Watching GOM for tropical development (Is INVEST 92L)

[USTropics]

Looking at model verifications, ECMWF at 144 hours really nailed the upper-level pattern in the NE/Canada (UKMET was solid here as well, but really failed to forecast the troughing out in the west coast). GFS was way too amplified with the trough in the EC as well:



src: https://www.wpc.ncep.noaa.gov/html/model2.shtml

[USTropics]

Anytime you see all the models drop below 0.9 anomaly correlation at 500mb heights simultaneously, it's indicative of a difficult pattern for models to forecast. Based on my post above, we should see the GFS take a pretty big dip here when this graphic updates.

[ColdMiser123]

12Z EPS:
- out of ~51 members, close to 20 get to sub 1000 either in Gulf or after coming inland
- I counted 8 that get to below 992 either in Gulf or after coming inland; 4 of those 8 hit between central LA and central TX coasts; other 4 hit mainly in MS/AL/W FL panhandle
- Landfalls between Thu 7/11 and Mon 7/14 with 7/12-13 dominating
- Mean heaviest rainfall has also shifted west from the 0Z's Big Bend of Gainesville, FL, to SE portions of GA/SC/NC to the 12Z's more spread out from FL Big Bend to NE TX and then coming inland with an impressive 1.5-2" mean centered on ATL-AHN -GSP-ASH


Meanwhile, I've still not seen even one GEFS or GEPS member get down to 1003 or lower in the Gulf! What a dichotomy!

The dichotomy between the EPS and GEFS/GEPS continues as the Happy Hour GEFS is still another one with zero members (out of ~21) with SLP of 1003 mb or lower!

In the context of the last several runs, there was a pretty notable shift in the ensemble spread with the 18z GEFS.

With the 18z GEFS, several members now take this pretty far west. Most members are also a tick stronger than previous runs.

[Hurricane Andrew]

Is it possible NHC tags this as an invest prior to exit over water just to get more eyes on it, in modeling terms?

[LarryWx]

12Z EPS:
- out of ~51 members, close to 20 get to sub 1000 either in Gulf or after coming inland
- I counted 8 that get to below 992 either in Gulf or after coming inland; 4 of those 8 hit between central LA and central TX coasts; other 4 hit mainly in MS/AL/W FL panhandle
- Landfalls between Thu 7/11 and Mon 7/14 with 7/12-13 dominating
- Mean heaviest rainfall has also shifted west from the 0Z's Big Bend of Gainesville, FL, to SE portions of GA/SC/NC to the 12Z's more spread out from FL Big Bend to NE TX and then coming inland with an impressive 1.5-2" mean centered on ATL-AHN -GSP-ASH


Meanwhile, I've still not seen even one GEFS or GEPS member get down to 1003 or lower in the Gulf! What a dichotomy!

The dichotomy between the EPS and GEFS/GEPS continues as the Happy Hour GEFS is still another one with zero members (out of ~21) with SLP of 1003 mb or lower!

In the context of the last several runs, there was a pretty notable shift in the ensemble spread with the 18z GEFS.

With the 18z GEFS, several members now take this pretty far west. Most members are also a tick stronger than previous runs.

https://i.imgur.com/cFrvC9t.gif

Also, I actually see one sub 1003 member (hits TX) on the Tidbits source that my source showing sub 1004s doesn't have...maybe that's because it is a control run that my source ignores.

[USTropics]

Below is a breakdown of each 12z ECMWF ensemble member (including master and control) tracking the vorticity and initial landfall by state.

FL: 17/52 (member02, member07, member10, member13, member14, member17, member21, member24, member28, member31, member33, member38, member39, member41, member44, member49, member50)


TX: 10/52 (member09, member18, member19, member20, member30, member32, member36, member37, member43, member46)


NGOM (LA/MS/AL): 16/52 (master, control, member01, member03, member04, member05, member06, member08, member11, member15, member23, member27, member29, member45, member47, member48)


NO DEVELOPMENT: 9/52 (member16, member22, member25, member26, member34, member35, member40, member42)

[Aric Dunn]

Is it possible NHC tags this as an invest prior to exit over water just to get more eyes on it, in modeling terms?

Almost certainly

[MGC]

Cyclonic spin is quite evident over junction of AL, TN and GA....slowly drifting southward. Will be an interesting few days down here on the gulf coast. I'd speculate that the odds will be increasing in the coming days that a TC will form in the GOM......MGC

[Aric Dunn]

Cyclonic spin is quite evident over junction of AL, TN and GA....slowly drifting southward. Will be an interesting few days down here on the gulf coast. I'd speculate that the odds will be increasing in the coming days that a TC will form in the GOM......MGC

Yes the fact there is convergence with it and its dropping more south than se is interesting if that continues overnight then it will be over water sooner. And likely farther south.

[Evil Jeremy]

Cyclonic spin is quite evident over junction of AL, TN and GA....slowly drifting southward. Will be an interesting few days down here on the gulf coast. I'd speculate that the odds will be increasing in the coming days that a TC will form in the GOM......MGC

I can't remember another time a Tropical Cyclone was pre-packaged days in advance with a "just add ocean and microwave" notice.

[CYCLONE MIKE]

Jeff Linder mentioned this and it is worth saying again, the euro did horrible with the invest in the gulf last month. I think it is of more importance than all the talk of gfs vs euro Debby 2012. Now maybe it was a fluke, maybe not. But will not be surprised in the least if in upcoming runs it shifts much further east and weaker.

[Aric Dunn]

Looking at the 18z Euro... it has this offshore in 45 to 48 hours.. faster now.

[stormlover2013]

Gfs is already shifting west in its last run

[USTropics]

Jeff Linder mentioned this and it is worth saying again, the euro did horrible with the invest in the gulf last month. I think it is of more importance than all the talk of gfs vs euro Debby 2012. Now maybe it was a fluke, maybe not. But will not be surprised in the least if in upcoming runs it shifts much further east and weaker.

If it was just the ECMWF operational all on it's own I would tend to agree, but over 50% of the 50 ECMWF ensembles, the UKMET operational, and now quite a few the 18z GFS ensembles are trending west. You can see in my model verification post above that the GFS has not handled the troughing or UL features over the NE/Canada properly. See GFS ensemble member trend below for the past 4 runs as well:

[robbielyn]

Jeff Linder mentioned this and it is worth saying again, the euro did horrible with the invest in the gulf last month. I think it is of more importance than all the talk of gfs vs euro Debby 2012. Now maybe it was a fluke, maybe not. But will not be surprised in the least if in upcoming runs it shifts much further east and weaker.

Well the ukmet and cmc also agree and so do the ensembles plus the circulation is headed more southerly vs. south easterly. and gfs is slowly coming around to the west. but it’s a wait and see game.

[cycloneye]

Looking at how things are evolving,I dont expect this thread to remain open for too long as the invest tag may be up earlier than some may be thinking,certainly not reaching the 45 pages thread about the system that eventually became Michael.

[Aric Dunn]

from the 18z an interesting view... a reason for the lack of deepening when otherwise all conditions appear great. looks like there might be some northerly shear/dry air.

[NDG]

Looking at model verifications, ECMWF at 144 hours really nailed the upper-level pattern in the NE/Canada (UKMET was solid here as well, but really failed to forecast the troughing out in the west coast). GFS was way too amplified with the trough in the EC as well:

https://i.imgur.com/25NBw8r.gif

src: https://www.wpc.ncep.noaa.gov/html/model2.shtml

Definitely the GFS has continued to over amplify troughiness over the NE US, making the Euro's solution with this possible system's track more right than wrong.

[USTropics]

Possible analogs for July/1st week of August storms that have formed within 100 miles of forecasted genesis.

GFS operational analog:
Brenda 1960 - https://en.wikipedia.org/wiki/Tropical_Storm_Brenda_(1960)


TS One 1937 - https://en.wikipedia.org/wiki/1937_Atlantic_hurricane_season


TS One 1911 - https://en.wikipedia.org/wiki/1911_Atlantic_hurricane_season


ECMWF operational analog:
Hurricane Two 1940 - https://en.wikipedia.org/wiki/1940_Atlantic_hurricane_season


TS Two 1987 - https://en.wikipedia.org/wiki/1987_Atlantic_hurricane_season


Hurricane One 1860 - https://en.wikipedia.org/wiki/1860_Atlantic_hurricane_season


TD 4 1975 - https://en.wikipedia.org/wiki/1975_Atlantic_hurricane_season

[gatorcane]

The 18Z GFS legacy (old GFS) is significantly east. It then deepens it as it heads NE along the coast of North and South Carolina: