Significant pattern change late week could spell trouble...

[Vortex]

Looking at the long range guidance this morning it certainly implies quite a change over the SW atlantic in about 5 days...Strong ridging sets up shop with a very deep moist easterly flow developing across Florida...This pattern more or less persists right into September. It appears by next week we may see systems tracking much further west from Africa and it's the pattern expected that raises an eyebrow. I think with this pattern the Carribean, Bahamas, Florida, and the Gulf of Mexico need to be very vigilant as we near the peak.

GFS 6Z 1 week from today.


http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_174l.gif

[flwxwatcher]

[quote="Vortex"]Looking at the long range guidance this morning it certainly implies quite a change over the SW atlantic in about 5 days...Strong ridging sets up shop with a very deep moist easterly flow developing across Florida...This pattern more or less persists right into September. It appears by next week we may see systems tracking much further west from Africa and it's the pattern expected that raises an eyebrow. I think with this pattern the Carribean, Bahamas, Florida, and the Gulf of Mexico need to be very vigilant as we near the peak.

I agree after looking over the conditions that the models are forecasting . it does seem ripe to get something to form underneath that building ridge and indeed the GFS is throwing out some hints of some trouble in the Gulf/ Caribbean.. It's something to watch for sure.

[Frank2]

But the same GFS run show the EC high short-lived and gone later in the run with another weaker trough in the western Atlantic:

http://weather.unisys.com/gfsx/10d/gfsx_500p_10d.html

[Stormcenter]

GFS....enough said.

Seriously though activity should be picking
just based where we will be at in season.

[Portastorm]

12z GFS continues the ridging trend. If the NAO does indeed go positive as some predictions suggest, we will be looking at a more dangerous pattern for US landfalls as ridging will replace the persistent trough we have seen.

Of course, gotta have a storm first and that has been challenging enough!

[hurricanetrack]

I love how the GFS gets insulted like some second rate model run on some kid's Commodore 64. Yet NO ONE ever posts links from independent sources highlighting such weaknesses in the GFS operational model. What exactly is wrong with it that is not wrong with say the ECMWF? Just wondering why it is NOT ok to insult people but it is ok to insult the main U.S. generated model which is maintained by real people.

[Steve]

>>12z GFS continues the ridging trend. If the NAO does indeed go positive as some predictions suggest...

GFS Ensembles and the ECMWF are now in opposite camps. 12Z ECMWF shows NAO staying weakly negative through the beginning of next month. European has long been the king of medium range patterns, though I'm not sure which has verified better with NAO. It's something to watch for throughout September to help clue us in on who may be potentially vulnerable at a given time.

12Z GFS
http://raleighwx.easternuswx.com/models ... ensnao.gif

12Z ECMWF
http://raleighwx.easternuswx.com/models ... mwfnao.gif

[lonelymike]

I love how the GFS gets insulted like some second rate model run on some kid's Commodore 64. Yet NO ONE ever posts links from independent sources highlighting such weaknesses in the GFS operational model. What exactly is wrong with it that is not wrong with say the ECMWF? Just wondering why it is NOT ok to insult people but it is ok to insult the main U.S. generated model which is maintained by real people.

Could you clarify by what you mean by "independent sources"?

[KWT]

Models aren't really showing any pattern change, this east coast troughing has been very hard to shift and whilst its not strong the fact it is there at all is enough to draw storms up.

May keep this pattern to the end of the season now, good for CV systems, very bad for Caribbean systems however....

[Steve]

I don't know man. ECMWF keeps flipping back and forth. But from 12z to 00z, the change is pretty drastic. It's something to observe, but those heights are > 100m higher than they were progged 12 hours ago.

http://raleighwx.easternuswx.com/models ... mwfnao.gif

[CourierPR]

Models aren't really showing any pattern change, this east coast troughing has been very hard to shift and whilst its not strong the fact it is there at all is enough to draw storms up.

May keep this pattern to the end of the season now, good for CV systems, very bad for Caribbean systems however....

Last week AccuWeather talked about a pattern shift as did TWC and Crown Weather. KWT, you have turned Talkin' Tropics into Talkin' Troughs and it's getting old.

[KWT]

Sorry if you don't like it BUT I've not exactly been wrong so far have I....ya know if I kept saying that and there was no clear evidence for it then for sure I can understand that but like it or lump it, thats what we have at the moment, deal with it...

Also yeah they did talk about a pattern change, so have I if you look about but the models have kept trying to bring this in for a good part of August and its not happened so far, we've only seen brief flings with a set-up more condusive, I need to see something far more concrete before I get too worried about a pattern change...

The thing is the pattern coming up is a pretty interesting one if a system can stay south and not develop...anything that develops east of 50W is going to be a goner for at least the next 10 days from the looks of things but often in La Ninas as we get deeper into September the waves start to develop more often in the Caribbean and that is when the real concern arrives because there is enough weakness present to lift out a system from the Caribbean and as we all know from the past that can lead to dangerous situations...

Also given how things are if a CV system can stay real deep then I suppose it'd be a bit foolish of me to completely say there is no chance this season because even in troughing seasons (and I'm sorry, clear as day as this one IS) some can sneak through at least as far as the E.Caribbean as we saw in 1995 but sometimes further then that.

When I see a major pattern shift I'll call it but for now its not the CV area we need to look for for threats, its much closer to the home so to speak...even if its not my home....oh and I've not totally given on Earl either fwiw!

ps, this season is abit like 2004 in reverse, we had strong ridging aloft for June and a good part of July, then it got to August and we flipped the pattern into a troughy pattern, the opposite way round to what happened in 04.