Dr. Jeff Masters' WunderBlog

La Niña is gone
Posted by: Dr. Jeff Masters, 03:13 PM GMT del 11 Maggio 2006 +0
The La Niña of 2006 proved to be short-lived. Sea Surface Temperatures (SSTs) in the eastern Pacific near the Equator have returned to near-normal values over the past month, according to the latest El Niño advisory issued today by the Climate Prediction Center (CPC). We are now in what is characterized as ENSO-neutral conditions (or El Niño-neutral conditions), which means that there is neither an El Niño nor a La Niña occurring. This is the case about 45% of the time, and was true for March through December of 2005. The CPC expects El Niño-neutral conditions to continue for at least the next 3-6 months, which means for all of hurricane season. The 2006 La Niña was an unusual one, because it started very late--no La Niña of similar magnitude has ever formed in the middle of winter, as this one did. However, the demise of this year's La Niña came at the usual time such events end--April and May are the typical months for the demise of both La Niña and El Niño.

How will this affect the hurricane season of 2006?
So, what does all this portend for the upcoming hurricane season? It is well-known that the presence of a La Niña usually means more Atlantic hurricanes, and stronger hurricanes, too. This is because the large-scale wind circulation that develops during a La Niña keeps wind shear levels relatively low over the main development region for hurricanes in the tropical Atlantic. So, the demise of La Niña is good news for those of you living in Hurricane Alley. However, before we get too cheerful about this, it is worth remembering that the unbelievable Hurricane Season of 2005 occurred in El Niño-neutral conditions, and El Niño-neutral conditions are expected for this hurricane season, too. So, let's look at some other factors that will influence this year's hurricane season.


Figure 1. Comparison of this year's May SST anomalies with last year's. Image credit: NOAA.

SST comparison--this year vs. last year
Let's compare last year's SST anomalies (the difference in temperature between observed and normal) with this year's, to see how things have changed (Figure 1). The key things to look at are the SSTs in the Caribbean and the tropical Atlantic between Africa and the Antilles Islands, since this is where 85% of all major hurricanes form. While SSTs are .5 to 1.5 degrees above normal--which is a lot!--SSTs are a full degree Centigrade cooler this year than last year at this time. This reduction in SSTs should keep this year's hurricane season from producing early major hurricanes, like Dennis and Emily of July 2005. However, once we enter the prime hurricane months of August through October, expect another above normal year for hurricanes and intense hurricanes. My worst-case scenario for 2006 is a year similar to 2004, which was awful, but modest compared to 2005. My best-case scenario is a year like 1995, which was still very active, but the Bermuda High set up much farther east and recurved most storms before they hit land. Of course, this would be bad for the northeastern Leeward Islands, which got pounded in 1995.

The Gulf of Mexico SSTs are much warmer this year than last, due in part to the record warm temperatures the U.S. experienced in January and April. This may allow for more intense that normal June systems to develop in the Gulf this year. However, remember that systems that develop in the Gulf usually only last a day or two, which doesn't give them much time to strengthen before they hit land. There has only ever been one major hurricane in June (Audrey of 1957).

The other item of interest is that the pattern of SSTs over the eastern Pacific is much different this year versus last year. Waters near the Equator were much warmer last year, thanks to the lingering effect of the El Niño event early in the year. There is also a much warmer pool of water north of Hawaii this year. These differences may end up having a significant influence on this year's jet stream pattern, and where the Bermuda high ultimately sets up camp. The jet stream and Bermuda high determine how hurricanes are steered, but unfortunately we don't know enough about long-range influences of unusual SST patterns on the weather to be able to predict where this year's hurricanes are likely to be steered. The bottom line is that SSTs are cooler and have a much different pattern this year compared to last year, and thus we should not expect a continuation of last year's ridiculously hyperactive, once-in-a-lifetime hurricane season.

Outlook for the rest of May
SSTs are already warm enough to support hurricane formation in the Gulf of Mexico, and the entire tropical Atlantic. What is saving us are the strong upper level winds of the jet stream, which has been dipping far to the south and creating lots of wind shear. The jet stream is forecast to remain active and fairly far south for at least the next two weeks, which should maintain unfavorable levels of wind shear over the Atlantic for the remainder of May. As long as we're talking about tornado outbreaks in the southern U.S., such as we've experienced this week, we don't have to worry about hurricane formation in the Gulf of Mexico. Tornado outbreaks require a stong jet stream, which is the bane of a hurricane trying to form.

The other missing ingredient--at least in the Caribbean and tropical Atlantic--has been the lack of an initial disturbance to get a hurricane started. Africa has just begun to produce its usual summer parade of tropical waves, which frequently serve as the nucleus for a tropical storm. These tropical waves are coming off of Africa at about 2 degrees North Latitude, which is too close to the Equator to allow a hurricane to spin up. I'm not expecting any tropical development for the rest of May in the Atlantic due to high wind shear and the lack of proper initial disturbances.

It's another story in the Eastern Pacific, where wind shear is less and the remains of an old cold front coming off of North America could serve to trigger tropical storm formation as early as next week. The hurricane specialists at the National Hurricane Center begin rotating shift work on Monday May 15, which marks the official beginning of the Eastern Pacific hurricane season.

My next blog will be on Monday. I'll talk about air pollution some next week, since May marks the beginning of air pollution season, and next week is EPA's Air Pollution Awareness Week.

Jeff Masters
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Reader Comments
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1. haydn 03:19 PM GMT del 11 Maggio 2006    
gone? Does this mean that season will be closer to normal?
2. southbeachdude 03:23 PM GMT del 11 Maggio 2006    
this is new thinking...everyone else has been talking about a really active season. Thank you for this new research.
Member Since: Luglio 29, 2005 Posts: 2 Comments: 694
3. WSI 03:25 PM GMT del 11 Maggio 2006    
He never said this season wouldn't active. He just said the conditions are not as favorable as those where a La Niña is present. Again, as Dr. Masters said, the La Niña conditions where the exact same during the record breaking season last year.
4. weatherguy03 03:26 PM GMT del 11 Maggio 2006    
Dr. Masters thank you so much for pointing out SST trends. This has been a big topic of discussion on the blogs for awhile. Thank you for finally sheding some light on the subject.
Member Since: Luglio 5, 2005 Posts: 581 Comments: 29680
5. NOLAinNC 03:27 PM GMT del 11 Maggio 2006    
I am learning so much from your blogs this year. Thanks Dr. Masters!
6. Dr. Jeff Masters, Director of Meteorology (Admin)
03:31 PM GMT del 11 Maggio 2006
   

Thanks for the comments, and I see I needed to add this sentence to the blog:

However, once we enter the prime hurricane months of August through October, expect another above normal year for hurricanes and intense hurricanes.


My thought for a worst-case scenario this year is a year similar to 2004, which was awful, but modest compared to 2005.

Jeff Masters
7. gcain 03:42 PM GMT del 11 Maggio 2006    
Seems like there are two issues: Number of storms and intensity of storms...and while the two are related they are determined by different factors. So really, when we all think about th upcoming season, the questions are, "How many?" and "How intense?" Factors such as temperature probably have more to do with intensity and factors like initial African disturbances has more to do with how many...in a year like 2005 all the factors seemed to be against us...maybe this year it will be one or the other, but not both. At least we can hope.
8. seflagamma 03:49 PM GMT del 11 Maggio 2006    
Dr Masters, thanks for the update and information. I was starting to dance a little jig but then read the rest! Oh well; at leas we are informed.

Appreciate your information! Looking forward to the next blog entry.


Gamma
Member Since: Agosto 29, 2005 Posts: 286 Comments: 40485
9. Levi32 03:52 PM GMT del 11 Maggio 2006    
Can I ask a dumb question? is the name "Chanchu" (referring to Typhoon Chanchu) a "he" or a "she".

I don't know Chinese lol.
Member Since: novembre 24, 2005 Posts: 586 Comments: 25459
10. oriondarkwood 03:53 PM GMT del 11 Maggio 2006    
From what I read for this and eariler posts (correct me if I am wrong Dr. Masters). Is we will have a later start but during the peak of the season will be some real monsters and the spooky part is the above average chance for rapid intenseification cycles near landfall. Specially in the gulf.
Member Since: Luglio 5, 2004 Posts: 51 Comments: 41
11. NOLAinNC 03:55 PM GMT del 11 Maggio 2006    
Levi,
There are no dumb questions, just the occasional dumb post ;)
I'm curious too.
-NOLA
12. Dr. Jeff Masters, Director of Meteorology (Admin)
04:02 PM GMT del 11 Maggio 2006
   

Posted By: oriondarkwood (13.13.137.2) at 11:53 AM EDT on May 11, 2006.
From what I read for this and eariler posts (correct me if I am wrong Dr. Masters). Is we will have a later start but during the peak of the season will be some real monsters and the spooky part is the above average chance for rapid intensification cycles near landfall. Specially in the gulf.

This sounds reasonable. I expect at least two Cat 4/5 storms this year. The key is where they will be steered. Hopefully, the Bermuda high will set up farther east, allowing the storms to recurve before hitting land, like happened in 1995. Of course, this would be bad for the Northeastern Leeward Islands, which got pounded in 1995.

Jeff Masters

13. GPTGUY 04:05 PM GMT del 11 Maggio 2006    
Dr. Masters

Do you think dust from the Sahara will play a factor this year?
Member Since: Agosto 26, 2005 Posts: 0 Comments: 391
14. NOLAinNC 04:06 PM GMT del 11 Maggio 2006    
Here is my dumb question: why is the water in the gulf so warm right now? It seems with all the hurricanes passing over the gulf last year that the water temps would have had some catching up to do.
15. GPTGUY 04:07 PM GMT del 11 Maggio 2006    
thats a good point NOLA! I think it has to do with the above avg. temps in the spring on the gulf coast.
Member Since: Agosto 26, 2005 Posts: 0 Comments: 391
16. Oceanwx2 04:18 PM GMT del 11 Maggio 2006    

The April update of Dr. Gray's hurricane outlook suggests something similar in that the "best analog years for 2006" are 1964, 1996, 1999 and 2003. You may notice that more storms turned northward theatening the US East Coast more than the Gulf Coast.

Track Charts from “wunderground.com”
1964

1996

1999

2003
17. GPTGUY 04:20 PM GMT del 11 Maggio 2006    
that would be real bad news for North Carolina!!
Member Since: Agosto 26, 2005 Posts: 0 Comments: 391
18. TheLuckyTacoBlizzard 04:24 PM GMT del 11 Maggio 2006    
oh boy not going to be a nic hurricane year this year is it could this year pass last year of 28 storms with may be 29 or 30 storms


DR M or any one ???
19. TheLuckyTacoBlizzard 04:26 PM GMT del 11 Maggio 2006    
is it me or is the gulf hoter then it was last year at this time?
20. GPTGUY 04:26 PM GMT del 11 Maggio 2006    
Na Taco i dont think so im thinking more like 16 named storms 9 hurricanes 5 major
Member Since: Agosto 26, 2005 Posts: 0 Comments: 391
21. NOLAinNC 04:27 PM GMT del 11 Maggio 2006    
Here in A'vill, we had our worst flooding in 100 years (2 years ago) from TS's tracking up from the Gulf and along the Appalachian ridge. A direct hit is not necessary - Mother Nature can find another way to wreak havoc!
22. TheLuckyTacoBlizzard 04:29 PM GMT del 11 Maggio 2006    
hmmm twc said 17 storms this year
23. whirlwind 04:30 PM GMT del 11 Maggio 2006    
that would be real bad news for North Carolina!!

Talkin about the Carolinas...they are long overdue....I see a cat 4 hittin them this year...eh StormTop?

I was curious to see if this year will be a another record breaking year but with news like this it may not happen....but again all smart asses at the NHC couldnt predict '06 so we will see...
24. GPTGUY 04:30 PM GMT del 11 Maggio 2006    
your right NOLA the #1 killer in tropical cyclones is freshwater flooding but if 2006 is similar in years posted above that would be bad news for coastal NC espcially if its similar to 1996 Bertha in July and Fran in September
Member Since: Agosto 26, 2005 Posts: 0 Comments: 391
25. TheLuckyTacoBlizzard 04:33 PM GMT del 11 Maggio 2006    
all we cn do is this wait and see
26. weatherhunter 04:33 PM GMT del 11 Maggio 2006    
yes but u also have to think about the mountains of NC because in 2004 They got it really bad I live in NCs Mountains so I know what it was like
27. GPTGUY 04:34 PM GMT del 11 Maggio 2006    
yep taco but we dont need another one down here on the Mississippi Coast!!
Member Since: Agosto 26, 2005 Posts: 0 Comments: 391
28. weatherhunter 04:35 PM GMT del 11 Maggio 2006    
and rememeber Isabel in 2003?
29. GPTGUY 04:35 PM GMT del 11 Maggio 2006    
yep forgot about Isabel
Member Since: Agosto 26, 2005 Posts: 0 Comments: 391
30. Inyo 04:40 PM GMT del 11 Maggio 2006    
Hmm, I'm glad to see that La Nina is indeed fizzling out... it seems to bring increased drought and more intense Atlantic hurricanes. I would say La Nina leads to more negative effects than El Nino in the US... since increased rainfall in California is usually a beneifit in the long run.

Looking at the eastern Pacific, it looks like the formative areas south of Baja are quite warm but the areas west of Baja are unusually cold. Will this 'zap' hurricanes rounding Baja faster than it normally does? We will see i guess.
Member Since: Settembre 3, 2002 Posts: 42 Comments: 765
31. WSI 04:41 PM GMT del 11 Maggio 2006    
We even had some flooding in the piedmont of NC from all those tropical storms if I remember right. I do remember the mountains getting hammered. We (NC) deal a lot with the tornado formations from these dying cyclones as well.
32. NOLAinNC 04:42 PM GMT del 11 Maggio 2006    
I wonder how coastal population density in NC compares to the Gulf Coast?
33. weatherhunter 04:42 PM GMT del 11 Maggio 2006    
yes we do
34. GPTGUY 04:43 PM GMT del 11 Maggio 2006    
good question NOLA
Member Since: Agosto 26, 2005 Posts: 0 Comments: 391
35. TheLuckyTacoBlizzard 04:43 PM GMT del 11 Maggio 2006    
i got my out look for this year on my blog and this to tell you i was off by 2 storms last year i was for casting 30 storm and i was off by only 2
36. weatherhunter 04:43 PM GMT del 11 Maggio 2006    
Nc ranks 3th of growing Coastal Population density so theres ur ansner
37. TheLuckyTacoBlizzard 04:44 PM GMT del 11 Maggio 2006    
is the gulf hoter this year then it was last year


and if any things get in the gulf then BOOOM you got a cat 4 or 5 hurricane
38. GPTGUY 04:45 PM GMT del 11 Maggio 2006    
well i know the MS coast WAS growing with the casinos and the boom of condos
Member Since: Agosto 26, 2005 Posts: 0 Comments: 391
39. Pensacola21 04:46 PM GMT del 11 Maggio 2006    
Thank you for all of the helpful information Dr. Masters.
Member Since: Settembre 16, 2005 Posts: 30 Comments: 3912
40. GPTGUY 04:46 PM GMT del 11 Maggio 2006    
yeah taco gulf is hotter than this time last year
Member Since: Agosto 26, 2005 Posts: 0 Comments: 391
42. TheLuckyTacoBlizzard 04:48 PM GMT del 11 Maggio 2006    
look like the ca waters arenot that hot like they where last year
43. WSI 04:48 PM GMT del 11 Maggio 2006    
Hey NOLA, here is your answer...

National Overview (PDF Document)


Came from this site.

Hope that answers your question.
44. TheLuckyTacoBlizzard 04:49 PM GMT del 11 Maggio 2006    
if the gulf is hoter then last year then look out if a hurricane gets in there then it can get to a cat 5 hurricane vary vary fast
46. NOLAinNC 04:50 PM GMT del 11 Maggio 2006    
Thanks w-hunter. I guess that is part of the problem, the population growth on the coast. And transportation inlets (and outlets) aren't big enough for massive evacuation.
I am praying for all hurricanes to avoid land this year. That would be a record worth celebrating.
47. NOLAinNC 04:52 PM GMT del 11 Maggio 2006    
Terrific resource WSI - thanks!
48. TampaSteve 04:55 PM GMT del 11 Maggio 2006    
In 2004, it was Florida...in 2005, it was the Northern Gulf...the Carolinas and Virginia are due this year, IMHO.

I remember Fran in 1996...people in the Shenandoah Valley thought they were too far inland to worry about tropical systems...they were wrong...the flooding in Western Virginia was horrendous. Whole towns were cut off by the raging flood waters. I remember visiting a friend in Page County after the storm. The water had picked up an entire house and carried it about half a mile...it came to rest in the endzone of the local high school's football field. That was a truly amazing thing to see.

I also remember Isabel in 2003...it was my last year in Virgina...it wasn't so bad around the DC area, just a blustery, rainy night...but on the coast, they got hammered...another friend of mine lost six feet of shoreline and his entire boat dock to Isabel.

As long as those big hurricanes stay far away from Tampa, I'll be happy!
49. weatherhunter 04:59 PM GMT del 11 Maggio 2006    
I think this year we'll(NC) get a Cat. 3 hurricane near the Borerter of NC and SC
50. ForecasterColby 04:59 PM GMT del 11 Maggio 2006    
Chanchu is an "it". It's chinese for pearl (the gemstone, not the name).

I see we all seem to be counting the Gulf out a bit early. *seems to remember certain storms going BOOM in the gulf recently*
51. louastu 05:07 PM GMT del 11 Maggio 2006    
Here is an audio pronunciation guide for WPAC storms. If you click on the name of the contributing country, it will show you what the meanings of each name contributed by that are.

Note: You will need RealPlayer in order to play the audio clips.

Link

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About JeffMasters
Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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