2014 ENSO Mega Thread

[skierinvermont]

09-10 was a strong Nino, it maxed out at +1.6, which is over the +1.5 threshold needed for a strong Nino.

 

I've had a hard time finding official definitions of strong and moderate. The thresholds are clear but the duration required doesn't seem to be defined. Most of the time it seems like weak is defined as 5 months at or above +.5. That is actually different than what people seem to do in practice which is 3 trimonthlies although that's basically the same thing as 5 months. If you use the same definition for strong (5 months at or above +1.5) I'm not sure 09-10 makes the cut.

[andyhb]

I've had a hard time finding official definitions of strong and moderate. The thresholds are clear but the duration required doesn't seem to be defined. Most of the time it seems like weak is defined as 5 months at or above +.5. That is actually different than what people seem to do in practice which is 3 trimonthlies although that's basically the same thing as 5 months. If you use the same definition for strong (5 months at or above +1.5) I'm not sure 09-10 makes the cut.

 

I usually go by the trimonthly threshold of actually declaring an ENSO event and then whatever it's strongest anomaly as being the definition for its strength.

[The_Global_Warmer]

It looks like the first signs of the sub-surface warmth has made it to the surface.

 

 

 

 

[OKpowdah]

Winter 2009-10 was the strongest west-based El Nino on record. Line of zonal convergence stayed right near 155w the whole winter.

[JBG]

As I said before, I don't think the PDO will be a factor or as large this time in the overall peak strength. 2009-2010 wasn't a strong El Nino, just moderate so if you put climatology in the mix we are "due" for a super Nino but I don't like to go by that. We won't see any huge responses til the warmth reaches the surface which might be late next month or May if this wild trend continues.

Why would PDO suddenly not be a major factor?

[NaoPos]

quite the depth of the warm pool:

[AvantHiatus]

Is that graphic accurate? 42C is 107.6 Degrees Farenheit...36C is 97 degrees Farenheit.

[ORH_wxman]

Is that graphic accurate? 42C is 107.6 Degrees Farenheit...36C is 97 degrees Farenheit.

 

 

Its not in degrees...its a depth anomaly. In meters.

[AvantHiatus]

Its not in degrees...its a depth anomaly. In meters.

20C water temperatures extend down to 36-42 Meters at peak (170W to 130W)? Pretty impressive indeed. Also, What do negative values imply?

[Msalgado]

20C water temperatures extend down to 36-42 Meters at peak (170W to 130W)? Pretty impressive indeed. Also, What do negative values imply?

 

Thats not correct.  Its the depth anomaly of the 20 degrees Celsius isotherm.  In other words, how much shallower or deeper the isotherm is from "normal".  The negative numbers represent times wen it was shallower than normal.  The larger the number the further the depth before you hit the 20 degree temperature measurement and the smaller the sooner.

[The_Global_Warmer]

And boom goes the dynamite.

 

 

 

 

[jgf]

Can someone help me with what the effects of a strong El Nino might be on New England spring and summertime weather?

 

I am specifically interested in the track and frequency of mid-latitude, extra tropical  lows

 

Mostly, for New England the effects that I read about are either for the winter, or are related to frequency of tropical storms.

 

I thought that there was a belief that the average track of mid-latitude Lows was shifted further south in the summer, resulting in a greater frequency of Lows over New England than in La Nina conditions.

 

Is there any truth to that?

[nzucker]

Can someone help me with what the effects of a strong El Nino might be on New England spring and summertime weather?

 

I am specifically interested in the track and frequency of mid-latitude, extra tropical  lows

 

Mostly, for New England the effects that I read about are either for the winter, or are related to frequency of tropical storms.

 

I thought that there was a belief that the average track of mid-latitude Lows was shifted further south in the summer, resulting in a greater frequency of Lows over New England than in La Nina conditions.

 

Is there any truth to that?

A developing strong El Niño tends to lead to wetter, cooler conditions in the Northeast during summer. See 1997 and 2009.

[Yellow Evan]

Why would PDO suddenly not be a major factor?

 

PDO is a factor, it's just positive for now.

[wxtrackercody]

Dr. Ventrice has published another guest post on Dr. Masters' WunderBlog over on Weather Underground.

 

http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2658

 

El Nino doesn't appear to be wasting any time.

 

[Dsnowx53]

I definitely agree with Dr. Ventrice about the strong evidence of a rapidly developing El Nino -- the thermocline definitely appears to be flattening. I wrote an article about it. 

 

http://www.nymetroweather.com/2014/04/10/strong-el-nino/

[andyhb]

Excellent post, I'm a bit surprised there wasn't much mention of Ita's potential effects on subsequent WWBs anywhere up until this point.

[Dsnowx53]

Excellent post, I'm a bit surprised there wasn't much mention of Ita's potential effects on subsequent WWBs anywhere up until this point.

 

 

Thanks!

 

And I'm merely speculating on that, but I think it makes plenty of sense. Considering its location and strength, and where we typically see these westerly wind bursts, I don't see why it wouldn't. 

[uncle W]

the earlier the development of an el nino the greater the chance it will be a strong one...this weeks oni was +0.3...the four strongest el nino's developed in the AMJ three month period...

[wxmx]

My assessment is high end moderate to low end strong El Niño. I have been doing decently the last few years with my WAGs. This year's WAG would be +1.7 trimonthly ONI. The reason I don't go higher is because I still see no evidence of WWBs effectively propagating thru ENSO 3.4 and 3 regions (they have, but I would like them stronger than they have been), that should limit a bit the very impressive oceanic Kelvin wave currently traveling east.

[Dsnowx53]

My assessment is high end moderate to low end strong El Niño. I have been doing decently the last few years with my WAGs. This year's WAG would be +1.7 trimonthly ONI. The reason I don't go higher is because I still see no evidence of WWBs effectively propagating thru ENSO 3.4 and 3 regions (they have, but I would like them stronger than they have been), that should limit a bit the very impressive oceanic Kelvin wave currently traveling east.

 

 

I see what you're saying, but I feel that considering all that has happened already with increasingly strong downwelling waves, WWBs, and more warm water progressing eastward to the point where the thermocline is already changing in slope significantly...it seems to me that we are starting a feedback process that will further slow the trade winds and allow for more eastward progression of Kelvin Waves down the road. I feel that the scale has started to be tipped. 

[Mike.Ventrice]

Hi all,

 

Not sure if you're aware of this (I wasn't) but a live ocean current graphic is now available on the earth.nullschool.net page. 

 

http://earth.nullschool.net/#current/ocean/surface/currents/orthographic=219.78,3.33,588

 

There's a general net eastward current of 1-1.3 m/s (eyeballing) with smaller scale eddies embedded within in the eastern half of the equatorial Pacific in conjunction to where the strong downwelling oceanic Kelvin wave is  trying to surface. Note there is also a strong eastward current in the western equatorial Pacific in the same location where lower tropospheric westerlies are being observed. 

 

Enjoy!

[Ed Lizard]

Pardon my 'how much snow for Philly question.

 

 

Those maps where one can combine years and get temp/rainfall anomalies, I forgot where they are.  I know everyone at the KHOU-TV 11 forum is excited by the chance of a wetter than normal Winter after almost 6 years of drought or near drought, but what does a 1997 mega-warm ENSO (or combination of years with the ENSO and other relavant indices) mean for rainfall anomalies in the warm months?

 

I should learn the URL for those and then learn how to use them.  Monday was decent for rain, but locally, an abnormally dry Winter/early Spring again.

 

This offers *some* hope...

Of course, not sure the warm ENSO had really kicked in, and so far, April, other than Monday, dry as a bone...

 

1997 APR 25 5"-7" of rain caused street, bayou and creek flooding.(8)

1997 MAR 12 Early morning flooding. Heavy rains stalled over Houston.

1997 MAY 21 - 22 Street flooding in west Houston 6"-8" of rain. Elderly man drowned as he drove into a flooded underpass. Buffalo Bayou at Piney Point 4.69' above flood stage. (17)(8)

1997 MAY 24 Severe flooding in Houston; 50-75 homes flooded. Creeks and Bayous out of their banks.(8)

1997 MAY 30 3"-5" of rain; 6 homes flooded in northern Harris County.(9)

[Ground Scouring]

 

Hi all,

 

Not sure if you're aware of this (I wasn't) but a live ocean current graphic is now available on the earth.nullschool.net page. 

 

http://earth.nullschool.net/#current/ocean/surface/currents/orthographic=219.78,3.33,588

 

There's a general net eastward current of 1-1.3 m/s (eyeballing) with smaller scale eddies embedded within in the eastern half of the equatorial Pacific in conjunction to where the strong downwelling oceanic Kelvin wave is  trying to surface. Note there is also a strong eastward current in the western equatorial Pacific in the same location where lower tropospheric westerlies are being observed. 

 

Enjoy!

 

Great link. What are your thoughts on the prospects of a strong vs. a moderate Niño? Some of the April ensemble plumes (ECMWF for one) suggest that the warming trend in NINO 3.4 will level off AOB +1.5 sometime between mid-August and mid-September 2014. A lot of models are showing a possible early peak in the early fall, but then split in the longer range, with some showing a decay of El Niño to weak/moderate and others showing continued warming up through early winter, resulting in a strong Niño.

[hurricaneman]

Seems as if the sub surface warm pool is starting to shrink or maybe decay a little. It may be a thing to keep an eye on the next few weeks

[blizzardof96]

Seems as if the sub surface warm pool is starting to shrink or maybe decay a little. It may be a thing to keep an eye on the next few weeks

It looks like the upwelling phase of the oceanic kelvin wave has began to propagate towards the dateline, albeit in a fairly weak phase ATM. This, along with some MJO aided low level easterlies, are making it difficult for the subsuface warmth to make a huge impact at the sfc with most of the warming remaining east-based for now. The upcoming H5 pattern looks to favour increased west based warming as the NOI stays predominantly negative with anticyclonic RWB across the east pac. This is being coupled with a considerable NA mountain torque spike and very nino like intraseasonal oscillation phases. Might see the tropac make a bit of a modiki comeback if this type of pattern works out with a bering sea trough and NE pac ridging showing up in the 5-15 day period.

[bluewave]

Seems as if the sub surface warm pool is starting to shrink or maybe decay a little. It may be a thing to keep an eye on the next few weeks

 

The WWB really ran out of gas after the initial early push to the east in early March with the trades dominating

again east of the dateline. It will be interesting to see what the models look like once we get past the spring

forecast barrier. The flip of the SOI from negative in March to positive in April is pretty much unheard

of when a El Nino warming begins. That is usually something you see at the tail end of an El Nino

like during the Spring 0f 2010 and not the start.

 

........................Nino1+2 Nino3 Nino34 Nino4

Week SST SSTA SST SSTA SST SSTA SST SSTA

12MAR2014 25.8-0.6 26.8-0.3 26.8-0.4 28.7 0.6

19MAR2014 25.2-1.2 27.3 0.1 27.4 0.1 28.8 0.6

26MAR2014 25.4-0.7 27.6 0.4 27.6 0.2 29.0 0.7

02APR2014 25.2-0.7 27.8 0.5 27.8 0.3 29.0 0.7

09APR2014 24.9-0.8 27.6 0.1 27.9 0.2 29.1 0.7

16APR2014 24.8-0.7 27.7 0.2 28.0 0.2 29.1 0.6

[Quixotic1]

The WWB really ran out of gas after the initial early push to the east in early March with the trades dominating

again east of the dateline. It will be interesting to see what the models look like once we get past the spring

forecast barrier. The flip of the SOI from negative in March to positive in April is pretty much unheard

of when a El Nino warming begins. That is usually something you see at the tail end of an El Nino

like during the Spring 0f 2010 and not the start.

 

........................Nino1+2 Nino3 Nino34 Nino4

Week SST SSTA SST SSTA SST SSTA SST SSTA

12MAR2014 25.8-0.6 26.8-0.3 26.8-0.4 28.7 0.6

19MAR2014 25.2-1.2 27.3 0.1 27.4 0.1 28.8 0.6

26MAR2014 25.4-0.7 27.6 0.4 27.6 0.2 29.0 0.7

02APR2014 25.2-0.7 27.8 0.5 27.8 0.3 29.0 0.7

09APR2014 24.9-0.8 27.6 0.1 27.9 0.2 29.1 0.7

16APR2014 24.8-0.7 27.7 0.2 28.0 0.2 29.1 0.6

Might be we are seeing a version of what happened a couple of years ago when a nino seemed like a foregone conclusion only to see negative anomalies return?  Granted, this one seems much more impressive thus far. 

[bluewave]

Might be we are seeing a version of what happened a couple of years ago when a nino seemed like a foregone conclusion only to see negative anomalies return?  Granted, this one seems much more impressive thus far. 

 

The WWB from late February into March was a very strong event for that time of year. But the SOI and wind pattern

reversed into April where we are at right now. We'll probably have to wait and see what things look like in another

month or two to get a handle on the exact strength going forward.

 

 

[Mike.Ventrice]

Hi guys,

 

The latest European weeklies are now isolating another period of strong anomalous lower tropospheric westerly wind flow near the Date Line late April in through early May.  Now while this may not be a true WWB in nature (reversal of trades to westerlies at the surface), it will still likely result in weak trade flow near the date line and to the west thereafter at a later time. With the structure of SSTs in its current state, I still see signs for this Nino to be a Full Basin event and not a Modoki. Of course there is still uncertainty and time will tell, but I'm still placing bets in the full basin Nino camp.  

 

Did a quick analysis understanding the differences between Full-basin Ninos and Modoki's. With regards to tropical cyclone statistics over the Atlantic, Full-basin Nino's average 7 named storms, 3 hurricanes, 1 major hurricane. Modoki's that are expressed during the JJAS period often experience higher TC stats, with 11 named storms, 6 hurricanes, and 2 major hurricanes.