2018 Tropics: Global Model Runs Discussion (Out to day 16)

[LarryWx]

I think there is enough of a threat now to consider starting a new thread addressing early Oct Caribbean potential TC so it doesn’t clutter up this thread. I mean we don’t even have a discussion thread for this yet as the remnants of Kirk thread may not be the best place to discuss it. Opinions?

Meanwhile, I think that one feature that shouldn’t be overlooked is for a residual Leslie trough being left behind for a time south of Bermuda even after she finally moves NE. This residual trough 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 level weakness to attract a TC. Even something as subtle as this can easily do it. Example: Anyone remember Jose’s residual trough off the NE US that was just enough to keep Maria from threatening NC like some models had been showing?

[gatorcane]

The GFS is finally unstuck and we see monster east coast ridging that turns the Caribbean system west in the Bahamas:

[LarryWx]

The GFS is finally unstuck and we see monster east coast ridging that turns the Caribbean system west in the Bahamas:

https://i.postimg.cc/W3BdDp5v/gfs_z500a_Norm_watl_30.png

Gator and others,
That slight relative 500 mb weakness on your map south of Bermuda, which is residual from Leslie, may very well be a key feature to determine whether any Car low initially gets pulled up E or W of FL. The model runs, including earlier FV3 and GFS runs, pulling it up E of FL are keying on that to delay the rebuilding ridging there long enough to pull it up E of FL before either continuing N and staying E of the US or turning back into the Carolinas.

[toad strangler]

12z GFS splits the vorticity in the Bahamas into two as if chopped in half. One goes W into the GOM towards S TX and Mexico and the other E into the open Atlantic.

[Aric Dunn]

GFS Gobbledygook is back... lol

[Aric Dunn]

the JMA has been very consistent with keeping the KIRK vorticity as the main feature. similar to the ICON again.

[LarryWx]

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.

[gatorcane]

12Z Euro shows more consolidation in the Western Caribbean at 120 hours:

[Aric Dunn]

12z EUro looking much much more realistic out to 120 hours.. typically after this point thing go a crap.

but at least it is one defined circ this time .

[gatorcane]

JMA shows gradual organization heading north:

[toad strangler]

12z Euro splits vorticity at 144

[Aric Dunn]

and more Gobbledygook.. so we wait now until we have some solid convection for models to latch onto. couple more days.

[AutoPenalti]

We won’t receive consistent runs with these monsoonal gyres until an actual center is formed.

Usually these take their sweet time to produce some form of genesis. These really drive me nuts.

[toad strangler]

Euro 500mb setup closes the Leslie weakness much more than GFS

[cycloneye]

I think there is enough of a threat now to consider starting a new thread addressing early Oct Caribbean potential TC so it doesn’t clutter up this thread. I mean we don’t even have a discussion thread for this yet as the remnants of Kirk thread may not be the best place to discuss it. Opinions?

Meanwhile, I think that one feature that shouldn’t be overlooked is for a residual Leslie trough being left behind for a time south of Bermuda even after she finally moves NE. This residual trough 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 level weakness to attract a TC. Even something as subtle as this can easily do it. Example: Anyone remember Jose’s residual trough off the NE US that was just enough to keep Maria from threatening NC like some models had been showing?

I will consult with the fellow admins about your point of a new thread.As you know,we have the two reasons for a new area of interest thread to be up.

1- Incipient disturbance
2- Mentioned in TWO.

[Aric Dunn]

I think there is enough of a threat now to consider starting a new thread addressing early Oct Caribbean potential TC so it doesn’t clutter up this thread. I mean we don’t even have a discussion thread for this yet as the remnants of Kirk thread may not be the best place to discuss it. Opinions?

Meanwhile, I think that one feature that shouldn’t be overlooked is for a residual Leslie trough being left behind for a time south of Bermuda even after she finally moves NE. This residual trough 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 level weakness to attract a TC. Even something as subtle as this can easily do it. Example: Anyone remember Jose’s residual trough off the NE US that was just enough to keep Maria from threatening NC like some models had been showing?

I will consult with the fellow admins about your point of a new thread.As you know,we have the two reasons for a new area of interest thread to be up.

1- Incipient disturbance
2- Mentioned in TWO.

I would say give it until tomorrow. Once there is some sort of coherent convective mass to track.

[LarryWx]

12Z Euro 228 just off SE FL in NW Bahamas. Weak. Then moves NNE (stays off FL) as ridging to north starts to weaken. I’d bet that later maps would have recurved it offshore the US as ridging would very likely keep pulling out/weaken. Different scenario of many possibilities.

[AutoPenalti]

In my opinion, I would wait until a 5-day outlook is put out... there’s just too many variables at the moment with convection that is yet to materialize.

[Aric Dunn]

not the best .... but this is the EURO simulated satellite through 192hrs.. gives a general idea of the mess the EURO has.

[blp]

This could be one explanation why it might struggle. Interesting that it splits off from Leslie and dives SW. I would argue that predicting ULL's out 10 days is tricky and sometimes they can help aide with outflow. Like others have mentioned this one will take it's sweet time and we need to be patient.

 https://twitter.com/AndyHazelton/status/1046475519951347720