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Tropical 2019 Atlantic Hurricane Season & Model Discussion

GaWx

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Well, while we were sleeping: check out the 0Z EPS. It is much more active with the W Caribbean system vs the last 3 days of runs. It is actually the 3rd most active of any EPS run as I count 10 sub 999 members (20%)! The most on any prior run was 12 (24%), which was on the 12Z Sunday (10/6) run. The 2nd most was the 11 (22%) on the 12Z Saturday (10/5) run. The prior 3rd highest had been the 7 (14%) of the 0Z Mon (10/7) run. And the 12Z from yesterday was one of the quietest with only 2 (4%)! Actually, all 5 of the runs from 12Z Mon through 12Z Wed were quiet. And now all of the sudden, boom, relatively speaking!
A whopping 9 of these 10 sub 999s hit the US (18%) with 6 of them hitting as a H (12%), with as many as 5 of these 6 possibly major. Of the 9 sub 999 US hits, 5 hit LA (3 on 10/20, 1 on 10/21, 1 on 10/22), 2 hit the AL-FL Panhandle corridor (10/18 and 10/20), and 2 hit W FL (10/18 and 10/23). I’m pretty sure these are the highest hit numbers on the US of ANY run!
What’s really weird is that the 0Z and 6Z GEFS are tied for THE quietest runs as there are ZERO sub 999 members!! So, how are forecasters going to handle this??
 

GaWx

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12Z EPS: I counted 8 (16%) sub 999 vs the 10 of the 0Z, making it the 4th largest number of sub 999 for any EPS. The 0Z was in 3rd place with its 10 (20%). I counted 4 Hs (8%) and 2 others that were at least high end TS. All 4 Hs (8%) hit the US vs 6 (12%) on the 0Z in addition to about 4 others that were 1004 or lower for a total US hit rate of 8 of the 51 (16%) vs the 9 (18%) of the 0Z, which were all sub 999. The 8 of 51 (16%) US hit rate is likely at or tied for the 2nd highest of any EPS just behind the 0Z's 9 of 51, which is I think is very likely the most of any.
Of the 4 H hits, 3 hit somewhere in E LA-W FL Panhandle corridor (10/19-20) and 1 hit W FL on 10/23.
 
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GaWx

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1. Landfall of 1001 mb on 10/20 on the 0Z GFS.
2. Landfall of cat 2ish H W FL Pan on 10/19 on 0Z CMC (take with a humongous grain):

 
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BirdManDoomW

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1. Landfall of 1001 mb on 10/20 on the 0Z GFS.
2. Landfall of cat 2ish H W FL Pan on 10/19 on 0Z CMC (take with a humongous grain):

Lol temps in the 20s that scour out just in time. Not far off from some initial “mix to rain” for Virginia too. I call bs on hurricane or temps.
 

GaWx

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Regarding the W Caribbean system on the12Z EPS: I count of the 51 members 11 (22%) at 1004 mb or lower and 9 (18%) 1000 mb or lower.

Out of 11, these 8 (16%) hit the US:
- 1 clear-cut H: hits AL/W Panhandle of FL on 10/20
- 4 strong TSs: FL Pan on 10/18, E LA on 10/19, N TX on 10/20, and E LA on 10/21
- 3 weaker TS or TD: W FL on 10/20, S TX on 10/20, E La on 10/21
 

GaWx

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Believe it or not, the tropical wave still inside Africa may not be the only CV wave that could become a TC. Although with a somewhat low probability of development as of now but of potentially much more concern should it develop, there's a sleeper wave not yet mentioned by the NHC located ~500 miles W of the CVs moving WSW. Although it would be quite unusual so late, the 12Z model consensus (Euro, UKMET, GFS, ICON, CMC) brings at least the vorticity/moisture from this all of the way across to near or north of the L Antilles by a week from now! Some models even form a weak sfc low from this by the end of this weekend. Going out further, the Euro and CMC takes this energy to just north of Hisp at 240 and in a position that could threaten the SE US due to a strong ridge to its north. There are actually 2 EPS members out of 51 that hit FL on 10/23. Also, out of 21 CDN ensemble members, 5 hit or skirt the SE US: 4 skirt some of the SE US coast 10/22-4 and 1 goes around and then hits SW FL on 10/26. In addition, a 6th member is still drifting westward over Cuba and in a threatening position at 384 (10/27).
Here are some maps:

1. 12Z UKMET has concentrated 850 vorticity located near 10N, 44W Sun evening:

2. 12Z UKMET then moves this WNW to just E of the Windwards next Thu morning (also note the track up to that point):

3. 12z CMC 240 has the low between Hisp and Cuba underneath a strong ridge moving WNW:

4. 12Z CMC ensembles hour 276: note the 4 members near or just E of FL (Also, 2 later members: one hits Cuba and other SW FL)
 
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Believe it or not, the tropical wave still inside Africa may not be the only CV wave that could become a TC. Although with a somewhat low probability of development as of now but of potentially much more concern should it develop, there's a sleeper wave not yet mentioned by the NHC located ~500 miles W of the CVs moving WSW. Although it would be quite unusual so late, the 12Z model consensus (Euro, UKMET, GFS, ICON, CMC) brings at least the vorticity/moisture from this all of the way across to near or north of the L Antilles by a week from now! Some models even form a weak sfc low from this by the end of this weekend. Going out further, the Euro and CMC takes this energy to just north of Hisp at 240 and in a position that could threaten the SE US due to a strong ridge to its north. There are actually 2 EPS members out of 51 that hit FL on 10/23. Also, out of 21 CDN ensemble members, 5 hit or skirt the SE US: 4 skirt some of the SE US coast 10/22-4 and 1 goes around and then hits SW FL on 10/26. In addition, a 6th member is still drifting westward over Cuba and in a threatening position at 384 (10/27).
Here are some maps:

1. 12Z UKMET has concentrated 850 vorticity located near 10N, 44W Sun evening:

2. 12Z UKMET then moves this WNW to just E of the Windwards next Thu morning (also note the track up to that point):

3. 12z CMC 240 has the low between Hisp and Cuba underneath a strong ridge moving WNW:

4. 12Z CMC ensembles hour 276: note the 4 members near or just E of FL (Also, 2 later members: one hits Cuba and other SW FL)
Icon appears to be aligning with UKMET.

icon_mslp_wind_atl_60.png
 

GaWx

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There seemed to be a bit of a low level circ per the last vis pics. But what IR loops suggest to me is moderate SW shear. Per models, SW to W 200 mb winds will be present through the entire trek toward the Lesser Antilles, which I assume is common in mid Oct and is probably why activity out there this late is typically limited despite very warm SSTs. The shear isn’t progged to get high but it is likely high enough to be the reason models are keeping this to no more than a weak sfc reflection all the way to the LAs.

This sleeper wave will be interesting to follow next week due to the unanimous model support to get it to the western basin. Will there then be much of anything left to it then? The Euro suite, the best out there, says no. Also, GEFS is very quiet. So, despite the 12Z CMC’s Central Caribbean H at the end of its run, I’d say genesis chances remain low at least for now. But this is certainly going to be watched closely as it does appear to have a compact low level circulation right now. Shear had better not get too low or there could be a surprise.
 
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There seemed to be a bit of a low level circ per the last vis pics. But what IR loops suggest to me is moderate SW shear. Per models, SW to W 200 mb winds will be present through the entire trek toward the Lesser Antilles, which I assume is common in mid Oct and is probably why activity out there this late is typically limited despite very warm SSTs. The shear isn’t progged to get high but it is likely high enough to be the reason models are keeping this to no more than a weak sfc reflection all the way to the LAs.

This sleeper wave will be interesting to follow next week due to the unanimous model support to get it to the western basin. Will there then be much of anything left to it then? The Euro suite, the best out there, says no. Also, GEFS is very quiet. So, despite the 12Z CMC’s Central Caribbean H at the end of its run, I’d say genesis chances remain low at least for now. But this is certainly going to be watched closely as it does appear to have a compact low level circulation right now. Shear had better not get too low or there could be a surprise.
To your point about wind shear.....


 

GaWx

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Opportunity galore on 06z GFS......one week apart. The second one appears to be the sleeper wave.


View attachment 24420
Henry,
I’m trying to figure this 6Z GFS run out, which is similar to the 0Z GFS. It appears that when the sleeper wave gets to near the Lesser Antilles and slows, there may be a northeastern extension of this wave that may be combining with additional energy that comes in from its east. This part is hard to decipher.

Meanwhile, the low level circulation portion of this sleeper wave looks like it is rather vigorous and stronger near 10-11N, 42-44W, on this morning’s vis loops with increased convection including some lightning. Shear may be lessening. Watching this just in case. IF this were to do the unexpected and actually strengthen into a TD soon and then come into the Lesser Antilles from that position, it would do what virtually no other system has done this late in the season on record from near this position as I see only one analog on this map doing something similar:

 
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I would be paying little more attention to the gulf end of this week. 6z and 12z gfs has a very weak system pulling up towards northern gulf coast. Other models has something as well.
 
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