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Gray-Wolf

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Posted
  • Location: Scunthorpe
  • Location: Scunthorpe

I thought now that we have got the individual monthly ENSO figures in for December, January and February it would be time to do some historic pattern matching to see what it could possibly mean for us in terms of possible spring CET, weather patterns and precipitation

First I have included this table based on the La Nina years from 1870 to 2020

Untitled.thumb.png.3e222710cc79e725b6408287f4fe251a.png

Next I have included the ONI figures for December, January and February as well as what strength of La Nina we got and where the cold anomalies were based

Untitled.thumb.png.81b42c16844183e9f0ed512f477e6c4b.png

As you can see we ended up with an average moderate La Nina which was a mixed or basin wide event overall

CET

What does all of this mean for the possible CET and anomalies for March, April and May as well as the overall spring

The initial table can be narrowed down to 3 relevant rows, Overall Mixed La Nina winters, Overall Moderate La Nina winters and the more precise Moderate Mixed La Nina winters.

Using just mixed events we come out with basically an average spring in terms of CET with anomalies very close to the long term average in all 3 spring months as well as the overall spring

In regards to just Moderate La Nina events we also come out basically bang on average too

However when we focus more specifically on the combination of both Moderate and Mixed La Nina's the story is a little different. We come out with milder March's with anomalies at +0.79C above the mean, colder Aprils with the anomalies around -0.54C below the mean and May around average with the cold and mild March and April cancelling each other out and the average May means the overall spring anomaly ends up close to average also

Overall 500mb Patterns for Moderate Mixed La Nina Springs

Time to see what the 500mb patterns come up with for each category

Overall

image.thumb.png.dd87556396ea3d95c89917aa0c052826.png

This overall would look like a cold pattern but the Moderate Mixed La Nina winters tend to produce mild weather in March with cold April and average May, maybe a cold April pattern has distorted the overall 500mb pattern. Time to look at each month separately.

March

image.thumb.png.63eb900290aeed7e5b45e05ad21e9de0.png

March is dominated here by average easterly winds and this at first glance looks like it would be cold but the CET anomaly for the March's would suggest a milder month so maybe more of a Mediterranean influence rather than Siberian with these easterlies

April

image.thumb.png.8dda39fbdebd7098a8eb5018b208ba55.png

Overall a colder pattern showing here for April's with higher pressure near Greenland and lower pressure to the east of this placing the UK in a generally cold and unsettled pattern. A snow risk cannot be ruled out here, especially earlier in the month

May

image.thumb.png.e18abcee88a5e3b10f04ffb475915719.png

A generally average CET May with the driest weather in the N and the wettest in the S. Not looking good for many European locations under that low pressure with a poor start to the late spring/early summer season

Precipitation

How does precipitation shape up for springs following Moderate Mixed La Nina's

Overall

image.thumb.png.a6aaac675d050ec621cb83a186fa5b51.png

The overall spring signal is looking drier than average away from the far SE corner of England with the driest anomalies in the W of the UK. How do the individual months break down then

March

image.thumb.png.1f3d0d0fa46cbbf199c219ebc5c0bc93.png

Looking like quite a dry signal for the March's that follow Moderate Mixed La Nina winters. A good sign if you want to avoid anymore flooding after some of the winter rain we have seen. The driest overall signal is in the NW of the UK with the least dry in the SE corner of the UK

April

image.thumb.png.5b3b5d3c71cd68a53810eba09e37ef66.png

A total flip around from March's to April's. Now wetter than average features quite a bit, especially the further north you go in the UK with the wettest in NW Scotland and average to slightly below average precipitation in the south and the Channel Islands.

May

image.thumb.png.856d0d76444e02d7b094b8070f769d1d.png

The May's that follow Moderate Mixed La Nina winters are a lot more mixed but generally west is best if you are after drier weather with the potential for some very wet conditions further east. SE England could see some very wet weather but other eastern areas look like they could be at risk from this too

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl

Thanks for this informative post - perhaps might be better located in the Spring 2021 forecast thread, as it may become a little lost in here, but equally relevant for this thread given it is about observations based on ENSO.

Just a hunch but I feel there is some credence in the forecast of a cold April, all that bottled up cold air in the arctic through March combined with a relatively weak atlantic suggests northerly airstreams could hold sway with the cold air needing to be released into mid lattitudes and the PV goes on the wane..

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Posted
  • Location: Longden, Shropshire
  • Location: Longden, Shropshire
16 minutes ago, damianslaw said:

Just a hunch but I feel there is some credence in the forecast of a cold April, all that bottled up cold air in the arctic through March combined with a relatively weak atlantic suggests northerly airstreams could hold sway with the cold air needing to be released into mid lattitudes and the PV goes on the wane..

Could well be the case this year with the late PV.  A similar April to 1989 perhaps?

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl
2 minutes ago, Don said:

Could well be the case this year with the late PV.  A similar April to 1989 perhaps?

Perhaps not as cold, but a good chance of at least one northerly episode at some stage, and not necessarily a 24 hr shot. April often brings northerlies so nothing unusual, but the depth of cold this year may be more extreme than normal.

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Posted
  • Location: Longden, Shropshire
  • Location: Longden, Shropshire
8 minutes ago, damianslaw said:

Perhaps not as cold, but a good chance of at least one northerly episode at some stage, and not necessarily a 24 hr shot. April often brings northerlies so nothing unusual, but the depth of cold this year may be more extreme than normal.

Yes, perhaps not that cold.  Maybe something akin to 1998 or 2008?

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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

03MAR2021 - Nino3: -0.4, Nino3.4: -0.7, Nino4: -0.8

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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

10MAR2021 - Nino3: +0.1, Nino3.4: -0.3, Nino4: -0.5

17MAR2021 - Nino3: -0.2, Nino3.4: -0.5, Nino4: -0.4

Sub-surface just went net positive as well so March will end flat for sub-surface and SOI despite the strong Winter values.

It does appear the Nina is being squeezed at both ends now.
 

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl
2 hours ago, summer blizzard said:

10MAR2021 - Nino3: +0.1, Nino3.4: -0.3, Nino4: -0.5

17MAR2021 - Nino3: -0.2, Nino3.4: -0.5, Nino4: -0.4

Sub-surface just went net positive as well so March will end flat for sub-surface and SOI despite the strong Winter values.

It does appear the Nina is being squeezed at both ends now.
 

What does  this mean for likely summer prospects?

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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
44 minutes ago, damianslaw said:

What does  this mean for likely summer prospects?

If a Nino actually tries to develop (doubtful for me) then actually most of our 18C+ summer months come in transition years (likely because relative AAM spikes rather than just stays stable even if high).

If we just drop back to neutral and nothing much happens then atmospheric memory will probably produce a Nina pattern even if we get periodic amplification.

If Nina tries to redevelop during the summer then expect it to be poor.

Options 2 and 3 are more likely in my opinion with a persistent neutral-negative ONI strengthening again in the Autumn (SOI monthly values suggest March is MJO disrupted and we have a -PDO).

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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

24MAR2021 - Nino3: -0.7, Nino3.4: -0.6,  Nino4: -0.6

 

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Posted
  • Location: Scunthorpe
  • Location: Scunthorpe

These are the daily NINO Region anomalies for the last month. These are from tropical tidbits

Untitled.thumb.png.77f0cb374cfb546797db3c38914c7abc.png

Using daily data it appears that the La Nina event ended on 6th March 2021 when the Region 3.4 anomaly was last at or below -0.5C

Between 7th March 2021 and 20th March 2021 it almost looked as if we were attempting to get a Weak EP El Nino going and we did get into weak El Nino territory in Region 1+2 for a time but Region 3.4 stayed below 0C anomaly but above -0.5C and just bounced around between ENSO Neutral on the colder side and True ENSO Neutral (close to 0 anomaly)

In the days between 21st March 2021 and today the ENSO Region has started to cool again, particularly in more eastern regions. The latest figures for 1st April 2021 show we have breached weak La Nina threshold again in both Regions 1+2 and 3 so a weak EP La Nina signature is developing

Region 3.4 is also cooling again somewhat but hasn't reached the threshold yet. March on its own would be classed as an ENSO Neutral month but with La Nina months in January and February along with a possible return to La Nina as early as during April could this mask the ENSO Neutral month in the tri monthly anomalies and just show a weakening of La Nina in the spring before it strengthens again during the summer

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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

Will have to wait until wait until Monday to find but if the 31st did provide a value of -0.3 for CPC then we would indeed end up with a monthly ONI just shy of -0.5 based from the weekly official data (albeit JFM still -0.7).  

We have seen a stronger pressure gradiant develop over the Pacific since mid-month though with stronger trades in the east (hence the fall) and stronger westerlies west of the dateline.

Edited by summer blizzard
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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

31MAR2021 - Nino3: -0.6, Nino3.4: -0.5,  Nino4: -0.6

ONI for March was still -0.5 rounded down and the JFM ONI is -0.9. We should (bar a positive value for FMA) still see a -0.5> value for FMA which would be our 8th tri-monthly value below the threshold, the longest since the 2010-2012 Nina. 

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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

07APR2021 - Nino3: -0.6, Nino3.4: -0.5,  Nino4: -0.3

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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

14APR2021 - Nino3: -0.7, Nino3.4: -0.4,  Nino4: -0.1

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Posted
  • Location: Mytholmroyd, West Yorks.......
  • Weather Preferences: Hot & Sunny, Cold & Snowy
  • Location: Mytholmroyd, West Yorks.......
WWW.CLIMATE.GOV

The tropical Pacific Ocean is warming up! What does that mean for the way we measure the El Niño-Southern Oscillation (ENSO)? Time to start looking at relative sea surface temperatures.

 

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Posted
  • Location: Solihull, West Midlands. - 131 m asl
  • Weather Preferences: Sun, Snow and Storms
  • Location: Solihull, West Midlands. - 131 m asl
2 hours ago, Gray-Wolf said:
WWW.CLIMATE.GOV

The tropical Pacific Ocean is warming up! What does that mean for the way we measure the El Niño-Southern Oscillation (ENSO)? Time to start looking at relative sea surface temperatures.

 

Latest data shows a very slow decline in the La NIna to neutral conditions.

 

 

image.thumb.png.e1eaf3f6173600f41523f4c291b022d1.png

Not sure that the above graph (taken from the report), and is used to justify that it is obvious that the world's SST's are rising at an increasing rate, actually justifies the claim. It compares the average temperatures over the period 1981-2020 and 1991 - 2020, so I would have expected much more warming?

I try to visualise the graphic (simply by removing the clear warming over the land)  and taking into account that grey is reserved for 'ice', I can see little change over the period for the worldwide SST's..

Remember that pink is 0.0 to +0.2C.

  • Take away the warming on land and there is only the North Pacific which shows any real  warming? with other areas balancing out.
  •  I would like to see a band of colouring of -0.1 to +0.1C on the SST's to give a better impression. 

I know I am just old and sceptical, but surely they could have done better?

MIA  

Edited by Midlands Ice Age
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Posted
  • Location: Solihull, West Midlands. - 131 m asl
  • Weather Preferences: Sun, Snow and Storms
  • Location: Solihull, West Midlands. - 131 m asl

Latest forecasts are indicating that the Pacific does not want to leave the 'colder' La Nina state.

A possible return to La Nina conditions according to many forecast members. This is for both BOM and the CFS forecasting systems. 

A typical forecast chart is now shown below with many of the latest members actually returning to La Nina. 

image.thumb.png.77618030dc5fd387b142be5ed8bad9ea.pngimage.thumb.png.c15b6b56e921a3117c91df7da685011d.pngimage.thumb.png.c3579161d0d8aef9a949fd1943b45d68.png

This indicates a continuing of the recently started cooling conditions as is shown in the the latest   Global UAH lower atmosphere temperatures just released  for April(above).  

MIA

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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

21APR2021 - Nino3: -0.4, Nino3.4: -0.3,  Nino4: -0.1

28APR2021 - Nino3: -0.5, Nino3.4: -0.4,  Nino4: -0.0

ONI for April came in around -0.4. ONI for FMA was -0.8.

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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

05MAY2021 - Nino3: -0.5, Nino3.4: -0.4,  Nino4: -0.2

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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

NOAA have called time on this event but interestingly believe that the current sub surface warmth is a dud.

E1RudyLWYAAfAVy?format=jpg&name=medium

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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

12MAY2021 - Nino3: -0.4, Nino3.4: -0.3,  Nino4: -0.1

 

 

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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

19MAY2021 - Nino3: -0.4, Nino3.4: -0.2,  Nino4: -0.0

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Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

26MAY2021 - Nino3: -0.3, Nino3.4: -0.3,  Nino4: -0.1

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