2017 Global Model Runs Discussion (Out to day 16)

[CourierPR]

Meteorologist Joe Bastardi tweeted that the Brazilian model is showing heavy rain and shifting wind for Havana and Miami around August 5th.

[Kingarabian]

Two runs in a row and one run yesterday where the GFS is showing Cape Verde development, animation between 120 hours and 240 hours below:

GFS plows this into a stout ridge. Don't know how believable that is.

Where? When? What level are you looking at. All I see is a TC moving WNW around the subtropical ridge.

I'm looking at the MSLP at 850mb.

The lines of MSLP show 1014-1020 extending from the STR (high pressure right?) and it's moving the weak system NW through those lines of high pressure. And so I compare it to other systems at 850mb when they move North but there's no lines present.

Happy to be corrected if I'm wrong of course.

[RL3AO]

I'm looking at the MSLP at 850mb.

The lines of MSLP show 1014-1020 extending from the STR (high pressure right?) and it's moving the weak system NW through those lines of high pressure. And so I compare it to other systems at 850mb when they move North but there's no lines present.

Happy to be corrected if I'm wrong of course.

Looks like a pretty typical case of a modeled tropical cyclone working its way around the subtropical ridge.

http://i.imgur.com/s5IEkvy.gif

Of course we're only looking at SLP here. A tropical cyclone is steered by the mean flow higher in the atmosphere.

[Blinhart]

Looking a little closer, the GFS seems to develop the wave associated with this strong MCS near Togo.



Then the vigorous wave develops when the AEJ extends over the ocean and appears to help develop the mid-level circulation.



I honestly don't know if this commonly how TC's develop in the Eastern Atlantic (where they interact with the AEJ). However, that appears to be whats happening here.

Is it possible that the first wave will clean up the environment in front of the next wave causing that one to be a long tracking CV system. I know every now and then that is what happens in the Atlantic Basin. I still believe it is a little to early to have a system form that far out, but you never know. I expect this system to struggle for the next week or so before finally being able to get its shape in order. Just a gut feeling.

[TheStormExpert]

18z GFS drops all Atlantic development in favor of East Pacific development.

[chaser1]

Side Note - At the very bottom of the Talking Tropics Page, a list exists showing Members and (anonymous) guests. Who in the world is "Google Adsense [Bot]"?

[chaser1]

18z GFS drops all Atlantic development in favor of East Pacific development.

At 0Z I'm seeing the GFS begin to slowly develop a strong wave and deepen a low just south of the Cape Verde Islands at about 117 hours. Thereafter, the low seems to maintain its integrity while moving generally WNW and slowly deepening north of the Antilles.

[Hammy]

18z GFS drops all Atlantic development in favor of East Pacific development.

At 0Z I'm seeing the GFS begin to slowly develop a strong wave and deepen a low just south of the Cape Verde Islands at about 117 hours. Thereafter, the low seems to maintain its integrity while moving generally WNW and slowly deepening north of the Antilles.

Looks like a Colin 2010 track if it plays out--another storm that was moving too quickly to remain organized, and then deepened slightly once it slowed down (until running into a shear wall.)

[NONAME]

Side Note - At the very bottom of the Talking Tropics Page, a list exists showing Members and (anonymous) guests. Who in the world is "Google Adsense [Bot]"?

I’m assuming that the site uses Google Adsense for their ads you see on the bottom of the page. Thats why you are seeing that. It surveys the site and tries to distribute ads correctly based on the targeted group I assume.

Sorry mods for the off-topic discussion.

[Siker]

Both the 06z GFS and 06z (and 00z) Parallel GFS are trying to spinup the next two waves (one that just emerged from the coast and one yet to) but they're so close together they seem to Fujiwhara?

Also worth noting the very healthy vorticity signature for the wave yet to leave Africa on the 00z Euro, with a closed low approaching the Caribbean at 240 hours.

Edit: It seems the Euro actually merges the vorticity of both waves.

[cycloneye]

@TropicalTidbits
The GFS Day 4 forecast of low-level westerlies along 8N all the way to 50W would be quite rare for early July. Can amplify African waves.

 https://twitter.com/TropicalTidbits/status/880459408345575424

[RL3AO]

Impressive westerly wind anomalies near 10N over the next 5 days or so. That's certainly a positive for TCs.

[Kingarabian]

Westerlies vs a Suppressed Kelvin Wave. Will be interesting to watch.

 https://twitter.com/MJVentrice/status/880376137494536192

[RL3AO]

^^^^

Thats the one primary negative in the Atlantic during the next few weeks. There's always gonna be some dry air, but it's not crushing right now.

[NDG]

Euro agrees with the GFS of anomalous westerlies across the MDR, indeed is very strange to see during the month of July.

[cycloneye]

@webberweather
Given recent suppressed CCKW & suppressed MJO passage + very poor climo, the fact that this AEW is still doing so well is a little unnerving

 https://twitter.com/webberweather/status/880538418165501952

[WeatherEmperor]

Euro agrees with the GFS of anomalous westerlies across the MDR, indeed is very strange to see during the month of July.

[img]http://i20.photobucket.com/albums/img]

Sorry for the stupid question but how does this particular graphic work? What do the colors indicate? What is favorable and what is unfavorable? Still trying to learn what this means lol



Sent from my iPhone 7 using Tapatalk

[NDG]

Euro agrees with the GFS of anomalous westerlies across the MDR, indeed is very strange to see during the month of July.

[img]http://i20.photobucket.com/albums/img]

Sorry for the stupid question but how does this particular graphic work? What do the colors indicate? What is favorable and what is unfavorable? Still trying to learn what this means lol



Sent from my iPhone 7 using Tapatalk

Brownish colors in the deep tropics indicate weaker than average easterly trade winds across the Tropical Atlantic and in some cases actual westerly winds which sets up nice convergence to feed the tropical waves that come off Africa. If the easterlies (purple shades) were to be stronger than average then we would not see convergence set up and the waves would just die out or weaken as they cross the tropical Atlantic.

[BobHarlem]

Is the 18z GFS really suggesting a storm making its way across the Atlantic all the way to Nassau, in July?

[Hurricaneman]

Is the 18z GFS really suggesting a storm making its way across the Atlantic all the way to Nassau, in July?

It happened in 1996 so who knows