Dr. Jeff Masters' WunderBlog

La Niña is here

Posted by: Dr. Jeff Masters, 1:16 PM GMT on July 15, 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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1951. xcool 7:13 AM GMT on July 16, 2010
i'm go bed bye all Member Since: September 26, 2009 Posts: 2 Comments: 15501

1952. NCHurricane2009 7:13 AM GMT on July 16, 2010
To post 1947: What? A cat-3 typhoon has winds of 65 knots (75 mph). That's a minimal cat-1 hurricane in the Atlantic. Member Since: September 15, 2009 Posts: 277 Comments: 3357

1955. IKE 7:21 AM GMT on July 16, 2010
Quoting xcool: shows hope Shows little to nothing....00Z ECMWF... Member Since: June 9, 2005 Posts: 23 Comments: 37044

1956. KoritheMan 7:23 AM GMT on July 16, 2010
Quoting IKE: Shows little to nothing....00Z ECMWF... I do agree that any development will be slow to occur with the Caribbean AOI. Member Since: March 7, 2007 Posts: 408 Comments: 15418

1957. Ivanhater 7:26 AM GMT on July 16, 2010
Actually Ike, the Euro shows a TD this run, coming in line with the Para GFS Member Since: June 11, 2010 Posts: 0 Comments: 53

1958. HadesGodWyvern 7:28 AM GMT on July 16, 2010
JMA goes as following 35-50 is Category One (Tropical Storm) 50-65 is Category Two (Severe Tropical Storm) 65-85 is Category Three (Strong Typhoon) 85-105 is Category Four (Very Strong Typhoon) 105 or greater is Category Five (Intense Typhoon) Member Since: May 24, 2006 Posts: 43 Comments: 36684

1959. IKE 7:29 AM GMT on July 16, 2010
Quoting Ivanhater: Actually Ike, the Euro shows a TD this run, coming in line with the Para GFS That's a 1010 mb low. It's at 1008mb's right now. Is it now listed as a TD from the NHC? Member Since: June 9, 2005 Posts: 23 Comments: 37044

1960. Ivanhater 7:35 AM GMT on July 16, 2010
Based on the resolution being a global model (even updated) that's a TD.Also check out the pressures in its environment during that time. Just go back to previous storms on this resolution, similar to the GFS showing a hurricane with 1000mb pressure (but not to that extreme). Also note it just had a wave of lower pressures in previous runs. 00Z Canadian Member Since: June 11, 2010 Posts: 0 Comments: 53

1961. HadesGodWyvern 7:38 AM GMT on July 16, 2010
hmm a low embedded in the intertropical convergence zone will probably not be identified as a depression this morning. Member Since: May 24, 2006 Posts: 43 Comments: 36684

1962. HadesGodWyvern 7:40 AM GMT on July 16, 2010
anyway.. what is this. 16L? Member Since: May 24, 2006 Posts: 43 Comments: 36684

1963. IKE 7:40 AM GMT on July 16, 2010
Here's the eastern ATL view through July 26th on the 00Z ECMWF. Also...look at TD 6E in the eastern Pacific and note it's pressure...and it's barely a TD anymore... ...SIX-E BARELY A TROPICAL DEPRESSION... 8:00 PM PDT Thu Jul 15 Location: 16.7°N 109.0°W Max sustained: 30 mph Moving: WNW at 8 mph Min pressure: 1006 mb Member Since: June 9, 2005 Posts: 23 Comments: 37044

1964. HadesGodWyvern 7:42 AM GMT on July 16, 2010
I can't even read the "storm" name =P Member Since: May 24, 2006 Posts: 43 Comments: 36684

1966. homelesswanderer 7:44 AM GMT on July 16, 2010
HMMMM? Link GULF OF MEXICO... LATEST BUOY OBSERVATIONS FROM ACROSS THE AREA SHOW RATHER LIGHT WINDS THROUGHOUT WITH WIND DIRECTION GENERALLY FROM THE E-SE...EXCEPT OVER THE FAR WESTERN PORTION WHERE WINDS ARE SE TO S IN LIGHT SLY RETURN FLOW. LATEST SEA STATE ANALYSIS REVEALED LOW SEAS THROUGHOUT A TROUGH OVER THE S CENTRAL GULF ROUGHLY ALONG 89W S OF 26N IS MOVING W ABOUT 10 KT. AN SCAT PASS FROM NEAR 0330 UTC LAST NIGHT INDICATED A WIND SHIFT FROM NE TO E W OF THE TROUGH AND E TO SE TO THE E OF THE TROUGH IT. ASIDE FROM CONTINUING TO PRODUCE SCATTERED SHOWERS AND TSTMS WITH POSSIBLE GUSTY WINDS IN THE SOUTHERN PORTION OF THE MIDDLE GULF TODAY...AND IN THEN IN THE EASTERN PORTION OF THE SW GULF ZONE AND SE PORTION OF THE NW GULF ZONE THIS EVENING AND SAT MORNING. MODELS IN GOOD AGREEMENT THE THE TROUGH THEN BECOMES DIFFUSE SAT AFTERNOON OR EARLY EVENING OVER THE FAR WESTERN WATERS. THE REGIONAL NAM FROM 00 UTC LAST NIGHT IS THE OUTLIER INDICATING THAT A WEAK LOW FORMS OVER THE NW WATERS TONIGHT...AND BEGINS TO TRACK NW AND N SAT EVENING INTO SUN AND REACHES THE NE TEXAS COAST SUN NIGHT. WILL DISCOUNT THIS SOLN FOR NOW AND GO WITH CONSENSUS WITH REGARDS TO TRACK AND ULTIMATE OUTCOME OF THE LOW. A 1018 MB HIGH PRES IS ANALYZED NEAR 28N93W WITH WEAK HIGH PRES OVER THE AREA ELSEWHERE OUTSIDE THE VICINITY OF THE TROUGH. THE HIGH IS FORECAST TO REMAIN STATIONARY THROUGH THE NEXT 24 HRS OR SO...THEN BE REPLACED BY A RIDGE NEAR 26N/27N. THE RIDGE WILL THEN LIFT N OF THE AREA LATE SUN INTO MON. ANOTHER TROUGH IS EXPECTED TO MOVE INTO THE FAR SE PORTION LATE SUN INTO MON...THEN MOVE THROUGH THE REST OF THE E GULF S OF ABOUT 27N MON...AND INTO MIDDLE GULF TO NEAR 90W BY TUE AFTERNOON. YET ANOTHER SURGE OF INCREASING E TO SE WINDS OF 15-20 KT SHOULD FOLLOW IN THE WAKE OF THE TROUGH DUE TO THE PRES DIFFERENCE BETWEEN ATLC RIDGING NE OF THE AREA AND THE TROUGH. Member Since: August 15, 2008 Posts: 10 Comments: 3665

1967. IKE 7:51 AM GMT on July 16, 2010
Quoting HadesGodWyvern: hmm a low embedded in the intertropical convergence zone will probably not be identified as a depression this morning. I understand your point, but.... A 1010mb low on a computer model is not a TD. Member Since: June 9, 2005 Posts: 23 Comments: 37044

1968. homelesswanderer 7:52 AM GMT on July 16, 2010
Quoting Ivanhater: Actually Ike, the Euro shows a TD this run, coming in line with the Para GFS Yeah to me looked like a few of the models were bringing whatever that is into TX/MX at around 144hrs. Member Since: August 15, 2008 Posts: 10 Comments: 3665

1970. HadesGodWyvern 8:13 AM GMT on July 16, 2010
the low is overland Columbia or looks like it. Member Since: May 24, 2006 Posts: 43 Comments: 36684

1971. homelesswanderer 8:40 AM GMT on July 16, 2010
Another well defined naked swirl in the GOM. At about 26/86. Lets hope it doesn't find it's clothes. Member Since: August 15, 2008 Posts: 10 Comments: 3665

1972. HadesGodWyvern 9:05 AM GMT on July 16, 2010
National Hurricane Center Tropical Cyclone Advisory #7 TROPICAL DEPRESSION EP062010 9:00 AM UTC July 16 2010 =============================== SUBJECT: "SIX" Degenerates Into A Remnant Low At 9:00 AM UTC, Tropical Depression SIX (1006 hPa) located at 17.2N 109.9W or 115 NM south southeast of Socorro Island has sustained winds of 25 knots with gusts of 35 knots. The low is reported as moving west northwest at 9 knots. THIS IS THE FINAL TROPICAL CYCLONE ADVISORY FROM THE NATIONAL HURRICANE CENTER Member Since: May 24, 2006 Posts: 43 Comments: 36684

1973. homelesswanderer 9:22 AM GMT on July 16, 2010
Channel 12 Beaumont, Tx Tropical development is not anticipated for the next couple of days. For the first time this hurricane season, July 20th through July 24th, the upper-level pattern will leave Texas unprotected. If anything gets into the Gulf of Mexico, then it would likely move into Texas during this period. This is a pattern similar to when Hurricane Ike and Rita struck the area. Link Member Since: August 15, 2008 Posts: 10 Comments: 3665

1974. TxKeef 9:33 AM GMT on July 16, 2010
I just heard that there was an earthquake in DC! How strange. It was a 3.6 magnitude. Member Since: August 30, 2008 Posts: 0 Comments: 71

1975. IKE 9:36 AM GMT on July 16, 2010
SYNOPSIS FOR THE GULF OF MEXICO 430 AM CDT FRI JUL 16 2010 .SYNOPSIS...HIGH PRES CENTERED NEAR 28N93W WILL BE REPLACED BY A RIDGE ALONG 27N SAT NIGHT...THEN N OF AREA SUN INTO MON. A TROUGH ALONG 89W S OF 27N WILL MOVE TO THE FAR WESTERN PORTION BY SAT EVENING WHILE BECOMING DIFFUSE. ANOTHER TROUGH IS EXPECTED TO ENTER THE EASTERN GULF MON...AND REACH THE MIDDLE GULF TUE. Member Since: June 9, 2005 Posts: 23 Comments: 37044

1976. HadesGodWyvern 9:52 AM GMT on July 16, 2010
Japan Meteorological Agency Tropical Cyclone Advisory #36 TYPHOON CONSON (T1002) 18:00 PM JST July 16 2010 ============================ SUBJECT: Category Three Typhoon In The South China Sea At 9:00 AM UTC, Typhoon Conson (975 hPa) located at 17.8N 109.7E has 10 minute sustained winds of 65 knots with gusts of 95 knots. The cyclone is reported as moving northwest at 11 knots. Dvorak Intensity: Storm Force Winds ================= 60 NM from the center Gale Force Winds ================= 200 NM from the center Forecast and Intensity ======================== 24 HRS: 19.7N 106.9E - 55 knots (CAT 2/Severe Tropical Storm) 45 HRS: 22.3N 104.8E - 30 knots (Tropical Depression) Member Since: May 24, 2006 Posts: 43 Comments: 36684

1977. homelesswanderer 9:53 AM GMT on July 16, 2010
Well the naked swirl is trying to build storms. But now I can't tell if its swirling. Lol Member Since: August 15, 2008 Posts: 10 Comments: 3665

1978. surfmom 10:07 AM GMT on July 16, 2010
Quoting TxKeef: I just heard that there was an earthquake in DC! How strange. It was a 3.6 magnitude. anywhere else - going to go look Member Since: July 18, 2007 Posts: 30 Comments: 26538

1979. TxKeef 10:32 AM GMT on July 16, 2010
Quoting surfmom: anywhere else - going to go look The epicenter was just south of Germantown Member Since: August 30, 2008 Posts: 0 Comments: 71

1980. stoormfury 10:37 AM GMT on July 16, 2010
morning the sahara dust seems to have settled and almost dissipated, there are two monstrous tropical waves over africa. one is about to exjt the coastand the other about 5 degE Member Since: August 22, 2006 Posts: 0 Comments: 2302

1981. MahFL 10:37 AM GMT on July 16, 2010
Morning all. Member Since: June 9, 2004 Posts: 0 Comments: 2418

1982. Tropicsweatherpr 10:44 AM GMT on July 16, 2010
Good morning to all. 00z ECMWF has a Cape Verde system at 216 hours. Member Since: April 29, 2009 Posts: 63 Comments: 8101

1983. blsealevel 10:49 AM GMT on July 16, 2010
Member Since: August 23, 2008 Posts: 0 Comments: 1916

1984. blsealevel 10:52 AM GMT on July 16, 2010
Member Since: August 23, 2008 Posts: 0 Comments: 1916

1985. homelesswanderer 11:03 AM GMT on July 16, 2010
Morning everyone. :) Link Found this interesting. Not sure who it is that writes these discussions for Crown Weather Service. But he has my respect. I like that he said he was wrong. Honesty is refreshing some times. :) Now what he wrote I'm not crazy about. Lol. One signal that is very, very troubling is the abnormally warm summer thus far in the northeastern United States. This points to an upper level pattern of the high pressure system setting up over the eastern United States. If this pattern continues, then the northwestern and western Gulf coast may be at a higher risk of a significant hurricane this season; this was something I was not anticipating earlier this year in my seasonal hurricane outlooks. Folks in the western Gulf need to be aware that Alex and Tropical Depression 2 may not be the last threats this hurricane season. Big sigh. :( Member Since: August 15, 2008 Posts: 10 Comments: 3665

1987. sporteguy03 11:13 AM GMT on July 16, 2010
Quoting StormW: Don't know his last name, but I believe that would be Rob, from Crown Weather. He's on my email list as well. Rob Lightbrown he lives up in Maine, he is a very respected and knowledgeable person. He brings up excellent points in his discussions. Member Since: July 7, 2005 Posts: 0 Comments: 4824

1988. stormwatcherCI 11:14 AM GMT on July 16, 2010
Quoting StormW: Don't know his last name, but I believe that would be Rob, from Crown Weather. He's on my email list as well. Lightbown Member Since: October 9, 2008 Posts: 0 Comments: 8038

1989. homelesswanderer 11:14 AM GMT on July 16, 2010
Quoting StormW: Don't know his last name, but I believe that would be Rob, from Crown Weather. He's on my email list as well. Oh ok. I knew I liked him for some reason. :) Member Since: August 15, 2008 Posts: 10 Comments: 3665

1990. earthlydragonfly 11:15 AM GMT on July 16, 2010
Member Since: July 1, 2005 Posts: 10 Comments: 1649

1992. stormwatcherCI 11:15 AM GMT on July 16, 2010
Quoting sporteguy03: Rob Lightbrown he lives up in Maine, he is a very respected and knowledgeable person. He brings up excellent points in his discussions. Rob & Meg Lightbown Member Since: October 9, 2008 Posts: 0 Comments: 8038

1993. blsealevel 11:16 AM GMT on July 16, 2010
Member Since: August 23, 2008 Posts: 0 Comments: 1916

1994. homelesswanderer 11:16 AM GMT on July 16, 2010
Quoting sporteguy03: Rob Lightbrown he lives up in Maine, he is a very respected and knowledgeable person. He brings up excellent points in his discussions. Yes he does. This morning's discussion was a good one too. Member Since: August 15, 2008 Posts: 10 Comments: 3665

1995. earthlydragonfly 11:18 AM GMT on July 16, 2010
Top of the morning to all Member Since: July 1, 2005 Posts: 10 Comments: 1649

1996. stormwatcherCI 11:19 AM GMT on July 16, 2010
Quoting earthlydragonfly: Top of the morning to all Good morning to all. Member Since: October 9, 2008 Posts: 0 Comments: 8038

1997. homelesswanderer 11:19 AM GMT on July 16, 2010
Quoting blsealevel: Shows our almost naked swirl spinning quickly to the west on the RGB loop. Hopefully it'll move too fast to organize. Member Since: August 15, 2008 Posts: 10 Comments: 3665

1999. homelesswanderer 11:21 AM GMT on July 16, 2010
Quoting earthlydragonfly: Top of the morning to all Good morning Dragonfly! And good morning all. :) Member Since: August 15, 2008 Posts: 10 Comments: 3665

2000. blsealevel 11:23 AM GMT on July 16, 2010
I don't see it doing much unless it has no real energy just some more rain to La.,Tx. Member Since: August 23, 2008 Posts: 0 Comments: 1916

2001. homelesswanderer 11:28 AM GMT on July 16, 2010
Quoting blsealevel: I don't see it doing much unless it has no real energy just some more rain to La.,Tx. Yeah you're probably right. I'm glad I'm sitting here watching naked swirls than something worse this a.m. :) Member Since: August 15, 2008 Posts: 10 Comments: 3665

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