Summer Blizzards Summer 2007 Forecast...

[summer blizzard]

My anologue based forecast will be released over the weekend into this thread, however here is my teleconnection based 2007 summer forecast.

June

Week 1 - NEGATIVE PNA - POSITIVE AO - POSITIVE NAO

Week 2 - POSITIVE PNA - POSITIVE AO - POSITIVE NAO

Week 3 - NEGATIVE PNA - POSITIVE AO - POSITIVE NAO

Week 4 - POSITIVE PNA - POSITIVE AO - POSITIVE NAO

Week 1 - I expect the first week of June to feature a mid-Altantic Low supporting a continental ridge over Europe, this is because i expect a ridge in the western Atlantic, typical of a negative PNA and low heights over Greenland, leading to very warm weather and southerly wind types, with temperatures and sunshine above average and rainfall below.

Week 2 - I expect the second week of June to feature an Azores High ridging over western Europe, this is because while there are low heights over Greenland, the Jet Stream will exit the USA on a southerly track, aloowing the Azores High to ridge north resulting in south westerly winds, and temperatures and sunshine above average, with rainfall below average.

Week 3 - I expect the third week of June to feature a mid-Altantic Low supporting a continental ridge over Europe, this is because i expect a ridge in the western Atlantic, typical of a negative PNA and low heights over Greenland, leading to very warm weather and southerly wind types, with temperatures and sunshine above average and rainfall below.

Week 4 - I expect the final week of June to feature an Azores High ridging over western Europe, this is because while there are low heights over Greenland, the Jet Stream will exit the USA on a southerly track, aloowing the Azores High to ridge north resulting in south westerly winds, and temperatures and sunshine above average, with rainfall below average.

Summary:

Because of the frequant pattern changes over the USA, despit this being a very warm month, i expect that it could also be quite a humid and thundery month due to an unstable Jet Stream meaning that while the pattern will reset to warmth very quickly, we will see a lot of instances of 3 hot days and a thunder storm with the possibilty of 30C being hit between the 1st and 7th and 14th and 21st of June.

CET - 17.1C, 3C above average, hottest since 1846

Rainfall - 25%

Sunshine - 200%

July

Week 1 - POSITIVE PNA - NEGATIVE AO - NEGATIVE NAO

Week 2 - POSITIVE PNA - POSITIVE AO - POSITIVE NAO

Week 3 - POSITIVE PNA - POSITIVE AO - NEGATIVE NAO

Week 4 - POSITIVE PNA - POSITIVE AO - POSITIVE NAO

Week 1 - I expect the first week of July to feature a Scandinavian High and cool east to north easterly winds, this is because of high heights over Greenland meaning that as the Jet Stream exits the USA on a southerly track, it will stay supressed, this will mean below average temperatures and average rainfall and sunshine.

Week 2 - I expect the second week of July to feature an Azores High ridging over western Europe, this is because while there are low heights over Greenland, the Jet Stream will exit the USA on a southerly track, allowing the Azores High to ridge north resulting in south westerly winds, and temperatures and sunshine above average, with rainfall below average.

Week 3 - I expect the third week of July to be very unsettled, this is because i expect high heights over both Greenland and the Azores meaning that the Jet Stream will be suppressed over the the lattitude of the British Isles resulting in very cyclonic and wet weather with average temperatures, above average rainfall and below average sunshine.

Week 4 - I expect the final week of July to feature an Azores High ridging over western Europe, this is because while there are low heights over Greenland, the Jet Stream will exit the USA on a southerly track, aloowing the Azores High to ridge north resulting in south westerly winds, and temperatures and sunshine above average, with rainfall below average.

Summary:

Despite being rather changable, i expect July to be a rather warm and pleasent month with frequant warm periods intersperssed with cooler periods.

CET - 17C, 0.5C above average

Rainfall - 75%

Sunshine - 125%

August

Week 1 - NEGATIVE PNA - NEGATIVE AO - NEGATIVE NAO

Week 2 - NEGATIVE PNA - POSITIVE AO - POSITIVE NAO

Week 3 - POSITIVE PNA - POSITIVE AO - POSITIVE NAO

Week 4 - POSITIVE PNA - POSITIVE AO - POSITIVE NAO

Week 1 - I expect the first week of August to be unusually cold, this is because of Large height rises over Greenland caused by a negative AO and a Scandinavian Trough, resulting in northerly winds, this means that temperatures will be below average and sunshine and rainfall average.

Week 2 - I expect the second week of August to feature a mid-Altantic Low supporting a continental ridge over Europe, this is because i expect a ridge in the western Atlantic, typical of a negative PNA and low heights over Greenland, leading to very warm weather and southerly wind types, with temperatures and sunshine above average and rainfall below.

Week 3 - I expect the third week of August to feature an Azores High ridging over western Europe, this is because while there are low heights over Greenland, the Jet Stream will exit the USA on a southerly track, allowing the Azores High to ridge north resulting in south westerly winds, and temperatures and sunshine above average, with rainfall below average.

Week 4 - I expect the final week of August to feature an Azores High ridging over western Europe, this is because while there are low heights over Greenland, the Jet Stream will exit the USA on a southerly track, allowing the Azores High to ridge north resulting in south westerly winds, and temperatures and sunshine above average, with rainfall below average.

Summary:

Despite a rather cold start, i expect August to be the best month of the summer, with a very warm second half to the month resulting in well below average rainfall, and above average temperatures and sunshine.

CET - 17.2C, 1C above average

Rainfall - 25%

Sunshine - 175%

Summer 2007:

On the whole, i expect summer 2007 to be warm, dry and sunny but not outstanding, mainly due to frequant pattern changes over the USA, it could also be quite thundery at times, especially during June and August. The main periods of interest to look out for are the first week of August for very low minima, and the first and third weeks of June for very high maxima (30C+) and also mid August for the highest temperature of the summer, which i think will be 36C.

CET - 17.1C, 1.5C above average

Rainfall - 40%

Sunshine - 170%

Please allow a 0.5C margin of error for all CET predictions, and a 25% margin of error for all rainfall and sunshine predictions...

Note, i may not back these CET outcomes in the CET competition.

[Weather-history]

:

On the whole, i expect summer 2007 to be warm, dry and sunny but not outstanding,

CET - 17.1C, 1.5C above average

Rainfall - 40%

Sunshine - 170%

Going off those values, how can you not call it outstanding?

It would be joint 6th warmest summer on record. The rainfall would make it in the top 5 driest summers on record and the sunshine would make it the sunniest summer on record by a mile.

June with 200% sunshine?!? Last July is the sunniest month in terms of total sunshine hours in the Areal series and that was 50% above the average.

Edited May 25, 2007 by Mr_Data

[The PIT]

Brave putting dates on it. Interesting if it'll turn out that way.

[richiec]

This year the I think the UK will hit 55c......on the tarmac in direct sunlight of course!

[summer blizzard]

Going off those values, how can you not call it outstanding?

It would be joint 6th warmest summer on record. The rainfall would make it in the top 5 driest summers on record and the sunshine would make it the sunniest summer on record by a mile.

June with 200% sunshine?!? Last July is the sunniest month in terms of total sunshine hours in the Areal series and that was 50% above the average.

I did'nt realise 17.1C would place it so high up, i thought top 20, rainfall and sunshine i am not so good on, i'll stand by my rainfall forecast, though i will have to make my sunshine forecast better.

[Rollo]

You are a brave man SB and I hope for one that you are spot on with that forecast.

[kold weather]

An intresting forecast, though I find it hard to believe that all three months would have 17-17.1C, has that ever happened before?

[Weather-history]

An intresting forecast, though I find it hard to believe that all three months would have 17-17.1C, has that ever happened before?

The summer of 1826. All three summer months were within 0.6 of each other

June: 17.3

July: 17.9

August: 17.6

[The PIT]

Well the first week has got a little wrong temp wise. Rainfall looking okay though. No sign of the 30C.

[summer blizzard]

Indeed, my anologue based summer forecast will be released into this thread either tonight or tommorow, as will my reveiw of my spring forecast, nevertheless, the CET came out as i believed it would for the first week, so lets wait and see.

[summer blizzard]

Here is my 2007 analogue based forecast for summer 2007!!!

This forecast will be split into six main areas...

1) PDO (Pacific Decadal Oscillation)

2) ENSO (El Nino Southern Oscillation)

3) AO (Arctic Oscillation)

4) QBO (Quasi-Biennial Oscillation)

5) Sea Surface Temperature anomalies

6) Conclusions

Each section will contain some information about the topic and its relevance to this forecast, as well as the analogues and expected state this summer...

PDO (Pacific Decadal Oscillation)

http://www.john-daly.com/theodor/pdotrend.htm

The Pacific Decadal Oscillation (PDO) is a long-lived ENSO-like pattern of Pacific climate variability (Tanimoto et al., 1993; Zhang et al., 1997). ENSO (El Niño/La Niña + Southern Oscillation) and PDO have similar spatial and temperature patterns, but show a different behaviour in time. While ENSO events are inter-annual phenomena, the PDO covers decades. A full oscillation, comprising a warm and a cool phase, may extend over more than 50 years.

For a hot summer, we should ideally have a positive PDO; this will increase the chances of a positive AO by around 30% over a monthly time period.

The only analogues which matched the March-April period were:

1960

1990

Both these analogues agree on near neutral values for all three summer months, though while they both agree on a neutral to positive value for June, they are either side of neutral during July and August, causing confidence to decrease..

The conclusions we can draw from these analogues are that with near neutral values all summer, the next most prevalent teleconnection, the ENSO should be allowed to dominate the pattern.

ENSO (El Nino Southern Oscillation)

http://www.cdc.noaa.gov/people/klaus.wolter/MEI/#discussion

El Niño/Southern Oscillation (ENSO) is the most important coupled ocean-atmosphere phenomenon to cause global climate variability on interannual time scales.

There are many different ways to measure the state of the ENSO, however I think that the best way to measure it is by the MEI index (Multivariate ENSO Index), because it takes into account six variables, these are:

1) Sea-level pressure

2) Zonal and meridional equatorial winds

3) Components of the surface wind

4) Sea surface temperature

5) Surface air temperature

6) Total cloudiness fraction of the sky

http://iri.columbia.edu/climate/ENSO/curre.../technical.html

This is also a very important link; it is the latest update on the ENSO from IRI, and points to a 55% chance of La Nina conditions developing this summer. Also on the IRI site is this link, which gives details on what each model expects to happen and the previous La Nina and El Nino event and how the models handled that.

http://iri.columbia.edu/climate/ENSO/curre.../SST_table.html

This table shows that how the models handled the other two events the best, however the models were not progressive enough in bringing in or exiting the La Nina events, in my opinion, we will enter a weak La Nina during July, at that point I would back a slow strengthening and a peak during October at the top end of weak La Nina territory.

The only analogues which matched the March-April period were:

1994

1979

Both analogues now agree on neutral to El Nino values during all summer months, suggesting that the IRI forecast is too progressive.

For a hot summer, we should ideally have a weak El Nino; this increases the chances of a positive AO.

The conclusions we can draw from these analogues are that with near neutral values all summer, the next most prevalent teleconnection, the QBO should be allowed to dominate the pattern although there is a chance of weak La Nina conditions developing during June.

QBO (Quasi-Biennial zonal wind Oscillation)

http://ugamp.nerc.ac.uk/hot/ajh/qbo.htm

http://en.wikipedia.org/wiki/Quasi-biennial_oscillation

The QBO is a quasi-periodic oscillation of the equatorial zonal wind between easterlies and westerly’s in the tropical stratosphere with a mean period of 28 to 29 months. The alternating wind regimes develop at the top of the lower stratosphere and propagate downwards at about 1 km per month until they are dissipated at the tropical tropopause. Downward motion of the easterlies is usually more irregular than that of the westerlies. The amplitude of the easterly phase is about twice as strong as that of the westerly phase. At the top of the vertical QBO domain, easterlies dominate, while at the bottom, westerlies are more likely to be found.

For a hot summer, westerly QBO values are preffered..

The only analogues which matched the March-April period were:

1979

2005

Both these analogues agree on very strong easterly QBO values during all summer months.

The conclusions we can draw from these analogues is that with very strong QBO values, that equates to a standard deviation of over -/+1, meaning that the QBO is likely to be a leading mode this summer, the easterly QBO should encourage stratospheric warming, promoting a more negative AO pattern, especially during July and August.

AO (Arctic Oscillation)

http://www.cpc.noaa.gov/products/precip/CW..._index/ao.shtml

The AO is effectively a measure of pressure at northern hemisphere high latitudes, with 1010mb to 1015mb being the thresholds for neutral values, the AO is a stratospheric teleconnection, meaning that observations are made in the upper atmosphere to define the AO value each day.

Below is a chart common to all winter lovers when the AO has a value above +1 in the winter months…

http://www.cpc.noaa.gov/products/precip/CW..._index/ao.shtml

Polar Vortex locked in and a classic Bartlett…

For a hot summer, positive AO values would be preferred…

The only analogues which matched the March-April period were:

1986

1994

All these analogues agree on neutral to positive AO values during June, and AO values either side of neutral during July and August.

The conclusions we can draw from this are that the QBO will be the leading telleconection mode this summer.

Sea Surface Temperature Anomolies

Firstly, starting in the Pacific, the anomolies this summer favour a strong Sub Tropical ridge in the Pacific, and subsequently a strong Pacific Jet Stream, with troughing at mid-lattitudes.

In the Atlantic however, the anomolies indicate that the sub-tropical ridge will become displaced as summer progresses to mid-lattitudes, this combined with a tendancy for stratospheric warmings, may result in a very amplified pattern with frequant builds of pressure over Scandinavia followed by retrogression towards Greenland, especially during the second half of the summer.

Conclusions

My conclusion after deliberating over the data, is that while sea surface temperature anomolies are essentially at odds with the anologue data, i believe that anologues will prevail this summer, based on the assumtion of very strong QBO values.

Based on this, here are the anologues for this summer in my opinion and the temperature profile this summer.

Summer

1994

1990

1979

1953

June

14.5

13.6

13.9

14.4

50% chance above average

50% below average

Predicted CET: 14.5C

July

18

16.9

16.2

15.5

50% above average

50% below average

Predicted CET: 18C

August

16

18

14.9

16.2

25% above average

50% below average

25% average

Predicted CET: 16C

Summer

June: 14C to 15C (14.5C) +0.4C - 90% chance of being above average, 10% chance of being below average

July: 17.5C to 18.5C (18C) +1.5C - 100% chance of being above average, 0% chance of being below average

August: 17.1C to 18.1C (16C) -0.2C - 70% chance of being below average, 30% chance of being above average

(Please allow a 0.5C margin of error for all CET predictions)

As you can see, July is predicted to be the warmest month relative to average, and August the coolest with a 70% chance of being below average.

Edited June 8, 2007 by summer blizzard

[summer blizzard]

For some reason i cannot edit my post so i will add the folowing charts as a seperate post..

This is an anotated chart showing ahat i expect to happen in responce to sea surface temperature anomolies at mid and low lattitudes, and as you can see, with a strong Sub-Tropical Ridge in the Pacific and dominant trough in the Atlantic, a positive PNA is favoured which will encourage a positive PNA, which favours higher pressure over Scandinavia, as a result of this, for the first half of summer, with a strong Azores High and ridge over Scandinavia, an upper trough is favoured to the south west of the British Isles however with stratospheric warming events, when the high over Scaninavia retrogresses, the upper trough may be allowed to seepen and move east, bringin in periods of cool and wet weather, similar to the end of May.

The second half of the summer is a little different, because troughing is favored across the whole Sub-Tropical Atlantic and a major ridge is encouraged over Scaninavia, this combined with stratospheric warming could indicate some very potent and sustained northerlies when retrogression occurs.

In summary, sea surface temperature anomolies indicate a summer of extremes with the weather swing rapidly from cold and wet to warm and dry.

[summer blizzard]

As you can see, this pattern strongly correlates with what sea surface temperature anomolies indicate with a strong Azores High and trough between another ridge over Scandinavia..

As you can see, this pattern is again supported by sea surface temperature anomolies, with the Azores High pushed east into Europe in response to a lowering of heights in the Sub-Tropical Atlantic, there is also a more well defined low to the west of the British Isles in response to a lowering of heights in the central Atlantic..

This is a pattern that is not so well supported by sea surface temperature anomolies as the sub-Tropical high is stronger than i expect, however there is still a strong ridge over Scandinavia and low pressure over the British Isles, though i expect the low to be further south in reality.

As you can see, these charts show a strong ridge over the eastern Arctic and Scandinavia, with higher heights in the Sub-Tropical Atlantic, which i believe to be false.

Edited June 8, 2007 by summer blizzard

[Gavin P]

Thanks SB. So, we could be in for a very cool and wet August?

[summer blizzard]

Thanks SB. So, we could be in for a very cool and wet August?

Yes, i expect August to be the coolest and wettest month relative to average.

[Don]

Yes, i expect August to be the coolest and wettest month relative to average.

The month when I'm away in Cornwall for two weeks would have to be wouldn't it! Much like last year infact.

[BLAST FROM THE PAST]

Yes, i expect August to be the coolest and wettest month relative to average.

I'll go along ith that, its in my summer forecast too

BFTP

[Weather-history]

My anologue based forecast will be released over the weekend into this thread, however here is my teleconnection based 2007 summer forecast.

June

CET - 17.1C, 3C above average, hottest since 1846

Rainfall - 25%

Sunshine - 200%

Are you going to review your teleconnection forecast techniques, SB, because its way out for this month.

[summer blizzard]

Yes, though it should be noted that i suspected June would be an outlier which is why i backed a lower outcome in the CET thread, i'll sort out the percentages of success for other months this year and post them here, though it turns out that until June, i was punting on average 1C higher than i should of been in the predicted synoptics.

[summer blizzard]

Here is my forecast update...

July

Week 1 - POSITIVE PNA - NEGATIVE AO - NEGATIVE NAO

Week 2 - POSITIVE PNA - POSITIVE AO - POSITIVE NAO

Week 3 - POSITIVE PNA - POSITIVE AO - NEGATIVE NAO

Week 4 - POSITIVE PNA - POSITIVE AO - POSITIVE NAO

Week 1 - I expect the first week of July to feature a Scandinavian High and cool east to north easterly winds, this is because of high heights over Greenland meaning that as the Jet Stream exits the USA on a southerly track, it will stay supressed, this will mean below average temperatures and average rainfall and sunshine.

Week 2 - I expect the second week of July to feature an Azores High ridging over western Europe, this is because while there are low heights over Greenland, the Jet Stream will exit the USA on a southerly track, allowing the Azores High to ridge north resulting in south westerly winds, and temperatures and sunshine above average, with rainfall below average.

Week 3 - I expect the third week of July to be very unsettled, this is because i expect high heights over both Greenland and the Azores meaning that the Jet Stream will be suppressed over the the lattitude of the British Isles resulting in very cyclonic and wet weather with average temperatures, above average rainfall and below average sunshine.

Week 4 - I expect the final week of July to feature an Azores High ridging over western Europe, this is because while there are low heights over Greenland, the Jet Stream will exit the USA on a southerly track, aloowing the Azores High to ridge north resulting in south westerly winds, and temperatures and sunshine above average, with rainfall below average.

Summary:

Despite being rather changable, i expect July to be a rather warm and pleasent month with frequant warm periods intersperssed with cooler periods.

CET - 17C, 0.5C above average, coolest since 2005

Rainfall - 125%

Sunshine - 75%

August

Week 1 - NEGATIVE PNA - NEGATIVE AO - NEGATIVE NAO

Week 2 - NEGATIVE PNA - POSITIVE AO - POSITIVE NAO

Week 3 - POSITIVE PNA - POSITIVE AO - POSITIVE NAO

Week 4 - POSITIVE PNA - POSITIVE AO - POSITIVE NAO

Week 1 - I expect the first week of August to be unusually cold, this is because of Large height rises over Greenland caused by a negative AO and a Scandinavian Trough, resulting in northerly winds, this means that temperatures will be below average and sunshine and rainfall average.

Week 2 - I expect the second week of August to feature a Azores Low supporting a continental ridge over western Europe, this is because i expect a ridge in the western Atlantic, typical of a negative PNA and low heights over Greenland, leading to very warm weather and southerly wind types, with temperatures and sunshine above average and rainfall below.

Week 3 - I expect the third week of August to feature an Azores High ridging over western Europe, this is because while there are low heights over Greenland, the Jet Stream will exit the USA on a southerly track, allowing the Azores High to ridge north resulting in south westerly winds, and temperatures and sunshine above average, with rainfall below average.

Week 4 - I expect the final week of August to feature an Azores High ridging over western Europe, this is because while there are low heights over Greenland, the Jet Stream will exit the USA on a southerly track, allowing the Azores High to ridge north resulting in south westerly winds, and temperatures and sunshine above average, with rainfall below average.

Summary:

Despite a rather cold start, i expect August to be the best month of the summer, with a very warm second half to the month resulting in well below average rainfall, and above average temperatures and sunshine.

CET - 17.2C, 1C above average, warmest since 2004

Rainfall - 50%

Sunshine - 150%

September

Week 1 - POSITIVE PNA - NEGATIVE AO - NEGATIVE NAO

Week 2 - NEGATIVE PNA - NEGATIVE AO - NEGATIVE NAO

Week 3 - NEGATIVE PNA - POSITIVE AO - NEGATIVE NAO

Week 4 - POSITIVE PNA - NEGATIVE AO - NEGATIVE NAO

Week 1 - I expect the first week of September to feature a Scandinavian High and cool east to north easterly winds, this is because of high heights over Greenland meaning that as the Jet Stream exits the USA on a southerly track, it will stay supressed, this will mean below average temperatures and average rainfall and sunshine.

Week 2 - I expect the first week of September to be unusually cold, this is because of Large height rises over Greenland caused by a negative AO and a Scandinavian Trough, resulting in northerly winds, this means that temperatures will be below average and sunshine above avergage and rainfall below average.

Week 3 - I expect the first week of September to be unusually cold, this is because of Large height rises over Greenland caused by a negative AO and a Scandinavian Trough, resulting in northerly winds, this means that temperatures will be below average and sunshine above average and rainfall below average.

Week 4 - I expect the first week of September to feature a Scandinavian High and cool east to north easterly winds, this is because of high heights over Greenland meaning that as the Jet Stream exits the USA on a southerly track, it will stay supressed, this will mean below average temperatures and average rainfall and sunshine.

Summary:

I expect a well below average month due to persistant high pressure over Greenland and a very negative NAO, suprisingly, i also expect September to be quite sunny and dry, with the coolness because of suppressed maxima at the stat and end of the month, and low minima during the middle of the month.

CET - 10.7C, 3C below average, coolest since 1703

Rainfall - 50%

Sunshine - 150%

July-September 2007:

On the whole, i expect the beggining of this period to be warm but not outstanding, but the latter half of this period to be very cool compared to average with some very low minima in mid-September, though i do expect 31C to be reached between 7th and 14th August.

CET - 15C, 0.5C below average

Rainfall - 75%

Sunshine - 140%

Please allow a 0.5C margin of error for all CET predictions, and a 25% margin of error for all rainfall and sunshine predictions...

Note, i may not back these CET outcomes in the CET competition.

June

Week 1 - NEGATIVE PNA - POSITIVE AO - POSITIVE NAO

Week 2 - POSITIVE PNA - POSITIVE AO - POSITIVE NAO

Week 3 - NEGATIVE PNA - POSITIVE AO - POSITIVE NAO

Week 4 - POSITIVE PNA - POSITIVE AO - POSITIVE NAO

CET - 17.1C, 3C above average, hottest since 1846

Rainfall - 25%

Sunshine - 200%

In short, a horribly wrong forecast..

Rainfall was closer to 200% above average..

Sunshine was closer to 75% above average..

This June was the coolest since 2000..

In regards to teleconnections, here were my success rates..

AO - 25%

NAO - 0%

PNA - 50%

Simply put, i had no grip on the Azores High whatsoever.

Edited July 1, 2007 by summer blizzard