Area in the Northwestern Caribbean Sea

[Clearcloudz]

 https://twitter.com/wxmann/status/1564018132288618496

[tolakram]

That's the right trigger but every single model but the GFS takes that overland, and now the GFS is correcting, finally.

[cycloneye]

Northwestern Caribbean Sea:
A trough of low pressure could develop over the northwestern
Caribbean Sea later this week. Environmental conditions could
support some slow development of the system thereafter while it
moves generally west-northwestward over the northwestern Caribbean
Sea and toward the Yucatan Peninsula of Mexico.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...20 percent.

[Cpv17]

I honestly wish this would develop at least into a tropical storm. This hurricane season has been a huge snooze fest. I’m not sure if anything is even going to get in the Gulf the rest of the season at this point.

[tomatkins]

That's the right trigger but every single model but the GFS takes that overland, and now the GFS is correcting, finally.

Yeah - they all seem to have the energy there - its just that most of them seem to develop it in the EPAC instead.

[wxman57]

GFS is slowly coming off of its crack high.

[Frank P]

strange world we live in.

[wxman57]

And with today's 12Z GFS, the phantom storm is gone. GFS will be going to weekly recovery sessions to attempt to get over its addiction to crack.

[Stormcenter]

I mean is the GFS a reliable model at all
this season? It’s down right embarrassing.
Why does the NHC continue to take what
it spits out with so much confidence?

[Ntxw]

I mean is the GFS a reliable model at all
this season? It’s down right embarrassing.
Why does the NHC continue to take what
it spits out with so much confidence?

Part of it I think the GFS is to blame, but part of it is also the season background state. To date generally the reliable models are the ones that don't form anything, because well nothing much have had an easy life. But there were pretty good flags it was phantom given how many have occurred in this region and TC genesis in this format is pretty unlikely. South American TCG it has been spitting out hitting the East Coast to Florida, to TX and then MX. Everyone covered.

[LarryWx]

I mean is the GFS a reliable model at all
this season? It’s down right embarrassing.
Why does the NHC continue to take what
it spits out with so much confidence?

Part of it I think the GFS is to blame, but part of it is also the season background state. To date generally the reliable models are the ones that don't form anything, because well nothing much have had an easy life. But there were pretty good flags it was phantom given how many have occurred in this region and TC genesis in this format is pretty unlikely. South American TCG it has been spitting out hitting the East Coast to Florida, to TX and then MX. Everyone covered.

A few weeks ago, I searched through archived seasons going back many decades and was unable to find even one storm that had a genesis anywhere near Suriname in South America. I posted about that then because one GEFS run had a lot of members doing just that. Of course, that one didn't pan out just like it appears this one won't either.

[Tireman4]

And with today's 12Z GFS, the phantom storm is gone. GFS will be going to weekly recovery sessions to attempt to get over its addiction to crack.

Should the NAVY go into recovery sessions too? LOL

[wxman57]

And with today's 12Z GFS, the phantom storm is gone. GFS will be going to weekly recovery sessions to attempt to get over its addiction to crack.

Should the NAVY go into recovery sessions too? LOL

NOGAPS has had issues for over a decade. I tell my team that if your track matches NOGAPS, then take another look at the data and adjust the track 180 degrees - the other direction. There may be no hope for NOGAPS.

The GFS isn't a bad model, but you have to be VERY wary of spurious storms that only IT can see. This one was a perfect example.

[wxman57]

Here's the history of this Caribbean feature, as told by GFS model forecasts valid 12Z this Sunday over the past week. From major hurricane striking anywhere from the SE U.S. Coast to all along the Gulf Coast, to "never mind". The only consistency is that each run was a completely different solution. Since it was all alone in forecasting this major hurricane, it was easy to spot as a modelcane. Be very careful accepting the latest GFS run at face value. Compare it against the EC, CMC, and ICON. Look for consistency.

[Deshaunrob17]

I mean is the GFS a reliable model at all
this season? It’s down right embarrassing.
Why does the NHC continue to take what
it spits out with so much confidence?

I don’t think any of the models have been great this year.. Euro had it's share of fantasy canes too...

[SoupBone]

Here's the history of this Caribbean feature, as told by GFS model forecasts valid 12Z this Sunday over the past week. From major hurricane striking anywhere from the SE U.S. Coast to all along the Gulf Coast, to "never mind". The only consistency is that each run was a completely different solution. Since it was all alone in forecasting this major hurricane, it was easy to spot as a modelcane. Be very careful accepting the latest GFS run at face value. Compare it against the EC, CMC, and ICON. Look for consistency.

http://wxman57.com/images/GFS-Trend.gif

Well this is laughably bad.

[MGC]

Bye-bye on the 18Z GFS run. Don't know what is wrong with the GFS this season.,,,,MGC

[cycloneye]

The end.

Northwestern Caribbean Sea:
A trough of low pressure could develop over the northwestern
Caribbean Sea later this week. The system however, is likely to
move inland over Central America or the southern portion of
the Yucatan Peninsula before significant development can occur.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...near 0 percent.

[NXStumpy_Robothing]

I mean is the GFS a reliable model at all
this season? It’s down right embarrassing.
Why does the NHC continue to take what
it spits out with so much confidence?

I don't believe the NHC has assigned any area of interest with anything higher than 20% or 30%, indicating quite low confidence in such areas becoming tropical cyclones. That's a 1 in 5 chance (or 3 out of 10 chance) of development if one were to take those percentages at face value. It's clear that the NHC is well aware of the known biases with the GFS given their relatively low confidence in it happening. The noted convective feedback + right of track bias (which is really a "too progressive" bias, but semantics aside) makes it spawn false positives in the Caribbean when they should be in the Eastern Pacific, which is pretty much what happened here and has been corrected in the short-range to showing a cyclone near the coast of Mexico by the end of the week, like most other global models. Again, there was a trackable source of vorticity that is currently traversing over the area and will soon cross over Central America in the form of a tropical wave + remnants of convection spawned by orographic lifting, but the GFS was too eager due to the aforementioned biases in causing it to undergo TCG. This is what led to the area developing where it did, and unsurprisingly it managed to take advantage of a favorable environment in the western Gulf. Now, this AOI is unlikely to do that as it will end up on the wrong side of Mexico relative to the favorable atmospheric solution the GFS had been modeling. This AOI wasn't necessarily a modelcane since there was a genuine precursor system/vorticity, but what was fake about it was where it developed thanks to the known biases of the GFS.

As for the GFS's reliability? Over the past several years it has remained one of the top scorers in official verification products in terms of track, and only slightly behind the hurricane models in terms of intensity. Therefore, even in an area where GFS is known to be overaggressive with TCG, the NHC has to acknowledge it in some manner because it was sending out major hurricanes to hit the western Gulf of Mexico within 10 days and TCG within 96 hours. You can't just ignore the area when it has the GFS deterministic support for several cycles with a timeframe moving closer and closer to the present (plus some limited EPS/GEFS support). An organization like the NHC just can't outright ignore the area if there is such a persistent signal from a model that has proven to be reliable in the past, even if it happens in a region of false positives. Sure, with the power of hindsight, we can see that even this may have been a bit too much confidence, but until we get time travel working, we can't use that.

As a follow-up and an aside, I will say that we've already had a few similar "false positive" situations occur earlier in this year - one of which was Hurricane Agatha (right of track bias striking again in the mid- to long-range), and another one was a tropical low that ended up nearly undergoing TCG as it moved near Nicaragua before moving ashore. GFS does catch on to areas generating vorticity near the SW Caribbean but one has to be mindful of its biases and whether there is model consensus before taking it at face value. As for me - I'm glad the NHC at least noted that this was a possibility and prevented it from going unmentioned, but I'm also glad they didn't jump the gun and go any higher than a 1 in 5 chance of development at any point for this AOI. Was a good call in the end.

Regardless, this AOI serves as a good reminder to have your hurricane kit/supplies ready to go even though this season has taken its time to get cranking. Glad it didn't verify for the potential impact it could've had. On to the next!