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Wild Tuesday for Newfoundland

September 20, 2010 — With Hurricane Igor quickly approaching Newfoundland, The Weather Network's meteorologist Chris Scott has been keeping a close eye on the storm.

Tropical storm warnings in place for Newfoundland
Tropical storm warnings in place for Newfoundland

Chris Scott, meteorologist

Newfoundland is no stranger to big storms. In fact, St. Johnís is the windiest city in Canada. The record wind gust at St. Johnís airport was set on March 15, 1956 when the wind gusted to 193 km/h! Igor wonít produce this kind of wind gust, but it will be a wild Tuesday across eastern Newfoundland.

There are two major weather impacts to come from this storm Ė rain and wind.

Letís detail the rain first of all. Our forecast team is very confident of heavy rainfall which is already building into central and eastern Newfoundland. It is likely that over 100 mm will fall in some places, and there is still a high-end potential of up to 200 mm. This is a tremendous amount of water and is close to half the yearly average precipitation for some of the drier places in Canada.

Residents of St. Johnís are likely wondering whether this will be a repeat of Gabrielle in 2001 which caused massive flooding. It will be impossible for St. Johnís to avoid the rain, but it is possible that the heaviest accumulations could be farther west closer to the Burin and Bonavista peninsulas. This would spare St. Johnís the worst flooding, but would put smaller communities like St. Lawrence and Clarenville on the line of the 100+ mm amounts.

This type of rainfall can wash out roads and cause significant property damage. Whatever the exact location of this heaviest rainfall, the message is that we wonít avoid some serious problems from the rain in eastern Newfoundland.

Now the wind... the big concern is that two U.S. computer models are suggesting that winds could gust to or exceed 150 km/h across the Avalon peninsula. This is much higher than any official forecast at this point, but it is a possibility. Tuesday, particularly the afternoon, will be windy regardless of the exact track of Igor.

But the danger is that the storm tracks closer to the Avalon peninsula and produces a cold northwest wind that could gust well beyond hurricane force. If this worst case scenario pans out, we will see widespread power outages all across the Avalon peninsula, widespread tree damage, and even some minor structural damage.

Heavy rain will fall as Igor approaches
Heavy rain will fall as Igor approaches

The best case scenario is a track slightly farther east which would still produce strong wind gusts near 100 km/h, but wouldnít cause widespread damage.

You may wonder why Igor will not die as it hits the cool water near Newfoundland. Tropical systems often weaken as they move over colder water and encounter the shearing winds of the jet stream across Atlantic Canada, but some maintain their strength and actually intensify under the right conditions (the fancy terminology to use - which is a sure-fire conversation killer - is called 'Re-intensification during Extratropical Transition in a Baroclinic Environment').

In this case, Igor is merging with an upper trough (dip in the jet stream) in just the right way to become a large powerful post-tropical storm. This process will occur overnight Monday into Tuesday as cold air starts to wrap around the south side of the storm centre.

Igorís personality change means that winds to the left of the storm centre will still be very strong Ė in fact, the strongest winds will occur Tuesday afternoon when cold air starts rushing in from the northwest across eastern Newfoundland.

In a meeting this morning at The Weather Network, we were planning our stormwatch coverage of Igor, and I mentioned that in a worst case scenario, Igor could be Newfoundlandís Juan. Well, that was a showstopper of a statement Ė I wouldnít say that on-air because itís a statement that needs clarification. Juan was an exceptional storm for Nova Scotia and PEI and caused tremendous damage Ė it also caught a lot of people off guard. Igor is a very different storm and will be a combination rain and wind event.

My concern is that the worst case scenario will give wind gusts that could do significant damage, and catch many people in eastern Newfoundland off guard. Letís hope the worst case does not materialize, but this will be a significant storm, and weíre hoping Newfoundlanders are ready for a bumpy ride on Tuesday.

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