2021 Indicators: SST's / SAL / MSLP / Shear / Steering / Instability / Sat Images

[toad strangler]

http://wxmaps.org/pix/atlpot.png

Imagine if we actually get a sub-900 mb storm.

Wilma 882 mb in 2005. Those are few are far between.
Michael 919 mb just in 2018.

Tis the Caribbean season ... wait and see

[toad strangler]

I did some quick research on FL peninsula landfalls minimum CAT 1 from Caribbean genesis in October since 1850. All SOUTH of Cedar Key. Please do correct me if I missed something.

UN 1857
UN 1865
UN 1870
UN 1873
UN 1876
UN 1880

UN 1904
UN 1906
UN 1910
UN 1921
UN 1924
UN 1944
UN 1946
UN 1947
UN 1948
KING 1950
HAZEL 1953
ISBELL 1964
GLADYS 1968
IRENE 1999
WILMA 2005

Just look at the period 1944 - 1953. SIX storms in 9 years!!!!
Then look ate the DROUGHT from 1968 through today. TWO storms in 52 years beginning in 1969. Wilma being the last SIXTEEN years ago. INCREDIBLE.
Tick tock tick tock.

[aspen]

http://wxmaps.org/pix/atlpot.png

Imagine if we actually get a sub-900 mb storm.

Seeing how 2021 has been playing out similarly to 2020 (except slightly less extreme), I’m half expecting a WCar pinhole major like Delta or Eta. Could it achieve what those two systems failed to? Who knows.

[Shell Mound]

I did some quick research on FL peninsula landfalls minimum CAT 1 from Caribbean genesis in October since 1850. All SOUTH of Cedar Key. Please do correct me if I missed something.

Looking at peninsular MH impacts in October since 1851, I found seven cases, six (~86%) of which originated in the Caribbean. (According to this preliminary reanalysis, Storm #5 of 1873 apparently originated in the MDR.) Given that the Keys are also sited east of the Panhandle, I included them as part of the peninsula, for the sake of this analysis. Of the seven peninsular MH impacts in October, the earliest was on 7 October and the latest was on 25 October. Based on the data, if a MH were to develop in the western Caribbean and threaten peninsular Florida in October, it would need to form no later than 20 October. (For reference, I would add that Wilma formed on 15 October and struck peninsular FL on 24 October.)

[abajan]

http://wxmaps.org/pix/atlpot.png

Imagine if we actually get a sub-900 mb storm.

Wilma 882 mb in 2005. Those are few are far between.
Michael 919 mb just in 2018.

Tis the Caribbean season ... wait and see

Gilbert had a minimum central pressure of 888 mb.

[chaser1]

I did some quick research on FL peninsula landfalls minimum CAT 1 from Caribbean genesis in October since 1850. All SOUTH of Cedar Key. Please do correct me if I missed something.

UN 1857
UN 1865
UN 1870
UN 1873
UN 1876
UN 1880

UN 1904
UN 1906
UN 1910
UN 1921
UN 1924
UN 1944
UN 1946
UN 1947
UN 1948
KING 1950
HAZEL 1953
ISBELL 1964
GLADYS 1968
IRENE 1999
WILMA 2005

Just look at the period 1944 - 1953. SIX storms in 9 years!!!!
Then look ate the DROUGHT from 1968 through today. TWO storms in 52 years beginning in 1969. Wilma being the last SIXTEEN years ago. INCREDIBLE.
Tick tock tick tock.

That's some good stuff! My take-away? The odds for any one year to push out a hurricane that results in a Florida landfall, are slim. At the same time with so few hurricanes hitting Florida in October over the last 50 years, I'd have to think that the law of averages would suggest Florida is quite overdue for the next October hurricane landfall. Actually, I think it would be interesting to review the larger number of Tropical Storm AND Hurricane frequency of occurrences which have impacted Florida over the years during October. I think this would serve a greater barometer of overall potential October risk to Florida (or any other region such as North GOM or the Carolina's) over time.

As for the discussion to what potential storm strength could impact Florida during any given October??? I'd be far less inclined to consider statistical or historical data and more inclined to consider present dynamic conditions (upper level conditions, humidity vs dry air infiltration, etc) as well as near to mid term modeled forecast conditions for the Western Atlantic basin. No doubt that many past weaker October T.S.'s that have impacted Florida over the years were a result of strong westerlies, TUTT conditions, broad scale El Nino conditions but overall relating to upper level shear conditions. Of course, other weaker landfall events also occurred as a result of dry continental air pushing into the GOM, cooler SST's, or the broad nature of any CAG circulation with limited time for that particular storm to better consolidate and strengthen prior to landfall. "If" and that's a big IF, any named storm were to track over Florida this October or November, I'd guess that the odds of it being a hurricane (verses a T.S.) would be greater this year simply for the reason of anticipated favorable La Nina conditions that are expected to amplify rising air and increased atmospheric instability. At the same time though, just how long of a time-lag will it be before these distinctly favorable conditions materialize over the Western Basin before this season's 4th quarter clock runs to zero? The idea of a November Florida hurricane landfall is even that much more rare. If one looks past Climo and the obvious guesswork of where such a November storm might form or even track, it's possible that the very very low odds of a November (South?) Florida hurricane landfall might be significantly higher this year depending on potential La Nina enhancing conditions (especially if earlier in the month).

[chaser1]

Imagine if we actually get a sub-900 mb storm.

Wilma 882 mb in 2005. Those are few are far between.
Michael 919 mb just in 2018.

Tis the Caribbean season ... wait and see

Gilbert had a minimum central pressure of 888 mb.

True, Gilbert was a monster. Different from Wilma or Michael though, Gilbert occurred in mid September. MH's in October are uncommon enough, and that's aside from potential debilitating upper level conditions as such storms gain latitude and typically begin to weaken. Opal displayed that tendency as well (though weakening at the time still managed to maintain MH status at landfall). I'm far more fearful of a Cat 2 impact simply given the potential impact that a Cat 2 hurricane can bring, but mostly given the more reasonable chances of that type of landfall event to occur as opposed to the greater rarity of a MH landfall during Oct.

[AlphaToOmega]

Nothing to see here

[abajan]

[youtube]https://youtu.be/5X1N16QDCxI[/youtube]

[aspen]

If activity were to magically shut down after Sam and we see nothing else develop, 2021 would still be quite a season: 20/7/4 and ~135 ACE with several notable statistics.
—Two 30+ ACE systems, including Sam, which will likely finish at about 50 ACE
—Ida becoming the second 130kt Louisiana landfall in two years, as well as one of the costliest Atlantic hurricanes
—The first occurrence of two or more major hurricane landfalls by September 1st since 2005
—The earliest 5th named storm (Elsa) as well as the second-earliest 18th (Sam), 19th (Teresa), and 20th (Victor) NS.
—A storm formation rate from late August all throughout September that rivaled 2020
—The first year since 2019 or 2017 where an Atlantic storm became the top ACE maker worldwide (Sam has passed both Chanthu and Surige)

As for how various indicators held up, a bunch were pretty close. The 2020-like VP anomaly forecasts did indeed result in a near record active September as Alpha predicted, although it was an extreme mix of high and low quality with extreme quantity — two high-ACE MDR majors (Larry and Sam) with a ton of short-lived slop forming between them. Elsa’s track and the forecasts for a southward-displaced ITCZ (at least compared to last year) also verified and served as good indicators for the type of activity we would see; Grace, Larry, and Sam all formed from low-latitude waves like Elsa and all became major hurricanes, although Grace only reached that intensity once it got into the BoC. The CFS’s activity predictions for late August through the end of September also verified quite well, and while its shear forecasts were excessive as usual, there was indeed some anomalously persistent shear around mid-month.

One thing that aged horribly was all the chatter about the MDR not being warm enough, and a -AMO pattern causing increased stability that would shut it down. I will admit I am guilty of contributing to some of that chatter. While several MDR storms did struggle (Kate, Peter, Rose, and Victor), the MDR in 2021 ended up being way more impressive than in 2020, with three hurricanes and two majors, including one that was likely a Cat 5. Only one system (Teddy) reached hurricane intensity in the MDR last year despite near record high SSTs, and that was due to the north displacement of the ITCZ and the massive size of AEWs that prevented rapid development, an issue that did not persist into 2021. Not only did the SST pattern-induced stability predictions age like milk, but the Atlantic did end up with a +AMO look later in the season, and now pretty much all of the tropics are running at least 0.3-0.5C above average.

[Category5Kaiju]

If activity were to magically shut down after Sam and we see nothing else develop, 2021 would still be quite a season: 20/7/4 and ~135 ACE with several notable statistics.
—Two 30+ ACE systems, including Sam, which will likely finish at about 50 ACE
—Ida becoming the second 130kt Louisiana landfall in two years, as well as one of the costliest Atlantic hurricanes
—The first occurrence of two or more major hurricane landfalls by September 1st since 2005
—The earliest 5th named storm (Elsa) as well as the second-earliest 18th (Sam), 19th (Teresa), and 20th (Victor) NS.
—A storm formation rate from late August all throughout September that rivaled 2020
—The first year since 2019 or 2017 where an Atlantic storm became the top ACE maker worldwide (Sam has passed both Chanthu and Surige)

As for how various indicators held up, a bunch were pretty close. The 2020-like VP anomaly forecasts did indeed result in a near record active September as Alpha predicted, although it was an extreme mix of high and low quality with extreme quantity — two high-ACE MDR majors (Larry and Sam) with a ton of short-lived slop forming between them. Elsa’s track and the forecasts for a southward-displaced ITCZ (at least compared to last year) also verified and served as good indicators for the type of activity we would see; Grace, Larry, and Sam all formed from low-latitude waves like Elsa and all became major hurricanes, although Grace only reached that intensity once it got into the BoC. The CFS’s activity predictions for late August through the end of September also verified quite well, and while its shear forecasts were excessive as usual, there was indeed some anomalously persistent shear around mid-month.

One thing that aged horribly was all the chatter about the MDR not being warm enough, and a -AMO pattern causing increased stability that would shut it down. I will admit I am guilty of contributing to some of that chatter. While several MDR storms did struggle (Kate, Peter, Rose, and Victor), the MDR in 2021 ended up being way more impressive than in 2020, with three hurricanes and two majors, including one that was likely a Cat 5. Only one system (Teddy) reached hurricane intensity in the MDR last year despite near record high SSTs, and that was due to the north displacement of the ITCZ and the massive size of AEWs that prevented rapid development, an issue that did not persist into 2021. Not only did the SST pattern-induced stability predictions age like milk, but the Atlantic did end up with a +AMO look later in the season, and now pretty much all of the tropics are running at least 0.3-0.5C above average.

We would end up beating 2018 and 2019 in ACE even if the season did suddenly end after Sam's dissipation. Now, to be realistic, it is very likely that we are still not done; in fact, as I have mentioned earlier, one or two more major hurricanes before season ends would not surprise me at all. I personally think there is a very real chance that if something like that occurs, 2021 will make it to the hyperactivity threshold.

[AlphaToOmega]

If activity were to magically shut down after Sam and we see nothing else develop, 2021 would still be quite a season: 20/7/4 and ~135 ACE with several notable statistics.
—Two 30+ ACE systems, including Sam, which will likely finish at about 50 ACE
—Ida becoming the second 130kt Louisiana landfall in two years, as well as one of the costliest Atlantic hurricanes
—The first occurrence of two or more major hurricane landfalls by September 1st since 2005
—The earliest 5th named storm (Elsa) as well as the second-earliest 18th (Sam), 19th (Teresa), and 20th (Victor) NS.
—A storm formation rate from late August all throughout September that rivaled 2020
—The first year since 2019 or 2017 where an Atlantic storm became the top ACE maker worldwide (Sam has passed both Chanthu and Surige)

As for how various indicators held up, a bunch were pretty close. The 2020-like VP anomaly forecasts did indeed result in a near record active September as Alpha predicted, although it was an extreme mix of high and low quality with extreme quantity — two high-ACE MDR majors (Larry and Sam) with a ton of short-lived slop forming between them. Elsa’s track and the forecasts for a southward-displaced ITCZ (at least compared to last year) also verified and served as good indicators for the type of activity we would see; Grace, Larry, and Sam all formed from low-latitude waves like Elsa and all became major hurricanes, although Grace only reached that intensity once it got into the BoC. The CFS’s activity predictions for late August through the end of September also verified quite well, and while its shear forecasts were excessive as usual, there was indeed some anomalously persistent shear around mid-month.

One thing that aged horribly was all the chatter about the MDR not being warm enough, and a -AMO pattern causing increased stability that would shut it down. I will admit I am guilty of contributing to some of that chatter. While several MDR storms did struggle (Kate, Peter, Rose, and Victor), the MDR in 2021 ended up being way more impressive than in 2020, with three hurricanes and two majors, including one that was likely a Cat 5. Only one system (Teddy) reached hurricane intensity in the MDR last year despite near record high SSTs, and that was due to the north displacement of the ITCZ and the massive size of AEWs that prevented rapid development, an issue that did not persist into 2021. Not only did the SST pattern-induced stability predictions age like milk, but the Atlantic did end up with a +AMO look later in the season, and now pretty much all of the tropics are running at least 0.3-0.5C above average.

We would end up beating 2018 and 2019 in ACE even if the season did suddenly end after Sam's dissipation. Now, to be realistic, it is very likely that we are still not done; in fact, as I have mentioned earlier, one or two more major hurricanes before season ends would not surprise me at all. I personally think there is a very real chance that if something like that occurs, 2021 will make it to the hyperactivity threshold.

The Atlantic Niño is responsible for the very favorable conditions across the North Atlantic; for it has been transferring thermal energy north into the MDR, and it has dragged the ITCZ further south. The Atlantic Niño was also responsible for strong -VP anomalies in West Africa. The Atlantic Niño along with the generally favorable SST and VP patterns caused 2021 to rival 2020 and 2005; this is not surprising.

The African Standing Wave, as has been the previous few seasons, is also responsible for the very favorable conditions across the North Atlantic and for the high storm count and major hurricane count of the season. Despite being in an unfavorable MJO phase during September, the African Standing Wave, along with uniform sinking air in the East Pacific and climatology, was enough to keep September active.

This favorable pattern was forecasted months in advance. A warm AMO phase guaranteed a +AMO +TNA pattern; climate models forecasted such patterns over the Atlantic. In the Pacific, a -PDO -ENSO pattern was well-established by the climate models by June. The CanSIPS and JMA both forecasted a favorable VP pattern with -VP in Afro-Eurasia and +VP in the Pacific Ocean and the Americas.

[AlphaToOmega]

As September 2021 established, MJO does not matter if you have an African Standing Wave.

[Ubuntwo]

Looks like the MDR season is winding down as we start honing in on the western basin. It has been a very active one, stretching from early July to at least early October. Here's an MDR comparison with other active and recent years. (TD/TS/HU/MH)

2021: 8/7/3/2
__________________
2020: 8/7/1/1
2019: 6/5/2/1
2018: 7/6/4/0
2017: 8/7/3/3
2016: 5/5/1/0
2012: 8/7/0/0
2011: 7/6/1/0
2010: 9/9/5/2
2008: 4/4/0/0
2007: 5/5/2/0
2005: 7/2/2/0
2004: 8/6/4/3
2003: 7/3/2/2
2001: 4/2/0/0
2000: 8/7/4/1
1999: 7/6/4/1
1998: 7/7/3/1
1995: 11/9/6/1

2021's proportion of majors to total MDR systems is above average. It's also worth noting that MDR activity is a terrible predictor of land impacts and damage. Just an interesting metric to track.

[AlphaToOmega]

Take this with a can of salt, but it is clear that is model is starting to adjust. The CFSv2 is starting to show a tropical cyclone developing north of the Bahamas around October 16, and on the same day, it shows another tropical cyclone developing east of the beforementioned one. On October 22, it shows a Cape Verde storm forming. On October 23, it shows another tropical cyclone developing in the Main Development Region. On October 25, it shows another tropical cyclone developing in the Caribbean. All of these are possible major hurricanes during October. There could be more activity than what is depicted here, for the CFSv2 is a very low-resolution model.







Most of this makes sense from a climatological perspective; for during the middle and later parts of October, the Caribbean, Gulf of Mexico, western Main Development Region, and subtropics should be the areas of focus. However, from 1851 to 2015, there has never been a Cape Verde storm in late October. The fact that the CFSv2 is showing Cape Verde activity in late October probably means that it needs more time to adjust.

[WiscoWx02]

Take this with a can of salt, but it is clear that is model is starting to adjust. The CFSv2 is starting to show a tropical cyclone developing north of the Bahamas around October 16, and on the same day, it shows another tropical cyclone developing east of the beforementioned one. On October 22, it shows a Cape Verde storm forming. On October 23, it shows another tropical cyclone developing in the Main Development Region. On October 25, it shows another tropical cyclone developing in the Caribbean. All of these are possible major hurricanes during October. There could be more activity than what is depicted here, for the CFSv2 is a very low-resolution model.

https://i.postimg.cc/bNbWq72w/21101600-0300.gif
https://i.postimg.cc/K82Vj0nr/21101712-0300.gif
https://i.postimg.cc/mDrL1LG4/21102212-0300.gif
https://i.postimg.cc/2S7tZnGp/21102312-0300.gif
https://i.postimg.cc/PqfRzNVC/21102612-0300.gif

Most of this makes sense from a climatological perspective; for during the middle and later parts of October, the Caribbean, Gulf of Mexico, western Main Development Region, and subtropics should be the areas of focus. However, from 1851 to 2015, there has never been a Cape Verde storm in late October. The fact that the CFSv2 is showing Cape Verde activity in late October probably means that it needs more time to adjust.

https://i.postimg.cc/h4LstT0V/oct-21-31.png

A Cape Verde TC is late October!? Okay to be fair though, TD 15L formed in the middle of October off the coast of Africa so it's not like it's totally outlandish. Nicholas was in the central Atlantic during the middle/end of October so definitely a MDR storm as well. The CFS adjusting gives me more faith in the idea something is going to happen though. Still taking this with 15 lbs of kosher salt as Alpha said though.

[Category5Kaiju]

Take this with a can of salt, but it is clear that is model is starting to adjust. The CFSv2 is starting to show a tropical cyclone developing north of the Bahamas around October 16, and on the same day, it shows another tropical cyclone developing east of the beforementioned one. On October 22, it shows a Cape Verde storm forming. On October 23, it shows another tropical cyclone developing in the Main Development Region. On October 25, it shows another tropical cyclone developing in the Caribbean. All of these are possible major hurricanes during October. There could be more activity than what is depicted here, for the CFSv2 is a very low-resolution model.

https://i.postimg.cc/bNbWq72w/21101600-0300.gif
https://i.postimg.cc/K82Vj0nr/21101712-0300.gif
https://i.postimg.cc/mDrL1LG4/21102212-0300.gif
https://i.postimg.cc/2S7tZnGp/21102312-0300.gif
https://i.postimg.cc/PqfRzNVC/21102612-0300.gif

Most of this makes sense from a climatological perspective; for during the middle and later parts of October, the Caribbean, Gulf of Mexico, western Main Development Region, and subtropics should be the areas of focus. However, from 1851 to 2015, there has never been a Cape Verde storm in late October. The fact that the CFSv2 is showing Cape Verde activity in late October probably means that it needs more time to adjust.

https://i.postimg.cc/h4LstT0V/oct-21-31.png

A Cape Verde TC is late October!? Okay to be fair though, TD 15L formed in the middle of October off the coast of Africa so it's not like it's totally outlandish. Nicholas was in the central Atlantic during the middle/end of October so definitely a MDR storm as well. The CFS adjusting gives me more faith in the idea something is going to happen though. Still taking this with 15 lbs of kosher salt as Alpha said though.

Could you explain that, I am a bit confused by that part

[AlphaToOmega]

Take this with a can of salt, but it is clear that is model is starting to adjust. The CFSv2 is starting to show a tropical cyclone developing north of the Bahamas around October 16, and on the same day, it shows another tropical cyclone developing east of the beforementioned one. On October 22, it shows a Cape Verde storm forming. On October 23, it shows another tropical cyclone developing in the Main Development Region. On October 25, it shows another tropical cyclone developing in the Caribbean. All of these are possible major hurricanes during October. There could be more activity than what is depicted here, for the CFSv2 is a very low-resolution model.

https://i.postimg.cc/bNbWq72w/21101600-0300.gif
https://i.postimg.cc/K82Vj0nr/21101712-0300.gif
https://i.postimg.cc/mDrL1LG4/21102212-0300.gif
https://i.postimg.cc/2S7tZnGp/21102312-0300.gif
https://i.postimg.cc/PqfRzNVC/21102612-0300.gif

Most of this makes sense from a climatological perspective; for during the middle and later parts of October, the Caribbean, Gulf of Mexico, western Main Development Region, and subtropics should be the areas of focus. However, from 1851 to 2015, there has never been a Cape Verde storm in late October. The fact that the CFSv2 is showing Cape Verde activity in late October probably means that it needs more time to adjust.

https://i.postimg.cc/h4LstT0V/oct-21-31.png

A Cape Verde TC is late October!? Okay to be fair though, TD 15L formed in the middle of October off the coast of Africa so it's not like it's totally outlandish. Nicholas was in the central Atlantic during the middle/end of October so definitely a MDR storm as well. The CFS adjusting gives me more faith in the idea something is going to happen though. Still taking this with 15 lbs of kosher salt as Alpha said though.

Could you explain that, I am a bit confused by that part

Probably Nicholas (2003)

[Shell Mound]

A Cape Verde TC is late October!? Okay to be fair though, TD 15L formed in the middle of October off the coast of Africa so it's not like it's totally outlandish. Nicholas was in the central Atlantic during the middle/end of October so definitely a MDR storm as well. The CFS adjusting gives me more faith in the idea something is going to happen though. Still taking this with 15 lbs of kosher salt as Alpha said though.

Could you explain that, I am a bit confused by that part

Probably Nicholas (2003)

 https://twitter.com/philklotzbach/status/1049670529680953344

[WiscoWx02]

Could you explain that, I am a bit confused by that part

Probably Nicholas (2003)

 https://twitter.com/philklotzbach/status/1049670529680953344

Never mind, discard everything I just said. MDR storm in late October is a ludicrous idea actually. Yeah I meant Nicholas in 2003, but there was actually a whole week where they were tracking it as a remnant low looking into it more so Nicholas doesn't count.

Edit: Now that I am actually awake The only way for us to even possibly see a MDR storm that late was if one hell of Convectively Coupled Kelvin Wave were to move through. I mean this thing would have to be a beast in order to 180 the hostile atmospheric pattern in the MDR in October. Fun fact, if I recall correctly, exactly that happened a few years ago where there was an invest likely to develop in the MDR IN NOVEMBER. It never happened but was close. I guess it's a one in a million shot.