Summer 2015 - Long Range Forecasts

M.T. Cranium

The chances of ten consecutive exceptional summers in either a good or bad direction are very low, I would think. If you even allow a wide spread for what you consider to be very warm or cool (I think very dry or wet is really what the discussion was about) and take the one-third of cases at each end of the spectrum, then if these occur at random, looking forward from now the chances are only one in three to the tenth power of either of these outcomes. That is one in 59049. Even the chance of three in a row is only one in 27, but if you take the proposition that the past two were good, then the random chance remains one in three for achieving three in a row.

Even if one accepts some modification of climate trends to be ongoing, it would not greatly affect the chances of having long runs but it might skew the numbers so that there would be a one in 20,000 chance for ten in a row hot summers and a one in 100,000 chance for ten in a row cool summers (or something similar).

As another poster mentions, a prediction of near normal is not a way of avoiding the challenge of this subject, said prediction is just as valid as any other estimate. However, the math of the situation tells you that you can't be more than half the range of possible errors out on such a prediction. Thus over time, predictions of near normal are likely to be proven correct more frequently than others, unless the others have a skill factor in their favour. Just to clarify, I would consider "near normal" on a monthly temperature forecast to be within 0.5 C deg of the long term averages, anything in the range 0.5 to 1.0 is moderately significant as a departure and anything more than 1.0 deg is of considerable significance (or "much above or below" normal). That would be in a maritime temperate climate, one might go double those ranges for qualifying predictions made for a more inland continental climate. More precise definitions would involve standard deviations which I don't have at hand for Irish climate stats but after running this many contests, I think the s.d. for monthly temperature must be fairly close to 0.5 deg and is almost certainly less than 1.0 deg. Last summer was probably about one s.d. warmer than average and the one before it likely two to three s.d. above normal. December 2010 may have been five or six s.d. below normal. An event like that is quite rare. In the comparable U.K. CET the last December in that range was 1890 (120 years before).

Jpmarn

Just commenting what M.T. Cranium is saying about this summer. It would be like 2011 with the jet stream mostly south of us for most of the season. That means that we would be in relatively cool air most of the time with average temperatures down a degree or so. We would still get at least normal sunshine and rainfall. He mentioned that the south of England would be wetter than normal. It probably be much wetter than normal over France and Nothern Spain because of the jet stream would be typically over them.

I'm no expert, but if previous (recent) years are anything to go by, I'm fearing a washout this year. Mainly due to the dry, warm April we just had.

Gonzo

Karsini wrote: »

I'm not expert, but if previous (recent) years are anything to go by, I'm fearing a washout this year. Mainly due to the dry, warm April we just had.

usually a warm, sunny April results in a crap summer and so far May is definitely delivering on the washout! Hopefully this year will be different with a decent June-September.

Oneiric 3

Probability plot for daily IMT* Summer maxima. Unfortunately, as the data is based on mean daily max values only since 2007, the sample size is very small (736 days) but may be just enough to give a rough estimate as to what to expect temp wise on any given Summer day (which is June-August period in this case)


Data C/O Met Eireann


You can see from this plot that very warm or even hot days (22° + ) are more the exception than the rule, as are cool/cold days (maxima below 15°) Whereas the daily mean max of between 16 - 19°c is more the norm.

Just for the record, the Summer max average for this small period is 18.1° ; the median 17.9° and the mode also at 17.9°.


*Note:
IMT in this case is based on the means of 9 synoptic stations, and not the usual 5 used in MT's competition. As well as the 5 inland station used in the traditional IMT indice, it also include 4 coastal stations so as to better infer a more rounded and representative 'national' average.

Birdnuts

Jpmarn wrote: »

Just commenting what M.T. Cranium is saying about this summer. It would be like 2011 with the jet stream mostly south of us for most of the season. .

God I hope not - was a wretched effort. I can see the similarities though as that year had a summer like April too.

s.m

Gonzo wrote: »

usually a warm, sunny April results in a crap summer and so far May is definitely delivering on the washout! Hopefully this year will be different with a decent June-September.

Not really april last year was warm and pleasant and we got a decent summer

twinkletoes

Hi Everyone..any long range forecast in sight yet? Not so good for beginning of June it would seem by todays's forecast from MT??.. but living in hope for rest of summer!!??

JM Skipton

Karsini wrote: »

I'm no expert, but if previous (recent) years are anything to go by, I'm fearing a washout this year. Mainly due to the dry, warm April we just had.

Stats don't back up this statement, Casement for example had a wetter and colder April than average. There was a lot of variation in rainfall around the country during April. However I think something like 17 of the 25 stations recorded below average temps.

pauldry

June will be a lot warmer than May has been with tempuratures of 20c a lot of days. Early June will be brutal but there will be a warm spell then with temperatures above normal.

This is still far away so I wouldnt say heatwave yet but by all accounts a vast improvement on May likely with warm sunshine especially for the South and East.
Some cloud and fog for North and West at times

It could be 18 to 22c

As for Bank Holiday weekend it could be the wettest one of 2015.

Cosmo Kramer

Has something significant changed on the models in the last 24 hours? I'm seeing a few forecasts (including MT's this morning) hinting at some decent weather in early June once we get over this coming weekend.

Rikand

Cosmo Kramer wrote: »

Has something significant changed on the models in the last 24 hours? I'm seeing a few forecasts (including MT's this morning) hinting at some decent weather in early June once we get over this coming weekend.

http://m.yr.no/place/Ireland/Leinster/Athlone/long.html

Yr.no has rain most of the weekend. Getting lashed out on Monday. And it's normally fairly reliable

Slattsy

Folks, I'm getting married on the 13th June in Sligo.

From what I have read, following a lot of long range forecasts and posters here lately, the models are showing a wet start to June commencing from a horrible bank holiday weekend.
However how is the following weekends looking??
Any improvements or still too early.

Any thoughts appreciated :-)

twinkletoes

pauldry wrote: »

June will be a lot warmer than May has been with tempuratures of 20c a lot of days. Early June will be brutal but there will be a warm spell then with temperatures above normal.

This is still far away so I wouldnt say heatwave yet but by all accounts a vast improvement on May likely with warm sunshine especially for the South and East.
Some cloud and fog for North and West at times

It could be 18 to 22c

As for Bank Holiday weekend it could be the wettest one of 2015.

Thanks Pauldry...Pity about the forecast for bank holiday that seems eminent, but at least there is hope now after that for a bit of heat in June, anything would be better than the chill of this May.

Storm 10

ME today are saying that it will get a bit warmer next week but will stay unsettled..

delahuntv

These "long range" arguments comes up every year.

IMO people with knowledge can forecast a trend in the weather due to jetstream, el nino or whatever and a trend can give a guideline to general expectations. MT seems to be forecasting a mixed trend for the summer - basically a "typical" Irish summer or good days, bad days, average days. Trtying to find out when the "good days" will appear is the difficult job!

Then you get the other types who want to grab newspaper headlines because they make money out of fools easily parted from their money and who give "accurate" forecasts that in 70% of cases are totally and utterly wrong, but in the periods they get it right, they shout from the rooftops and again the tabloid media lap it up. (if I flip a coin 100 times, I'll get a better result rate - so they are REALLY bad)

We won't mention anyone on particular, though i wonder how the weather is in New Zealand!

Storm 10

Never heard of this guy before


https://www.facebook.com/windywilson.weather.roads

delahuntv

Storm 10 wrote: »

Never heard of this guy before


https://www.facebook.com/windywilson.weather.roads

Love it - but google translate doen;t reach to Scottish dialect for some of his posts.

Looks like a wild scottish version of MT

twinkletoes

" MT seems to be forecasting a mixed trend for the summer - basically a "typical" Irish summer or good days, bad days, average days."

Did MT make his summer long range forecast yet???! I didnt think it was up yet?

jArgHA

twinkletoes wrote: »

Did MT make his summer long range forecast yet???! I didnt think it was up yet?

See: http://www.boards.ie/vbulletin/showpost.php?p=95338450&postcount=26

twinkletoes

jArgHA wrote: »

See: http://www.boards.ie/vbulletin/showpost.php?p=95338450&postcount=26

Cheers

Sam Kade

ComfortKid wrote: »

The weather can't be predicted for more than a few days, even at that it's rarely right. Any of these long range forecasts are completely made up. But going from previous years, usually when we get a sunny spring like this we have a fairly wet summer.

You're right 4 days ahead is as accurate as it gets but you may as well be talking to a brick wall trying to get it into a lot of peoples heads.

What sunny spring? Nothing but a cold miserable spring down south.

Cosmo Kramer

Storm 10 wrote: »

Never heard of this guy before


https://www.facebook.com/windywilson.weather.roads

He's quite popular in Scotland, keeps popping up on my Facebook feed because a lot of people share his page. Suffers from the annoying habit of constantly referring to himself in the third person. He tends to focus on shortish range stuff I think, interpreting FI models etc. rather than anything too long term.

Anyway I was told in a pub in Mayo last night that the man from New Zealand 'says we're in for a shocker this summer' so we might as well all just pack it in now...(true story, it's crazy how seriously people take his forecasts).

pauldry

Right to everyone who doesnt believe in long range weather why are ye on this thread begrudging people who have a common interest in predicting long range weather for the summer.

For the past 4 weeks on 5 days met eireann got the weather forecast COMPLETELY wrong the DAY before. Three sundays in the past 2 months that were forecast wet on the saturday were indeed sunny everywhere .

Rainfall of 15mm that was presicted was trace.

Now im not picking on met eireann coz theyr class but forecasting weather can never be exact. Thats why let long rangw forecasts exist.

At the very least they are a guide to the weather that commonly occurs during the season at most they can predict obvious trends such as a barage of low pressures at present and a high pressure build in early june

Sorry for my poor typing. Samsung tiny letters

allthedoyles

Well looking at June on accu , it seems to be a month of sunny spells and scattered showers with temps of 18-20 degrees .

Sam Kade

allthedoyles wrote: »

Well looking at June on accu , it seems to be a month of sunny spells and scattered showers with temps of 18-20 degrees .

Oh dear what did I say about forecasting after 4-5 days :mad:

Gonzo

allthedoyles wrote: »

Well looking at June on accu , it seems to be a month of sunny spells and scattered showers with temps of 18-20 degrees .

considering how cool and miserable May was, temps of 18-20 for June would be a massive improvement. The start of June could still be cool as the next 5 to 6 days is going to be well below average temps at times.

mitresize5

A wet and windy May fills the barn with corn and hay.

You heard it here first ..... its going to be a scorching summer.

ch750536

mitresize5 wrote: »

A wet and windy May fills the barn with corn and hay.

You heard it here first ..... its going to be a scorching summer.

It rhymes, must be true.

delahuntv

mitresize5 wrote: »

A wet and windy May fills the barn with corn and hay.

You heard it here first ..... its going to be a scorching summer.

I won't believe it until I see it on the front page of the Daily Muck Mail :P