2018 Indicators: SST's / MSLP / Sal / Steering / Shear / Instability (Graphic updates at first post)

[chaser1]

Well...... there's about 36 hours to the official kick off of the Atlantic hurricane season and I've already lowered my initially bullish forecast in our annual Tropical Activity Contest forum for the second time in recent weeks. (If you're reading this, jump in and make a prediction! Worse that can happen is that you wont win the $1 Million Dollars lol).

The upper divergence predicted over the Pacific, may "bleed" into the S. Gulf and W. Caribbean thus providing one of the relative few spots in the Atlantic basin where conditions might still be favorable for development this year. Here too, surface pressures are more likely to be closer to normal (as compared to higher surface pressures throughout much of the Atlantic) and SST's will be plenty warm. Of course the other line of thought might well be that if E. Pac upper level conditions are prime for frequent development there, than this in fact could inhibit Caribbean development by virtue of increase upper level shear generated by those tropical systems. For now though, I'm seeing cooler waters in the far E. Pac and limited development altogether thus my assumption that W. Caribbean and S. Gulf conditions might not mitigate somewhat favorable conditions in this relative smaller region of the tropical Atlantic.

While this season might well under-produce and potentially exhibit inhibiting conditions that may largely limit or hinder the stronger storms that recent years have shown.... I think that a relative smaller region of potential development, coupled with strong W. Atlantic ridging, might spell a number of pesky shorter track T.D's, T.S., and lower end hurricanes that could well affect Central America, Cuba, Bahamas, CONUS Gulf States, and perhaps that one or two "highlight" hurricanes that could threaten the mid-North Atlantic coastal regions. If overall conditions truly prove out to be largely unfavorable throughout much of the basin and if we in fact finally see El Nino begin to develop around late Sept/October, then this season might also come to an abrupt and somewhat early end as well. With any luck this year wont be one to plague many with severe wind impact but even if that were to ring true, this does not mean that the threat from flooding rains and storm surge won't pose a significant threat and impact some regions. Always have to keep an eye out - stay safe everyone.

[StruThiO]

 https://twitter.com/philklotzbach/status/1001924624823738368

[cycloneye]

That tweet from Phil Klotzbach is a big hint they will lower the numbers on their forecast that comes out on Thursday.

[Ntxw]

With late May now a little better insight than early May, it seems to me ENSO may not play a large role during peak (perhaps late into the season) as any +ENSO will be later to mature. The main inhibiting factors is mainly the Atlantic itself with both more dominant 500mb ridge (fueling an above average subtropical ridge) via the warm subtropics and cold ring around it. The wild card is the EPAC+CPAC season.

[NotSparta]

Agree, imo would mean the difference between average to inactive/below average

[TheStormExpert]

One things for sure, unless the MDR suddenly warms back up quickly over the course of the next two months this season will be average at best. Chances of a above average season or worse have gone down over the past several weeks.

[tolakram]

I don't think the MDR outside of the Caribbean is all that important for an active season. If you didn't know SST anomalies and just looked at the 2005 tracking charts you might assume the MDR was colder than normal due to all the weak storms. If the western Caribbean stays below normal then I think the season will certainly be slower than normal, otherwise I believe we have to look at other indicators like shear and the number of disturbances moving into favorable areas.

I do think normal is the best bet right now.

2013 for reference.

[NDG]

I don't think the MDR outside of the Caribbean is all that important for an active season. If you didn't know SST anomalies and just looked at the 2005 tracking charts you might assume the MDR was colder than normal due to all the weak storms. If the western Caribbean stays below normal then I think the season will certainly be slower than normal, otherwise I believe we have to look at other indicators like shear and the number of disturbances moving into favorable areas.

I do think normal is the best bet right now.

2013 for reference.

[img]https://i.imgur.com/iFL7zsB.png

I give it a couple of weeks for the western Caribbean to get back up to at least average if not warmer, the wet pattern during the past couple of weeks cooled it down temporarily, IMO.
Believe it or not the deepest warm waters in the Atlantic Basin are there right now.

[gatorcane]

While it is early to know what things will look like during the peak months of the Atlantic Hurricane season my gut is telling me it will be a pretty quiet season this year, going with around seasonal averages for an Atlantic season for my numbers this year. My main reasons for thinking this are: 1) SST anomaly signature is basically the opposite is was last year - cooler than normal deeper tropics 2) warmer than normal Eastern EPAC waters south of Central America inducing a bit more shear than normal over the Caribbean 3) 3 years after last El Ninos are generally not particularly busy seasons.

For Florida thinking we may not see the threat from the east this year materialize like we have seen the past couple of years (Matthew, Irma), maybe something from the south though from the Caribbean but feel early indicators suggest highest risk to mid-Atlantic region of US for any US East coast threats, the main indicator being a weaker Bermuda this year than years past.

[Bocadude85]

One things for sure, unless the MDR suddenly warms back up quickly over the course of the next two months this season will be average at best. Chances of a above average season or worse have gone down over the past several weeks.

While it is early to know what things will look like during the peak months of the Atlantic Hurricane season my gut is telling me it will be a pretty quiet season this year, going with around seasonal averages for an Atlantic season for my numbers this year. My main reasons for thinking this are: 1) SST anomaly signature is basically the opposite is was last year - cooler than normal deeper tropics 2) warmer than normal Eastern EPAC waters south of Central America inducing a bit more shear than normal over the Caribbean 3) 3 years after last El Ninos are generally not particularly busy seasons.

For Florida thinking we may not see the threat from the east this year materialize like we have seen the past couple of years (Matthew, Irma), maybe something from the south though from the Caribbean but feel early indicators suggest highest risk to mid-Atlantic region of US for any US East coast threats, the main indicator being a weaker Bermuda this year than years past.

One thing I have noticed when looking at hurricane history is that Southeast Florida has been hit quite a few times during normal to below normal seasons, a few examples are 1945,1947,1960,1965,1979 & 1992. The last hurricane landfall in Southeast Florida (Palm Beach,Broward and Miami-Dade counties) was Katrina in 2005, so I would say we are due for a hurricane landfall sooner then later. Of course there are plenty of inactive years where we did not experience any hurricane effects.

[Kingarabian]

 https://twitter.com/BenNollWeather/status/1002510388288557056

[gatorcane]

Wow the SST anomaly configuration across the Atlantic couldn't be more different than last year at this time, nearly a 180 degree flip in the configuration:

[Alyono]

2009 still had 6 storms form in the deep tropics. The subtropics/GOM were dead that year with only 3 storms. In 2006, there were only 3 as well

now take a year like 2005, 15 storms formed in the subtropics/GOM

how the subtropics perform is what will determine if this year is active or not. 6 storms in the subtropics allowed 2015 to not be as quiet as everyone thought

[TheStormExpert]

2005 at this time looked very similar to last year at this time with a warm Tropical Atlantic to only have that warmth pushed west which his why that was such a Western Atlantic based season.

2006 had a more favorable SST configuration all throughout the season compared to what we have now with mostly neutral SST's basin wide despite the El Niño.

2009 was even less ideal than 2006 in terms of SST's which is why it was even less active with the overall numbers when compared to 2006.

2015 started out with an overall cooler Atlantic to only warm up basin wide by peak season which is probably why we were able to squeeze out the storms we did in the Tropical Atlantic.

As for this year, I can't imagine it being able to get much cooler than it is now especially in the Tropical Atlantic where SST's are the coldest they've been in 25 years. Like gatorcane said thats a 180 degree flip for that part of the North Atlantic when compared to this day last year. It's just a matter as to what and where the coldest and warmest SST's are as to how and where the storms will focus and thrive. Look at this year as a COMPLETE wildcard in what will happen. I'd for sure say its more unpredictable than last season.



The area circled in red should easily warm up in the coming weeks since the conveyer belt of tropical moisture has greatly eased up. If that area warms up nicely then that's where I'd expect a good chunk of storms to cluster and develop this season.

[NDG]

Below are the closest analog years to the current SSTs over the Tropical MDR, per Dr Phil K:

Philip Klotzbach


@philklotzbach
Closest years (since 1982) are: 1984, 1985, 1986, 1989, 1994. Here's a plot of May SST anomalies and September SST anomalies in those years. In those years, the cold anomalies persisted in the MDR and in the far North Atlantic. Warm anomaly off of US East Coast went away.

 https://twitter.com/philklotzbach/status/1001949631192928256

[NotSparta]

[tweet]https://twitter.com/BenNollWeather/status/1002510388288557056[tweet]

Maybe 2009 is a good analog for this year? The ENSO warm pool looks similar, we are a bit behind that year on the surface, and the tropical ATL isn't hugely different. Might have to lower my numbers again in that case

[LarryWx]

Below are the closest analog years to the current SSTs over the Tropical MDR, per Dr Phil K:

Philip Klotzbach


@philklotzbach
Closest years (since 1982) are: 1984, 1985, 1986, 1989, 1994. Here's a plot of May SST anomalies and September SST anomalies in those years. In those years, the cold anomalies persisted in the MDR and in the far North Atlantic. Warm anomaly off of US East Coast went away.

 https://twitter.com/philklotzbach/status/1001949631192928256

4 of those 5 years had a H hit on the US east coast SC north during Aug/Sep fwiw.

[NDG]

If we don't end up having an El Nino by ASO/SON, 1985 has always been in my mind as an analog year. IMO.
That year the gulf coast got hit with 4 hurricanes.

[Hammy]

It seems like we're in an average to slightly above if no Nino, but below average if there is one setup, but have to ask about 1984--why were there so few hurricanes that year given the high number of storms? Was there lingering Nino effects or something else going on?

[NDG]

It seems like we're in an average to slightly above if no Nino, but below average if there is one setup, but have to ask about 1984--why were there so few hurricanes that year given the high number of storms? Was there lingering Nino effects or something else going on?

I am thinking yes maybe a lingering Nino effects and on top of that the far EPAC off the coast of western MX was very active, late June through late September, with 13 hurricanes which 7 reached major hurricane status, it must have created a lot shear across the Caribbean and southern GOM.

Edit: I also now see that June & July had one heck of a positive PDO, July '84 recorded the second highest PDO on record, the reason why such an active EPAC season that year, IMO.