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Tropical Global Model Runs Discussion 2017

GaWx said:
The 18Z GEFS does it again with many hits on FL and the NE Gulf 10/3-8. Of course this could be a false signal but even the 12Z EPS has some hint of it.
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What in the wide, wide world of sports is a going on here? Today's 18Z GEFS is the 3rd 18Z GEFS in a row showing numerous members with western Caribbean TC genesis in the first week of October!! No other GEFS run in between these 3 runs has had much of anything! That is really, really strange. Come to think of it, I think there have been similar instances of sudden heavy signals of TC activity in the western part of the basin that were limited to some past 18Z GEFS runs earlier this season. What gives about the Happy Hour GEFS? Isn't there a Tshirt that says "We toss" in regard to the 18Z GFS? Deltadog used to talk about a drunk
model a lot though that may have been the "drunk doc". Maybe the problem is that the 18Z GEFS is drunk?

In all seriousness, is it possible that there is some kind of programming glitch in the 18Z GEFS? Is that possible? I'm going to try to start following and possibly even posting more regularly about future 18Z GEFS runs as regards the tropics to see if there really does appear to be a problem.
 
GaWx said:
In all seriousness, is it possible that there is some kind of programming glitch in the 18Z GEFS? Is that possible? I'm going to try to start following and possibly even posting more regularly about future 18Z GEFS runs as regards the tropics to see if there really does appear to be a problem.
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Maybe we need to all keep track of every run and document this. Perhaps this can even become a short term study to see which run is most accurate based off of time of day, since we all know the 18Z GFS is cursed or something lol.
 
From a pro met at Storm2K in response to me about my concern about the 18Z GEFS, there apparently really is something to the 18Z GEFS (and GFS) being overly biased toward TC genesis in the western basin:

"I've heard that there might be an actual bias in the 18z run relating to how the model is initializing during near-peak solar radiation in this part of the world. I can't remember the exact details or if it's been shown to occur in other parts of the world during other model runs.

Whatever is causing it, there has seemed to be a bias in over-forecasting TCs in the long range of the 18z GFS/GEFS. The programming doesn't change, but how the model initializes millions of data points each run is critical. If there is even a small bias in how the GFS starts the 18z run, it could grow into large errors over time."

Fascinating stuff!
 
I just went back to Tropical Tidbits and see that they still have GEFS runs going back to 18Z of 9/16. If one first chooses the 384 hour map for the 9/16 GEFS run (which is the map for 18Z of 10/2) and then repeatedly clicked on "next run", one can clearly see a strong tendency for the 18Z GEFS mean having lower pressures in/near the W Caribbean as of 18Z on 10/2 pretty much every run as compared to the nearby 0Z, 6Z, and 12Z runs! I'll never think of the 18Z GFS suite the same way again when it is on its own with a strong TC genesis signal in the western basin...well until if/when this bias toward too much TC activity apparently due to 18Z being the time near peak solar insolation is fixed.

Dang, I thought the "We toss" of the 18Z GFS was just being silly. Now I know why as there's science behind it!
 
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Taking the above further, would the 6Z tend to underdo TC genesis chances due to
it being in the middle of the night/zero solar insolation? Also, would the 12Z runs tend to show less activity than the 0Z runs due to it being a cooler time of day than 0Z in the western basin even though solar insolation is similar? Finally, do other models show these same biases?
 
GaWx said:
I just went back to Tropical Tidbits and see that they still have GEFS runs going back to 18Z of 9/16. If one first chooses the 384 hour map for the 9/16 GEFS run (which is the map for 18Z of 10/2) and then repeatedly clicked on "next run", one can clearly see a strong tendency for the 18Z GEFS mean having lower pressures in/near the W Caribbean as of 18Z on 10/2 pretty much every run as compared to the nearby 0Z, 6Z, and 12Z runs! I'll never think of the 18Z GFS suite the same way again when it is on its own with a strong TC genesis signal in the western basin...well until if/when this bias toward too much TC activity apparently due to 18Z being the time near peak solar insolation is fixed.

Dang, I thought the "We toss" of the 18Z GFS was just being silly. Now I know why as there's science behind it!
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Larry - the 18 Z is like eating left-over breakfast and lunch all over again, then immediately eating supper on top, and wondering afterwards why the system is upset ...
or so it seems IMHO ... o_O
Phil
 
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Like clockwork, the 0Z GEFS has much weaker (though not none) W Caribbean TC action in the means vs the 18Z GEFS. This was almost 100% predictable based on what we learned this evening about the 18Z. For the same reason, I predict that the next very active GEFS will be the next 18Z. Let's see what it will show.
 
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The 6Z GEFS mean, also like clockwork, shows very few sub 1,000 mb TCs in/near the W Caribbean in early Oct. The quiet contrast to last evening's (and the last week or so of 18Z GEFS runs) is almost laughable. I'm still looking for another active 18Z GEFS run this evening as silly as that sounds. I wish there were a way this could be fixed.

Meanwhile, the 0Z EPS has about 30% of its members with sub-1,000 mb TCs form in/near the W Caribbean during early Oct., a respectable signal, an increase over the 20% of yesterday's 12Z EPS, way more active than the 6Z GEFS run, and more active than the 0Z GEFS run on a % basis. However, it is nowhere near as active %wise as the 18Z GEFS run, of course.
 
The size comparison between Lee and Maria is crazy. There is the chance that later on today or tomorrow that Lee cold exceed Maria's winds too.
Lee_And_Maria_Sep242017morning.jpg
 
I just looked at the Tropical Tidbits GEFS runs again for 18Z on 10/2 and sure enough the 6Z GEFS was always the quietest run!! So, the 18Z GEFS was by far the most active, the 6Z was by far the least active, and the 0Z/12Z were in between every single day for the week's worth of runs available at the site.

So, my hypothesis is now that the 18Z GEFS is biased too active, the 6Z GEFS is biased too inactive, and the 0Z/12Z are closest to accurate/least biased.
 
The 12Z GEFS is much more active than the quiet biased 6Z GEFS and even a good bit more active than the 0Z GEFS in/near the western Caribbean in early Oct. The only recent runs more active are the last few 18Z GEFS runs (no surprise there). So, I consider this a legitimately somewhat stronger signal for development. Looking forward to seeing the Happy Hour GEFS, which I fully expect to be very active due to high activity bias and even a good bit more active than this relatively active 12Z GEFS.
 
Fwiw, the 12Z Euro has a weak (1006 mb), broad low in the NW Caribbean about 150 miles south of west-central Cuba moving slowly northward. It appears to then be slowly strengthening amidst low shear.
This is just something to keep in the back of your mind for potential in early October.
 
GaWx said:
Fwiw, the 12Z Euro has a weak (1006 mb), broad low in the NW Caribbean about 150 miles south of west-central Cuba moving slowly northward. It appears to then be slowly strengthening amidst low shear.
This is just something to keep in the back of your mind for potential in early October.
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Dadgum it Larry ... too much on the table already ... :confused:
 
GaWx said:
Fwiw, the 12Z Euro has a weak (1006 mb), broad low in the NW Caribbean about 150 miles south of west-central Cuba moving slowly northward. It appears to then be slowly strengthening amidst low shear.
This is just something to keep in the back of your mind for potential in early October.
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pcbjr said:
Dadgum it Larry ... too much on the table already ... :confused:
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That area is notorious for pressure bombs and its been virtually untouched this season :eek:
 
Looking at the 11-15 day 12Z EPS in/near the W Caribbean/Gulf/just off the SE US coast, it is somewhat more active than the already fairly active 0Z EPS for the 50 members as a whole with 10 (20%) potential Hs or sub 990 mb vs 9 (18%) on the 0Z EPS; and about 22/44% potential TS+ (sub 1000 mb) vs ~15 (30%) on the 0Z EPS and ~10 (20%) on yesterday's 12Z EPS.

Regarding the 10 apparent Hs, 1 hits N MX, 1 hits TX/LA line, and 2 hit E LA/MS. Regarding the other 6 as of day 15: 1 is about to hit LA, 3 are about to hit W FL, 1 is still well out in the W GOM moving slowly N, and 1 is moving NE well out in the open Atlantic.

Next up: the often over-dramatic 18Z GEFS (and 18Z GFS). I expect to see strong activity on this considering the rather significant signal on the 12Z GEFS, the pretty strong signal on the 12Z EPS, and the 18Z GEFS bias toward activity.
 
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GaWx said:
Looking at the 11-15 day 12Z EPS in/near the W Caribbean/Gulf/just off the SE US coast, it is somewhat more active than the already fairly active 0Z EPS for the 50 members as a whole with 10 (20%) potential Hs or sub 990 mb vs 9 (18%) on the 0Z EPS; and about 22/44% potential TS+ (sub 1000 mb) vs ~15 (30%) on the 0Z EPS and ~10 (20%) on yesterday's 12Z EPS.

Regarding the 10 apparent Hs, 1 hits N MX, 1 hits TX/LA line, and 2 hit E LA/MS. Regarding the other 6 as of day 15: 1 is about to hit LA, 3 are about to hit W FL, 1 is still well out in the W GOM moving slowly N, and 1 is moving NE well out in the open Atlantic.

Next up: the often over-dramatic 18Z GEFS (and 18Z GFS). I expect to see strong activity on this considering the rather significant signal on the 12Z GEFS, the pretty strong signal on the 12Z EPS, and the 18Z GEFS bias toward activity.
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Thanks for the info! Meanwhile, here comes the 18Z GEFS and it continues to hold the streak as it seems.
 
ForsythSnow said:
Thanks for the info! Meanwhile, here comes the 18Z GEFS and it continues to hold the streak as it seems.
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Yes, indeed, the 18Z GEFS streak of being by far the most tropically active of the GEFS runs in the western basin in early Oct. continues. The predictability of it is kind of funny. Practically every member becomes a TS+ and 50%+ become a H with several monster Hs. Contrast to the typical quietest GEFS, the 6Z, which had only one H and a few TSs.

So, there will practically definitely be a big downtick from this 18Z GEFS on tonight's 0Z GEFS and likely a further downtick on the 6Z GEFS. But don't let that fool you into thinking these downticks would mean much of anything.
 
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I'm going to restate what I have been saying about western ATL basin TC genesis/development GEFS biases in case some are not following what I'm saying:

- the 18Z GEFS has day after day been the most active GEFS run BY FAR. A theory has been presented at Storm 2K that this is due to 18Z being the time of max solar insolation in/near the western ATL basin.
- the 6Z GEFS has day after day been the least active GEFS run BY FAR.
- the 0Z/12Z GEFS have been in between the surrounding 18Z/6Z GEFS every time.

With a repeating pattern like this, there are obvious biases that need to be considered when looking at each GEFS run as randomness definitely doesn't explain this. When I see the 18Z GEFS, I assume it is too active. When I see the 6Z GEFS, I assume it is too quiet. The 0Z/12Z GEFS seem to be the most reasonable to me of the 4 runs since they're in between.
 
In the western ATL basin during 10/4-9, today's 0Z EPS wasn't as active as yesterday's 12Z EPS though it still had notable activity:

Out of 50 runs, 9 (18%) were Hs vs 10 the prior run and 9 two runs ago. 3 hit W FL as Hs 10/7-8, 2 hit the Bahamas 10/7-9, 1 hit MS/AL 10/7, 1 hit LA 10/9, and the other 2 were still in the middle of the GOM moving slowly N/NW at the end of the run (10/10). I counted ~15 (~30%) TS+ vs ~22 (~44%) TS+ the prior run and ~15 (~30%) TS+ two runs ago.
 
At hour 216, the 12Z Euro develops a NW Caribbean surface low that moves NNW to just south of west central Cuba at hour 240.
 
The 11-15 day 12Z EPS is quite active and more active than the 0Z EPS in the western Caribbean/Gulf! More details to come once I've had time to examine the individual members. I can already tell you that the 240 hour 12Z EPS has many members with a low between 1004 and 1000 mb in the W Caribbean similar to the 12Z Euro op.
 
12Z EPS 50 members: the most active yet

Hurricanes: 13 H (26%) vs 9, 10, 9 three prior runs; 5 of the 13 H hit W FL 10/8-10 (panhandle or SW peninsula) while 3 others are threatening out in the Gulf to hit W FL ~10/11-2. 1 of these SW FL hits later hits NC as a H. Other 5 Hs: 2 hit SC and 3 move NE offshore the SE US while a H

TS+: ~25 of 50 or ~50% vs 30%/44%/30% prior 3 runs

Primary movement: genesis W Caribbean or S GOM with initial movement NW to N followed by turn to NE into NE GOM/FL or S of FL to offshore SE US though 2 of those curve back into SC
 
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GaWx said:
12Z EPS 50 members:

Hurricanes: 13 H (26%) vs 9, 10, 9 three prior runs; 5 of the 13 H hit W FL 10/8-10 (panhandle or SW peninsula) while 3 others are threatening out in the Gulf to hit W FL ~10/11-2. 1 of these SW FL hits later hits NC as a H. Other 5 Hs: 2 hit SC and 3 move NE offshore the SE US while a H

TS+: ~25 of 50 or ~50% vs 30%/44%/30% prior 3 runs

Primary movement: genesis W Caribbean or S GOM with inital movement NW to N followed by turn to NE into NE GOM/FL or S of FL to offshore SE US though 2 of those curve back into SC
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Well, it sounds like TCG is coming in the next week or so. I expect the numbers to keep climbing up as we get closer. It is getting to be that time of year. What worries me is that untapped region between the Yucatan and Cuba.The potential for a monster is there.
atlpot.png
 
GaWx said:
12Z EPS 50 members: the most active yet

Hurricanes: 13 H (26%) vs 9, 10, 9 three prior runs; 5 of the 13 H hit W FL 10/8-10 (panhandle or SW peninsula) while 3 others are threatening out in the Gulf to hit W FL ~10/11-2. 1 of these SW FL hits later hits NC as a H. Other 5 Hs: 2 hit SC and 3 move NE offshore the SE US while a H

TS+: ~25 of 50 or ~50% vs 30%/44%/30% prior 3 runs

Primary movement: genesis W Caribbean or S GOM with initial movement NW to N followed by turn to NE into NE GOM/FL or S of FL to offshore SE US though 2 of those curve back into SC
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Working too much on this end (which is a good thing) - Thanks, Larry, for the continued updates. Without them I'd be lost! If you see anything ominous before the 9th, please PM me with a heads-up!
Best!
Phil
 
pcbjr said:
Working too much on this end (which is a good thing) - Thanks, Larry, for the continued updates. Without them I'd be lost! If you see anything ominous before the 9th, please PM me with a heads-up!
Best!
Phil
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YW. The 12Z EPS says that ~80% of the 25 members that become a TS+ hit the CONUS from the Gulf (centered on FL from Panhandle south to south tip/Keys) while most of the other 20% slip just SE of S FL while moving NE. A few curve back into the SE coast, mainly SC/NC. I saw virtually none that went west and got buried in Central America.

The highest threat period is 10/6-12. So, we may be following this potential threat for quite a long time should it materialize.
 
GaWx said:
I'm going to restate what I have been saying about western ATL basin TC genesis/development GEFS biases in case some are not following what I'm saying:

- the 18Z GEFS has day after day been the most active GEFS run BY FAR. A theory has been presented at Storm 2K that this is due to 18Z being the time of max solar insolation in/near the western ATL basin.
- the 6Z GEFS has day after day been the least active GEFS run BY FAR.
- the 0Z/12Z GEFS have been in between the surrounding 18Z/6Z GEFS every time.

With a repeating pattern like this, there are obvious biases that need to be considered when looking at each GEFS run as randomness definitely doesn't explain this. When I see the 18Z GEFS, I assume it is too active. When I see the 6Z GEFS, I assume it is too quiet. The 0Z/12Z GEFS seem to be the most reasonable to me of the 4 runs since they're in between.
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Yeah, I've noticed that watching winter threats. Someone always throws out the "no statistical difference line" but I've noticed that 6z will always be weaker and less precip and 18z is the weenie run.
 
Arcc said:
Yeah, I've noticed that watching winter threats. Someone always throws out the "no statistical difference line" but I've noticed that 6z will always be weaker and less precip and 18z is the weenie run.
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Interesting! I never realized this. I used to think that the "We toss" the 18Z was just to be silly. Not anymore! Speaking of which, it wouldn't be Happy Hour without the presentation of the drunk (thank you Chris for inspiring the use of the word drunk for models) 18Z GEFS. It is no surprise that it is the most active GEFS in the W Caribbean/Gulf since the prior 18Z though it doesn't get really active til days 13-16. I counted about 40% of the members with a hurricane and the vast majority of members with at least a TS. Oh, 18Z GEFS, you really must love the attention!
 
GaWx said:
Interesting! I never realized this. I used to think that the "We toss" the 18Z was just to be silly. Not anymore! Speaking of which, it wouldn't be Happy Hour without the presentation of the drunk (thank you Chris for inspiring the use of the word drunk for models) 18Z GEFS. It is no surprise that it is the most active GEFS in the W Caribbean/Gulf since the prior 18Z though it doesn't get really active til days 13-16. I counted about 40% of the members with a hurricane and the vast majority of members with at least a TS. Oh, 18Z GEFS, you really must love the attention!
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I think there probably isn't much difference in verification with tracks, but the other things I've mentioned definitely are different. I can't tell you how many times I've rode the coaster up from 12z to the 18z weenie run, the down slightly to the 0z run and then heartbreak on the 6z run to only start over a few hours later.
 
GFS tries a bit of east coast of Florida development this run, while the CMC has a storm in the gulf in a few days. The NAM at 6Z had a low around there too. May be worth watching.
Meteorologist1999 said:
22014579_1517733914976304_766522110_n.jpg

Beware For Stalling Fronts off the SE COAST!!!
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This seems to be the area the GFS wants to develop something, though no official NHC TWOs mention it.
 
^ Today's 12Z was a really strange Euro run. It has 3 teeny weeny lows from and move westward into FL 10/1-3. It also has a broader 1012 mb surface low coming in westward to near Fort Pierce around hours 108-114. So, there are 4 different small sfc lows coming westward into FL between 9/30 and 10/3 and then moving out into the Gulf! They all form underneath the big high that camps out over the NE US. This illustrates that being south of a strong surface high often is conducive for a low to form to the south of the high (due to low level convergence causing air to pile up and thus rise). None of them may ever amount to much tropically due to shear. Most likely none of them will become a TC. However, this Euro along with the recent GFS/CMC runs is a reason that the SE US coast, especially FL, should monitor the area just east of FL for surprise tropical mischief just in case.

Even without tropical development, the Euro is showing nonstop strong onshore winds 10/1-4 for the SE US with the strongest centered on NE FL/SE GA. This run has winds just offshore as high as 40 knots just to the north of some of these microlows due to pinching of the gradient. Onshore winds actually continue into 10/6. The Euro may very well be overdone. Regardless, I'm becoming concerned about is coastal flooding near high tides in the CHS-St. Augustine corridor, especially around the full moon 10/4-6, as well as rip currents 10/1-4.

Edit: The 18Z GFS fwiw has onshore winds, sometimes strong, for the SE US coast from CHS southward through FL nonstop 10/1-12! This run may be overdoing things, but the idea of many days in a row of onshore winds has been showing up on a good number of model runs of various models. The highest astronomical tides of the month are 10/6-10, near and just after the full moon. This is something that coastal flooding vulnerable SE coasters might want to keep in the back of their head, especially CHS to St. Augustine.
 
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Folks,
The 00Z GFS has a weak surface low form along a stationary front over Sofla on Friday. Then it moves on Saturday NE to ~100 miles E of Melbourne, where it stalls. Then it moves back SW to Sofla on Sunday followed by a westward move into the Gulf on Monday. It remains weak the entire time.

The CMC (take with a huge grain) has a low form just n of W Cuba on Friday followed by a move NE to just off SW FL, where it stalls and becomes a TC on Saturday. Then on Sunday it moves westward out into the Gulf as a TS and reaches N MX late on Tuesday.
 
An area of disturbed weather associated with a trough of low
pressure is located over the northwestern Caribbean Sea. This
system is forecast to move slowly north-northwestward across Cuba
and the Straits for Florida during the next day or so. Some
development of this system is possible when it moves near the
Florida peninsula or the northwestern Bahamas on Friday or Saturday
before upper-level winds become less favorable early next week.
Regardless of development, this system is likely to produce locally
heavy rainfall over portions of Cuba, southern Florida, the Florida
Keys, and the Bahamas during the next several days.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...low...20 percent.
 
Meanwhile we have this at the end of the 12z euro something else entirely(probably related to the w Carib development the lr gfs has hinted at )
received_1534674223282562.png
 
Storm5 said:
12z eps is very excited
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Further to this: the 12Z EPS has a whopping 16 hurricanes from the 50 members or 32% of them, which is 3 more than any previous run! Also, keep in mind that the EPS members are supposedly run at a lower resolution than the operational meaning SLPs can easily be underdone. Of these 16, 5 hit western FL (Panhandle to Keys/Naples) 10/7-12, 1 hits S TX 10/6, and 1 hits eastern Long Island, NY 10/8.
 
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