Will October / November be active with La Nina in place?

[cycloneye]

IMO, the months of October and November may see several tropical developments,4 in October and 3 in November. This late season activity may be enhanced by La Nina that officially has been declared by Climate Prediction Center in the September update.

See the CPC update here

[Hylian Auree]

I do think it'll be a generally active late season, although personally I'd go with 3-4 storms in October and 1-2 in November.

[Macrocane]

This is the activity in the Atlantic basin for October and November during La Niña years since 1995:

1995 4/2/1
1998 3/3/1
1999 4/3/1
2000 4/1/0
2007 2/1/0
2010 5/5/0

I guess that the best analogue would be 1999 as it was a 2nd La Niña year. Other season that may have some analogies as the Pacific cool down a little near the end of the season are:

2005 11/5/2
2008 4/2/2

[BigA]

Tomorrow is September 10, the climatological peak of the hurricane season. This is slightly after the average date of formation for the middle storm, which occurs on September 2 (September 5 for La Nina seasons).

The Cape Verde season will soon be winding down, and activity will most likely be shifting west into the western Atlantic and western Caribbean.

One thing I have noticed is that every late-season La Nina since this active cycle began has produced at least one storm after September 25 whose name was retired. Therefore, based on climatology, and the activity of the first half of the season (in numbers if not in quality), the second half should see a lot of storms.

What are learned and experienced people's thoughts on how the pattern is shaping up for the second half of the season? How will the forecasted fall pattern for the eastern US affect and direct the storms that are likely to form in the western Caribbean in the next two months? What areas, if any, are most at risk, both inside and outside the US?

[cycloneye]

This is the activity in the Atlantic basin for October and November during La Niña years since 1995:

1995 4/2/1
1998 3/3/1
1999 4/3/1
2000 4/1/0
2007 2/1/0
2010 5/5/0

I guess that the best analogue would be 1999 as it was a 2nd La Niña year. Other season that may have some analogies as the Pacific cool down a little near the end of the season are:

2005 11/5/2
2008 4/2/2

Interesting stats. Lets see how the rest of the 2011 season does.

[weatherwindow]

IMHO, after taking a look at the longer range modelling, it would appear that the cape verde season is virtually over. perhaps a last gasp east of the windwards with a sharp recurve over puerto rico around the third week of sept...no coherent ridging evident west of 60deg.....i would suggest an early entry into an october pattern in the GOM and the caribbean. this will favor a lowering of pressures in the western and southwestern caribbean. the source of credible CONUS threats will shift west to those basins with typical october storm tracks favoring the fla peninsula, cuba and the bahamas. as mentioned by cyloneye, la nina has returned and should enhance late season formation particularly in the favored basins, the northwest and southwest caribbean. i also favor the use of 1999 as an analog year and would suggest two US landfalls in october and a cuba/ fla straits/bahamas runner in november. as the latitude of recurvature drops south of the florida straits, november favors cuba and hispaniola landfalls. la nina should favor an extension of activity thru november perhaps into december. greek is possible.....rich

[gatorcane]

Good thread. I really think we are going to see at least one MAJOR, maybe two in October and November, October might be a busy month for the Caribbean with the onset of La Nina, good upper-level conditions and very warm SSTs.

[BigA]

This is somewhat sobering. Every hurricane season with a late-season La Nina since the active cycle began has produced at least one hurricane after September 25th whose name was retired.

1995: Opal, Roxanne
1998: Mitch
1999: Lenny
2000: Keith
2007:Noel
2010:Tomas

The western Caribben will likely be raring to go come late September and October. Where those storms go though, is all about the individual pattern when the storm forms, but given the troughiness in the eastern US, I imagine there is a good chance they will be pulled northward.

[northjaxpro]

Good thread. I really think we are going to see at least one MAJOR, maybe two in October and November, October might be a busy month for the Caribbean with the onset of La Nina, good upper-level conditions and very warm SSTs.

I generally agree with your assessment Gatorcane. Florida has been spared to this point, but be wary heading into the final 1/3 of the season. There will most likely be a few more threats to the peninsula where these systems will move up from the south out of the Western Caribbean as these toughs will pick them up during the autumn season.

[northjaxpro]

IMHO, after taking a look at the longer range modelling, it would appear that the cape verde season is virtually over. perhaps a last gasp east of the windwards with a sharp recurve over puerto rico around the third week of sept...no coherent ridging evident west of 60deg.....i would suggest an early entry into an october pattern in the GOM and the caribbean. this will favor a lowering of pressures in the western and southwestern caribbean. the source of credible CONUS threats will shift west to those basins with typical october storm tracks favoring the fla peninsula, cuba and the bahamas. as mentioned by cyloneye, la nina has returned and should enhance late season formation particularly in the favored basins, the northwest and southwest caribbean. i also favor the use of 1999 as an analog year and would suggest two US landfalls in october and a cuba/ fla straits/bahamas runner in november. as the latitude of recurvature drops south of the florida straits, november favors cuba and hispaniola landfalls. la nina should favor an extension of activity thru november perhaps into december. greek is possible.....rich

Good post! You are pretty much on the mark with all what you stated in your post. Yeah, look for an active time for tropical cyclones to develop in the Caribbean for October and November. We may see a situation with a storm like Tomas from last year to develop late into November and affect the islands.

[JtSmarts]

This is not a forecast but for some reason I'm expecting to see a Hurricane Kate (1985) like storm at some point in late October/Early November. I also think there is potential for a storm similar to 2009's Hurricane Ida.

[Ptarmigan]

October 2005 saw the most named storms in the hyperactive 2005 season with 7 named storms.

[blp]

Take a look at the similarities. Quite remarkable so far especially in back to back years. Notice the void in the SW Carribean, as others have stated very soon comes the time when that area fills up.

2011


2010

[rainstorm]

im looking for an early end to the season. the only way for late sept/oct to mean anything would be for a high to LOCK IN over the nw atl. no sign of that at all. 2 or 3 slop storms possible but conditions in the gom/w carib arent all that great.

[cycloneye]

Take a look at the similarities. Quite remarkable so far especially in back to back years. Notice the void in the SW Carribean, as others have stated very soon comes the time when that area fills up.

2011
http://weather.unisys.com/hurricane/atl ... /track.gif

2010
http://weather.unisys.com/hurricane/atl ... /track.gif

Less CV activity so far in 2011 is interesting being a Neutral to La Nina season.

[NDG]

Yeah, I agree, I would think October and November will be a little busier than average now that we have a La Nina, though the pattern stayed like La Nina all along, IMO.
Interesting but yet not surprising is how the GOM has yet to produce or support a storm to become a hurricane, thanks to the heat ridge, IMO.

[BigA]

Yeah, I agree, I would think October and November will be a little busier than average now that we have a La Nina, though the pattern stayed like La Nina all along, IMO.
Interesting but yet not surprising is how the GOM has yet to produce or support a storm to become a hurricane, thanks to the heat ridge, IMO.

Isn't it a near certainty that the heat ridge will become less prominent as summer moves into fall?

[cycloneye]

BigA, I merged your topic of what to expect during the rest of the 2011 season with this one as is the same theme so we dont have two threads.

[NDG]

Yeah, I agree, I would think October and November will be a little busier than average now that we have a La Nina, though the pattern stayed like La Nina all along, IMO.
Interesting but yet not surprising is how the GOM has yet to produce or support a storm to become a hurricane, thanks to the heat ridge, IMO.

Isn't it a near certainty that the heat ridge will become less prominent as summer moves into fall?

The ridge will still be present more than not with a La Nina pattern still in place, may not be the "heat" ridge that was felt in the summer as the wx will cool down some eventually.

[psyclone]

i neglected to read this thread before posting something similar in the long term models thread but i agree with these posts. this is the time of year to look to the western caribbean. the very troughy pattern that has helped turn recent cyclones approaching from the east could could aid in pulling storms north should it persist. i generally bet against significant activity in november since it's usually pretty quiet (maybe one storm) but the latter half of september through october could get very dicey imo. it's also worth noting that the western caribbean has been quiet so those waters are packing max energy.