2024 Global Model Runs Discussion (Out thru day 16)

[ChrisH-UK]

I Was looking at what the NAM had on 90L had when it popped a little storm off the coast of Georgia in a couple of days, well GFS and ECMWF also have it.

NAM 3k



GFS



ECMWF

[TomballEd]

I think the 3km NAM had a sub 700 mb storm in the Gulf. The 3km hurricane models are calibrated to somewhat accurately predict strength, but the 3km NAM is a smidge enthusiastic developing systems.

[Hammy]

I think the 3km NAM had a sub 700 mb storm in the Gulf. The 3km hurricane models are calibrated to somewhat accurately predict strength, but the 3km NAM is a smidge enthusiastic developing systems.

Never seen that on the NAM, I think that was the HWRF or related model at one point.

It's gone sub-900 several times on hurricanes that ended up low-end Cat 2 in the end

[Kazmit]

GFS has liked the idea of a westward tracking MDR major for 3 of the past 4 runs. The 18z one looks very Irma-esque. Still a ways out since the wave that forms it doesn’t exit Africa until Monday. Even if it doesn’t verify the fact that it’s been showing anything at all is perhaps a hint of the switch flip happening as we enter mid-September.

[cheezyWXguy]

I think the 3km NAM had a sub 700 mb storm in the Gulf. The 3km hurricane models are calibrated to somewhat accurately predict strength, but the 3km NAM is a smidge enthusiastic developing systems.

Never seen that on the NAM, I think that was the HWRF or related model at one point.

It's gone sub-900 several times on hurricanes that ended up low-end Cat 2 in the end

The only storm I’ve ever seen it come even reasonably close on was Michael (predicted 895-905, ended up being 919), and I couldn’t think of a better example of a blind squirrel finding a nut if I tried.

[Teban54]

GFS has liked the idea of a westward tracking MDR major for 3 of the past 4 runs. The 18z one looks very Irma-esque. Still a ways out since the wave that forms it doesn’t exit Africa until Monday. Even if it doesn’t verify the fact that it’s been showing anything at all is perhaps a hint of the switch flip happening as we enter mid-September.

Maria may be a better track analog, as it does clip NE Caribbean and then Puerto Rico, and it also moves due north starting from around Bahamas.

Regardless, track at this lead time is almost meaningless, but GFS has shown a long-tracking CV hurricane for 6 out of its 9 most recent runs now, including 4 out of the 5 most recent ones. Euro has also shown development of the same wave for all but one of its recent full-length runs ever since this wave entered the 10-day time frame, albeit at varying intensities. CMC also jumped on board for the first time in its 12z run today.

[Hypercane_Kyle]

Modest GEFS support for the MDR system later next week.

[Cachondo23]

GFS has liked the idea of a westward tracking MDR major for 3 of the past 4 runs. The 18z one looks very Irma-esque. Still a ways out since the wave that forms it doesn’t exit Africa until Monday. Even if it doesn’t verify the fact that it’s been showing anything at all is perhaps a hint of the switch flip happening as we enter mid-September.

Maria may be a better track analog, as it does clip NE Caribbean and then Puerto Rico, and it also moves due north starting from around Bahamas.

Regardless, track at this lead time is almost meaningless, but GFS has shown a long-tracking CV hurricane for 6 out of its 9 most recent runs now, including 4 out of the 5 most recent ones. Euro has also shown development of the same wave for all but one of its recent full-length runs ever since this wave entered the 10-day time frame, albeit at varying intensities. CMC also jumped on board for the first time in its 12z run today.

Agree with the Maria analog. That date, 9/17 to 9/21, always dangerous for the NE Caribbean. Not every year is a MH in that area but some type of system comes around.

[MEANINGLESS_NUMBERS]

GFS has liked the idea of a westward tracking MDR major for 3 of the past 4 runs. The 18z one looks very Irma-esque. Still a ways out since the wave that forms it doesn’t exit Africa until Monday. Even if it doesn’t verify the fact that it’s been showing anything at all is perhaps a hint of the switch flip happening as we enter mid-September.

Bermuda paying attention to that run.

[LarryWx]

GFS has liked the idea of a westward tracking MDR major for 3 of the past 4 runs. The 18z one looks very Irma-esque. Still a ways out since the wave that forms it doesn’t exit Africa until Monday. Even if it doesn’t verify the fact that it’s been showing anything at all is perhaps a hint of the switch flip happening as we enter mid-September.

I don’t know if that would mean a complete flip to active then but my impression in looking at ensembles is that the AEW to come off ~9/10, the one causing these operational MDR TCs, may eventually need a bear watch. I don’t recall seeing one that active right off Africa on ensembles/operationals in at least quite awhile. And note that this is coming off Africa at about the same latitude as recent ones. Not further south. And yet it still may turn into something.

Looking back at history for AEWs that developed in the E Atlantic near or just after Sept 10th, these were 3 of the worst.
-Hugo (1989)
-Gloria (1985)
-Long Island Express (1938)

I’m not saying a track anything like that would occur but rather am saying that isn’t at all too late in September for a long-tracked CV storm, especially with cold neutral/weak Niña:

[Teban54]

In addition to the operational models (including Euro itself), 12z EPS is also quite active, a tad more so than 0z:

[LarryWx]

In addition to the operational models (including Euro itself), 12z EPS is also quite active, a tad more so than 0z:

https://i.postimg.cc/D0WztnXj/ecens-2024-09-05-12-Z-240-50-258-0-350-MSLP-Surface-tracks-lows.png

And note that despite many members having TCG that the members aren’t coming off Africa any further S than prior AEWs.

[Pelicane]

GFS still shows the MDR tracker. The Bermuda high looks strong and shear looks low but obv too early to say for certain. Four days until it gets over water so long time to watch it.

[Teban54]

Did GFS just weaken the CV storm from 969 mb to 995 mb in 6 hours after landfall in Hispaniola?

Otherwise, Georges is probably the best analog so far for this run: another mid-September CV hurricane that trekked through Greater Antilles, on a much more southernly track than most mid-September CV storms.

[MarioProtVI]

In addition to the operational models (including Euro itself), 12z EPS is also quite active, a tad more so than 0z:

https://i.postimg.cc/D0WztnXj/ecens-2024-09-05-12-Z-240-50-258-0-350-MSLP-Surface-tracks-lows.png

And now the Euro doesn’t even develop it anymore on 00z. Given its past history of detecting supposedly favorable conditions and adjusting (and ending up right quite often), I have to wonder if this is yet another false flag by the models that may easily end up falling flat on its face.

[Hammy]

In addition to the operational models (including Euro itself), 12z EPS is also quite active, a tad more so than 0z:

https://i.postimg.cc/D0WztnXj/ecens-2024-09-05-12-Z-240-50-258-0-350-MSLP-Surface-tracks-lows.png

And now the Euro doesn’t even develop it anymore on 00z. Given its past history of detecting supposedly favorable conditions and adjusting (and ending up right quite often), I have to wonder if this is yet another false flag by the models that may easily end up falling flat on its face.

Waves are still coming off too far north it looks like, even that far into September

[Teban54]

0z EPS is also less active than 12z, though still with a good number of developing members. Waiting to see if it's a fluke.

Could also be delayed development that resulted in not as many tracks in eastern Atlantic. (I only looked at the density of TS tracks, and didn't count the lows.)

[kevin]

06z GFS finally shows some development. After many attempts, is this finally 'the switch'? Also added storm names for fun, but of course it's just one GFS run.



Short-range (0 - 96 hrs)
*99L becomes Francine as is develops more consistent (sheared) convection and deepens to 994 mb over the next 18 hours with wind speeds up to 45 kt.
*90L slowly moves south and reaches TS strength in about 48 hours, becoming Gordon. Depeens to 997 mb and 45 - 50 kt before landfall in Texas in about 5 days. Brings more than 16 inches of rain in some places in Texas.

Medium-range (96 - 168 hrs)
*Two MDR waves form in about 7 days. The first one is west of the one many people are looking at and forms around 19N, 57W at +168 hrs, becoming Helene. A very compact storm, recurving from the US. Deepens to 982 mb and goes just east of Bermuda as a low-end hurricane. Strenghtens and deepens as it passes, remaining very compact for a storm this far north and reaching a pressure in the low 970s. Based on its forward speed and structure I think a scenario like this GFS run would result in a low-end major hurricane before becoming extra-tropical.

Long-range (168+ hrs)
*Of course the 'big' storm in the run would get the I-name, Isaac. Forms around +192 hrs at 16N, 48W. Strenghtens into a hurricane over the next 2 days and goes just north of Puerto Rico (973 mb). Strengthens into a major hurricane and peaks at 946 mb. Recurves just east of the Bahamas and goes just west of Bermuda.
*A broad low-pressure system of the East coast forms into a TS (would be Joyce) at +240 hrs. Wind speeds of 40 kt, but very broad and as such it can't really intensify. Landfalls in North Carolina at +270 hrs, 1000 mb.

If this exact GFS run would play out we'd be at Joyce by Sept 19 and season statistics of 10/5/3 with 5 TCs forming over the next 10 days. Now let's see what the ensemble says and whether it will actually stick for a few runs. Notably, the EPAC almost complete shuts down this run with only one weak short-lived TS. The WPAC still produces storms, but is also trending much weaker with no systems below 980 mb in the next 384 hours except for of course 95W (even though that potential monster is also weaker in recent runs). So unlike with previous false switch flips this season, it looks like the other basins might also shut down, which makes an active Atlantic basin more realistic.

[Hypercane_Kyle]

Climatology alone makes me believe the notional MDR system will probably develop. I don't think this season is quite 2013 levels of hostile, the unusually quiet period not withstanding.

[MetroMike]

It’s rather odd the NHC gave the lemon only 0% to10% this morning in the east Atlantic. Discounting the GFS ideas as bogus maybe.