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Tropical Global Model Runs Discussion 2018

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.
 
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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.
 
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

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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.
 
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

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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

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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.
 
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....
 
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?
 
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.

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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.
 
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
 
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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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.
 
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.
 
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.
 
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