Full Text: Dr. Mark Guishard on Igor

September 17, 2010

The statement made earlier today [Sept 17] by Dr. Mark Guishard, Director of Bermuda Weather Service on Hurricane Igor follows below:

This storm is one that should be taken extremely seriously – as the Minister has already stated, the threat is high. A Hurricane Watch is already in effect.

We at the Bermuda Weather Service, in consultation with the US National Hurricane Center, will be issuing a Hurricane Warning this afternoon. this Warning is issued whenever hurricane conditions are expected within 36 hours.

If there is any doubt, let me make a few basic comparisons – Hurricane Fabian in 2003 was a Category 3 when it made a direct hit on Bermuda – this storm, Hurricane Igor is also forecast to be at or near Category 3 intensity when it moves close to Bermuda on Sunday night.

Fabian had a wind swath at the equivalent time frame 2 days before the CPA, of about 110 nm in diameter. The swath of Hurricane Force winds associated with Igor is currently approximately 150 nautical miles across. The tropical storm force winds (otherwise known as gales in winter storms) extend some 500 miles across the storm’s diameter (Fabian’s were 350nm). So, not only is Igor of similar intensity to Fabian, it is actually bigger, making us an even more likely target. Make no mistake, even if the center of this system misses the island, we will experience significant impacts.

The current forecast is indeed for a direct hit on the island, the worst case scenario in these situations. Accordingly, we should prepare for sustained winds of on the order of 100 knots (115 mph), with gusts to 120 knot or 140 mph. Again, this is comparable to the wind speeds we experienced during Hurricane Fabian in 2003.

The baseline level of the water (without putting wind driven waves on top of

it) is what we refer to as storm surge, and it is expected to be on the order of 5 to 7 feet above the normal tide levels. high tides through the weekend are in the pre-dawn hours and early evenings, low tides are generally near noon and midnight. I must reiterate the comments of the Minister – if your property is prone to surge, then it will likely have some inundation during this event.

Analyses of the wave heights associated with Igor indicate that the maximum waves at the centre of the storm are in excess of 50 feet. Already we are starting to see large swells on the south shore in advance of the approach of Igor. Expect rip currents and battering waves on the reefline, and potentially dangerous surf at the beaches.

Rainfall is always of concern and isolated road flooding is to be expected.

Of course with all tropical systems, which are intensely rotating, there is the potential for the spin up of tornado activity, which we saw in both Hurricane Fabian, and in Category 1 Hurricane Emily in 1987. In recent years, we have seen tornado activity associated with outer rain bands – Hurricane Florence in 2006 and Hurricane Bill last year are examples of this. The point I am making is that even in advance of the worst conditions, we could see some severe weather affect the island several hours before the onset of worst conditions.

Regarding levels of certainty, computer models on which we base these forecasts have been not only consistent with each other, but also consistent through time, in saying that we will have an impact from Igor. However, one of the very reasons that we treat tropical systems with such caution is their ability to make sudden changes in track and intensity – hence, as with all tropical systems, there is uncertainty inherent in this forecast. We all hope and pray that Igor will veer a little further away than is currently forecast, but we must take all action now to prepare to safeguard life and property.

Please have a plan of action to protect your life, your family, your property and your business. If you have a plan, please implement it now – Saturday evening will be too late to make any further preparations – as I have already said in previous media statements, this is not the time to be complacent. Be safe and god bless.

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