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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451. Levi32 03:44 PM GMT del 14 Maggio 2006    
People Michael made a good point in my blog just now that this is reminding him of Katrina and New Orleans. The new forecast track has Chanchu as a borderline Cat 5 at landfall in Hong Kong. If the landfall is just to the left of the bay, we are looking at China's Katrina and that is no exaggeration. Please stop and pray for these people. This situation is much more grim for them than we realize being way over here in America.

Here is latest Microwave. Shows a complete eye wall has finally formed.

Member Since: novembre 24, 2005 Posts: 586 Comments: 25445
452. MZT 03:45 PM GMT del 14 Maggio 2006    
It would be very unusual to see a storm form that close to the coast of Africa. They usually need to wander off to the west a few days, even asa Cape Verde type storm.
Member Since: Settembre 24, 2005 Posts: 0 Comments: 775
453. RL3AO 04:52 PM GMT del 14 Maggio 2006    
454. RL3AO 04:55 PM GMT del 14 Maggio 2006    
This is our wave in the EPac.

LARGE CONVECTIVE BLOW-UP BEGAN AROUND 00Z LAST NIGHT AND WAS
FOCUSED MAINLY AROUND THE S/SE PERIPHERY OF THE CENTER OF
CIRCULATION. THIS ACTIVITY CREATED A NEARLY CIRCULAR 180 NM WIDE
EXPANDING CIRRUS SHIELD BUT MORE RECENTLY THE CONVECTION HAS
BROKEN UP INTO SEVERAL CLUSTERS ALIGNED ALONG THE ITCZ AXIS AND
S OF THE CENTER. A 1252Z QUIKSCAT PASS INDICATES THAT THE
LOW-LEVEL CENTER IS STILL SOMEWHAT ELONGATED SINCE IT HAS NOT
YET DETACHED FROM THE ITCZ...BUT IT IS BECOMING INCREASINGLY
MORE CIRCULAR AND COMPACT. THE DEEP CONVECTION HAS NOT DIED OFF
LIKE IT DID THIS TIME YESTERDAY SO IF THIS TREND CONTINUES THEN
TROPICAL CYCLONE DEVELOPMENT WOULD BE MORE LIKELY IN THE NEXT
FEW DAYS.
455. TampaSteve 04:58 PM GMT del 14 Maggio 2006    
Damn...Hong Kong is about to get crushed!
456. TheLuckyTacoBlizzard 05:00 PM GMT del 14 Maggio 2006    
Tropical weather discussion
NWS TPC/National Hurricane Center Miami FL
205 am EDT sun may 14 2006
Tropical weather discussion


would any one like to tel me where the 805am one is note it say time 2:05am on there so where the new update one
457. atmosweather 05:02 PM GMT del 14 Maggio 2006    
Hong Kong will not be crushed Steve. This storm will be no higher than Category 3 at landfall because the heat potential up there is virtually zero. The outflow looks restricted and it will run into cold water near the coast. And, it still has not turned north yet, so it will cross the coast 50-75 miles west of Hong Kong, maybe more. It will not be a catastrophe.
Member Since: Settembre 24, 2005 Posts: 33 Comments: 9255
458. RL3AO 05:04 PM GMT del 14 Maggio 2006    
yet, I will be surprised if less than 250 die
459. atmosweather 05:15 PM GMT del 14 Maggio 2006    
Chanchu actually looks a lot like Wilma. Extremely deep convection around a very tiny eye. And it is a very small storm, so it won't take much to weaken it.
Member Since: Settembre 24, 2005 Posts: 33 Comments: 9255
460. watchingnva 05:48 PM GMT del 14 Maggio 2006    
gotta love people telling other people their wrong...so much fine...

the best part is when those people are proved wrong...

will see...
Member Since: Settembre 7, 2005 Posts: 3 Comments: 1310
461. TheSnowman 06:16 PM GMT del 14 Maggio 2006    
What's the Deal with these INSANE STORM!!!! -First 2 Cat. 5's in AUS
-Then Monica - and I need say no more about one of the most amazing cyclones the world has seen
-Then Mala
-NOW THIS!!!!!! Poss. Cat 5 for a Wold Power City!!!!
462. plywoodstatenative 06:16 PM GMT del 14 Maggio 2006    
atmos, any more forecasts?? I know that you had wanted to stay away from wunderground earlier, but am wondering for those of us who live in South Fla anymore forecasts on the season coming up? As for preparations, for some odd reason south florida medics and such have been put on alert due to hurricane season coming up. Any input those here can give as to why would be helpful.
Member Since: novembre 15, 2005 Posts: 16 Comments: 4147
463. plywoodstatenative 06:19 PM GMT del 14 Maggio 2006    
Well I wonder if La Nina had any effect on any of this that we have seen. Also as for the storms, remember that we are going to see worse and worse storms as the years go on because of the cycle we are in and the fact as some say global warming.
Member Since: novembre 15, 2005 Posts: 16 Comments: 4147
464. ForecasterColby 06:24 PM GMT del 14 Maggio 2006    
NRL now says 115kt/917mb, and I believe them. This is looking like an absolute disaster for Hong Kong. And it's still only May!
465. Cavin Rawlins 06:25 PM GMT del 14 Maggio 2006    
comment on this wave

Member Since: Luglio 24, 2005 Posts: 407 Comments: 19076
466. Inyo 06:25 PM GMT del 14 Maggio 2006    
Isn't it too early for Cape Verde development? I mean i guess anything is possible this year but...
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467. Cavin Rawlins 06:27 PM GMT del 14 Maggio 2006    
yeah it is too early but it could make to the western caribbean
Member Since: Luglio 24, 2005 Posts: 407 Comments: 19076
468. typhoonwatcher 06:28 PM GMT del 14 Maggio 2006    
TampaSteve:

I'm living in Hong Kong right now. Thanks for the reassurance! ;)

Looks like I'm about to get pounded by a SUPER typhoon.
469. louastu 06:38 PM GMT del 14 Maggio 2006    
Chanchu sorta reminds me of the Perfect Disaster series. If I remember correctly, one of the episodes was about a cat-5 typhoon hitting Hong Kong (though I think the one on that show had winds of 200 mph).
470. Alec 06:40 PM GMT del 14 Maggio 2006    
sorry to the folks in China, water temps near the Hong Kong coast aren't too warm, so hopefully it wont make landfall as a cat5...this season has gone CRAZY in the Western Pacific!!!
471. typhoonwatcher 06:43 PM GMT del 14 Maggio 2006    
Alec, it won't. It'll still be a very strong Category 4 typhoon (125 knots) when it lands here.
472. Alec 06:46 PM GMT del 14 Maggio 2006    
How deep is the warm water just off the coast of Hong Kong? Deep warm water will help super typhoons sustain themselves..
473. atmosweather 06:48 PM GMT del 14 Maggio 2006    
I think we need to calm down and forget Monica, Glenda and all the other strong cyclones we have seen lately. This is its own unique storm. We can't compare them. The fact is that the heat content near the coast (and up to 150 miles away) is almost zero. The water is a lot cooler and the outflow is going to be pretty restricted. A Category 5 storm (and thats if she makes it to Category 5) will not be able to sustain itself up there. I don't think a Category 4 will either. My guess would be 110 kts at landfall about 70 miles west of Hong Kong.
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474. typhoonwatcher 06:48 PM GMT del 14 Maggio 2006    
Alec - around 27 degrees.
475. atmosweather 06:50 PM GMT del 14 Maggio 2006    
The water is not very deep Alec

Member Since: Settembre 24, 2005 Posts: 33 Comments: 9255
476. louastu 06:52 PM GMT del 14 Maggio 2006    
This is interesting. Chanchu is expected to make landfall near the mouth of the Pearl River (Zhujiang). The name Chanchu means pearl.
477. atmosweather 06:53 PM GMT del 14 Maggio 2006    
That Atlantic wave is too far south to develop. It probably won't survive to the Caribbean but if it does it may be organized enough to watch.
Member Since: Settembre 24, 2005 Posts: 33 Comments: 9255
478. Alec 06:53 PM GMT del 14 Maggio 2006    
I agree Rich. Those waters wont be able to sustain such a powerful typhoon(especially if the heat content isnt all that great)...but if memory serves me correct, Monica didnt have the greatest heat content either but continued to be one of the top storms for the southern hemisphere...
479. atmosweather 06:53 PM GMT del 14 Maggio 2006    
Wow, that's some irony.
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480. atmosweather 06:56 PM GMT del 14 Maggio 2006    
Yeah Alec that's true but the water near the Australian coast was warmer and deeper than the water around Hong Kong. I'm not particularly worried about a major catastrophe with Chanchu.
Member Since: Settembre 24, 2005 Posts: 33 Comments: 9255
481. louastu 07:01 PM GMT del 14 Maggio 2006    
Eastern Pacific system now an invest.
482. LemonAromatique 07:02 PM GMT del 14 Maggio 2006    
New invest in the east pacific. Check it out.

http://www.nrlmry.navy.mil/tc_pages/tc_home.html

Oh, by the way, I'm new here. Name's Mishka.
483. Alec 07:03 PM GMT del 14 Maggio 2006    
Well looking at our Gulf temps they are warmer than this same time last yr(they were in fact BELOW average last yr at this time)...and Dennis survived off of relatively cooler water last season in early July and after that the Gulf STILL managed to muster up enough potential energy to sustain Katrina, Rita, and Wilma! If the storms dont start impacting the Gulf till Aug/Sept(which some experts believe) there will be TREMENDOUS heat energy stored in there for those that venture in there!
484. LemonAromatique 07:04 PM GMT del 14 Maggio 2006    
ah, louastu beat me to it.
485. louastu 07:06 PM GMT del 14 Maggio 2006    
Here is a sattelite image of the system in the Eastern Pacific.
486. atmosweather 07:08 PM GMT del 14 Maggio 2006    
Hey Mishka, welcome to the Weather Underground!
Member Since: Settembre 24, 2005 Posts: 33 Comments: 9255
487. Alec 07:10 PM GMT del 14 Maggio 2006    
welcome to wunderground Lemon!:)
488. louastu 07:14 PM GMT del 14 Maggio 2006    
Welcome Mishka. Nice to meet you.
489. Cavin Rawlins 07:19 PM GMT del 14 Maggio 2006    
welcome Mishka
This blog is very informative especially between June and November
Member Since: Luglio 24, 2005 Posts: 407 Comments: 19076
490. atmosweather 07:19 PM GMT del 14 Maggio 2006    
FNMOC now estimates 130 kts and 910 mb

Member Since: Settembre 24, 2005 Posts: 33 Comments: 9255
491. LemonAromatique 07:21 PM GMT del 14 Maggio 2006    
Eh, I've actually been reading around here for a pretty good time now. I just never really did get around to posting. Probably because I didn't realize that there WAS a free membership availible, so I didn't register at all.

Anywho, those warmer temperatures in the mid atlantic and new england region look kind of worrying. Does anyone think that some storms might be steered into that area this year?
492. atmosweather 07:24 PM GMT del 14 Maggio 2006    
I think there is a very good chance of at least 1 hurricane hitting the mid-Atlantic or northeast region. It all depends on where and how strong the Bermuda High is this season. In spite of that though, I think no area is out of the picture this season (just because of the possibility of another hyperactive landfalling season for the U.S). My 2 biggest threat areas would be south Florida and the central to eastern Gulf Coast.
Member Since: Settembre 24, 2005 Posts: 33 Comments: 9255
493. atmosweather 07:27 PM GMT del 14 Maggio 2006    


AWESOME!!! Perfect CDO once again. Extremely small eye which surely can't hold up for much longer.
Member Since: Settembre 24, 2005 Posts: 33 Comments: 9255
494. Alec 07:27 PM GMT del 14 Maggio 2006    
Rich, would it be fair to say Apalachicola to the Big Bend has a decent shot this yr? If the Bermuda High is more East then that would mean many storms wont have the blocking high near FL and be more prone to curving northward once in the NW Caribbean and Gulf....
495. atmosweather 07:30 PM GMT del 14 Maggio 2006    
Yeah Alec, that's why I have Texas at a low risk. Also, not only might the Bermuda High be further east, but this year we have seen an active trof pattern in the southern United States, reinforcing my notion that Gulf Storms will end up SE LA and eastward. I think the west coast of FL and all of the panhandle is at pretty high risk this year.
Member Since: Settembre 24, 2005 Posts: 33 Comments: 9255
496. Alec 07:33 PM GMT del 14 Maggio 2006    
Well Rich, if a tropical system hits the Gulf and heads toward the central panhandle to near us and its 90 degrees in the water...IM SCARED!!!
497. atmosweather 07:34 PM GMT del 14 Maggio 2006    
Yep I'm scared too living in central FL. If we have a really strong west coast storm with a trof approaching (very posssible this season) then it will hit me hard. Charley was bad enough.
Member Since: Settembre 24, 2005 Posts: 33 Comments: 9255
498. Alec 07:36 PM GMT del 14 Maggio 2006    
Rich, what's your take on the Gulf SST's right now? Do you think they will fall slightly due to the cooler than normal nights recently? I think we may be on to our FINAL cold front soon...by the end of May they stop reaching us.
499. LemonAromatique 07:40 PM GMT del 14 Maggio 2006    
We can't completely rule out the possiblity of a Texas hit though. I mean, if this is an analogue year to 1999, we can't forget that in that year we had Bret hit the state as a strong Cat. 3. So I'm definitely not going to rule out the possiblity of something hitting Texas.
500. atmosweather 07:40 PM GMT del 14 Maggio 2006    
Yeah Alec they will fall next week because this front is incredibly strong for this late in the season. After that we enter the short period (10-15 days) where the Gulf loop current will heat up significantly and the entrie Gulf will warm rapidly. And, it just so happens that the Gulf will have fair and hot weather for those days!
Member Since: Settembre 24, 2005 Posts: 33 Comments: 9255
501. StormJunkie 07:41 PM GMT del 14 Maggio 2006    
Atmos, I geuss you might as well put the whole e coast in your risk area with that kind of pattern. I mean waht is the difference between an Appalachacola landfall and a Jacksonville landfall...not much.

Am I wrong here?

SJ
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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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