La Niña by July?

By: Dr. Jeff Masters , 1:42 PM GMT on June 08, 2010

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El Niño rapidly dissipated in May, and we are now very close to entering into a La Niña event, according to the latest sea surface temperature (SST) data over the tropical Eastern Pacific. The weekly SST readings in the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region", fell to 0.4°C below average on June 7, a full 1°C drop in just one and a half months. This puts us very close to the -0.5°C threshold needed to be considered a La Niña event, according to NOAA's latest El Niño Discussion. The Australian Bureau of Meteorology showed conditions in the Niña 3.4 region were not quite that cool--0.2°C below average for the week ending June 6. Nevertheless, the speed of the collapse of El Niño makes it likely that a La Niña event is on its way this summer, and NOAA's Climate Prediction Center has issued a La Niña watch. Ten of the 23 El Niño models (updated as of May 19) are predicting La Niña conditions for hurricane season. However, as NOAA's Climate Prediction Center commented in their June 3 advisory, a number of the more reliable models are now calling for La Niña to develop this summer. They comment, "there is an increasing confidence in these colder model forecasts, which is supported by recent observations that show cooling trends in the Pacific Ocean and signs of coupling with the atmospheric circulation." Historically, about 35 - 40% of El Niño events are followed by a La Niña within the same year.


Figure 1. Atlantic named storm, hurricane, and intense hurricane activity since the active hurricane period we are in began in 1995. Both La Niña and neutral years have shown similar levels of Atlantic hurricane activity, though the figures are somewhat skewed by the record-setting year of 2005. Background photo: Hurricane Dean, taken from the Space Shuttle.

It is interesting to note that the last time we had a strong El Niño event, in 1998, El Niño collapsed dramatically in May, and a strong La Niña event developed by hurricane season. History appears to be repeating itself, and I predict the emergence of La Niña by July. Since La Niña events tend to bring lower amounts of wind shear to the tropical Atlantic, we can expect a much more active Atlantic hurricane season than usual in 2010. Since 2010 is similar to 1998 in the behavior of the El Niño/La Niña cycle, it is possible that this year's hurricane season could resemble the 1998 Atlantic hurricane season. That year had about 40% above-average activity, with 14 named storms, 10 hurricanes, and 3 intense hurricanes. The season was relatively late-starting, with only one named storm occurring before August 20. Once the season got going, six named storms affected the Gulf of Mexico, including two hurricanes, Earl and Georges, that passed directly over the location of the Deepwater Horizon oil spill.


Figure 2. Tracks of all named storms for the 1998 Atlantic hurricane season.


Figure 3. Typical regional weather anomalies observed during June - August when La Niña conditions are present. The Caribbean tends to be cloudier and wetter than average, but there is typically little change to temperature and precipitations patterns over North America. Image credit: NOAA Climate Prediction Center.

Oil spill update
Light east, southeast, or south winds of 5 - 15 knots will blow today through Saturday, according to the latest marine forecast from NOAA. These winds will keep oil near the beaches of Alabama, Mississippi, and the extreme western Florida Panhandle, according to the latest trajectory forecasts from NOAA and the State of Louisiana. The latest ocean current forecasts from the NOAA HYCOM model are not predicting eastward-moving ocean currents along the Florida Panhandle coast this week, and it is unlikely that surface oil will affect areas of Florida east of Fort Walton Beach. Long range surface wind forecasts from the GFS model for the period 8 - 14 days from now show a southeasterly wind regime, which would prevent any further progress of the oil eastwards along the Florida Panhandle, and would tend to bring significant amounts of oil back to the shores of eastern Louisiana next week. If you spot oil, send in your report to http://www.gulfcoastspill.com/, whose mission is to help the Gulf Coast recovery by creating a daily record of the oil spill.


Figure 4. The oil spill on June 6, 2010 at 8:32pm EDT, as seen by Synthetic Aperture Radar (SAR) imagery from the Italian Cosmo-SkyMed (COnstellation of small Satellites for Mediterranean basin Observation) satellite. A large region of oil was a few miles offshore of Pensacola, Florida. Image credit: University of Miami Center for Southeastern Tropical Advanced Remote Sensing, Rosenstiel School of Marine and Atmospheric Science.

Oil spill resources
My post, What a hurricane would do the Deepwater Horizon oil spill
NOAA's fact sheet on Hurricanes and the Oil Spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
Oil trajectory forecasts from NOAA
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
Synthetic Aperture Radar (SAR) imagery from the University of Miami

"Hurricane Haven" airing again this afternoon
The tropical Atlantic is quiet right now, with no models predicting tropical cyclone development over the next seven days. I'll talk about all this nothingness on my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question in the comments area on Shaun Tanner's blog. Some topics I'll cover on the show:

1) What's going on in the tropics right now--is this typical?
2) New advancements in hurricane science presented at this month's AMS Conference on Hurricanes and Tropical Meteorology last month

Today's show, which will probably be just 1/2 hour, will be at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast, as last week's show was.

I may take a break from blogging Wednesday, as I've got some catching up to do on other duties.

Jeff Masters

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Quoting pottery:

WOW! I have had a touch over 5" in that timespan. But 3+" fell today!


Why Uncle has some business clients in the Antilles. Apparently have had their gardens ruined every few years from the amount of rain that can fall there.
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2341. Levi32
Out to play tennis on this very nice summer day here (51 degrees, yes that is shorts weather for me).

Later all.
Member Since: November 24, 2005 Posts: 635 Comments: 26652
Quoting Levi32:


The wave is strongest in the low-levels, from the surface to 850mb, and then becomes progressively weaker as you go above that. It is weaker at 700mb and weaker still at 500mb. This happens a lot after a tropical wave has passed the point on its journey west where the AEJ ceases to exist (it only extends a little way out into the eastern Atlantic).

Oh, thanks for the explanation.
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2338. gator23
Quoting Baltimorebirds:
What happen.It's been cloudy in batimore all day.

is Baltimore nice? How far from DC is it? I was going to go to DC for vacation and I wanted to see Baltimore
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I am not an expert but the area north of Panama looks like a storm in a making, watch out we may have Alex soon.
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2336. pottery
Quoting Levi32:


The wave is strongest in the low-levels, from the surface to 850mb, and then becomes progressively weaker as you go above that. It is weaker at 700mb and weaker still at 500mb. This happens a lot after a tropical wave has passed the point on its journey west where the AEJ ceases to exist (it only extends a little way out into the eastern Atlantic).

Nice! Thanks..
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2335. Levi32
18z GFS 180 hours: A royal mess around central America in both ocean basins:

Member Since: November 24, 2005 Posts: 635 Comments: 26652
2334. pottery
Quoting DDR:
Hello pottery
Rain,rain and more rain,we need it but its hampering my work,6 inches in 9 days.I guess we'll have around 20 by the end of the month.

WOW! I have had a touch over 5" in that timespan. But 3+" fell today!
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Quoting Levi32:


By 36 hours that anticyclone provides much lighter winds over the wave.

Correct.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Weak anticyclone should be placed aloft to this area of showers and thunderstorms over the Antilles. Any signs of a closed low at the surface, actually let me rephrase that, any signs of a surface low?

Member Since: September 2, 2009 Posts: 130 Comments: 21194
2330. Levi32
Quoting Hurricanes101:
New shear maps are out, there is an anticyclone in South America moving north


By 36 hours that anticyclone provides much lighter winds over the wave.

Member Since: November 24, 2005 Posts: 635 Comments: 26652
Quoting Hurricanes101:
Shear map
Thanks!
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2328. DDR
How was your trip to our sister isle?
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Circulation on the increase. We might have an invest within 48 hours, all we need is consistency to have an invest.

12z - 18z coming out soon.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Shear map
Member Since: March 10, 2010 Posts: 1 Comments: 7816
2325. Levi32
Quoting pottery:

He was, actually. And I seem to have spoiled the question he asked. Which was a good one too.

"why that difference in the vort between 850 and 500" ??


The wave is strongest in the low-levels, from the surface to 850mb, and then becomes progressively weaker as you go above that. It is weaker at 700mb and weaker still at 500mb. This happens a lot after a tropical wave has passed the point on its journey west where the AEJ ceases to exist (it only extends a little way out into the eastern Atlantic).
Member Since: November 24, 2005 Posts: 635 Comments: 26652
Quoting Hurricanes101:
New shear maps are out, there is an anticyclone in South America moving north
Link please.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
2323. DDR
Hello pottery
Rain,rain and more rain,we need it but its hampering my work,6 inches in 9 days.I guess we'll have around 20 by the end of the month.
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2322. Levi32
Quoting ShenValleyFlyFish:


Good analogy but the stick is upside down? The drag on the storm would be winds (sheer) at the upper level?


The dimensions of the visual image were not supposed to be perfect. For a tropical wave, the ground would be in a northerly direction, the Bermuda High north of the wave axis.
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2321. pottery
CHEERS! CRS.
:)
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Pottery...

I was thinking of you and your flight earlier while looking at the satellite images. I figured you would be ready for a "double" when you got home this evening!

CRS
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2319. pottery
Quoting ShenValleyFlyFish:


I thought he was talking about the yellow circle you've been complaining about.

He was, actually. And I seem to have spoiled the question he asked. Which was a good one too.

"why that difference in the vort between 850 and 500" ??
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Quoting Levi32:


For those who may still be a little fuzzy on this, think of it like a stick. When you hold one end of the stick and place the other end on the ground, it is encountering higher pressure (like the north end of a tropical wave axis pointing into the Bermuda High). Now try dragging that end of the stick along the ground while applying some pressure. If you're dragging it behind you with the end that's touching the ground pointing back in the direction from which you came, then it's pretty easy to drag it along the ground. But if you now hold the stick pointing in front of you in the direction you are trying to go, with the end in the ground and try to push, it becomes very hard, and the stick will try to dig up some of the dirt underneath it.

This is very much like what happens with negatively-tilted troughs. Positively-tilted troughs can be thought of as getting "dragged" through the air flow, and thus there is little convergence because it is pretty easy to drag that stick when it's pointing behind you. If the trough becomes negatively-tilted, its axis is pointing into the high pressure (the ground) out in front of you, and that stick becomes harder to push and causes fierce resistence along it. For a trough, this resistance causes strong convergence along the axis which forces air to rise, much like the stick in the ground starts digging up dirt as you push it.

If that made no sense at all, I apologize.


Good analogy but the stick is upside down? The drag on the storm would be winds (sheer) at the upper level?
Member Since: September 9, 2007 Posts: 36 Comments: 4687
2317. gator23
Quoting Baltimorebirds:
Some guy I heard you don't want to know.He is the other infamous blogger besides JFV.He has be sited by other bloggers as a troll/know it all.


oh man you def. dont want to know JFV.
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Levi, post #2311 -great analogy!!
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New shear maps are out, there is an anticyclone in South America moving north
Member Since: March 10, 2010 Posts: 1 Comments: 7816
2314. JLPR2
Quoting Levi32:


For those who may still be a little fuzzy on this, think of it like a stick. When you hold one end of the stick and place the other end on the ground, it is encountering higher pressure (like the north end of a tropical wave axis pointing into the Bermuda High). Now try dragging that end of the stick along the ground while applying some pressure. If you're dragging it behind you with the end that's touching the ground pointing back in the direction from which you came, then it's pretty easy to drag it along the ground. But if you now hold the stick pointing in front of you in the direction you are trying to go, with the end in the ground and try to push, it becomes very hard, and the stick will try to dig up some of the dirt underneath it.

This is very much like what happens with negatively-tilted troughs. Positively-tilted troughs can be thought of as getting "dragged" through the air flow, and thus there is little convergence because it is pretty easy to drag that stick when it's pointing behind you. If the trough becomes negatively-tilted, its axis is pointing into the high pressure (the ground) out in front of you, and that stick becomes harder to push and causes fierce resistence along it. For a trough, this resistance causes strong convergence along the axis which forces air to rise, much like the stick in the ground starts digging up dirt as you push it.

If that made no sense at all, I apologize.


yeah, but the last line was priceless! XD
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2313. pottery
Quoting NRAamy:
dinner? red vines....

sounds like some mad hippy whole food. Unless those vines have little purple orbs hanging in bunches and desirous of being transmogrified into liquids.
In which case, Purple Orbs for Purple Hippo.
Sounds good!
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2312. EricSFL
God bless you Levi!
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2311. Levi32
Quoting Levi32:


A negatively-tilted wave, which StormW just described in case you need clarification, results in more surface convergence because the wave axis is pointing forwards into the flow, instead of backwards. This is like a trough digging in over the eastern United States in the winter. When they become negatively tilted, they are stronger and usually result in a bad winter storm for the eastern seaboard. This doesn't mean a negatively-tilted tropical wave will develop, but it usually means that the wave is vigorous and there is good convergence going on along the axis.


For those who may still be a little fuzzy on this, think of it like a stick. When you hold one end of the stick and place the other end on the ground, it is encountering higher pressure (like the north end of a tropical wave axis pointing into the Bermuda High). Now try dragging that end of the stick along the ground while applying some pressure. If you're dragging it behind you with the end that's touching the ground pointing back in the direction from which you came, then it's pretty easy to drag it along the ground. But if you now hold the stick pointing in front of you in the direction you are trying to go, with the end in the ground and try to push, it becomes very hard, and the stick will try to dig up some of the dirt underneath it.

This is very much like what happens with negatively-tilted troughs. Positively-tilted troughs can be thought of as getting "dragged" through the air flow, and thus there is little convergence because it is pretty easy to drag that stick when it's pointing behind you. If the trough becomes negatively-tilted, its axis is pointing into the high pressure (the ground) out in front of you, and that stick becomes harder to push and causes fierce resistence along it. For a trough, this resistance causes strong convergence along the axis which forces air to rise, much like the stick in the ground starts digging up dirt as you push it.

If that made no sense at all, I apologize.
Member Since: November 24, 2005 Posts: 635 Comments: 26652
Quoting pottery:

There is also a very pronounced eye, just north of the Great Lakes.
Well, willyalookat dat?? LOL


I thought he was talking about the yellow circle you've been complaining about.
Member Since: September 9, 2007 Posts: 36 Comments: 4687
2309. NRAamy
dinner? red vines....
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Quoting Levi32:


Sorry should have clarified, the top part, the northern end. For a longwave trough over the US it would be the southern end, but tropical waves are inverted troughs. It is whichever end of the trough is pointing towards high pressure, which for a tropical wave is the north end (Bermuda High to the north)


Ahh, thanks!
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Quoting StormW:


If you take a trof, like we see over the U.S., or like a trof that steers a storm away, if you draw the axis, and it tilts forward, in the direction the trof is moving, then it is classified as a "positive tilt", usually indicating the trof hasn't reached it's full potential. A negative tilted trof, has the axis pointing in the opposite way, or backward (as in a N-S direction, it would tilt from SE-NW) and is an indication of a maturing trof.

In a tropical wave, it is opposite, because with the inverted "V" signature, it is like an inverted trof.


so how woulod you know if it was a maturing trof or a tropical wave??
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2306. xcool
Baltimorebirds /bad
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2305. pottery
Quoting weatherwatcher12:
There is an area of 850mb vorticity just east of Trinidad:


But, There is very little 500mb vorticity


Does anyone know what that means?

There is also a very pronounced eye, just north of the Great Lakes.
Well, willyalookat dat?? LOL
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Quoting MiamiHurricanes09:
Wow, very interesting. This is from that wave that should be emerging on Friday or this weekend, correct?


where will it be emerging??
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There is an area of 850mb vorticity just east of Trinidad:


But, There is very little 500mb vorticity


Does anyone know what the lack of 500mb vorticity means?
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2300. xcool



hi.
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2299. EricSFL
Quoting xcool:
hmmm


Hi xcool.
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2298. Levi32
Quoting MiamiHurricanes09:
Ok. So if a wave from Africa makes it towards the Antilles and develops and becomes Alex will it be considered a Cape Verde storm?


Well they have to develop close to the Cape Verde islands to be called a "Cape-Verde storm". I think in general we like to see them form east of about 35W to call them that.
Member Since: November 24, 2005 Posts: 635 Comments: 26652
2296. pottery
Amy!! I am good. But I'm all shook-up. uh-huh-huh...
Bumpy plane rides do that. So I am settin' here, Recouping before dinner.
Sort of ReHydrating
What we eating tonight?
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2295. xcool
hmmm
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Quoting Tazmanian:



WU WIND SHEAR MAP IS CRAP
No it isn't.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting Grothar:



You found my globe, did ya? How do you like it 09????
Lol. I love the coloring on it.
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2292. Levi32
Quoting HurricaneSwirl:


I'm confused. Does the top tilt forward into the flow or does the bottom tilt forward into the flow?


Sorry should have clarified, the top part, the northern end. For a longwave trough over the US it would be the southern end, but tropical waves are inverted troughs. It is whichever end of the trough is pointing towards high pressure, which for a tropical wave is the north end (Bermuda High to the north)
Member Since: November 24, 2005 Posts: 635 Comments: 26652

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About

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