2020 Indicators: SST's / SAL / MSLP / Steering / Shear / Instability / Sat Images

[Shell Mound]

Biggest possible negative factors in 2020, come ASO:

1. +NAO per relatively reliable ECMWF/UKMET runs: higher MSLP and stronger trades over MDR/Caribbean (also factor in strong African easterly jet)
2. +NPMM enhancing convection over the tropical EPAC and thus resulting in bouts of higher VWS over the Caribbean, thanks to strong convective outflow
3. Ambiguous AMO state: cold far North Atlantic and near-average MDR/Caribbean could suppress activity during peak season (MJO state will also be critical)

[NotSparta]

Biggest possible negative factors in 2020, come ASO:

1. +NAO per relatively reliable ECMWF/UKMET runs: higher MSLP and stronger trades over MDR/Caribbean (also factor in strong African easterly jet)
2. +NPMM enhancing convection over the tropical EPAC and thus resulting in bouts of higher VWS over the Caribbean, thanks to strong convective outflow
3. Ambiguous AMO state: cold far North Atlantic and near-average MDR/Caribbean could suppress activity during peak season (MJO state will also be critical)

Uh, the ECMWF isn't all that reliable at seasonal timescales, and a strong African easterly jet is not a negative factor as it reduces shear and suppresses the TUTT

[BYG Jacob]

ShellMound, I respect your input and you're a great poster here. This season it feels more like you're engaging in confirmation bias than honestly analyzing the current setup for this hurricane season. You don't want it to be active this year (perfectly understandable, NOBODY does) rather than taking how any factors are favoring an active Atlantic into account.

[BYG Jacob]

Two fully tropical systems before June, and neither were as sloppy as the early systems last year. I have a feeling we get so busy there won't be time for season cancel to set in.

[toad strangler]

Two fully tropical systems before June, and neither were as sloppy as the early systems last year. I have a feeling we get so busy there won't be time for season cancel to set in.

lol season cancel posts will happen. That's as given as the sun is rising.

[BYG Jacob]

Two fully tropical systems before June, and neither were as sloppy as the early systems last year. I have a feeling we get so busy there won't be time for season cancel to set in.

lol season cancel posts will happen. That's as given as the sun is rising.

You're right. We'll hit the dead zone in July and August and we'll hear about how the MDR is too hostile and cold

[aspen]

Two fully tropical systems before June, and neither were as sloppy as the early systems last year. I have a feeling we get so busy there won't be time for season cancel to set in.

lol season cancel posts will happen. That's as given as the sun is rising.

You're right. We'll hit the dead zone in July and August and we'll hear about how the MDR is too hostile and cold

2012 and 2019 are two good examples to show that a dead July and/or August does NOT mean an inactive season. 2012 had no storms form in July until the very very end, but once the season wrapped up, it had produced 19 named storms, the third highest on record in the Atlantic. It also became the second-costliest season on record at the time thanks to Sandy in October. 2019 also had an extremely inactive July and majority of August, but then we got 160 kt Dorian in late August/early September, and the season finished off with 18 named storms and 130 ACE.

It’s entirely possible 2020 could have another quiet July (although I’m thinking we’ll get some activity this time), and then it goes berserk in August-October.

[Hurricaneman]

lol season cancel posts will happen. That's as given as the sun is rising.

You're right. We'll hit the dead zone in July and August and we'll hear about how the MDR is too hostile and cold

2012 and 2019 are two good examples to show that a dead July and/or August does NOT mean an inactive season. 2012 had no storms form in July until the very very end, but once the season wrapped up, it had produced 19 named storms, the third highest on record in the Atlantic. It also became the second-costliest season on record at the time thanks to Sandy in October. 2019 also had an extremely inactive July and majority of August, but then we got 160 kt Dorian in late August/early September, and the season finished off with 18 named storms and 130 ACE.

It’s entirely possible 2020 could have another quiet July (although I’m thinking we’ll get some activity this time), and then it goes berserk in August-October.

2004 and 1999 are 2 more great examples, 1999 had 1 before August 20th in June and went nuts right on cue. 2004 had nothing until August but as soon as August started things went nuts so please no season cancel unless nothing else forms between now and September 15 which if I had money this season really gets into gear early to mid August

[BYG Jacob]

lol season cancel posts will happen. That's as given as the sun is rising.

You're right. We'll hit the dead zone in July and August and we'll hear about how the MDR is too hostile and cold

2012 and 2019 are two good examples to show that a dead July and/or August does NOT mean an inactive season. 2012 had no storms form in July until the very very end, but once the season wrapped up, it had produced 19 named storms, the third highest on record in the Atlantic. It also became the second-costliest season on record at the time thanks to Sandy in October. 2019 also had an extremely inactive July and majority of August, but then we got 160 kt Dorian in late August/early September, and the season finished off with 18 named storms and 130 ACE.

It’s entirely possible 2020 could have another quiet July (although I’m thinking we’ll get some activity this time), and then it goes berserk in August-October.

Climatology wise, July-August is the dead one for hurricanes. I agree though, given how many favorable factors are stacking for a busy season, we likely won't hit too much a lull

[Ubuntwo]

You're right. We'll hit the dead zone in July and August and we'll hear about how the MDR is too hostile and cold

2012 and 2019 are two good examples to show that a dead July and/or August does NOT mean an inactive season. 2012 had no storms form in July until the very very end, but once the season wrapped up, it had produced 19 named storms, the third highest on record in the Atlantic. It also became the second-costliest season on record at the time thanks to Sandy in October. 2019 also had an extremely inactive July and majority of August, but then we got 160 kt Dorian in late August/early September, and the season finished off with 18 named storms and 130 ACE.

It’s entirely possible 2020 could have another quiet July (although I’m thinking we’ll get some activity this time), and then it goes berserk in August-October.

Climatology wise, July-August is the dead one for hurricanes. I agree though, given how many favorable factors are stacking for a busy season, we likely won't hit too much a lull

Nope, August is one of the most active months of the season, though July does have a little slowdown.

[BYG Jacob]

2012 and 2019 are two good examples to show that a dead July and/or August does NOT mean an inactive season. 2012 had no storms form in July until the very very end, but once the season wrapped up, it had produced 19 named storms, the third highest on record in the Atlantic. It also became the second-costliest season on record at the time thanks to Sandy in October. 2019 also had an extremely inactive July and majority of August, but then we got 160 kt Dorian in late August/early September, and the season finished off with 18 named storms and 130 ACE.

It’s entirely possible 2020 could have another quiet July (although I’m thinking we’ll get some activity this time), and then it goes berserk in August-October.

Climatology wise, July-August is the dead one for hurricanes. I agree though, given how many favorable factors are stacking for a busy season, we likely won't hit too much a lull

https://www.nhc.noaa.gov/climo/images/peakofseason.gif
Nope, August is one of the most active months of the season, though July does have a little slowdown.

I didn't say the end of August

[Ubuntwo]

Climatology wise, July-August is the dead one for hurricanes. I agree though, given how many favorable factors are stacking for a busy season, we likely won't hit too much a lull

https://www.nhc.noaa.gov/climo/images/peakofseason.gif
Nope, August is one of the most active months of the season, though July does have a little slowdown.

I didn't say the end of August

You can see on the chart that even early August is far more active than any period of the season before it.

[CyclonicFury]

You're right. We'll hit the dead zone in July and August and we'll hear about how the MDR is too hostile and cold

2012 and 2019 are two good examples to show that a dead July and/or August does NOT mean an inactive season. 2012 had no storms form in July until the very very end, but once the season wrapped up, it had produced 19 named storms, the third highest on record in the Atlantic. It also became the second-costliest season on record at the time thanks to Sandy in October. 2019 also had an extremely inactive July and majority of August, but then we got 160 kt Dorian in late August/early September, and the season finished off with 18 named storms and 130 ACE.

It’s entirely possible 2020 could have another quiet July (although I’m thinking we’ll get some activity this time), and then it goes berserk in August-October.

Climatology wise, July-August is the dead one for hurricanes. I agree though, given how many favorable factors are stacking for a busy season, we likely won't hit too much a lull

The past two Augusts have been unusually quiet, especially 2018. Historically August is the second most active month of the season.

[Shell Mound]

Two fully tropical systems before June, and neither were as sloppy as the early systems last year. I have a feeling we get so busy there won't be time for season cancel to set in.

That doesn’t necessarily say very much about the rest of the season, given that both systems first formed outside the MDR/Caribbean (deep tropics). If anything, seasons with a lot of pre-season development in the subtropics tend to be relatively quiet or even dead during ASO. Several of those seasons ended up with pronounced negative velocity (sinking air/suppressed convection) and/or enhanced VWS (due to stronger TUTT and low-level easterlies) over the MDR/Caribbean. I will be more concerned about a very active season if we start to see development in the MDR/Caribbean later in June and July, à la 1933, 2005, 2017, and even 2018 (Beryl).

[TheAustinMan]

"Season cancel" is a tale as old as time. It even happened in August 2005 (after Dennis and Emily... I know, I'm as shocked as you are. Here's a few threads).

Climatologically, the early season doesn't contribute much to overall seasonal activity. In the historical record, there are two significant upticks in activity, on average, moving into the season. The beginning August typically sees an increase in storms overall, while August 15 seems to roughly signify a "switch flip" when hurricanes and major hurricanes become more prevalent.

Just as we should be careful not to assume an inactive early-season leads to an inactive season, we should also be careful not to assume that an active early-season implies an active season. The broader environmental features and patterns are much more impactful than individual storms.

I mentioned a few days ago that we would probably see some warming of the MDR thanks in part to suppressed low-level easterlies. That appears to be taking place right now, though anomaly-wise we're holding pretty steady.

107 KB. Source: NOAA Coral Reef Watch


On the not steady side of things are the Nino regions in the Pacific, which have been absolutely tanking this past week. Here's Nino3.4:

37 KB. Source: Tropical Tidbits


The Nino situation isn't too surprising if you've been following the tremendous cold pool in the subsurface anomalies, but the equatorial Pacific could be on the fast track to colder anomalies a lot faster than what some of the guidance was suggesting.

[Siker]

"Season cancel" is a tale as old as time. It even happened in August 2005 (after Dennis and Emily... I know, I'm as shocked as you are. Here's a few threads).

Holy crap, those threads are really something. The New Orleans-based topic creator in the third link asking about when things would pick up on August 20th, 2005 is also quite eerie.

[Shell Mound]

If this system offshore the SE US were to transpire, it could offer clues as to the rest of the year. Years that featured a similar development and track in the month of May include 1908, 1940, and 1948. Most of the storms in these seasons curved OTS east of the mainland U.S., though some clustered over Central America, TX/LA, and the Carolinas. So these areas might be at highest risk in 2020, based on the ECMWF’s latest run. Of course, first we need to see whether such a system as depicted actually evolves over or near the Bahamas around 20 May.

To add to this: since 1851, the following years featured at least one (S)TS formation over the Southwestern North Atlantic in the month of May—1862, 1887, 1889, 1908, 1951, 1954, 1958, 1997, 2007, 2012, 2015, 2016, and 2019. Collectively, these seasons went on to produce a total of twenty-seven major hurricanes. Of these twenty-seven major hurricanes, only two went on to strike the mainland U.S.: Carol and Hazel (1954). The rest of the major hurricanes either a) curved offshore or b) continued westward over the Caribbean Sea to strike the Yucatán Peninsula. Since Arthur seems likely to form over the Southwestern North Atlantic shortly, history seems to signal rather strongly that the mainland U.S. may be at low risk of a major hurricane in 2020, regardless of how active the season is in terms of named storms or ACE. The steering currents in the years listed above heavily favoured offshore tracks and/or Yucatán impacts rather than MH landfalls on the mainland U.S.

To add to this: Bertha’s formation, trajectory, and impact were similar to those of Ana (2015) and Bonnie (2016), both of which also struck South Carolina. 2015 and 2016 are listed among the years that featured at least one (S)TS formation over the Southwestern North Atlantic in the month of May. As the record above indicates, I think we’re already getting a good general idea as to steering patterns and clustering of tracks come peak season (August through October). If one inserts the years listed above, one finds that they predominantly featured a) OTS or b) Yucatán impacts. In regard to the latter, the +NPMM could also protect the Caribbean from significant impacts, thanks to shear from enhanced EPAC convection. Only 1887 featured hyperactivity. The remainder were slightly above average at most, well below average at least. Per TheAustinMan, data indicate that the recent suppression of the trades, however short-lived, did not result in any pronounced warming of the MDR/Caribbean, suggesting the influence of North Atlantic Deep Water (NADW) and hence a possible -AMO indicator.

[galaxy401]

I found that early August can sometimes be just as inactive as June and July before it. It's not really until August 20th that hurricane season begins its overdrive. Many active seasons had a mostly dead August, most recently 2018 and 2019.

[BYG Jacob]

https://www.nhc.noaa.gov/climo/images/peakofseason.gif
Nope, August is one of the most active months of the season, though July does have a little slowdown.

I didn't say the end of August

You can see on the chart that even early August is far more active than any period of the season before it.

Still not really active in the first couple of weeks, especially compared to climo peak.

None of which was the original point of my first post. That we might be so busy there won't be an opportunity for anybody screaming season cancel.

[CyclonicFury]

Two fully tropical systems before June, and neither were as sloppy as the early systems last year. I have a feeling we get so busy there won't be time for season cancel to set in.

That doesn’t necessarily say very much about the rest of the season, given that both systems first formed outside the MDR/Caribbean (deep tropics). If anything, seasons with a lot of pre-season development in the subtropics tend to be relatively quiet or even dead during ASO. Several of those seasons ended up with pronounced negative velocity (sinking air/suppressed convection) and/or enhanced VWS (due to stronger TUTT and low-level easterlies) over the MDR/Caribbean. I will be more concerned about a very active season if we start to see development in the MDR/Caribbean later in June and July, à la 1933, 2005, 2017, and even 2018 (Beryl).

This graphic from today's blog post on Weather Underground suggests otherwise. There have been five recorded seasons with two pre-June 1 storms. The least active of the bunch, 1908, had 95.6 ACE, which was before the satellite era. 1951, 2012 and 2016 were all above average, and 1887 was hyperactive.