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

[Category5Kaiju]

Perhaps as an easier reference, I'll pull up some timelines of some of the past years that people have been comparing and hypothesizing 2021 to resemble; notice how in many cases the actual intense bulk of the season does not begin until mid-August or so.

1933 (much like what CSU predicts 2021 to be, it was also a 20 NS season with one MDR hurricane in July):
https://upload.wikimedia.org/wikipedia/en/timeline/3b421e37dac1e01b00a61fef2736d5f0.png

1961 (also had an MDR hurricane in July):
https://upload.wikimedia.org/wikipedia/en/timeline/3b9dff2050afdd757b583a9fa1b47195.png

1996 (also had an MDR hurricane in July and was almost a second year La Nina):
https://upload.wikimedia.org/wikipedia/en/timeline/1c95b41abbf2e2c96d0b49c159d390a7.png

2001 (was an analog year CSU provided earlier this season and many people have been suggesting some track similarities):
https://upload.wikimedia.org/wikipedia/en/timeline/90ba223b3671d4c8191b5dbcf7dd2385.png

2004 (based on the steering patterns expected by peak season for 2021 as well as a decent number of low latitude-born systems):
https://upload.wikimedia.org/wikipedia/en/timeline/d4d50aebce18875a0269ef4032684bb4.png

2008 (was an analog year CSU provided earlier this season and was also a second year La Nina):
https://upload.wikimedia.org/wikipedia/en/timeline/e885c0aa78907642b05e266a1f80e9f0.png

2011 (was an analog year CSU provided earlier this season and was also a second year La Nina):
https://upload.wikimedia.org/wikipedia/en/timeline/92af13febe68158251323e54eda45350.png

2013 (I mean, people never cease to compare a given season with this year at any point, especially early in the season; 2021 is no exception):
https://upload.wikimedia.org/wikipedia/en/timeline/b675c21952cf6e33f9e0e6ce7499d7be.png

2017 (was an analog year CSU provided earlier this season and was also a second year La Nina with very high land impacts):
https://upload.wikimedia.org/wikipedia/en/timeline/155d6cf6cbab384ff37c09d69ff253e9.png

2020 (also had an MDR hurricane in July, and 2021 comes at the heels of this very active year):
https://upload.wikimedia.org/wikipedia/en/timeline/035706c7b11bc4ee05424c6f4d0f2a89.png

2020 did not have a MDR hurricane in July. Isaias did not become a hurricane until it was near Hispaniola.

Yeah no you're right; I fixed that, thanks anyways. It just shows you how having a July MDR hurricane is quite impressive considering how many seasons in the past, even some of the more notable ones, did not feature such an event in a climatologically hostile month

[jconsor]

I would watch for homegrown development (in GOM or off the coast of eastern US) through the first third of Aug, with limited chance of anything forming in the MDR. Then I would expect MDR activity to begin picking up by around the third week of Aug.

However, either type of development would pose higher than usual US landfall risks by mid to late Aug based on the projected upper-level pattern (similar to the pattern from late Jun to first week of Jul that led to the all-time record heat in the Pacific NW/W. Canada as well as very hot conditions in the ne US).

 https://twitter.com/yconsor/status/1418245564181921801




 https://twitter.com/yconsor/status/1418248084371476485

[AlphaToOmega]

Perhaps as an easier reference, I'll pull up some timelines of some of the past years that people have been comparing and hypothesizing 2021 to resemble; notice how in many cases the actual intense bulk of the season does not begin until mid-August or so.

1933 (much like what CSU predicts 2021 to be, it was also a 20 NS season with one MDR hurricane in July):
https://upload.wikimedia.org/wikipedia/en/timeline/3b421e37dac1e01b00a61fef2736d5f0.png

1961 (also had an MDR hurricane in July):
https://upload.wikimedia.org/wikipedia/en/timeline/3b9dff2050afdd757b583a9fa1b47195.png

1996 (also had an MDR hurricane in July and was almost a second year La Nina):
https://upload.wikimedia.org/wikipedia/en/timeline/1c95b41abbf2e2c96d0b49c159d390a7.png

2001 (was an analog year CSU provided earlier this season and many people have been suggesting some track similarities):
https://upload.wikimedia.org/wikipedia/en/timeline/90ba223b3671d4c8191b5dbcf7dd2385.png

2004 (based on the steering patterns expected by peak season for 2021 as well as a decent number of low latitude-born systems):
https://upload.wikimedia.org/wikipedia/en/timeline/d4d50aebce18875a0269ef4032684bb4.png

2008 (was an analog year CSU provided earlier this season and was also a second year La Nina):
https://upload.wikimedia.org/wikipedia/en/timeline/e885c0aa78907642b05e266a1f80e9f0.png

2011 (was an analog year CSU provided earlier this season and was also a second year La Nina):
https://upload.wikimedia.org/wikipedia/en/timeline/92af13febe68158251323e54eda45350.png

2013 (I mean, people never cease to compare a given season with this year at any point, especially early in the season; 2021 is no exception):
https://upload.wikimedia.org/wikipedia/en/timeline/b675c21952cf6e33f9e0e6ce7499d7be.png

2017 (was an analog year CSU provided earlier this season and was also a second year La Nina with very high land impacts):
https://upload.wikimedia.org/wikipedia/en/timeline/155d6cf6cbab384ff37c09d69ff253e9.png

2020 (also had an MDR hurricane in July, and 2021 comes at the heels of this very active year):
https://upload.wikimedia.org/wikipedia/en/timeline/035706c7b11bc4ee05424c6f4d0f2a89.png

2020 did not have a MDR hurricane in July. Isaias did not become a hurricane until it was near Hispaniola.

Hannah was a hurricane in july

Hurricane Hannah formed in the Gulf of Mexico, not the Main Development Region.

[jconsor]

Actually, Isaias became a hurricane on Jul 30 according to the best track: http://www.atms.unca.edu/ibtracs/ibtrac ... 0211N13306

[2020 did not have a MDR hurricane in July. Isaias did not become a hurricane until it was near Hispaniola.

[SFLcane]

I would watch for homegrown development (in GOM or off the coast of eastern US) through the first third of Aug, with limited chance of anything forming in the MDR. Then I would expect MDR activity to begin picking up by around the third week of Aug.

However, either type of development would pose higher than usual US landfall risks by mid to late Aug based on the projected upper-level pattern (similar to the pattern from late Jun to first week of Jul that led to the all-time record heat in the Pacific NW/W. Canada as well as very hot conditions in the ne US).

https://twitter.com/yconsor/status/1418245564181921801

https://twitter.com/yconsor/status/1418248084371476485

Sure, I have been hammering that very same thing for weeks now. This could very well be an impactful season.

[jconsor]

I have warned in the past about the limitations of using precipitation anomaly maps alone to infer areas of likely tropical cyclone risks. However, when taking the forecast 500 mb pattern along with the precip. anomalies, the implication of two of my favorite seasonal models (Australian ACCESS model and Japanese JMA) is that in-close development (W Atlantic, GOM, Caribbean) will be more favored than further east during peak season. This is similar to 2021, 2005 and 1985, which were all high-impact US landfall seasons.

I would watch for homegrown development (in GOM or off the coast of eastern US) through the first third of Aug, with limited chance of anything forming in the MDR. Then I would expect MDR activity to begin picking up by around the third week of Aug.

However, either type of development would pose higher than usual US landfall risks by mid to late Aug based on the projected upper-level pattern (similar to the pattern from late Jun to first week of Jul that led to the all-time record heat in the Pacific NW/W. Canada as well as very hot conditions in the ne US).

https://twitter.com/yconsor/status/1418245564181921801

https://twitter.com/yconsor/status/1418248084371476485

Sure, I have been hammering that very same thing for weeks now. This could very well be an impactful season.

[Shell Mound]

I would watch for homegrown development (in GOM or off the coast of eastern US) through the first third of Aug, with limited chance of anything forming in the MDR. Then I would expect MDR activity to begin picking up by around the third week of Aug.

However, either type of development would pose higher than usual US landfall risks by mid to late Aug based on the projected upper-level pattern (similar to the pattern from late Jun to first week of Jul that led to the all-time record heat in the Pacific NW/W. Canada as well as very hot conditions in the ne US).

https://twitter.com/yconsor/status/1418245564181921801
https://twitter.com/yconsor/status/1418248084371476485

Homegrown systems usually tend to be on the weak(-er) side (<Category 4). Of the eleven hurricanes to strike the U.S. at Cat-4+ status in the month of August since 1851, eight originated as a TD or stronger in the MDR. The eight storms were the 1886 Indianola hurricane, the 1915 Galveston hurricane, the 1916 Texas hurricane, the 1949 Florida hurricane, Andrew (1992), Charley (2004), Harvey (2017), and Laura (2020). Based on modelled projections the MDR should not become favourable until the last week of August. By the time a strong CV system is “out there” the strong ridging could be gone or displaced. Additionally, the ACCESS and JMA suggest that the storms that do develop during the peak of the 2021 AHS are likely to be smaller and homegrown, thus posing less of a hazard than a large long-tracker, because a tiny homegrown system that intensifies close to shore is a) less likely to be Cat-4+ at landfall and b) is less likely to deliver a wide range of hazards over a broad area than a large system like, say, Hugo or Irma. Those models are also showing EPAC convection during August and September that will likely shear anything that manages to form close to land. Therefore, truly high-impact storms (as measured by the Hurricane Severity Index) are less likely to occur this year.


Source

[SFLcane]

Yconsor, A 2005 impactful kinda year unfortunately I agree with you if the model forecast verify.

[Category5Kaiju]

I would watch for homegrown development (in GOM or off the coast of eastern US) through the first third of Aug, with limited chance of anything forming in the MDR. Then I would expect MDR activity to begin picking up by around the third week of Aug.

However, either type of development would pose higher than usual US landfall risks by mid to late Aug based on the projected upper-level pattern (similar to the pattern from late Jun to first week of Jul that led to the all-time record heat in the Pacific NW/W. Canada as well as very hot conditions in the ne US).

https://twitter.com/yconsor/status/1418245564181921801
https://twitter.com/yconsor/status/1418248084371476485

Homegrown systems usually tend to be on the weak(-er) side (<Category 4). Of the eleven hurricanes to strike the U.S. at Cat-4+ status in the month of August since 1851, eight originated as a TD or stronger in the MDR. The eight storms were the 1886 Indianola hurricane, the 1915 Galveston hurricane, the 1916 Texas hurricane, the 1949 Florida hurricane, Andrew (1992), Charley (2004), Harvey (2017), and Laura (2020). Based on modelled projections the MDR should not become favourable until the last week of August. By the time a strong CV system is “out there” the strong ridging could be gone or displaced. Additionally, the ACCESS and JMA suggest that the storms that do develop during the peak of the 2021 AHS are likely to be smaller and homegrown, thus posing less of a hazard than a large long-tracker, because a tiny homegrown system that intensifies close to shore is a) less likely to be Cat-4+ at landfall and b) is less likely to deliver a wide range of hazards over a broad area than a large system like, say, Hugo or Irma. Those models are also showing EPAC convection during August and September that will likely shear anything that manages to form close to land. Therefore, truly high-impact storms (as measured by the Hurricane Severity Index) are less likely to occur this year.

https://i.ibb.co/VLYWBTT/Ska-rmavbild-2021-07-22-kl-20-07-42.png
Source

While it was not a Cat 4 at landfall in August, Katrina is a great example of how homegrown systems does not necessarily mean they have to be small and struggle to make a devastating blow on a population center. Katrina was very large and had a pretty low minimum pressure of 902 mbar for a 175 mph hurricane and made landfall as a 920 mbar storm (core pressure is usually pretty indicative of how intense and subsequently dangerous a storm can be at landfall). In addition, a large Cat 2 landfall like Ike can also be pretty bad; it generated a record high surge for the continental US. You don't always need a Cat 4+ storm at landfall to cause major problems and have a storm that is remembered for years. Also, if we're headed toward a weak La Nina as a very realistic outcome, I'm not exactly sure why EPAC convection in August or September would really shear anything that manages to form near land; I do not know how much of a problem that would really be frankly. We'll see though.

[Shell Mound]

I would watch for homegrown development (in GOM or off the coast of eastern US) through the first third of Aug, with limited chance of anything forming in the MDR. Then I would expect MDR activity to begin picking up by around the third week of Aug.

However, either type of development would pose higher than usual US landfall risks by mid to late Aug based on the projected upper-level pattern (similar to the pattern from late Jun to first week of Jul that led to the all-time record heat in the Pacific NW/W. Canada as well as very hot conditions in the ne US).

https://twitter.com/yconsor/status/1418245564181921801
https://twitter.com/yconsor/status/1418248084371476485

Homegrown systems usually tend to be on the weak(-er) side (<Category 4). Of the eleven hurricanes to strike the U.S. at Cat-4+ status in the month of August since 1851, eight originated as a TD or stronger in the MDR. The eight storms were the 1886 Indianola hurricane, the 1915 Galveston hurricane, the 1916 Texas hurricane, the 1949 Florida hurricane, Andrew (1992), Charley (2004), Harvey (2017), and Laura (2020). Based on modelled projections the MDR should not become favourable until the last week of August. By the time a strong CV system is “out there” the strong ridging could be gone or displaced. Additionally, the ACCESS and JMA suggest that the storms that do develop during the peak of the 2021 AHS are likely to be smaller and homegrown, thus posing less of a hazard than a large long-tracker, because a tiny homegrown system that intensifies close to shore is a) less likely to be Cat-4+ at landfall and b) is less likely to deliver a wide range of hazards over a broad area than a large system like, say, Hugo or Irma. Those models are also showing EPAC convection during August and September that will likely shear anything that manages to form close to land. Therefore, truly high-impact storms (as measured by the Hurricane Severity Index) are less likely to occur this year.

https://i.ibb.co/VLYWBTT/Ska-rmavbild-2021-07-22-kl-20-07-42.png
Source

...

I didn’t count Ike, as it was a CV-type system, and, moreover, it occurred in September; I was only looking at Cat-4+ impacts on the CONUS during the month of August. Among hyperactive seasons, 2005, like 2020, was very unusual in that most of its activity was concentrated in the western part of the basin, whereas most hyperactive seasons tend to feature intense activity farther east, in the MDR. During inactive phases, one actually tends to see more “homegrown” development or formation in the subtropics than activity in the MDR. During inactive cycles storms tend to be smaller, weaker, and concentrated farther west vs. storms that form during active cycles. Inactive cycles also tend to feature a greater proportion of small storms that intensify rapidly close to shore, like the 1935 Labor Day hurricane, Gracie (1959), Camille (1969), Celia (1970), Eloise (1975), Diana (1984), or Michael (2018). Unlike large systems such as Beulah (1967), Agnes (1972), Frances (2004), Ivan (2004), Katrina (2005), or Ike (2008), smaller systems tend to produce fewer tornadoes as they move ashore, usually produce less flooding from either surge or precipitation, and confine their worst wind-related impacts to small areas. Andrew barely produced TS winds just 30 n mi north of its eye, and Charley was even smaller than Andrew. A tiny but intense system would basically need to directly hit the very centre of a populated area to produce extreme impacts within the span of a few miles, with minimal impacts on either side of that swath. So the possibility that large, intense systems, which tend to form farther east before tracking westward, will be less likely in 2021 is very good news for the Western Hemisphere. I’d rather take my chances with another Andrew than with another Audrey, Carla, or Katrina.

[cycloneye]

 https://twitter.com/webberweather/status/1418304621416751104




 https://twitter.com/webberweather/status/1418298200524460035

[storminabox]

Homegrown systems usually tend to be on the weak(-er) side (<Category 4). Of the eleven hurricanes to strike the U.S. at Cat-4+ status in the month of August since 1851, eight originated as a TD or stronger in the MDR. The eight storms were the 1886 Indianola hurricane, the 1915 Galveston hurricane, the 1916 Texas hurricane, the 1949 Florida hurricane, Andrew (1992), Charley (2004), Harvey (2017), and Laura (2020). Based on modelled projections the MDR should not become favourable until the last week of August. By the time a strong CV system is “out there” the strong ridging could be gone or displaced. Additionally, the ACCESS and JMA suggest that the storms that do develop during the peak of the 2021 AHS are likely to be smaller and homegrown, thus posing less of a hazard than a large long-tracker, because a tiny homegrown system that intensifies close to shore is a) less likely to be Cat-4+ at landfall and b) is less likely to deliver a wide range of hazards over a broad area than a large system like, say, Hugo or Irma. Those models are also showing EPAC convection during August and September that will likely shear anything that manages to form close to land. Therefore, truly high-impact storms (as measured by the Hurricane Severity Index) are less likely to occur this year.

https://i.ibb.co/VLYWBTT/Ska-rmavbild-2021-07-22-kl-20-07-42.png
Source

...

I didn’t count Ike, as it was a CV-type system, and, moreover, it occurred in September; I was only looking at Cat-4+ impacts on the CONUS during the month of August. Among hyperactive seasons, 2005, like 2020, was very unusual in that most of its activity was concentrated in the western part of the basin, whereas most hyperactive seasons tend to feature intense activity farther east, in the MDR. During inactive phases, one actually tends to see more “homegrown” development or formation in the subtropics than activity in the MDR. During inactive cycles storms tend to be smaller, weaker, and concentrated farther west vs. storms that form during active cycles. Inactive cycles also tend to feature a greater proportion of small storms that intensify rapidly close to shore, like the 1935 Labor Day hurricane, Gracie (1959), Camille (1969), Celia (1970), Eloise (1975), Diana (1984), or Michael (2018). Unlike large systems such as Beulah (1967), Agnes (1972), Frances (2004), Ivan (2004), Katrina (2005), or Ike (2008), smaller systems tend to produce fewer tornadoes as they move ashore, usually produce less flooding from either surge or precipitation, and confine their worst wind-related impacts to small areas. Andrew barely produced TS winds just 30 n mi north of its eye, and Charley was even smaller than Andrew. A tiny but intense system would basically need to directly hit the very centre of a populated area to produce extreme impacts within the span of a few miles, with minimal impacts on either side of that swath. So the possibility that large, intense systems, which tend to form farther east before tracking westward, will be less likely in 2021 is very good news for the Western Hemisphere. I’d rather take my chances with another Andrew than with another Audrey, Carla, or Katrina.

So you believe that we are now in a less active cycle aka -AMO?

[AlphaToOmega]

TUTT = high potential vorticity

[SFLcane]

Maybe we’re skipping this season? Lol…

No TCs through September 5 on the EPS control.

[AlphaToOmega]

Maybe we’re skipping this season? Lol…

No TCs through September 5 on the EPS control.

https://i.postimg.cc/Vvvcw0Gn/8-B884703-C69-B-4-E72-A970-A0-B34-E90-C874.png

Watch as someone uses this as evidence that the season will be inactive

I could have sworn a while ago that the model was showing an MDR storm circa August 22.

[aspen]

Maybe we’re skipping this season? Lol…

No TCs through September 5 on the EPS control.

https://i.postimg.cc/Vvvcw0Gn/8-B884703-C69-B-4-E72-A970-A0-B34-E90-C874.png

Windshield wipers and split personality disorder in full effect. Going from active to inactive, and showing both positive and negative conditions at the same time from different outputs.

I find it very hard to believe that will verify. I mean, we had the earliest 5th named storm on record and one of the earliest MDR hurricanes on record, and we’re entering another La Niña with a very active WAM and a favorable ITCZ location. No way a season with this setup has a TC gap spanning mid July through early September. Not even the Super Nino year 2015 had a gap like that! And it even had a MDR major.

[cycloneye]

Oh boy, let's brace for those SC now.

[AlphaToOmega]

Oh boy, let's brace for those SC now.

The people of Storm2K have wised up to the fact that a lull of activity does not mean an inactive season; even record-breaking seasons have lulls. I think it is people on Twitter who need to be reminded of this.

[SFLcane]

Oh boy, let's brace for those SC now.

lol!

[aspen]

Oh boy, let's brace for those SC now.

The people of Storm2K have wised up to the fact that a lull of activity does not mean an inactive season; even record-breaking seasons have lulls. think it is people on Twitter who need to be reminded of this.

Yeah, good luck. It’s Twitter, so you’ll probably have more success blowing away the next hurricane with a regular fan than changing their stances.

The Euro has been consistently garbage with TCG since early last year, so a run showing absolutely no TCs for over a month should be expected.