Exceptional acqua alta foreseen in Venice again December 10, 2008
Posted by dorigo in astronomy, news, science.Tags: acqua alta, venice, weather, weather forecasts
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Nine days ago Venice withstood the assault of an exceptional surge of sea water, the fourth highest in recent history. Water reached the level of +1.56 meters above average sea level at 11.15AM, flooding most of Venice’s streets with two feet of water. I reported about the event in real time here.
Now, conditions are again favourable for another flooding. Below you can see the forecast of the water level for the next few days.
The red line is the astronomical tide (which does not consider weather conditions such as atmospheric pressure, rain, winds, and coherent oscillation of the water of the Adriatic sea basin), while the blue line is the actual forecast. As you can see, there are two distinct floodings predicted to surge above 1.30 m above sea level. 1.30 m is not too rare, but 1.40 m is (fortunately) something that only happens every four or five years. Or at least, that is what used to happen in the past.
I again point to a couple of web cams from where you will be able to follow the events in real time, if you are that nosy:
- webcam 1 (looking at S.Marco square, a place which gets flooded already with 0.75m of high tide);
- webcam 2 (looking at a canal in Cannaregio)
- real time forecasts here.
Update: if you look at the first webcam above right now (early morning of 12/10), you can see S.Marco square flooded by a minor peak in the tide.
Update -12/10, 7PM: the forecast for 12/12 now says +1.55m above sea level, which would just be 1cm below the fourth highest tide ever experienced in recent history (the one of December 1st 2008). Check it below:
Watch the acqua alta in Venice today! December 1, 2008
Posted by dorigo in news, personal, science, travel.Tags: acqua alta, venice, weather
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Oh, I love the feeling.
I was woken up this morning at 6.30AM by the sirens, but then forgot about it and tried to concentrate on a last half hour of sleep. Then I got up, showered, checked my mailbox, had a quick coffee, and got ready to go to work. Then, upon getting down the stairs into the flooded atrium, I remembered. Acqua alta!
Venice is constantly under siege, particularly between September and December. Low barometric pressure, heavy rainfalls, a south-eastern wind, or the phenomenon of “Sesse” -a coherent oscillation of the waters of the Adriatic Sea basin- these are all possible sources of the phenomenon called “acqua alta”, a sea tide which surpasses +80cm above average sea level. That is enough to flood part of the streets, in their lowest points. When the tide is predicted to get above 110cm over average sea level, Venice inhabitants get an early warning with high-pitch sirens which they cannot ignore -and which usually wake them up, since the highest tides usually occur in the morning hours. And when the water is predicted to get to 130cm above sea level, as this morning, or above that level, well -things get ugly.
130cm above sea level, as will happen in about three hours in the Venice lagoon (see graph above), is enough to flood 80% of the town, and make unusable some of the highways created for pedestrians with wooden gangways (see picture below). A few commercial business will get in trouble because water will soar above their protective bulkheads. Some places will be basically unreachable unless you wear thigh-high protections -or swim.
It should be fun for an outsider to visit Venice today. The city will appear under siege. People wandering around, trying to figure out how to go from A to B; public transportation making detours to avoid low bridges; water a bit everywhere; and a general feeling of disconcert. If you want to have a peek, there are webcams around. Try this one, looking down to Piazza San Marco (a place which is only 75cm above sea level, so it is already flooded right now):
UPDATE:Another webcam showing a canal in Cannaregio, with the water almost closing in on the passage under a bridge.
You can find many others around… Have fun.
UPDATE: the water is now predicted to get to 140cm above sea level, which configures itself as a real flood, one of the twenty or thirty highest in Venice’s history. For a comparison, the highest ever measured was 194cm on November 4th, 1966 -but that was a real catastrophe. Check the updated graph below:
UPDATE: the tide should be peaking right now (at noon, so a bit later than expected), and the level it has reached is the fourth highest, ever: 156 centimeters above average sea level. That means about two feet of water over most of the streets of the city.
A Quantum Diaries Survivor 