La Niña drawing to a close

By: Dr. Jeff Masters , 3:39 PM GMT on February 27, 2012

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La Niña, the cooling of the equatorial Pacific waters off the coast of South America that has dramatically affected our weather for most of the past two years, is almost done. 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", have warmed rapidly over the past two weeks, and were 0.4°C below average on February 27. This is slightly warmer than the -0.5°C threshold to be considered La Niña conditions, and is the first time since early August that La Niña conditions have not been present. It is likely that SSTs will continue to warm during March and April, and NOAA's Climate Prediction Center is predicting that they will declare an official end to La Niña sometime between March and April. A moderate to strong La Niña began in the summer of 2010, weakened briefly during May - July 2011 to neutral status, then re-intensified to a borderline weak/moderate La Niña from August 2011 - January 2012.


Figure 1. Comparison of the sea surface temperature departure from average from January 4 and February 22, 2012, over the tropical Eastern Pacific. During January, a large region of the ocean was more than 0.5°C cooler than average, meaning a La Niña event was present. Beginning in mid-February, waters warmed rapidly from east to west along the Equator, signaling and end to the La Niña event. Image credit: NOAA.

The forecast: neutral or El Niño conditions by fall
The period March - May is the typical time of year that El Niño or La Niña events end, and it is common for the opposite phenomena to take hold by fall. Since 1950, there have been twelve La Niña events that ended during the first half of the year; during six of those years (50%), an El Niño event formed in time for the August - September - October peak of hurricane season. The official forecast from Columbia University's IRI and NOAA's Climate Prediction Center calls for a 31 - 32% chance of an El Niño event during the 2012 Atlantic hurricane season. El Niño conditions tend to suppress Atlantic hurricane activity by creating high levels of wind shear that tends to tear hurricanes apart. Given the relatively high chance of an El Niño event this fall, plus ocean temperatures over the tropical Atlantic that are cooler than we saw in 2011 and 2010, I doubt we'll see an Atlantic hurricane season as active as the ones in 2010 and 2011 (nineteen named storms both years, third busiest seasons on record.) The demise of La Niña also means that global temperatures should begin to approach record warm levels by the end of the year. The cool waters of a La Niña event keep global temperatures cooler than average.


Figure 2. Computer model forecasts of El Niño/La Niña made in mid-February 2012. The forecasts that go above the red line at +0.5°C denote El Niño conditions; -0.5°C to +0.5°C denote neutral conditions, and below -0.5°C denote La Niña conditions. Most of the computer models are predicting neutral or El Niño conditions during the fall peak of the Atlantic hurricane season. Image credit: Columbia University's IRI.

I'll have a new post by Wednesday.

Jeff Masters

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Quoting SPLbeater:


something really pleasant occur today?
No not really.I'm just looking forward to mah fat pay check come Thursday!.
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ok why isnt the rest of the US loading....all it shows is the SE CONUS :/
Member Since: August 4, 2011 Posts: 46 Comments: 4481
Quoting SPLbeater:
i downloaded the 21 day trial and cant find it now lol.


seek and you have to go looking in folders
search and your os will find for you!

clear skies ahead of the squall line.
imagine if this had been late afternoon!
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NEVERMIND 622 i found it lol...stupid me...right there on the 'start' menu!!!
Member Since: August 4, 2011 Posts: 46 Comments: 4481
Quoting washingtonian115:
Oh yeah!.


something really pleasant occur today?
Member Since: August 4, 2011 Posts: 46 Comments: 4481
The guy who created facebook is a stone nut case.No one can tell me other wise.I look at him personally and the way he talks and his actions..and they aren't normal.Then to top it all off he wants to take over the internet and make it one big social netowrk(Basically one big Facebook in disguise).I'm on to him...
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i downloaded the 21 day trial and cant find it now lol.
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Quoting TampaSpin:
Golf ball size hail falling in Kansas...WOW....thata hurt!


dont forget the 70-80 mph winds with it!
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Quoting SPLbeater:


you seem cheery this evening :D
Oh yeah!.
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Golf ball size hail falling in Kansas...WOW....thata hurt!
Member Since: September 2, 2007 Posts: 178 Comments: 20439
Ouch. storms are moving into the 1000 srh
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For those who want to try out GR2Analyst, get the 21 day trial tonight or tomorrow, so you can use it tomorrow, and then especially during the potential tornado outbreak on Friday and Saturday.
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These storms are boring me to sleep
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Quoting WDEmobmet:


Have you checked out the rotation feature?
Not any storms I can really use it on right now :(.
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Quoting hurricanehunter27:
So far thats my favorite part, have not been able to use the 3D Rotation feature yet.


Have you checked out the rotation feature?
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Quoting washingtonian115:
Hey!!


you seem cheery this evening :D
Member Since: August 4, 2011 Posts: 46 Comments: 4481
Quoting KoritheMan:


Um, what difference would it make with regards to the tornado's intensity if it's in an open field?
Do you mean typically tornadoes in fields get lower ratings? If a tornado takes off enuf soil it should be considered a EF5.
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Quoting StormTracker2K:


Saturday appears like it may be very bad in the same areas that got hit the end of last April in SE US!


Yea the setup doesnt look good. I am in Mobile so most of the worst should stay a little bit north of where Im at
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Quoting StormTracker2K:


Good evening!
Hey!!
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Quoting hurricanehunter27:
To be honest I wouldn't mind some strong tornado's myself, just leave out the part of people getting hurt. Just some good EF5's in a field.


Um, what difference would it make with regards to the tornado's intensity if it's in an open field?
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Quoting GeorgiaStormz:



shhhhhh....or youll jinx my severe weather again.
To be honest I wouldn't mind some strong tornado's myself, just leave out the part of people getting hurt. Just some good EF5's in a field.
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Quoting WDEmobmet:
Identifies Hail Cores

So far thats my favorite part, have not been able to use the 3D Rotation feature yet.
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Quoting washingtonian115:
Igor,Igor,Igor!!!!!!


Good evening!
Member Since: October 26, 2011 Posts: 0 Comments: 2651
Quoting StormTracker2K:
Temps are forecast to hit 90 in C FL so we have plenty of heat to feed these storms from LA to GA on Saturday. This could be ugly folks!



shhhhhh....or youll jinx my severe weather again.
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Quoting WDEmobmet:


That was exactly my thought process, after Friday early Saturday I will know by then whether I will buy for sure or not.


Saturday appears like it may be very bad in the same areas that got hit the end of last April in SE US!
Member Since: October 26, 2011 Posts: 0 Comments: 2651
Identifies Hail Cores

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Temps are forecast to hit 90 in C FL so we have plenty of heat to feed these storms from LA to GA on Saturday. This could be ugly folks!
Member Since: October 26, 2011 Posts: 0 Comments: 2651
Igor,Igor,Igor!!!!!!
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Quoting hurricanehunter27:
Well if there is a large tornado outbreak on Friday & Saturday I will most likely make a choice.


That was exactly my thought process, after Friday early Saturday I will know by then whether I will buy for sure or not.
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Member Since: October 26, 2011 Posts: 0 Comments: 2651
Quoting sunlinepr:
brettadair 2000 j k/g of Cape in North Alabama on Friday Night oh bring it on -TS about 1 hour ago � reply � retweet � favorite


I hope it hits N Ga hard in the Afternoon.
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just for those who are wondering this is a general breakdown of the software and how to use it. Hints are provided to achieve the desired picture.

Link
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Boy the NAM spells BIG TIME trouble for the SE on Saturday.



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brettadair 2000 j k/g of Cape in North Alabama on Friday Night oh bring it on -TS about 1 hour ago reply retweet favorite

28storms RT @USWeatherExpert Tornado may be crossing I-135 north of Hesston, KS. Tornado signature on radar at 7:24pm is moving northeast. #kswx about 1 hour ago reply retweet favorite

28storms Pics of today's tornado in Nebraska fb.me/UCURe15e about 1 hour ago reply retweet favorite

Member Since: August 2, 2010 Posts: 21 Comments: 9780
NWS STORM PREDICTION CENTER NORMAN OK
0351 AM CST TUE FEB 28 2012

VALID 021200Z - 071200Z

...DISCUSSION...
IN MID-UPPER LEVELS...PROGRESSIVE WRN-CONUS TROUGH DESCRIBED IN DAYS
2-3 OUTLOOKS WILL PROCEED EWD ACROSS UPPER MIDWEST AND CENTRAL
PLAINS DAY-4/2ND-3RD. MREF MEMBERS AND OPERATIONAL PROGS VARY A
GREAT DEAL ON AMPLITUDE OF THIS SYSTEM BY THEN. THEY ALSO VARY
CONSIDERABLY ON POLEWARD EXTENT OF WARM-SECTOR SFC ISODROSOTHERMS IN
50S/60S F...WHILE DIFFERING SOMEWHAT ON TIMING OF OTHER SFC AND
MIDLEVEL FEATURES. IN MOST SCENARIOS...HOWEVER...SFC COLD FRONT
SHOULD SWEEP EWD/SEWD ACROSS LOWER-MID MS VALLEY AND LOWER OH VALLEY
DAY-4...WHILE SFC LOW LIFTS NEWD FROM SRN/CENTRAL PLAINS TO GREAT
LAKES. POSITIVELY-TILTED NATURE OF MID-UPPER TROUGH...WITH
APPRECIABLE LARGE-SCALE ASCENT LAGGING BEHIND COLD FRONT...INDICATE
1. LAPSE RATES WILL BE WEAK ABOVE SFC FRONT AND IN WARM SECTOR...AND
2. BOUNDARY-PARALLEL FLOW ALOFT. THIS CERTAINLY DOES NOT *PRECLUDE*
SVR...IN FACT...SOME PART OF PREFRONTAL CORRIDOR MAY NEED AOA 30%
PROBABILITIES IN FUTURE OUTLOOKS VALID THIS DAY
. HOWEVER...THREAT
APPEARS TOO UNCERTAIN SPATIALLY FOR UNCONDITIONAL 30% AREA ATTM.

THEREAFTER...PRESENCE OF DEEP/ERN CONUS TROUGH ALOFT AND LACK OF
LOW-LEVEL THETAE SHOULD REDUCE SVR RISK TO BELOW CATEGORICAL 30%
CRITERIA.
Member Since: October 26, 2011 Posts: 0 Comments: 2651
Member Since: August 2, 2010 Posts: 21 Comments: 9780
Quoting hurricanehunter27:
Well if there is a large tornado outbreak on Friday & Saturday I will most likely make choice.


If so ill start with the trials.
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Quoting WDEmobmet:


Yea 250 is rough but its worth it I TELL YA... Thats what I keep telling my wife. I dont think she has bought it yet
Well if there is a large tornado outbreak on Friday & Saturday I will most likely make a choice.
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Member Since: October 26, 2011 Posts: 0 Comments: 2651
Quoting hurricanehunter27:
Yah on trial right now had other software that used Level 2 for years and thinking about it. But wow $250 is a LOT!

I'm interested in buying Analyst and I heard from several people like TA13 that it's worth the money.
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Quoting hurricanehunter27:
Yah on trial right now had other software that used Level 2 for years and thinking about it. But wow $250 is a LOT!


Yea 250 is rough but its worth it I TELL YA... Thats what I keep telling my wife. I dont think she has bought it yet
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Wow what an increase here!

Member Since: October 26, 2011 Posts: 0 Comments: 2651
Quoting WDEmobmet:


I gotcha do you currently have GR2Anal, if not they offer a 21 day free trial... I have used GRlevel3 for three years and just now am trying out Analyst....great software so far.
Yah on trial right now had other software that used Level 2 for years and thinking about it. But wow $250 is a LOT!
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Quoting hurricanehunter27:
TY! My AllisonHouse subscription expired :(


I gotcha do you currently have GR2Anal, if not they offer a 21 day free trial... I have used GRlevel3 for three years and just now am trying out Analyst....great software so far.
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it looks like it flattened out
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Well, of course La Nina is drawing to a close. Just look at the huge SST anomalies in the Humboldt Current, offshore Chile and Peru - this area has been warming for several weeks now, cutting off the cold water of La Nina downstream toward the Galapagos. We even had an INVEST forming offshore Peru earlier in February.

In North American news, the tornado season in the US is ramping up. A winter storm is heading toward the great lakes and will incur great temperature fluctuations throughout early March.

Mozambique could get hit by yet another cyclone this week. Tropical Cyclone Irina (not to be confused with Irene) is dumping heavy rains in northern Madagascar and northern Mozambique, and will likely make landfall in southern Mozambique, and may impact Swaziland. Mozambique is still recovering from floods reminiscent of the deadly 2000 event that hit the country early this year, alongside cyclones Dondo and Funso.
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Quoting WDEmobmet:


http://mesonet.agron.iastate.edu/data/nexrd2/raw/

a free site so you know....
TY! My AllisonHouse subscription expired :(
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Quoting hurricanehunter27:
What are you using for your Level 2 data source?


http://mesonet.agron.iastate.edu/data/nexrd2/raw/

a free site so you know....
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578. HadesGodWyvern (Mod)
Mauritius Meteorological Services
Tropical Cyclone Advisory #1
PERTURBATION TROPICALE 12-20112012
4:00 AM RET February 29 2012
==============================

At 0:00 AM UTC, Tropical Disturbance 12 (999 hPa) located at 12.5S 69.2E has 10 minute sustained winds of 25 knots with gusts of 40 knots. The disturbance is reported as moving south at 3 knots.

Dvorak Intensity: T2.0/2.0/D0.5/12 HRS

Forecast and Intensity
==============

12 HRS: 13.3S 69.1E - 30 knots (Depression Tropicale)
24 HRS: 14.5S 68.2E - 30 knots (Depression Tropicale)
48 HRS: 16.6S 67.7E - 30 knots (Depression Tropicale)
72 HRS: 19.0S 68.8E - 35 knots (Tempête Tropicale Modérée)

Additional Information
================

Since 1800 PM UTC, deep convective activity has consolidated near the center and organized on a curved band pattern. SSMI F15 2310 PM UTC confirms this better feature. Low level inflow improves on the both sides and easterly vertical wind shear has temporarily weakened but is forecast to enforce back today late and tomorrow Thursday. Numerical weather prediction models are now in good agreement to forecast a globally southwards motion. Over this expected track, environmental conditions should become favorable on Friday under the upper level ridge but a new northerly vertical wind shear constraint should established on and after Saturday. Potential for intensification is therefore limited at short or medium range.

The next tropical cyclone advisory from Mauritius Meteorological Services will be issued at 6:30 AM UTC..
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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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