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

[NotSparta]

Do Y'all have a bad feeling about a 2013 Sneak attack? I do have that feeling . . .

Another 2013, as said many times, is highly unlikely. 2013 was abnormal due to a collapse of the Thermohaline Cycle, which led to spring-like atmospheric conditions persisting and ruining the apparently good conditions forecast prior to the Spring Predictability Barrier. For another 2013, we would need to see the THC collapse again, and since we’ve already gone through 2013, we know the warning signs of such an anomalous event occurring.

By the way, what are the signs of a thermohaline collapse?

Little to no activity during peak season

[aspen]

Do Y'all have a bad feeling about a 2013 Sneak attack? I do have that feeling . . .

Another 2013, as said many times, is highly unlikely. 2013 was abnormal due to a collapse of the Thermohaline Cycle, which led to spring-like atmospheric conditions persisting and ruining the apparently good conditions forecast prior to the Spring Predictability Barrier. For another 2013, we would need to see the THC collapse again, and since we’ve already gone through 2013, we know the warning signs of such an anomalous event occurring.

By the way, what are the signs of a thermohaline collapse?

The 2013 event was technically a weakening of the THC, not a complete collapse. A gradual weakening of the THC has been observed since around the 1930s and has been attributed to anthropogenic climate change. I don’t know the exact signs of a sudden weakening, but theoretically, there should be signs that the circulation is weakening more so than normal.

THC weakenings could become more common with anthropogenic climate change, which would actually result in cooler North Atlantic temperatures and less active hurricane seasons whenever a weak phase occurs. Those would offset the slightly increased SSTs that would allow more intense storms to bomb out.

[Category5Kaiju]

With the African monsoon being hyperactive once again, waves are likely to be highly amplified, the ITCZ displaced farther to the north, and systems much slower to develop over the MDR relative to normal. Along with a transition toward neutral or warm neutral ENSO, this means that the MDR is becoming less favourable than originally expected, given that the AMO is lukewarm at best rather than strongly positive at the moment. Additionally, the various models suggest steering may favour OTS tracks that avoid the Caribbean, GoM, and most of the U.S. East Coast (excluding New England). The lack of a busy MDR alone tends to the decrease the risk of major hurricanes striking the CONUS, since climatologically three-fourths of all MH to strike the CONUS since 1851 developed first over the MDR. I think 2006 might be a decent analog in terms of tracks, if not numbers.

Just curious but is there a specific reason why you think 2006 is a good analog year for tracks? Years like 2001 or 2012 were what came to my mind as well

Also a busy MDR alone does not actually mean less major US hurricane strikes; Wilma, Dennis, Katrina, Opal, Rita, Charley are some examples of this.

Vice versa. I pointed out that an inactive MDR tends to mean fewer MH impacts on the CONUS, based on climatology, given that approximately three-fourths of all historical MH to strike the CONUS developed at first in the MDR. As far as analogs are concerned, I chose 2006 because ENSO will likely be warming through the peak of the season, and we are transitioning out of moderate Niña conditions to neutral or even warm neutral ENSO, unlike 2001 or 2012. Additionally, in line with NDG’s observation, most of the recent guidance suggests above-average precipitation over the easternmost tropical Pacific either during or around ASO, suggesting that shear may be above average over the Caribbean basin during the peak of the season, owing to outflow from convection induced by warming SSTs over the NINO zones. Warming ENSO also tends to result in more sinking air over the MDR, a somewhat stronger TUTT, and higher MSLP, meaning more hostile conditions over the MDR as well as the Caribbean. The more persistent TUTT may also pull storms that do form northward and/or OTS.

Oh ok my bad, I misread what you were trying to say regarding the MDR favorability stuff. Now regarding potential analog years, I am still not exactly sure if 2006 is a decent fit for 2021 though because 2005 was not a robust moderate La Nina year. The episode lasted only for 5 total 3-consecutive month time frames and reached -0.8 at its peak, and as a result it is no surprise that 2006 easily became a weak Nino year. The La Nina we are coming out of reached a peak of -1.3 and is more robust than 2005, so to be honest I would assume that even in the hurricane season's heart if we were in neutral the atmospheric conditions would take some time to shift and consequently be still coupled to a La Nina-like behavior during that time. To be fair, I think better examples of analog years would be 1985, 1996, and 2008 (as all of those years followed a Nina about as strong as the one seen last year) but that is just me.

[ClarCari]

The models are most definitely showing some biases towards less favorable conditions because the ENSO has only very recently risen into Neutral territory. They are processing these recent changes and some are predicting the ENSO may warm more than it actually will.
Models tend to overestimate the effects of recent changes right after they happen.
I imagine the models like CanSips will start showing wetter forecasts again across the basin later on once this ENSO settles more and they all get a better grasps on things.
For now the upcoming passage of an MJO across the Pacific may cause some models to go crazy in predicting the ATL to shutdown or something during ASO before returning to more realistic forecasts.

[Nawtamet]

REMINDER that the models are showing some biases towards less favorable conditions because the ENSO has only very recently switched into Neutral territory. They are processing these recent changes and some are predicting the ENSO may warm more than it actually will.
Models tend to overestimate the effects of recent changes right after they happen.
I imagine the models like CanSips will start showing wetter forecasts again across the basin later on once this ENSO settles more and they all get a better grasps on things.
For now the upcoming passage of an MJO across the Pacific may cause some models to go crazy in predicting the ATL to shutdown or something during ASO before returning to more realistic forecasts.

So this is why this is called the Spring Predictability Barrier, huh?

[ClarCari]

REMINDER that the models are showing some biases towards less favorable conditions because the ENSO has only very recently switched into Neutral territory. They are processing these recent changes and some are predicting the ENSO may warm more than it actually will.
Models tend to overestimate the effects of recent changes right after they happen.
I imagine the models like CanSips will start showing wetter forecasts again across the basin later on once this ENSO settles more and they all get a better grasps on things.
For now the upcoming passage of an MJO across the Pacific may cause some models to go crazy in predicting the ATL to shutdown or something during ASO before returning to more realistic forecasts.

So this is why this is called the Spring Predictability Barrier, huh?

For many reasons yea haha but this is definitely one of them. Theres some skill in long-term forecast modeling and then when the spring changes do actually occur it’s almost like all the models starting second-guessing themselves.
Then they go back to being a bit more reasonable once everything settles.
This is why during SPB it’s generally more wise to go off of meteorological knowledge, precedent, and instinct than the modeling when it comes to current indicators and trends.

[AnnularCane]

Gotta love that Spring Predictability Barrier, it seems to give everyone fits about this time every year.

[Category5Kaiju]

I am willing to bet that once the SPB passes, the models will trend wetter again. I really have a gut feeling the SPB is making these models behave the way they are right now (along with the fact that we've just entered neutral) and displaying a Nino-like pattern in the Atlantic.

[cycloneye]

ECMWF forecast calls for active season.

 https://twitter.com/RyanMaue/status/1379080087153356802




 https://twitter.com/RyanMaue/status/1379080709172830209




 https://twitter.com/RyanMaue/status/1379081906814382084

[DorkyMcDorkface]

ECMWF forecast calls for active season.

https://twitter.com/RyanMaue/status/1379080087153356802

[Iceresistance]

Is the Main Development Region going to have higher tropical activity this year?

[SFLcane]

ECMWF forecast calls for active season.

https://twitter.com/RyanMaue/status/1379080087153356802

https://twitter.com/RyanMaue/status/1379080709172830209

https://twitter.com/RyanMaue/status/1379081906814382084

That is interesting. Especially because the EC usually undersells. Curious what the SST looks like.

[tolakram]

If the Euro is calling for an active season, given it's performance in these long range forecasts, my bet is for a normal to slightly below normal season. The truth is we won't have any reliable signals until May.

[DorkyMcDorkface]

ECMWF forecast calls for active season.

https://twitter.com/RyanMaue/status/1379080087153356802

https://twitter.com/RyanMaue/status/1379080709172830209

https://twitter.com/RyanMaue/status/1379081906814382084

Probably should have included this in my first reply, but I made an animation to compare these TS frequency forecasts ever since this product was first released back in 2017.


And here's the hurricane forecast for good measure. Same thing:

So for those of you keeping track at home, that's 16.5 NS and 8.2 HU. Apparently this is the most active out of all the April runs so far; not even 2017 or 2020 came close. Obviously it's still pretty far out but it's pretty eyebrow-raising if you ask me, especially considering the seasonal Euro typically lowballs activity as mentioned above.

[ClarCari]

Maybe the Euro decided it’s not going along with the other models crying wolf for a less active season because of the typical spring changes.

[Kingarabian]

April Euro seasonal rainfall anomalies for ASO:



Not too different from the Canadian.

[Shell Mound]

ECMWF forecast calls for active season.

https://twitter.com/RyanMaue/status/1379080087153356802

https://twitter.com/RyanMaue/status/1379080709172830209

https://twitter.com/RyanMaue/status/1379081906814382084

Probably should have included this in my first reply, but I made an animation to compare these TS frequency forecasts ever since this product was first released back in 2017.
https://cdn.discordapp.com/attachments/733552978572869632/828650313175007302/ezgif-2-590573b8d77a.gif

And here's the hurricane forecast for good measure. Same thing:
https://i.ibb.co/xCrN0XN/ezgif-2-867bef892199.gif
So for those of you keeping track at home, that's 16.5 NS and 8.2 HU. Apparently this is the most active out of all the April runs so far; not even 2017 or 2020 came close. Obviously it's still pretty far out but it's pretty eyebrow-raising if you ask me, especially considering the seasonal Euro typically lowballs activity as mentioned above.

May you kindly make a similar animated sequence for the forecast STSD during ASO, going back to 2017?

[DorkyMcDorkface]

ECMWF forecast calls for active season.

https://twitter.com/RyanMaue/status/1379080087153356802

https://twitter.com/RyanMaue/status/1379080709172830209

https://twitter.com/RyanMaue/status/1379081906814382084

Probably should have included this in my first reply, but I made an animation to compare these TS frequency forecasts ever since this product was first released back in 2017.
https://cdn.discordapp.com/attachments/733552978572869632/828650313175007302/ezgif-2-590573b8d77a.gif

And here's the hurricane forecast for good measure. Same thing:
https://i.ibb.co/xCrN0XN/ezgif-2-867bef892199.gif
So for those of you keeping track at home, that's 16.5 NS and 8.2 HU. Apparently this is the most active out of all the April runs so far; not even 2017 or 2020 came close. Obviously it's still pretty far out but it's pretty eyebrow-raising if you ask me, especially considering the seasonal Euro typically lowballs activity as mentioned above.

May you kindly make a similar animated sequence for the forecast STSD during ASO, going back to 2017?

Sure:

[Shell Mound]

Probably should have included this in my first reply, but I made an animation to compare these TS frequency forecasts ever since this product was first released back in 2017.
https://cdn.discordapp.com/attachments/733552978572869632/828650313175007302/ezgif-2-590573b8d77a.gif

And here's the hurricane forecast for good measure. Same thing:
https://i.ibb.co/xCrN0XN/ezgif-2-867bef892199.gif
So for those of you keeping track at home, that's 16.5 NS and 8.2 HU. Apparently this is the most active out of all the April runs so far; not even 2017 or 2020 came close. Obviously it's still pretty far out but it's pretty eyebrow-raising if you ask me, especially considering the seasonal Euro typically lowballs activity as mentioned above.

May you kindly make a similar animated sequence for the forecast STSD during ASO, going back to 2017?

Sure:

https://i.ibb.co/C1nh47g/ezgif-2-3e9d224c5cac.gif

By “STSD” I was referring to the Standardised Tropical-Storm Density. May you please post the animated sequence for those?

Interestingly, the SST profile, with + anomalies over the Gulf of Guinea, suggests -AMO, yet the NS/H suggest otherwise.

[aspen]

April Euro seasonal rainfall anomalies for ASO:

https://i.imgur.com/plTjejF.png

Not too different from the Canadian.

Euro: *predicts an active season as a rare case of it not succumbing to its forecast biases*

Also the Euro: *forecasts a dry Atlantic as normal*

....I don’t get what it’s trying to do here, nor how both results work with each other.