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

[Category5Kaiju]

The Atlantic uno reversing the EPAC and getting its own El Nino is quite the observation indeed

[cycloneye]

There is more from Mr Andy.

 https://twitter.com/AndyHazelton/status/1415068607571169281

[toad strangler]

There is more from Mr Andy.

https://twitter.com/AndyHazelton/status/1415068607571169281

There it is finally and I’ve been harping on the word for weeks. …. SLIGHTLY …. The MDR is SLIGHTLY below normal. Those map color choices throw everyone off. Even the pros

[aspen]

There is more from Mr Andy.

https://twitter.com/AndyHazelton/status/1415068607571169281

I agree with the possibility of some enhanced stability, but the warm southern MDR combined with the south-displaced ITCZ might negate that issue, keeping AEWs away from shear and stability and cool SST problems that many waves faced last year. Even if the MDR is overall 0.2-0.3C below average by peak season, that won’t be too much of a detriment by itself as long as waves stick to the lower latitudes. Or every wave is gonna struggle until it gets further west, which as we saw last year, isn’t a good thing.

I do hope we get a couple of hurricanes in the subtropics that don’t bother anyone, like Lee ‘17 and Epsilon ‘20. Cool to track, boost the season’s totals, and don’t cause any loss of life unless they catch a stray ship off guard.

[toad strangler]

Uh huh, yup

 http://twitter.com/jacksillin/status/1415075540835344384

[toad strangler]

While some get hung up on SST's others look elsewhere. #INDICATORS

 http://twitter.com/BenNollWeather/status/1415055949903982594

[Shell Mound]

There is more from Mr Andy.

https://twitter.com/AndyHazelton/status/1415068607571169281

Smaller, faster storms due to heightened stability would be very good news. Even if a MH were to strike land the risk of surge and rain would be reduced due to size.

Getting hit with a Charley or Andrew is much better than getting hit with a Katrina, Hugo, Carla, Audrey, or 1926 Miami hurricane. The IKE index would be lower.

 https://twitter.com/DerekOrtt/status/1415070063254716418



 https://twitter.com/DerekOrtt/status/1415076770743832581



 https://twitter.com/DerekOrtt/status/1415078353577684997



 https://twitter.com/AndyHazelton/status/1415076399984021507



 https://twitter.com/AndyHazelton/status/1415076001248333827

[AxaltaRacing24]

There is more from Mr Andy.

https://twitter.com/AndyHazelton/status/1415068607571169281

Smaller, faster storms due to heightened stability would be very good news. Even if a MH were to strike land the risk of surge and rain would be reduced due to size.

Getting hit with a Charley or Andrew is much better than getting hit with a Katrina, Hugo, Carla, Audrey, or 1926 Miami hurricane. The IKE index would be lower.

https://twitter.com/DerekOrtt/status/1415070063254716418
https://twitter.com/DerekOrtt/status/1415076770743832581
https://twitter.com/DerekOrtt/status/1415078353577684997
https://twitter.com/AndyHazelton/status/1415076399984021507
https://twitter.com/AndyHazelton/status/1415076001248333827

It would still not be good though. Those are two of the worst Florida hits in history in terms of impact. Easily

[cycloneye]

More discussions about MDR.

 https://twitter.com/yconsor/status/1415263702241226757

[SFLcane]

More discussions about MDR.

https://twitter.com/yconsor/status/1415263702241226757

This is quite interesting.

[cycloneye]

 https://twitter.com/AndyHazelton/status/1415290696920178694

[aspen]

There is more from Mr Andy.

https://twitter.com/AndyHazelton/status/1415068607571169281

Smaller, faster storms due to heightened stability would be very good news. Even if a MH were to strike land the risk of surge and rain would be reduced due to size.

Getting hit with a Charley or Andrew is much better than getting hit with a Katrina, Hugo, Carla, Audrey, or 1926 Miami hurricane. The IKE index would be lower.

https://twitter.com/DerekOrtt/status/1415070063254716418
https://twitter.com/DerekOrtt/status/1415076770743832581
https://twitter.com/DerekOrtt/status/1415078353577684997
https://twitter.com/AndyHazelton/status/1415076399984021507
https://twitter.com/AndyHazelton/status/1415076001248333827

A heightened chance for smaller storms is not good at all. While they are prone to rapid decreases in intensity like Gonzalo and Delta, they can explode just as quickly to become major threats. Maria, Dorian, and Eta are recent examples of small-core AEW-born systems that became extremely powerful and devastating, and they even mentioned Dorian in those tweets. Small-core systems in peak season is never a good thing, unless there’s abrupt mid-level shear to stop them just like with Delta. The reason why Beryl, Gonzalo, and Elsa all struggled was that they still had to deal with July climatology; Maria, Dorian, and Eta all were in a more favorable time of year (although late last season was abnormally favorable).

[Shell Mound]

There is more from Mr Andy.

https://twitter.com/AndyHazelton/status/1415068607571169281

Smaller, faster storms due to heightened stability would be very good news. Even if a MH were to strike land the risk of surge and rain would be reduced due to size.

Getting hit with a Charley or Andrew is much better than getting hit with a Katrina, Hugo, Carla, Audrey, or 1926 Miami hurricane. The IKE index would be lower.

https://twitter.com/DerekOrtt/status/1415070063254716418
https://twitter.com/DerekOrtt/status/1415076770743832581
https://twitter.com/DerekOrtt/status/1415078353577684997
https://twitter.com/AndyHazelton/status/1415076399984021507
https://twitter.com/AndyHazelton/status/1415076001248333827

A heightened chance for smaller storms is not good at all.

I go by the Hurricane Severity Index (HSI). Clearly, a large, slow-moving Category-4 hurricane (i.e., 1961’s Carla) has the potential to be far more destructive over a wider area, and to generate a wider variety of hazards besides wind, than a small, rapidly intensifying, fast-moving Cat-5 (i.e., 1992’s Andrew). Years with a warmer MDR, cooler subtropics, and less intense African monsoon than 2021 tend to allow for waves to consolidate earlier and become larger storms as the intensify over the MDR and track westward, as was seen in years such as 1926, 2004, and 2017. One should not focus solely on maximum sustained wind in terms of hazards. A storm like Carla, Katrina, or even Sandy, to not mention Hugo or Ivan, would be far more destructive than another 1935- or Charley-type system. A repeat of the 1935 hurricane, Charley, or Cyclone Tracy (Australia) would need to precisely target a major metropolitan area to produce significant impacts, principally wind-related, whereas a larger, slower-moving, and only marginally less intense system would generate higher waves, greater surge, heavier rainfall, and more tornadoes, in addition to severe winds, over a wider area and thus have greater potential for high-end, full-spectrum cataclysm. This is not to say that coastal residents should be unprepared, but I personally am encouraged by the indications that high-end impacts may not happen in 2021, or are less likely to occur, based on conditions favouring smaller, faster-moving storms due to greater stability and higher background pressures (thanks in part to the -AMM/-AMO configuration offsetting the Atlantic Niño). If conditions this year were to favour large, intense storms like the 1926 hurricane, Ivan, Katrina, or Irma, then I would be more worried, personally. What’s worse: a tiny but extremely intense storm that devastates one small town on the immediate coastline, or a sprawling monster that affects multiple communities, including major metro areas, and delivers multiple hazards to multiple states?

[tolakram]

What research do we have that reliably shows storms this year will tend to be smaller? A tweet is not research, an opinion is not fact.

Let's be careful using twitter as a source of anything but interesting opinions, or hot takes as someone I trust likes to call them.

[jconsor]

 https://twitter.com/yconsor/status/1415306297721901056

[jconsor]

Here are some papers about the influence of relative humidity on tropical cyclone size. According to them, drier air surrounding a tropical cyclone tends to result in a smaller cyclone.
https://ams.confex.com/ams/28Hurricanes ... 138172.htm
https://journals.ametsoc.org/view/journ ... 2679.1.xml

This paper (based on a modelling study) disagrees that RH is a significant influence on tropical cyclone size.
https://rmets.onlinelibrary.wiley.com/d ... 02/qj.2537

What research do we have that reliably shows storms this year will tend to be smaller? A tweet is not research, an opinion is not fact.

Let's be careful using twitter as a source of anything but interesting opinions, or hot takes as someone I trust likes to call them.

[jconsor]

https://twitter.com/yconsor/status/1415306297721901056

That is still a rising cell over the East Pacific even during hyperactive years. 2020 was the only year without -VP anomalies in the East Pacific.

No, the rising cell over the E Pacific is in the active (slightly above normal) year composite. The hyperactive years have a *sinking* cell over the eastern Pacific.

[Category5Kaiju]

So do we know what the models are forecasting for this year at least in VP, like do they forecast a sinking EPAC cell or is this not what the prediction is calling for?

[aspen]

So do we know what the models are forecasting for this year at least in VP, like do they forecast a sinking EPAC cell or is this not what the prediction is calling for?

I remember one recent VP model output showing a tiny rising cell over the EPac like in the typical “above-average” selection of seasons. However, if that rising cell fails to verify and suppressive VP anomalies cover the entire EPac instead of part of it, then the Atlantic could have a better shot of a hyperactive year. I doubt the EPac will be very impressive either way, though.

[Shell Mound]

There is more from Mr Andy.

https://twitter.com/AndyHazelton/status/1415068607571169281

Smaller, faster storms due to heightened stability would be very good news. Even if a MH were to strike land the risk of surge and rain would be reduced due to size.

Getting hit with a Charley or Andrew is much better than getting hit with a Katrina, Hugo, Carla, Audrey, or 1926 Miami hurricane. The IKE index would be lower.

https://twitter.com/DerekOrtt/status/1415070063254716418
https://twitter.com/DerekOrtt/status/1415076770743832581
https://twitter.com/DerekOrtt/status/1415078353577684997
https://twitter.com/AndyHazelton/status/1415076399984021507
https://twitter.com/AndyHazelton/status/1415076001248333827

It would still not be good though. Those are two of the worst Florida hits in history in terms of impact. Easily

Respectfully, those two are not even close to Florida’s worst. One cannot simply look at the past fifty years or so. Numerous studies have shown that the 1926 Miami hurricane would be the costliest U.S. hurricane on record if it were to occur today, with or without inflation. Also, both the 1926 and 1928 hurricanes were far larger and deadlier than either Charley or Andrew, the 1928 storm being the second-deadliest to hit the CONUS on record (roughly tied with 2017’s Maria and the 1899 San Ciriaco hurricane, if one includes U.S. territories such as Puerto Rico), behind the 1900 Galveston hurricane. Both the 1926 and 1928 storms killed hundreds and even thousands of people, both in metropolitan South Florida and beside Lake Okeechobee. Even the 1935 Labor Day hurricane killed hundreds of people, unlike Charley and Andrew. The 1947 Fort Lauderdale hurricane caused 17 direct fatalities in (South) Florida, whereas Andrew caused 15 and Charley just nine, by comparison. One cannot also omit storms such as the the 1896 Cedar Keys hurricane, which caused scores or even hundreds of deaths across rural portions of North Florida. Given that the 1896 hurricane was a very small and intense system, perhaps comparable to Andrew in size, it killed far more people than Andrew did, despite crossing a more sparsely populated region than Andrew. While officially listed as a high-end Category 3 (110 kt) at landfall, the 1896 storm, according to numerous accounts from old newspapers, literally left entire forests devoid of mature trees, destroyed centuries-old (cedar) groves as well as individual trees, and left miles of interior high pine resembling prairies. A storm surge of 12.6 ft ASL occurred in Yankeetown, FL, just to the right of the centre but outside the small inner RMW, indicating surge was likely even higher closer to the centre, despite the storm’s small size and likely RI prior to and during landfall. This to me suggests that this storm was more likely a high-end Category 4, if not stronger, roughly comparable to Michael (2018).