Seasonal Indicators (Beyond Day 16): Instability / SST's / MSLP / Steering / Sal

[gatorcane]

not looking too good for the Atlantic (or EPAC) based on this latest MJO graphic for August. Lot's of sinking air everywhere as we head deeper into August and when the Atlantic usually ramps up based on climatology. The graphic is showing some rising air through rest of this month across the Atlantic MDR so let's see if we can squeeze out a TC.

Of course that is if you believe what it is showing which is not always correct

[TheStormExpert]

It seems for the past 3-4 seasons the MJO has become such a dependent factor towards Tropical Development in the Atlantic basin. Danielle was lucky and somehow formed without aid from the MJO when most storms in the Atlantic nowadays form thanks to the MJO being favorable.

[beoumont]

Extrapolation based on what has occurred through mid July might be a fun exercise, but can prove totally useless. 1961 is a prime example. Only one named storm through Sept. 1; then many Cape Verde systems thereafter and a season that produced three cat #3 storms, 2 cat #4 storms, and 2 cat #5s.(Carla, Hattie).

# Name Date Wind Pres Cat
1 Hurricane-3 ANNA 20-24 JUL 100 976 3
2 Hurricane-4 BETSY 2-12 SEP 120 945 4
3 Hurricane-5 CARLA 3-16 SEP 150 931 5
4 Hurricane-3 DEBBIE 6-16 SEP 105 970 3
5 Hurricane-4 ESTHER 10-27 SEP 125 927 4
6 Tropical Storm 6 12-15 SEP 35 0 -
7 Hurricane-3 FRANCES 30 SEP-10 OCT 110 948 3
8 Tropical Storm GERDA 16-22 OCT 60 987 -
9 Hurricane-5 HATTIE 27 OCT- 1 NOV 140 920 5
10 Hurricane-1 JENNY 1- 9 NOV 70 974 1
11 Tropical Storm INGA 5- 8 NOV 60 992 -

[tarheelprogrammer]

Anyone have charts that show what the MJO looked like during the 2010, 2005, 2004, 1998, and 1996 seasons? During the heart of the seasons?

[Hammy]

It seems for the past 3-4 seasons the MJO has become such a dependent factor towards Tropical Development in the Atlantic basin. Danielle was lucky and somehow formed without aid from the MJO when most storms in the Atlantic nowadays form thanks to the MJO being favorable.

MJO tends to be a bigger factor during El Nino years, and was certainly a bigger factor in 2014 than 2015. 2013 was an anomaly in general, as global activity was down, so I don't think there's really any trend here given that two of those three were Nino.

[USTropics]

I feel that 1998 could be a really great analog to this season. After reading the NHC's analysis of the 1998 Hurricane Season in their AMS Journal there are some really strong parallels to how this season may turn out. Here are a few excerpts:

Figure 10 summarizes the tropical wave activity during 1998 and highlights the TCs that formed from the waves. For the period of May to November, 60 tropical waves crossed Dakar and moved westward over the tropical Atlantic, the Caribbean Sea, and Central America. Most of them appeared to continue into the eastern North Pacific. There was approximately one wave crossing at Dakar every 3.5 days. The long-term average number of waves observed for the same period is 61. Note that, except for Hurricanes Karl and Nicole in the Atlantic and Tropical Storm Kay in the eastern North Pacific, the rest of the TCs developed in the “envelope” region of genesis attributed to tropical waves.

Fig. 10. Total number of waves that maintained their identities while traveling the Atlantic, Caribbean, Gulf of Mexico, and the eastern Pacific during 1998. The figure highlights the (shaded) envelope in which tropical cyclones developed, as shown by the lettered symbols (named cyclones) or numbered symbols (tropical depressions). Symbols outside the envelope are the approximate locations of tropical cyclone formation from disturbances other than tropical waves

A few takeaways from this. There were quick burst periods of tropical activity in the EPAC that year, particularly from tropical waves that crossed over Central America. Three storms formed within a week in June, followed by a 3 week lull, and then another burst of 4 storms in 2 weeks during July. The Atlantic and Pacific basins then essentially took turns pushing out storms.

The Pacific had 3 storms in the first 2 weeks of August, followed by four storms in the Atlantic mid-end of August. The Pacific had 3 storms at the end of August through the first week of September. Starting September 8th, the Atlantic then had six storms in 2 weeks.

Also worth noting we typically see 60+ tropical waves enter the Atlantic from June-November. By my calculations, we've only seen 10-15.

As noted above, 1998 saw an increased number of tropical systems develop from TWs. This was further illustrated in the article:

Table 10 summarizes the tropical system statistics from 1967 to 98. The ratio, R, between the number of tropical storms forming from tropical waves to the total number of tropical storms is used to describe the overall character of the hurricane season (Avila and Clark 1989). Low values of R indicate that many tropical storms originated from nontropical “seedling” disturbances such as upper-tropospheric cold lows or perturbations along frontal zones. High values of R indicate that storms mostly develop from tropical waves in the tropical Atlantic, generally south of 20°N. With a few exceptions, years with high values of R are years of strong hurricanes. The 1967–97 average contribution from tropical waves to the total number of storms is 0.62. In 1998, R was 0.86. Thus 1998 had many intense hurricanes in the deep Tropics.

Table 10. Atlantic tropical system statistics for 1967–98

Tropical waves were very well defined through July and in fact, one of these waves produced Tropical Storm Alex late that month. This earlier than normal TC genesis from waves suggested that the large-scale environment was already becoming favorable for waves to initiate TC formation. The waves continued to be quite strong, and the environment mostly favorable, during August and September. Satellite imagery shows distinct tropical waves crossing Dakar between 15 August and 15 September. Note the deep and sharp cyclonic wind shift below 400 mb associated with the waves as they crossed Dakar. These waves were embedded within a deep easterly flow that extended to at least 200 mb throughout the period.

Satellite imagery Hovmöller diagrams constructed operationally from May to November reveal the westward-propagating cloudiness associated with the waves during the period. The waves became distinct and convectively active over the tropical Atlantic during the second half of August. Although waves were well defined in the wind field during early September, their convective activity was rather suppressed between the Antilles and Africa. This period was dominated by upper-level westerlies, alluded to above, and coincided with a relatively inactive 2-week period of no TC activity in the tropical Atlantic. During this period, most of the convection was concentrated in the western Caribbean and the Gulf of Mexico, where TC activity also was concentrated.

The full summaries can be found here:
Atlantic - http://journals.ametsoc.org/doi/full/10.1175/1520-0493%282001%29129%3C3085%3AAHSO%3E2.0.CO%3B2
Pacific - http://journals.ametsoc.org/doi/full/10.1175/1520-0493%282000%29128%3C2990%3AENPHSO%3E2.0.CO%3B2

[SFLcane]

Jeff masters...

Don't expect to see much activity in the Atlantic until the Eastern Pacific's burst of activity slows down. When we finally do get the surface low pressure, rising air, low wind shear, plentiful low to mid-level moisture and an African tropical wave needed to spawn an Atlantic hurricane, watch out


Record to near-record levels of heat energy are in the Atlantic in the Caribbean, Gulf of Mexico and waters surrounding the Bahamas (Figure 2), exceeding even the heat energy that was available during the notorious Hurricane Season of 2005. This year's high levels of ocean heat content in the Atlantic increases the odds of dangerous rapidly-intensifying major hurricanes if the other conditions needed for intensification are present.

Wow so much potential out there! enjoy these few weeks folks could be a rude awaking for many come Aug.

[ninel conde]

Jeff masters...

Don't expect to see much activity in the Atlantic until the Eastern Pacific's burst of activity slows down. When we finally do get the surface low pressure, rising air, low wind shear, plentiful low to mid-level moisture and an African tropical wave needed to spawn an Atlantic hurricane, watch out


Record to near-record levels of heat energy are in the Atlantic in the Caribbean, Gulf of Mexico and waters surrounding the Bahamas (Figure 2), exceeding even the heat energy that was available during the notorious Hurricane Season of 2005. This year's high levels of ocean heat content in the Atlantic increases the odds of dangerous rapidly-intensifying major hurricanes if the other conditions needed for intensification are present.

Wow so much potential out there! enjoy these few weeks folks could be a rude awaking for many come Aug.

To me, SST's are the least inportant factor but it will matter if something can survive and make it there.

[WPBWeather]

Jeff masters...

Don't expect to see much activity in the Atlantic until the Eastern Pacific's burst of activity slows down. When we finally do get the surface low pressure, rising air, low wind shear, plentiful low to mid-level moisture and an African tropical wave needed to spawn an Atlantic hurricane, watch out


Record to near-record levels of heat energy are in the Atlantic in the Caribbean, Gulf of Mexico and waters surrounding the Bahamas (Figure 2), exceeding even the heat energy that was available during the notorious Hurricane Season of 2005. This year's high levels of ocean heat content in the Atlantic increases the odds of dangerous rapidly-intensifying major hurricanes if the other conditions needed for intensification are present.

Wow so much potential out there! enjoy these few weeks folks could be a rude awaking for many come Aug.

To me, SST's are the least inportant factor but it will matter if something can survive and make it there.

PAC grinds to a halt next week, per Mike Ventrice on Twitter.

[Hammy]

What if any is the connection between Pacific activity and eastern Atlantic conditions?

[tolakram]

This tweet seemed timely.

 https://twitter.com/philklotzbach/status/755094692035858432

[Ntxw]

What if any is the connection between Pacific activity and eastern Atlantic conditions?

I'm not sure about the eastern Atlantic, but the relationship can be seen if you dive into the walker circulation (or walker cell). This is the driver of how ENSO effects the Atlantic but there is a more comprehensive approach. The shift of the walker circulation across the globe drives where areas are moist or dry on a global scale. SST's from El Nino/La Nina does not do anything to the Atlantic and other basins, it is the movement of the walker cell that brings shear/sinking air etc.

https://www.climate.gov/news-features/blogs/enso/walker-circulation-ensos-atmospheric-buddy This is a good read if you want to understand it.

As for the MJO; The MJO seems to play an important role of late because I think it's just the fact we are now tracking it more with an understanding of it and how to look at it. Before data on it was limited and not readily available, doesn't mean it wasn't important back then or didn't exist.

[USTropics]

What if any is the connection between Pacific activity and eastern Atlantic conditions?

I think it's a direct result of tropical influences, such as convectively coupled Kelvin waves and an active Madden-Julian Oscillation creating rising motion in one basin and suppressing activity in the other. That would explain part of 1998's transition from Pacific to Atlantic development and vice versa.

[Hurricaneman]

What Mark Sudduth has been saying on his youtube channel is that what we are seeing now is quite normal but hes also concerned about a hurricane going over the areas with record high heat content and I cant blame him since if we get a low shear environment and rising motion we might have real trouble come late August

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the National Hurricane Center and National Weather Service

[Steve]

What Mark Sudduth has been saying on his youtube channel is that what we are seeing now is quite normal but hes also concerned about a hurricane going over the areas with record high heat content and I cant blame him since if we get a low shear environment and rising motion we might have real trouble come late August

Great post. And all I have is a theory, but when you look at the size of some of 2005's storms, and particularly from memory, Rita, Katrina and Wllma, they really seemed really large in comparison to many other notable western basin systems. I wonder if the jet fuel Atlantic (which does seem more concentrated in the Caribbean than ever) that year had anything to do with the radius/diameter of how large some of those systems were able to grow to.

[Hurricaneman]

What Mark Sudduth has been saying on his youtube channel is that what we are seeing now is quite normal but hes also concerned about a hurricane going over the areas with record high heat content and I cant blame him since if we get a low shear environment and rising motion we might have real trouble come late August

Great post. And all I have is a theory, but when you look at the size of some of 2005's storms, and particularly from memory, Rita, Katrina and Wllma, they really seemed really large in comparison to many other notable western basin systems. I wonder if the jet fuel Atlantic (which does seem more concentrated in the Caribbean than ever) that year had anything to do with the radius/diameter of how large some of those systems were able to grow to.

Otherwise the bet I have out there on US landfalls still stands if anyone would care to back up his or her mouth

I think you meant 2005 but there will definitely be some hurricane landfalls this year maybe 3 with 1 major landfall but Im being a bit conservative on the hurricane landfalls as I'm not sure how much of the dry air in the Atlantic moves out

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the National Hurricane Center and National Weather Service

[Hammy]

Models showing abnormally high shear returning in a week or so basin-wide. Combined with the waves continuing to come up at almost 20N, and a return of Pacific activity as per the last several runs, I don't see anything forming for another month or so. I'm having doubts about my 1998 analog as well given that I don't recall the ITCZ being nearly this far north over Africa, nor do I remember the shear being high in late July/early August over the western part of the basin.

[Steve]

What Mark Sudduth has been saying on his youtube channel is that what we are seeing now is quite normal but hes also concerned about a hurricane going over the areas with record high heat content and I cant blame him since if we get a low shear environment and rising motion we might have real trouble come late August

Great post. And all I have is a theory, but when you look at the size of some of 2005's storms, and particularly from memory, Rita, Katrina and Wllma, they really seemed really large in comparison to many other notable western basin systems. I wonder if the jet fuel Atlantic (which does seem more concentrated in the Caribbean than ever) that year had anything to do with the radius/diameter of how large some of those systems were able to grow to.

Otherwise the bet I have out there on US landfalls still stands if anyone would care to back up his or her mouth

I think you meant 2005 but there will definitely be some hurricane landfalls this year maybe 3 with 1 major landfall but Im being a bit conservative on the hurricane landfalls as I'm not sure how much of the dry air in the Atlantic moves out

Yeah. You caught that before the edit. Otherwise I agree. I think 2016 is the season that I'd be way more surprised with a lack of US threat than the rest of the last 5-10 years or so. I'm still not sure on the timing. I'm biding my time being patient and will give everything a look in mid August. The main things I'm looking at is when do the threats commence and do they come in succession for 4-6 weeks or do they come in 2 or 3 pulses.

[TheStormExpert]

Models showing abnormally high shear returning in a week or so basin-wide. Combined with the waves continuing to come up at almost 20N, and a return of Pacific activity as per the last several runs, I don't see anything forming for another month or so. I'm having doubts about my 1998 analog as well given that I don't recall the ITCZ being nearly this far north over Africa, nor do I remember the shear being high in late July/early August over the western part of the basin.

August is supposed to be one of the busiest months of any given hurricane season and if wind shear is high it is basically game over!

Not trying to just cry season cancel but the models are really starting to make it hard for me to believe a 1998 redux when the East Pacific just won't let up.

If models don't show something in about 1-2 weeks I'm really inclined to call this season a bust.

[Hammy]

Models showing abnormally high shear returning in a week or so basin-wide. Combined with the waves continuing to come up at almost 20N, and a return of Pacific activity as per the last several runs, I don't see anything forming for another month or so. I'm having doubts about my 1998 analog as well given that I don't recall the ITCZ being nearly this far north over Africa, nor do I remember the shear being high in late July/early August over the western part of the basin.

August is supposed to be one of the busiest months of any given hurricane season and if wind shear is high it is basically game over!

Not trying to just cry season cancel but the models are really starting to make it hard for me to believe a 1998 redux when the East Pacific just won't let up.

I'm still thinking 1998 is the most likely -at the moment- but am a bit less sure--I don't have model runs to compare to, nor do I have actual instability/upper air/moisture/low level flow charts to compare this year to for certainty one way or the other, only memory. The positioning of the ITCZ is certainly the biggest source of my doubt at the moment though, the lows are coming off far too north as even in the best of conditions the waters are too cool. The shear though will certainly shut down the western half of the basin for the next several weeks if it plays out.