Tropical Global Model Runs Discussion 2018

[Webberweather53]

Webb is that what the gfs been keying on as well? Larry mentioned it last night I think too with watching SW Caribbean for possible TC development. 18z has a concearning system post d10 in Caribbean, and hints of development with previous runs too. Is the phase 8/1 in MJO a good phase for increase TC development?
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The GFS is usually too overzealous w/ CA convection and TCG so I'd take any of the GFS forecasts w/ salt nor take them too seriously at least this far in advance. My post above shows all major NWP guidance showing the MJO going into phase 8-1 as we get into early October. You should understand however that this may not be a "true" MJO pulse (at least initially) in the sense that the leading Empirical Orthogonal Functions that comprise the MJO are actually just projecting onto the CA monsoon and not an MJO event propagating from the Pacific into the Western Hemisphere. Whether the MJO is "real" or not doesn't actually change the eventual result that much in this case. (I'll just mention that here, EOFs in a hand-wavy sense are essentially the main spatial patterns in meridional wind, zonal wind, & OLR in the tropics (20S-20N) derived from observations, and these same fields in real-time are then projected onto the EOFs, how well the real-time fields match the EOFs gives you a number which is then normalized and calculated to produce the MJO index.)

 

[BHS1975]

Being that the fv3 is showing development too is adding more weight .


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[BHS1975]

It’s looking like anything that does form will get swept up by a trough during the pattern change.


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[GaWx]

Being that the fv3 is showing development too is adding more weight .

FWIW: The 6Z FV3 develops a wave that moves off of Africa within only about the next 2 days. It doesn’t become a TD til near 50W on 9/25. So, this is a much earlier wave than the one the Euro/EPS has been developing just off Africa near 9/25. The run ends on 10/4 with a H recurving NNE near 30N, 75W. Climowise, this FV3 scenario is quite possible.

 

[RBR71]

FWIW: The 6Z FV3 develops a wave that moves off of Africa within only about the next 2 days. It doesn’t become a TD til near 50W on 9/25. So, this is a much earlier wave than the one the Euro/EPS has been developing just off Africa near 9/25. The run ends on 10/4 with a H recurving NNE near 30N, 75W. Climowise, this FV3 scenario is quite possible.

Oddly enough at the end of it's run there is a system to it's east that helps create a weakness for the recurve, that can actually be backtracked all the way to another piece of energy breaking off of Florence's remnants in the Atlantic... you can't make this stuff up

 

[BHS1975]

Oddly enough at the end of it's run there is a system to it's east that helps create a weakness for the recurve, that can actually be backtracked all the way to another piece of energy breaking off of Florence's remnants in the Atlantic... you can't make this stuff up

Flo was like oh hell no I ain’t go out that easy.


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[pcbjr]

Lordy I've been looking for something upbeat to share today; all to no good; so here's this, which is just the opposite of preconceived intentions looking at Africa and the mess out in front ... but it's weather ...

 

[BHS1975]

Lordy I've been looking for something upbeat to share today; all to no good; so here's this, which is just the opposite of preconceived intentions looking at Africa and the mess out in front ... but it's weather ...

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ITCZ looks active


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[pcbjr]

ITCZ looks active


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...and though by no means a forecast (and most certainly not a wish), other than some dust, conditions are not too bad for something to begin trying to spin (like we really need another tropical thread) ...

 

[GaWx]

^ However, fwiw, the new 12Z EPS suggests little chance for a CONUS hit over the next 2 weeks. OTOH, the GEFS keep showing something in the W Caribbean though as Webb has said this could be due to a GFS bias there.

Maybe we'll get a long much deserved break as so many want. Who knows?

Up next Happy Hour GFS/GEFS fwiw.

 

[pcbjr]

^ However, fwiw, the new 12Z EPS suggests little chance for a CONUS hit over the next 2 weeks. OTOH, the GEFS keep showing something in the W Caribbean though as Webb has said this could be due to a GFS bias there.

Maybe we'll get a long much deserved break as so many want. Who knows?

Up next Happy Hour GFS/GEFS fwiw.

Larry,
Was just a daily muse ... and a tad bit of spice ...
Phil

 

[GaWx]

Larry,
Was just a daily muse ... and a tad bit of spice ...
Phil

I know, So, is mine. Nobody knows what will or won't happen. That's what makes this hobby interesting enough to generate so much discussion.

 

[ForsythSnow]

And now, there are 0 active storms in the Atlantic.

 

[Snowfan]

And now, there are 0 active storms in the Atlantic.

Not for long. There is a area in the northeastern Atlantic that could develop into a tropical or subtropical depression.

 

[stormcentral]

CMC 12Z coastal low Sept 25, 2018
Heavy rainfall 4-10" indicated idk

 

[RBR71]

View attachment 6483

CMC 12Z coastal low Sept 25, 2018
Heavy rainfall 4-10" indicated idk

It's definitely an outlier and what do the Canadians know about the tropics?

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[ForsythSnow]

It's definitely an outlier and what do the Canadians know about the tropics?

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The energy shows up on all the models so you can tell there is something, but the CMC seems to make it stronger than the other models, which just have moisture. Of course the CMC shows more tropical systems than the other models in the MR and LR, so it's definitely an outlier.

 

[RBR71]

Yeah that's basically what I meant by being an outlier. It is concerning to see however that would be Devastation in that area.

The energy shows up on all the models so you can tell there is something, but the CMC seems to make it stronger than the other models, which just have moisture. Of course the CMC shows more tropical systems than the other models in the MR and LR, so it's definitely an outlier.

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[Brent]

And now, there are 0 active storms in the Atlantic.

for a brief moment last night the NHC had zero storms in the EPAC and Atlantic after having 6 or 7 last week

Then some TD formed in the EPAC this morning that has no future lol

 

[MichaelJ]

Seems like the ITCZ is suppressed way south, around Latitude 5 degrees North which makes it extremely unlikely of Tropical formation in the East or Central Atlantic, perhaps one makes it into the gulf but formation would have to wait until it gains more Latitude

 

[stormcentral]

Models stall florence remnants near Bermuda or southward for a week

 

[GaWx]

Models stall florence remnants near Bermuda or southward for a week

A portion of the remnants of Flo (call it Flo’s baby) continue to show up on all models moving SE toward Bermuda today before making a clockwise turn back to westerly this weekend as it becomes positioned below a 200 mb high that moves offshore in the W Atlantic tomorrow and sticks around near Bermuda into early next week. This disturbance then approaches the SE US coast Mon before either recurving just offshore or coming into the coast by Tue. This general scenario has been showing up on model consensus for many days now only as a weak system. Still, no model at this time brings it in as more than a trough that ups shower activity. So, conditions aren’t expected to be favorable tropically. However, shear doesn’t appear to be strong as there are no westerlies nearby due to this strong 200 mb Bermuda high to Flo’s baby’s north keeping the westerlies away for the next 4-5 days and instead providing easterlies. Also, SSTs off the SE coast are still very warm (midsummer warmth of 29-30C). So, this will probably get some attention at the BBs over the weekend whether or not warranted.

 

[RBR71]

A portion of the remnants of Flo (call it Flo’s baby) continue to show up on all models moving SE toward Bermuda today before making a clockwise turn back to westerly this weekend as it becomes positioned below a 200 mb high that moves offshore in the W Atlantic tomorrow and sticks around near Bermuda into early next week. This disturbance then approaches the SE US coast Mon before either recurving just offshore or coming into the coast by Tue. This general scenario has been showing up on model consensus for many days now only as a weak system. Still, no model at this time brings it in as more than a trough that ups shower activity. So, conditions aren’t expected to be favorable tropically. However, shear doesn’t appear to be strong as there are no westerlies nearby due to this strong 200 mb Bermuda high to Flo’s baby’s north keeping the westerlies away for the next 4-5 days and instead providing easterlies. Also, SSTs off the SE coast are still very warm (midsummer warmth of 29-30C). So, this will probably get some attention at the BBs over the weekend whether or not warranted.

Looks somewhat decent on satellite and you could almost argue there is a llc that is being displaced to the west of the deep convection, I guess it's an elongated low pressure but for something that's not even mentioned by NHC it looks kind of organized.

 

[RBR71]

The ICON actually keeps a very weak lopsided system as it approaches the coast... I just hope it stays lopsided and offshore, no one in NC needs the rain

 

[GaWx]

The Happy Hour GEFS has nothing like GEFS runs of recent days in the W Caribbean end of month to start of Oct. If even the 18Z has very little, I think we can rest a bit easier than we were for the time being. But keep in mind that the peak of W Caribbean genesis doesn’t even start petering out til the last week or so of October.

 

[RBR71]

This map is far more ominous looking than it is in reality.... I don't see anything other then the potential out in the central Atlantic, having much of a chance to develop

 

[GaWx]

This map is far more ominous looking than it is in reality.... I don't see anything other then the potential out in the central Atlantic, having much of a chance to develop

And that central Atlantic one is expected to meander way out in the middle of the ocean for the next 14 days! Only the Azores have to worry about this one.

The one just off Africa may not do much for awhile. We’ll see. But it is at a very low latitude (6.5 or so), which gives it a good chance to make it to near the Lesser Antilles in about a week. Will it then develop and become a Caribbean Cruiser? Who knows? No model has it strong then but we’ll need to make sure the models are correct in keeping it weak through then.

 

[DaculaWeather]

Too much dust and too much shear for anything major to develop right now.




Links to the images:
SAL - http://www.daculaweather.com/4_sal_strength.php
Shear: http://www.daculaweather.com/4_shear_forecast.php

 

[RBR71]

And that central Atlantic one is expected to meander way out in the middle of the ocean for the next 14 days! Only the Azores have to worry about this one.

The one just off Africa may not do much for awhile. We’ll see. But it is at a very low latitude (6.5 or so), which gives it a good chance to make it to near the Lesser Antilles in about a week. Will it then develop and become a Caribbean Cruiser? Who knows? No model has it strong then but we’ll need to make sure the models are correct in keeping it weak through then.

The ICON does develop that wave just off Africa as it approaches the Lesser Antilles, no surprise the CMC develops it also then turns it north to be absorbed by that mega low in the central Atlantic that apparently will be there for weeks gobbling up anything that comes near it, the GFS shows some signs of development but never does anything with it....

 

[DaculaWeather]

Time is starting to run out for a tropical systems in the Gulf. The probabilities started their steep drop around the middle of September.

 

[Arcc]

12z GFS is wall to wall SE ridge. Anything that gets or forms beneath it is a easy forecast hit.

 

[Henry2326]

12z GFS is wall to wall SE ridge. Anything that gets or forms beneath it is a easy forecast hit.

Navgem, CDC, and Icon setting up the same ridge. 12z GFS3 runs the low up the east coast in a familiar pattern. Any opportunity for the low to convert to tc?

 

[Brick Tamland]

WRAL saying the disturbance off the coast might bring us some moisture, but acting like it is not a big deal. But then I see this from the NHC.

Even though it's the 1st day of fall, the Atlantic remains active with tropical systems. Tropical Storm Kirk, Depression 11 and two disturbances are active via the National Hurricane Center. Keep an eye on disturbance 1, south of Bermuda, which has a medium chance for development, may track west and perhaps approach the Southeast/Mid-Atlantic coast next week with hopefully minimal hazards.

 

[Henry2326]

1 hour ago from NHC......how close is "moving by"? Feels like dejavu!

Elsewhere over the Atlantic basin, a broad area of low pressure located between Bermuda and the Bahamas continues to produce limited shower and thunderstorm activity. The strong upper-level winds currently affecting the system are expected to diminish, and this could favor some development during the next couple of days. The low is forecast to move westward and west-northwestward at about 10 mph over the southwestern Atlantic Ocean. However, Tuesday or Wednesday, upper-level winds are forecast to strengthen again, likely limiting the development. By then, the system is expected to be moving by the southeastern coast of the United States.

 

[RBR71]

Seems these days TC's either want to last forever or pop up one day and gone in the next 2 or 3, it's like the political climate we live in today, only extremes no in between's Lol

 

[SD]

Gotta watch the Caribbean over the next few days to see if anything can get going. A track toward the US would seem somewhat possible if development occurred

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[GaWx]

Gotta watch the Caribbean over the next few days to see if anything can get going. A track toward the US would seem somewhat possible if development occurred

The 12Z ICON is going at hour 180 with a potentially VERY dangerous for US east coast H position in Bahamas considering the strong mid-Atlantic states ridge to the north that is then hardly budging as well as SSTs in Bahamas and surrounding areas that are well above normal and close to typical late August/early Sep maxima due to extreme warmth this entire month. Whereas this is not as common as the W Caribbean to Gulf track for significant US H hits in Oct, they are not that rare and do happen from time to time such as did Sandy, Matthew, and Hazel among others. I have to wonder just as I wondered for Florence if these very warm waters there and also in the W Atlantic further north are going to make it more difficult than normal to dislodge any ridging on or near the US east coast. Also, when I get a chance, I want to check tracks of past early to mid Octobers TCs coming out of the Caribbean during El Ninos vs non-Ninos.

I expect that Leslie’s track, which is largely controlled by ridges/troughs near her, will play a significant role.

By the way, two runs of the FV3 yesterday had a Carolina hit (pretty close to NC/SC border) for those who didn’t see them.

 

[BHS1975]

Yeah very concerning. If Hazel happened today no internet or power for weeks.


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[GaWx]

Yeah very concerning. If Hazel happened today no internet or power for weeks.

I think that one feature that shouldn’t be overlooked is for a residual slight Leslie weakness being left behind for a time south of Bermuda even after she finally moves NE. You can see this on 6Z and earlier GFS and FV3 runs. This residual slight 500 mb weakness may delay a rebuild of ridging south of Bermuda long enough to maintain a steering influencing weakness there long enough to be the primary reason any Caribbean low may initially lift out E of FL instead of into the Gulf. Remember that it often doesn’t take much of a 500 mb weakness to attract a TC. Even something as subtle as this can easily do it. Example: Anyone remember Jose’s residual weakness off the NE US that was just enough to keep Maria from threatening NC like some models had been showing?

Meanwhile, the 12Z GFS is the 1st in at least awhile not having the primary low go up east of FL. There is a very weak low that was headed that way, but it then gets trapped under the rebuilding MidAtlantc states to Bermuda high and is then shunted westward into the GOM though it never gets that strong.

 

[GaWx]

The 12Z FV3 illustrates quite well the forecasting nightmare that may be ahead and may last a long time. The run once again leaves behind a residual Leslie related 500 mb weakness long enough to attract Caribbean energy up E of FL on 10/9 instead of into the Gulf. Afterward, the very strong MidAtlantic states ridge gets established and traps it just off the SE US coast 3 days before finally moving NE OTS 10/13-14.