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Posted at 02:00 PM ET, 11/24/2010

Weather forecast for royal wedding now, seriously?

The international community is buzzing about the upcoming nuptials of Prince William and Kate Middleton slated for April 29, 2011 in London. But will all the pomp and circumstance be dulled by dreary clouds and dampness or radiate under brilliant sunshine and warmth?

One forecaster thinks he knows the answer more than five months in advance. As quoted in the London Evening Standard:

"It will be essentially dry with sunny spells, although there is likely to be some cloud, so glorious sunshine is unlikely," said Jonathan Powell, senior forecaster at Positive Weather Solutions.
"Mild, warm weather is more or less certain, with temperatures in the late teens or early twenties [celsius]."

In that case, it "is more or less certain" that I'll win the lottery in late April too.

Simply put, the weather is impossible to predict with any skill months into the future. This is particularly true in London where the weather is notoriously fickle. The limit of reliable weather forecasts is more like four to seven days, not months.

A much better account of what can be said about the royal wedding's weather prospects was printed in the News Mirror.

It smartly starts off stating: "The only consistent thing about April's weather [in London] is its inconsistency."

And it then it quotes Aisling Creevey, from the private forecasting company MeteoGroup, who prudently says:

"No doubt there will be lots of bets on the weather but there is just no way of knowing that sort of thing."
"There are no indications at this point."
"We can only look at climatology - average temperatures and conditions over the years."

So what does climatology say? The UK Met Office released a fact sheet that tells us the following about what has happened in London, England over the past 21 years on April 29:

* The average high was 62 F (or 16.6 C), and ranged from 50 F (9.7 C, 2004) to 74 F (23.5 C, 1994)

* Days (9am to 9pm) were dry in 15 of the last 21 years, with only 6 seeing rain. The wettest was in 1991 when 0.6" (15.6 mm) of rain fell at Heathrow.

* The sunniest days occurred in 1990 and 2000 both with 13.2 hours. 2010, 2004, 1995 and 1991 experienced no sunshine at all.

The Met Office concludes that there is a 1-in-3 chance of receiving more than 0.04" (1mm) of rain and a 1-in-30 chance of getting more than 0.4" (10mm) of rain this April 29.

By  |  02:00 PM ET, 11/24/2010

Categories:  International Weather

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