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

[AlphaToOmega]

Below-average MSLPs in the MDR are forecasted by the CFS for the rest of August into September.

[tolakram]

It's interesting how everything is pointing positive, but the MJO appears to be stuck, or just slow to move into phase II. My guess is even though the conditions look bad what we're actually seeing is storms than in most years would not develop. We shall see in a couple of weeks. If Fred ends up doing anything, and right now it's a depression just north of Cuba, it may be our first sign.

[AlphaToOmega]

It's interesting how everything is pointing positive, but the MJO appears to be stuck, or just slow to move into phase II. My guess is even though the conditions look bad what we're actually seeing is storms than in most years would not develop. We shall see in a couple of weeks. If Fred ends up doing anything, and right now it's a depression just north of Cuba, it may be our first sign.

According to the GFS and ECMWF, the MJO is already in Phase II. Phase II generally favors Western Atlantic development anyways.

[Steve]

It's interesting how everything is pointing positive, but the MJO appears to be stuck, or just slow to move into phase II. My guess is even though the conditions look bad what we're actually seeing is storms than in most years would not develop. We shall see in a couple of weeks. If Fred ends up doing anything, and right now it's a depression just north of Cuba, it may be our first sign.

Word. Spin should be in the basin over the next couple weeks. In my mind because it's still relatively early August, this pulse probably won't produce anything extreme. But it's more than likely going to produce at least a couple of named systems (and a possible US landfall(s) assuming Fred still classified). After that, what does the MJO do? Does it rotate back through 5/6/7 putting a clamp on or does it go back into the circle and then say rotate back down through 8-1-2-3 again maybe early to mid or mid to late September? Things might go a lot of different ways over the next 2 1/2 months, but the MJO will be an important factor especially if we hit favorable at a time when the La Nina is coming out strong in the Pacific.

[Shell Mound]

So far there is still no sign that the TUTT and the AEJ are going to subside any time soon. Westerly shear in the Caribbean, easterly shear in the MDR...

[Teban54]

IIRC every season around August 15, some people and even experts are saying "there are no signs of [insert unfavorable conditions here] changing anytime soon", only for them to actually change a few weeks later.

Of course this season could theoretically be the one exception, and it's fine to discuss the current unfavorable conditions as they are, but keep in mind they typically go away more often than not. The climo peak is there for a reason.

[Shell Mound]

IIRC every season around August 15, some people and even experts are saying "there are no signs of [insert unfavorable conditions here] changing anytime soon", only for them to actually change a few weeks later.

Do you see any factor that could finally allow the African monsoon to weaken and thereby reduce easterly shear over the MDR?

[Kingarabian]

IIRC every season around August 15, some people and even experts are saying "there are no signs of [insert unfavorable conditions here] changing anytime soon", only for them to actually change a few weeks later.

Do you see any factor that could finally allow the African monsoon to weaken and thereby reduce easterly shear over the MDR?

It's nagging mid shear for the most part in the eastern Atlantic that will eventually let up, or, systems will find a sweet spot to develop. Stuff like this happens during exceptional events. I recall the 2015 Super El Nino there was spotty nagging mid shear across the CPAC and EPAC. I really doubt the WAM can get too strong that it inhibits development.

[aspen]

IIRC every season around August 15, some people and even experts are saying "there are no signs of [insert unfavorable conditions here] changing anytime soon", only for them to actually change a few weeks later.

Do you see any factor that could finally allow the African monsoon to weaken and thereby reduce easterly shear over the MDR?

It's nagging mid shear for the most part in the eastern Atlantic that will eventually let up, or, systems will find a sweet spot to develop. Stuff like this happens during exceptional events. I recall the 2015 Super El Nino there was spotty nagging mid shear across the CPAC and EPAC. I really doubt the WAM can get too strong that it inhibits development.

Speaking of 2015, despite the Super Niño inhibiting development in the Atlantic, there was still a major in the MDR in August and a borderline Cat 5 the next month. Systems can find a sweet spot even in a base state like that — unless it’s 2013.

[Shell Mound]

IIRC every season around August 15, some people and even experts are saying "there are no signs of [insert unfavorable conditions here] changing anytime soon", only for them to actually change a few weeks later.

Do you see any factor that could finally allow the African monsoon to weaken and thereby reduce easterly shear over the MDR?

It's nagging mid shear for the most part in the eastern Atlantic that will eventually let up, or, systems will find a sweet spot to develop. Stuff like this happens during exceptional events.

What do you mean by “exceptional events”? Are you suggesting that this year will be hyperactive in the Atlantic? Currently I think the AEJ will help keep ACE low.

[AlphaToOmega]

IIRC every season around August 15, some people and even experts are saying "there are no signs of [insert unfavorable conditions here] changing anytime soon", only for them to actually change a few weeks later.

Do you see any factor that could finally allow the African monsoon to weaken and thereby reduce easterly shear over the MDR?

2020 had a strong West African Monsoon and the Godzilla Dust Storm, yet the season was hyperactive. The models show a VP anomaly pattern very similar to the one in 2020.

[Iceresistance]

IIRC every season around August 15, some people and even experts are saying "there are no signs of [insert unfavorable conditions here] changing anytime soon", only for them to actually change a few weeks later.

Do you see any factor that could finally allow the African monsoon to weaken and thereby reduce easterly shear over the MDR?

2020 had a strong West African Monsoon and the Godzilla Dust Storm, yet the season was hyperactive. The models show a VP anomaly pattern very similar to the one in 2020.

I remember that back in July 2020, it was brown haze, normally it's either red or orange when there it's hazy outside . . .


2017 & 2019 had a major dust storm, & ended up with a Hyperactive Hurricane season . . .

[Shell Mound]

IIRC every season around August 15, some people and even experts are saying "there are no signs of [insert unfavorable conditions here] changing anytime soon", only for them to actually change a few weeks later.

Do you see any factor that could finally allow the African monsoon to weaken and thereby reduce easterly shear over the MDR?

2020 had a strong West African Monsoon and the Godzilla Dust Storm, yet the season was hyperactive. The models show a VP anomaly pattern very similar to the one in 2020.

2020 only managed to be hyperactive because VWS in the Caribbean was very low, especially in October and November. Otherwise the MDR was unfavourable due to dry air, a sprawling African monsoon (and thus a strong AEJ imparting easterly shear), and typhoon-aided TUTT activity. Thus far 2021 has been featuring the same issues that plagued 2020 in the MDR, but in addition has also seen numerous PV streamers impinging on the Caribbean, preventing African easterly waves from finding more conducive conditions there, unlike in 2020. So 2021 is like 2020, but without the favourable Caribbean to compensate...

[tolakram]

Don't confuse commenting on current conditions with a forecast for the rest of the season. I see I generated a lot of comments with a picture and a tweet about how strong the shear is over the eastern and central Atlantic.

[AlphaToOmega]

Do you see any factor that could finally allow the African monsoon to weaken and thereby reduce easterly shear over the MDR?

2020 had a strong West African Monsoon and the Godzilla Dust Storm, yet the season was hyperactive. The models show a VP anomaly pattern very similar to the one in 2020.

2020 only managed to be hyperactive because VWS in the Caribbean was very low, especially in October and November. Otherwise the MDR was unfavourable due to dry air, a sprawling African monsoon (and thus a strong AEJ imparting easterly shear), and typhoon-aided TUTT activity. Thus far 2021 has been featuring the same issues that plagued 2020 in the MDR, but in addition has also seen numerous PV streamers impinging on the Caribbean, preventing African easterly waves from finding more conducive conditions there, unlike in 2020. So 2021 is like 2020, but without the favourable Caribbean to compensate...

It is August; conditions are not typically favorable in the Caribbean in August. Conditions are only typically favorable from September onwards. A La Nina will likely make conditions more favorable in the Caribbean by late season. Plus, wind shear in the Caribbean seemed pretty high, yet everyone in Central America knows what happened last year. Early/mid August is not a bellwether period for conditions in the Caribbean later in the season.

[SteveM]

Do you see any factor that could finally allow the African monsoon to weaken and thereby reduce easterly shear over the MDR?

2020 had a strong West African Monsoon and the Godzilla Dust Storm, yet the season was hyperactive. The models show a VP anomaly pattern very similar to the one in 2020.

2020 only managed to be hyperactive because VWS in the Caribbean was very low, especially in October and November. Otherwise the MDR was unfavourable due to dry air, a sprawling African monsoon (and thus a strong AEJ imparting easterly shear), and typhoon-aided TUTT activity. Thus far 2021 has been featuring the same issues that plagued 2020 in the MDR, but in addition has also seen numerous PV streamers impinging on the Caribbean, preventing African easterly waves from finding more conducive conditions there, unlike in 2020. So 2021 is like 2020, but without the favourable Caribbean to compensate...

It's August...

[Category5Kaiju]

The way I see it, if by late August activity is clearly not ramping up with no foreseeable ramp up in the near future, I would become skeptical or an active season. If by early to mid September the same holds true, then I would say that this season is highly likely going to underperform. However, there was only one recent season that this thought process would hold true for (the legendary 2013), and I highly doubt that 2021 will be the same. There are just too many factors that differ between both years, and I expect climo to do its thing later this month and possibly starting with 95L

[Iceresistance]

I've noticed this recently . . .



Vertical Wind Shear is really low in the Caribbean . . .

[chaser1]

Present strong East Atlantic monsoonal flow and unclear MJO forecast notwithstanding, do keep in mind that the increasingly confident La Nina signal will likely not be a "flip of the switch" impact to upper level flow for the Atlantic basin. I have always found that there is a few week lag for ENSO evolution to truly impact the Atlantic basin in terms of upper air pattern, zonal flow changes, and their mitigating (Nino) or enhancing (Nina) impact to tropical cyclone development to occur. In terms of teleconnections for an emerging August-October La Nina event as it relates to "enhanced" conditions for the Atlantic basin, we may well not see these conditions verify until perhaps mid-late September. From a climo perspective, I think that it's unlikely that we will see much impact to Eastern Atlantic MDR development. Where I DO foresee the potential for a greater impact to otherwise disruptive upper level conditions, would be those regions that are typically more climatologically active during this period. This in conjunction with seemingly favorable conditions for genesis which we've already witnessed "closer in" (ie: Eastern Caribbean, Western Atlantic basin) leads me to think that the greatest threat for a significant landfall threat could well range anywhere from the Northeast U.S. coastline southward to the mid-Atlantic in September. That threat likely shifting to Cuba, Jamaica, Florida and Northern GOM into October.

[aspen]

Seems like Fred and Grace, instead of ending the season cancel talks, have only added more fuel to the fire — persistent MDR shear, shredder tracks being favored, the reluctance of the MJO to move to Phase II, and the EPac being able to produce a strong hurricane while the supposedly favored Atlantic is struggling to get anything of significance. I don’t see how shredder tracks will be the only tracks MDR storms would take this year; that’s quite a thin strip of latitude for every MDR storm to hit, and it would require a very specific and unchanging ridge setup to keep it happening.

Extrapolating the last week out to the rest of the season presents quite a season cancel prediction: the African monsoon shearing anything in most of the MDR, but nothing can recurve and it instead heads into the shredder to never develop. However, extrapolating a short-term trend to judge the next 2-3 months is foolish, as a developing Nina will likely lead to development focusing to the Caribbean and Gulf instead of the MDR by October. Also, it is impossible for the MJO to remain in one place for months.