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

[Yellow Evan]

So if the overall oceans are warming but the anomalies in the Atlantic are lower than this 'new warm normal' they will show up as cool? All we really want to know is if the temps are above the 30 year average, or really if the temps are warm enough to support a TS or Hurricane. I'll take the simple 30 year average approach.

It's not a just a matter if the waters are warm enough to support a TS or hurricane; SST configuration is important to. If the waters in the tropics are 1C above normal, but the subtropics are 2C above normal that isn't exactly favorable as that is a -AMO/-Atlantic tripole configuration that leads to increased shear over the tropics.

[Ntxw]

Waters in the tropical and even subtropical Atlantic are always warm enough to support strong hurricanes every year regardless. What SST anomalies tell us is what the atmosphere is doing. The atmosphere often trumps anything the ocean sst's are saying.

[cycloneye]

 https://twitter.com/philklotzbach/status/748244962756558848

[cycloneye]

Here comes the strong Kelvin Wave very soon to the Atlantic. Will it cause tropical developments to pop up in the basin?

 https://twitter.com/MJVentrice/status/748508971170992129

[RL3AO]

In another thread someone asked why everything is developing in the EPac. Besides a favorable MJO pulse and CCKW moving into the EPac, there is still the big picture to look at.

Where is there convergence in the tropical Atlantic and Pacific?

Above is the surface analysis for the Atlantic and EPac from TAFB. Notice where the ITCZ/Monsoon trough is. In the Atlantic it's generally below 10°N while in the East Pacific it's generally at or above 10°N. This is normal and the ITCZ in the Atlantic will continue moving north during July. Let's dig in a little deeper looking at three ASCAT passes from today (color coded for your convenience)

ASCAT #1



We notice where TAFB is identifying a monsoon trough due to the southerly and southwesterly winds to the south of the convergence zone. This differs from an ITCZ where you generally see SE winds coming together with NE winds.

ASCAT #2



We've transitioned to an ITCZ here as we generally see SE winds come together with NE winds to create the convergence zone. In the convergence map below, you can see there is plenty of low level convergence, but the ITCZ is just too far south (as to be expected on June 30th).

Things are much more lively in the East Pacific where there is a strong monsoon trough north of 10°N. You can even see areas of westerly winds coming together with easterly winds (ALL THE VORTICITY!). Combine this with a favorable MJO/CCKW, and you have everything set up for a very active 7 to 10 days in the East Pacific.

Lastly, we put everything together with a low level convergence map from CIMSS that everyone loves. The main axis of convergence is further north in the East Pacific than in the Atlantic (once again...normal).

Hope people found this informative!

[Kingarabian]

Great post RL3AO.

Very informative.

[Hammy]

The Atlantic setup right now almost reminds me of 1998 at this point--we had continuing troughs along the EC/northern Gulf, and a few strong waves in June (which actually developed in this case) but not much east of the Caribbean until mid-July. Wouldn't surprise me given the setup to not see any more storms form until the latter third of July.

Interestingly 1998 was also a transitioning El Nino-La Nina year.

[ninel conde]

The Atlantic setup right now almost reminds me of 1998 at this point--we had continuing troughs along the EC/northern Gulf, and a few strong waves in June (which actually developed in this case) but not much east of the Caribbean until mid-July. Wouldn't surprise me given the setup to not see any more storms form until the latter third of July.

Interestingly 1998 was also a transitioning El Nino-La Nina year.

Reminds me more of 1997 where we had a constant flood pattern on the east coast with no dry weather. Could be a dead season like 1997 with a bunch of early slop storms then basically nothing. Years with east coast floods are rarely active.

[Yellow Evan]

=Years with east coast floods are rarely active.

Umm 1999?

[ninel conde]

=Years with east coast floods are rarely active.

Umm 1999?

It didnt flood like this. In 1999 we had a trof centered west of the appalacians and no WNW flow. This season all the floods are coming due to the constant 11 year wnw flow. The east coast was basically in a south to north flow in 1999, opposite of the last 11 years now. Its going to be very difficult for a hurricane to hit anywhere in the US with a non-stop WNW flow ripping through the west atlantic.

[ninel conde]

This also reminds me of 1993 where the midwest had record flooding with a pattern that didnt change a bit the entire season. Strong wnw flow ripped through the east all cane season long that year.

[ninel conde]

That image is worth 1000 words(luckily my post will be less than 1000 words). huge east coast trof with low pressure anchored over the nw atlantic and se canada just like it has for the last 11 years. Not possible for a cane to get through that rock solid wall. You can already see the next surge in the WNW flow over the plains ripping east to replace the current surge. In 1999 there was a strong bermuda high that blocked the fronts from just blasting through west atlantic like a hot knife through butter. There was a south to north flow in 1999 that allowed canes to approach the coast. And dont bring up irene in 2011. a rarity in an otherwise dead landfall pattern. When someone can post this same picture a month from now showing that nw atlantic low gone then wake me up.

[Hammy]

This also reminds me of 1993 where the midwest had record flooding with a pattern that didnt change a bit the entire season. Strong wnw flow ripped through the east all cane season long that year.

There's really no correlation between east coast flooding and Atlantic hurricane numbers. Could be a steering indication, but it tells nothing of actual numbers. And both 1993 and 1997 were very wet in the Southeast, in contrast to this year where there is a drought similar to 2005 so regional occurrences can't be used as an indicator like large-scale basin-wide patterns can.

huge east coast trof with low pressure anchored over the nw atlantic and se canada just like it has for the last 11 years.

We did not have such troughs season-wide in 2008, 10, or 15 (in fact last year the only thing that stopped landfall was the massive El Nino-induced shear.)
I also direct your attention to 2004 and 2005 at this time.
https://www.ncdc.noaa.gov/gibbs/image/GOE-12/IR/2004-07-01-00
https://www.ncdc.noaa.gov/gibbs/image/GOE-12/IR/2005-07-01-00
Both years had a massive number of landfalls and ridging--the trough is very typical for June/July and does not give any indication of how the rest of the season will be.

And dont bring up irene in 2011. a rarity in an otherwise dead landfall pattern.

This warrants being called out as it's a horrible argument--You can't demand people ignore something that happened counter to your argument just because it contradicts it. This alone proves that even with a persistent trough, landfalling systems are possible and that even with a trough being there, you can't just completely discount that possibility as being an absolute zero. All while using 1999 as your example of what the pattern this time of year needs to be, when 1999 was itself anomalous and bucked the usual flow that every other year (even landfall-heavy) ones had.

(And can you crop/resize your picture just a bit?)

[ninel conde]

This also reminds me of 1993 where the midwest had record flooding with a pattern that didnt change a bit the entire season. Strong wnw flow ripped through the east all cane season long that year.

There's really no correlation between east coast flooding and Atlantic hurricane numbers. Could be a steering indication, but it tells nothing of actual numbers. And both 1993 and 1997 were very wet in the Southeast, in contrast to this year where there is a drought similar to 2005 so regional occurrences can't be used as an indicator like large-scale basin-wide patterns can.

the picture i posted shows the wnw flow perfectly. IT SWEEPS the whole west atlantic clean from tropical trouble. This has zero resemblece to 2005 where we had a huge bermuda high. Numbers mean nothing to me. Its all about landfalls as far as whether the seaon is active or not. Since 2005 there has been a hurricane landfall drought for the entire US which will continue until that 11 year nw atlantic low is gone. as an aside, the cali drought will worsen this winter while the east suffers through a rain filled winter.

[WPBWeather]

=Years with east coast floods are rarely active.

Umm 1999?

It didnt flood like this. In 1999 we had a trof centered west of the appalacians and no WNW flow. This season all the floods are coming due to the constant 11 year wnw flow. The east coast was basically in a south to north flow in 1999, opposite of the last 11 years now. Its going to be very difficult for a hurricane to hit anywhere in the US with a non-stop WNW flow ripping through the west atlantic.

There is really no such thing in nature as a "non stop" anything. That includes the "permanent" east coast trough that has been cited here once in a while. Just pointing out the obvious.

[ninel conde]

This also reminds me of 1993 where the midwest had record flooding with a pattern that didnt change a bit the entire season. Strong wnw flow ripped through the east all cane season long that year.

There's really no correlation between east coast flooding and Atlantic hurricane numbers. Could be a steering indication, but it tells nothing of actual numbers. And both 1993 and 1997 were very wet in the Southeast, in contrast to this year where there is a drought similar to 2005 so regional occurrences can't be used as an indicator like large-scale basin-wide patterns can.

huge east coast trof with low pressure anchored over the nw atlantic and se canada just like it has for the last 11 years.

We did not have such troughs season-wide in 2008, 10, or 15 (in fact last year the only thing that stopped landfall was the massive El Nino-induced shear.)
I also direct your attention to 2004 and 2005 at this time.
https://www.ncdc.noaa.gov/gibbs/image/GOE-12/IR/2004-07-01-00
https://www.ncdc.noaa.gov/gibbs/image/GOE-12/IR/2005-07-01-00
Both years had a massive number of landfalls and ridging--the trough is very typical for June/July and does not give any indication of how the rest of the season will be.

And dont bring up irene in 2011. a rarity in an otherwise dead landfall pattern.

This warrants being called out as it's a horrible argument--You can't demand people ignore something that happened counter to your argument just because it contradicts it. This alone proves that even with a persistent trough, landfalling systems are possible and that even with a trough being there, you can't just completely discount that possibility as being an absolute zero. All while using 1999 as your example of what the pattern this time of year needs to be, when 1999 was itself anomalous and bucked the usual flow that every other year (even landfall-heavy) ones had.

(And can you crop/resize your picture just a bit?)

Dan Leonard from TWC would disagree with you. He clearly stated that when a summer pattern is established in june it doesnt change. 2008 notwithstanding there has been a cane drought since 2005 and i can assure you 2010 and 2015 had a very persistent wnw flow.

[WPBWeather]

Ninel. You quote a one off guy from the Weather Channel to support your point of view?? You can do better than that.

[ninel conde]

Umm 1999?

It didnt flood like this. In 1999 we had a trof centered west of the appalacians and no WNW flow. This season all the floods are coming due to the constant 11 year wnw flow. The east coast was basically in a south to north flow in 1999, opposite of the last 11 years now. Its going to be very difficult for a hurricane to hit anywhere in the US with a non-stop WNW flow ripping through the west atlantic.

There is really no such thing in nature as a "non stop" anything. That includes the "permanent" east coast trough that has been cited here once in a while. Just pointing out the obvious.

Tell that to California where a super el nino still resulted in a drier than normal rainy season. the reason for that was the permanent WNW flow that gave the pac nw above normal rain and forced a ridge over california that blunted what should have been a drought busting winter. the same WNW flow has resulted in yet another way below normal tornado season. the east coast trof has dominated since 2005 and thats just a fact. I suppose at some point the bermuda high will return but there is zero sign of that this season. California better hope the pattern reverses because this winter rainfall there will be far below normal.

[ninel conde]

:uarrow: Ninel. You quote a one off guy from the Weather Channel to support your point of view?? You can do better than that.

I will then quote the weather itself where florida has been cane free since 2005, no majors have hit anywhere since 2005, and we have had well below normal cane landfalls since 2005 all due to the persistent WNW flow.

[Hammy]

the east coast trof has dominated since 2005 and thats just a fact. I suppose at some point the bermuda high will return but there is zero sign of that this season. California better hope the pattern reverses because this winter rainfall there will be far below normal.

Again, there are always "zero sign" of the trough lifting out in early July.

http://i.imgur.com/MNsfBKX.png 1998
http://i.imgur.com/ENreIZW.png 2004
http://i.imgur.com/J9mK2mA.png 2005
http://i.imgur.com/HKnOAdZ.png 2008
http://i.imgur.com/b3lpEde.png 2016

Interestingly 2008's pattern looks almost identical to the current one.