2021, going on to becoming the season with the most ACE as well as a very high impact year. Oh yeah, did bizarre 2013 feature a July MDR hurricane? Nope, it only got its first in September.
Season cancelled posts only seemed to make sense in 2013. Any other year and it's pretty dumb.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
cycloneye wrote:I know many dont know what is the Atlantic Niño so here is a detailed explanation about it and how it influences TC activity especially in the MDR.
https://cpaess.ucar.edu/sites/default/f ... tation.pdf
Is there a webpage that shows the Atlantic Nino years? The study only references 71 years, but doesn’t list the dates.
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- cycloneye
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
JPmia wrote:cycloneye wrote:I know many dont know what is the Atlantic Niño so here is a detailed explanation about it and how it influences TC activity especially in the MDR.
https://cpaess.ucar.edu/sites/default/f ... tation.pdf
Is there a webpage that shows the Atlantic Nino years? The study only references 71 years, but doesn’t list the dates.
I am posting a google search that I made and there are plenty of different articles but I am not sure there is the information you want but anyway check them.
https://scholar.google.com.pr/scholar?q ... i=scholart
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
While the SST profile rn is not ideal by any stretch, and I don’t think some posters here understand their importance in normal circumstances, any season cancel talk is ridiculous given how insanely wet the Sahel region of Africa has been. If there’s anything to slow down the season, it’ll be the monsoon trough making storms too broad.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
cycloneye wrote:JPmia wrote:cycloneye wrote:I know many dont know what is the Atlantic Niño so here is a detailed explanation about it and how it influences TC activity especially in the MDR.
https://cpaess.ucar.edu/sites/default/f ... tation.pdf
Is there a webpage that shows the Atlantic Nino years? The study only references 71 years, but doesn’t list the dates.
I am posting a google search that I made and there are plenty of different articles but I am not sure there is the information you want but anyway check them.
https://scholar.google.com.pr/scholar?q ... i=scholart
Since the Atlantic Nino is a relatively rare and poorly understood phenomenon (and if I am not mistaken this year is the first year at least in more recent times that we've had such an alarmingly apparent and strong Atlantic Nino), it would be very interesting to see how it affects the upcoming hurricane season. More importantly, I am personally very curious to see if it simply fades by the time we reach ASO or if it literally "drags" the MDR southward from its usual position. I think we are in some uncharted waters here.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
Yellow Evan wrote:While the SST profile rn is not ideal by any stretch, and I don’t think some posters here understand their importance in normal circumstances, any season cancel talk is ridiculous given how insanely wet the Sahel region of Africa has been. If there’s anything to slow down the season, it’ll be the monsoon trough making storms too broad.
The African monsoon is going to pump out waves like crazy no matter what the SST profile is like. Either the waves take longer to develop like last year (either due to cooler SSTs or a trough or TUTT) and we see more west AEW development, or they’re able to develop further east by being further south, within very warm waters fueled by the Atlantic Nino and out of the way of a TUTT.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
I am convinced that 2021 is just 2020 but delayed
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
AlphaToOmega wrote:I am convinced that 2021 is just 2020 but delayed
Interestingly, 2020 had a burst of activity from mid to late-July and then a lull until mid to late-August. I think at least for this year it could be the opposite, at least regarding that mid to late-July is the lull but then we spring into action during the time of the calendar between end of July and mid-August when last year was quiet.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
Category5Kaiju wrote:AlphaToOmega wrote:I am convinced that 2021 is just 2020 but delayed
Interestingly, 2020 had a burst of activity from mid to late-July and then a lull until mid to late-August. I think at least for this year it could be the opposite, at least regarding that mid to late-July is the lull but then we spring into action during the time of the calendar between end of July and mid-August when last year was quiet.
That is not a good thing. Instead of one month with September levels of activity, we might have two (August and September); and these months are not like normal Septembers; they will probably be well-above-average Septembers (2018, 2019, and 2020).
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
JPmia wrote:Is there a webpage that shows the Atlantic Nino years? The study only references 71 years, but doesn’t list the dates.
This 2020 paper discussing four types of Atlantic Ninos lists years where Atl Ninos occurred:
https://digital.csic.es/bitstream/10261 ... l_2020.pdf
Here is the key figure from the paper with the list of years:

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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
AlphaToOmega wrote:I think looking at raw MDR SSTs is very misleading. The ITCZ is much farther south this year than last year, meaning tropical waves are going to develop in warmer waters. Therefore, while the MDR might be slightly cooler than last year, waves are developing in warmer waters.
Well if they are going anywhere other than South America they have to actually cross the MDR. There's a reason why the correlation between SSTs and ACE is strongest in the MDR. Tc’s Don't stay at 10N all the way across If they do they hit land real quick.
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Re: 2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images
SFLcane wrote:AlphaToOmega wrote:I think looking at raw MDR SSTs is very misleading. The ITCZ is much farther south this year than last year, meaning tropical waves are going to develop in warmer waters. Therefore, while the MDR might be slightly cooler than last year, waves are developing in warmer waters.
Well if they are going anywhere other than South America they have to actually cross the MDR. There's a reason why the correlation between SSTs and ACE is strongest in the MDR. Tc’s Don't stay at 10N all the way across If they do they hit land real quick.
This is generally true; however, interestingly enough, among the highest ACE-producing Atlantic storms recorded, Ivan and Allen are striking in that they started off at an unusually low latitude south of the typical MDR per se (kind of near where Elsa originated and tracked) while Matthew became a major hurricane and maintained Cat 4 strength well west of the typical MDR. So yes, while seasons with intense MDR activity generally score higher in total ACE, there have been notable exceptions to the "strong classic MDR storm equals very high ACE" notion as noted with such storms. Also for reasons that I personally am not 100% sure of, it seems like storms making landfall in the northern coast of South America are rare in general, and we have not had recorded major hurricanes make landfall in South America. If anything, it seems like as noted with storms like Ivan, Allen, or Matthew, they simply scrape the northern SA coast and trek in a more northerly direction afterwards (thereby avoiding directly smashing into countries like Venezuela or Guyana).
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