Dr. Jeff Masters' WunderBlog

La Niña is here

Posted by: Dr. Jeff Masters, 13:16 GMT le 15 juillet 2010

The equatorial Eastern Pacific Ocean continues to cool, and we have now crossed the threshold into La Niña conditions. Sea surface temperatures (SSTs) over the tropical Eastern Pacific in the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region", fell to 0.8°C below average by July 12, according to NOAA.. The Australian Bureau of Meteorology put this number at 0.7°C below average (as of July 11.) Since La Niña conditions are defined as occurring when this number reaches 0.5°C below average, we are well into the territory of a weak La Niña event. La Niña conditions must be present for several months before this will be officially classified as a La Niña event, but it is highly likely that a full-fledged La Niña event lasting at least eight months has arrived. We started out the year with a strong El Niño, so it may seem surprising that we have transitioned La Niña so quickly, However, historically, about 35 - 40% of El Niño events are followed by a La Niña within the same year. Given current trends, I expect the current La Niña to cross the threshold needed to be defined as "moderate" strength--temperatures at least 1.0°C below average in the equatorial Eastern Pacific--by September.

Figure 1. Progression of El Niño to La Niña over the past year, as measured by SSTs in the the tropical Eastern Pacific in the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region". Image credit: NOAA Climate Prediction Center.

The implications
It is well-known that both the number and intensity of hurricanes in the Atlantic tend to increase during La Niña events. However, as I discussed in a post last month, since 1995, neutral years (when neither an El Niño or La Niña are present) have had Atlantic hurricane activity equal to La Niña years. The last time we had a strong El Niño event followed by a La Niña event in the same year, in 1998, we had a Atlantic hurricane season 40% above average in 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. I'm thinking this year's season may be similar, though four or more intense hurricanes are a good bet due to the record warm SSTs.

Both El Niño and La Niña events have major impacts on regional and global weather patterns. For the remainder of July and August, we can expect La Niña to bring cloudier and wetter than average conditions to the Caribbean, but weather patterns over North America should not see much impact (Figure 2.) Globally, La Niña conditions tend to cause a net cooling of surface temperatures. Thus, while the past twelve month period has been the warmest globally since record keeping began in 1880, it is unlikely that the calendar year of 2010 will set the record for warmest year ever.

Figure 2. 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 precipitation patterns over North America. Image credit: NOAA Climate Prediction Center.

The tropics are quiet
There are no threat areas to discuss in the Tropical Atlantic today, and none of the reliable computer models is calling for tropical cyclone development over the next seven days.

Next post
I'll have a new post on Friday.

Jeff Masters

Categories: Climate Summaries

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2152. AussieStorm 14:43 GMT le 16 juillet 2010
Quoting weathermanwannabe: Thanks for keeping me on track.....Good Morning Aussie..... :) Mornin' Member Since: 30 septembre 2007 Posts: 5 Comments: 13358

2158. CybrTeddy 14:46 GMT le 16 juillet 2010
Member Since: 8 juillet 2005 Posts: 253 Comments: 20276

2161. Floodman 14:49 GMT le 16 juillet 2010
Atlantic Basin Shear at 144 hours: Looking pretty light...144 hours = 6 days Member Since: 2 août 2006 Posts: 10 Comments: 9919

2162. 1900hurricane 14:51 GMT le 16 juillet 2010
Quoting btwntx08: hey jeff it is true its still 5 days out it could hit anywhere from ms to mx imo If it even develops at all, that is. Still though, it'll help keep this blog sane for at least a little while. Heck, I might even come out of lurk mode and have something to say on here more than one time a day! Member Since: 2 août 2006 Posts: 43 Comments: 10368

2163. MahFL 14:51 GMT le 16 juillet 2010
Anyone who owns a house on a FL shoreline knows there is a chance that one day it might be destroyed, it's the risk people take for living near the ocean. Member Since: 9 juin 2004 Posts: 0 Comments: 2430

2164. weathermanwannabe 14:52 GMT le 16 juillet 2010
2154. jasoniscoolman2010x 10:44 AM EDT on July 16, 2010 Interesting shot and I just had to run some vis loops.....Sheer is very low down there but nothing was forecast in this area by the models, and it does not have a lot of time over water, so I would not expect a "surprise" spin up but stranger things have happend...Hopefully it will just remain a rain event for South Florida. Member Since: 8 août 2006 Posts: 0 Comments: 6703

2166. wunderkidcayman 14:53 GMT le 16 juillet 2010
well it it a ULL jasoniscoolman2010x hmm much closer to us here in Cayman than the last two systems btwntx08 Member Since: 13 juin 2009 Posts: 2 Comments: 5492

2169. CaribbeanIslandStorm 14:56 GMT le 16 juillet 2010
Quoting weathermanwannabe: There's a good journal article out on that point from a few years ago but I don't remember the source......Basically a "geometry" type of answer in terms of the trajectory of storms, movement towards the poles as they approach FL/Eastern Seabord (i.e, fish storms unless the A-B high blocks northward movement), and, the "protected" position of the JAX area as compared to the Carolinas which juts out into the Atlantic where the storms on the western edge of the A-B high tend to curve back out to sea........ wow, great!! sorry, i took a while, we were getting some heavy storms here in PR.

2170. caneswatch 14:56 GMT le 16 juillet 2010
Palm Beach and Broward Counties under a Severe Thunderstorm Warning. Member Since: 8 octobre 2008 Posts: 14 Comments: 4473

2171. AussieStorm 14:57 GMT le 16 juillet 2010
Quoting AussieStorm: GOOOOD morning all. How is everyone's little piece of this planet 3rd from the sun today? It was a clear blue sky day here, the temps didn't move very much, but tonight's going to be very cold, chance of heavy frost. While I was at work today, I had this thought, Say in 100-250 years, If man-kind is still on this planet, If a time machine was invented and worked with out fault. Would anyone go back to the start of the 2005 Hurricane season and warn New Orleans about Katrina. Would anyone go back 2008 when Ike devastated Galveston. And back to earlier this year and warn Haiti and Chile. Or would you just let everything take it's course, and just be extra prepared? No one wants to answer my question? Member Since: 30 septembre 2007 Posts: 5 Comments: 13358

2172. VAbeachhurricanes 14:58 GMT le 16 juillet 2010
Anyone feel this? Member Since: 6 septembre 2007 Posts: 0 Comments: 4802

2173. weathermanwannabe 14:59 GMT le 16 juillet 2010
Quoting AussieStorm: No one wants to answer my question? To prevent the loss of life?......Of course I would go back. Member Since: 8 août 2006 Posts: 0 Comments: 6703

2174. CaribbeanIslandStorm 15:00 GMT le 16 juillet 2010
Quoting StormW: Thanks for answering that. CaribbeanIslandStorm, wasn't ignoring you, just typing up my synopsis and trying to get it out. Sorry, we had some strong storms that moved over us in Puerto Rico, i'm back, my internet connection acts weird when that happens, my apologizes. I wasn't ignoring anyone ;-)

2175. muddertracker 15:00 GMT le 16 juillet 2010
Link Nam 4 panel.."The nam be trippin'" Member Since: 16 août 2007 Posts: 1 Comments: 2127

2176. HurricaneNewbie 15:00 GMT le 16 juillet 2010
Can this lurker be thrown some scraps sometimes? Member Since: 11 septembre 2009 Posts: 0 Comments: 263

2177. Patrap 15:00 GMT le 16 juillet 2010
BP: Pressure inside well is 6,700 pounds per square inch and rising Published: Friday, July 16, 2010, 7:09 AM Updated: Friday, July 16, 2010, 9:20 AM Jaquetta White, The Times-Picayune Pressure inside the blown out Maconodo well in the Gulf of Mexico is at about 6,700 pounds per square inch and slowly rising, BP Vice President Kent Wells said this morning. BP shut in the well Thursday so that it no longer is shooting oil into the sea and is measuring pressure inside of it to determine if the well can remain closed. Wells said six remote operated vehicles monitoring the site have not found signs of oil leaking out of the well and into the rock formation surrounding it. Oil in the rock formation would have been a sign that the well was damaged and would need to be reopened. Later today BP will conduct a seismic survey of the site to determine if oil is leaking out lower in the well bore. The results of that survey won't be available for 24 hours, Wells said. Wells said pressure of 8,000 to 9,000 pounds per square inch would indicate that the well is completely intact and signal that it can be left closed until a relief well pumps it with cement to permanently seal it next month. Pressure of lower than 6,000 psi, Wells said would indicate that the well does not have integrity and that oil is escaping through fissures somewhere along the well. In that instance the well would be reopened and oil would be pumped to vessels on the surface. Pressure between those two numbers provide a grey area that needs "detailed analysis" by a team of scientists before a decision is made on how to proceed, Wells said. Member Since: 3 juillet 2005 Posts: 372 Comments: 111617

2179. AussieStorm 15:01 GMT le 16 juillet 2010
Quoting VAbeachhurricanes: Anyone feel this? I just read about that. Maybe Obama was pounding his head against the wall. Member Since: 30 septembre 2007 Posts: 5 Comments: 13358

2180. Patrap 15:02 GMT le 16 juillet 2010
Quoting AussieStorm: No one wants to answer my question? Time is Linear..and no one can go back. It s a parodox one could say. And for those of us who lost friends and family..well. It dosent savvy I guess. Member Since: 3 juillet 2005 Posts: 372 Comments: 111617

2181. WeatherNerdPR 15:02 GMT le 16 juillet 2010
Quoting btwntx08: nam at 84 hr looks like a cancun landfall note its much stronger this run than the previous The central pressure must be around 1000-995 millibars, with winds around 50 to 70 mph. Member Since: 7 juillet 2010 Posts: 0 Comments: 5464

2183. AussieStorm 15:03 GMT le 16 juillet 2010
Quoting weathermanwannabe: To prevent the loss of life?......Of course I would go back. But, think of the consequences of doing that. Member Since: 30 septembre 2007 Posts: 5 Comments: 13358

2184. Patrap 15:03 GMT le 16 juillet 2010
Quoting AussieStorm: I just read about that. Maybe Obama was pounding his head against the wall. Actually it was Dick Cheney's new Heart assisted device being rejected I think, Member Since: 3 juillet 2005 Posts: 372 Comments: 111617

2185. VAbeachhurricanes 15:03 GMT le 16 juillet 2010
Quoting AussieStorm: I just read about that. Maybe Obama was pounding his head against the wall. LOL Member Since: 6 septembre 2007 Posts: 0 Comments: 4802

2186. GrumpyWeather 15:03 GMT le 16 juillet 2010
Quoting MahFL: Anyone who owns a house on a FL shoreline knows there is a chance that one day it might be destroyed, it's the risk people take for living near the ocean. Our high insurance rates reminds us every month when it's time to pay. Member Since: 15 juillet 2010 Posts: 0 Comments: 11

2187. WeatherNerdPR 15:03 GMT le 16 juillet 2010
Quoting AussieStorm: I just read about that. Maybe Obama was pounding his head against the wall. LOL. But don't joke about the president. Member Since: 7 juillet 2010 Posts: 0 Comments: 5464

2189. weathermanwannabe 15:08 GMT le 16 juillet 2010
As to the Florida/Bahamas area, winds gusting to 19 knots at this location in the Bahamas, but, pressure is rising: Station SPGF1 NDBC Location: 26.704N 78.994W Conditions as of: Fri, 16 Jul 2010 14:00:00 UTC Winds: ESE (110°) at 17.1 kt gusting to 19.0 kt Atmospheric Pressure: 30.12 in and rising Air Temperature: 84.6 FDew Point: 72.5 F Member Since: 8 août 2006 Posts: 0 Comments: 6703

2191. ElConando 15:12 GMT le 16 juillet 2010
Quoting Patrap: Actually it was Dick Cheney's new Heart assisted device being rejected I think, Actually that was a result of a phone call from Mel Gibson. ZING! Member Since: 6 septembre 2009 Posts: 2 Comments: 3703

2192. mikatnight 15:17 GMT le 16 juillet 2010
Quoting AussieStorm: No one wants to answer my question? Member Since: 18 octobre 2005 Posts: 0 Comments: 1983

2193. TheUno 15:27 GMT le 16 juillet 2010
Quoting VAbeachhurricanes: Anyone feel this? Yep - and I felt the Loma Prieta quake in '89 - the time 5:04 is ingrained in our heads from that one...and lo and behold, when I woke to the shaking, looked at the clock this morning - 5:04. Of course I laughed this one off...but folks were freakin' out a little here this morning... Member Since: 15 août 2008 Posts: 0 Comments: 10

2194. Floodman 15:30 GMT le 16 juillet 2010
Quoting AussieStorm: No one wants to answer my question? What if we went back and tried to warn poeple about Katrina, or Ike, or for that matter the other events in your example...firstly, who would believe you? You'd likely end up in a 5150 hearing and potentially heavily sedated in a state run institution. It it were finally proven you weren't nuts (after landfall, say) you would be held by the government (they couldn't have someone with knowledge of the furture ruinning around...think about what you could do to the markets/economies, etc? Now here comes the biggie: you are chosen by the authorities of the furture to go back and warn people; the majority of those that would have died survive and someone you save kills your great great grandad before he has children...POOF! you disappear and no one is sent back...or someone else that isn't effected is sent and they CAN'T convince people...see the paradox? You'd have to think that any time traveling society would not, under any circumstqances, want to go back into history to change the way things were done...time travel is like any other travel; over long distances even tiny course changes early on translate into wide variances at point of arrival. Member Since: 2 août 2006 Posts: 10 Comments: 9919

2195. NttyGrtty 15:31 GMT le 16 juillet 2010
Quoting AussieStorm: No one wants to answer my question? Not sure what I would do, but whatever you're drinking to come up with the question, pour me some Member Since: 11 février 2010 Posts: 0 Comments: 664

2196. Floodman 15:37 GMT le 16 juillet 2010
Quoting Patrap: Time is Linear..and no one can go back. It s a parodox one could say. And for those of us who lost friends and family..well. It dosent savvy I guess. Per the numbers, time travel is possible, but not in the way one imagines it, though there are some physicists who say with the right technology a ton of study and enough power it be possible. I don't pretend to understand the math (it's WAY above my pay grade) but remember: there was a time when phyicists thought that a controlled nuclear reaction was impossible and that any attempt at one could very well result in a run-away reaction that envelopes the planet and beyond. Even Oppenheimer was only 70% convinced that the Trinity test wouldn't result in a planet wide conflagration involving the atmosphere; think about it: he thought that the first test would pretty wipe the planet (yet we still did it...hmmmm). Our great grand kids my figure it out, but I hope they're smart enough to not mess with history... Member Since: 2 août 2006 Posts: 10 Comments: 9919

2198. TheUno 15:49 GMT le 16 juillet 2010
Best quote on the DC earthquake this morning, "Albert Haynesworth must've come to town." Member Since: 15 août 2008 Posts: 0 Comments: 10

2199. JBirdFireMedic 16:30 GMT le 16 juillet 2010
NEW BLOG Member Since: 10 août 2009 Posts: 0 Comments: 246

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