Irene Early Wednesday

At 11:oo pm Tuesday, Hurricane Irene was 980 miles south-southeast of Cape Hatteras with winds clocked at 90 mph and a central pressure of 28.61 inches.

Irene has developed an eye and is beginning to move over the Bahama Island chain.

The guiding factor in Irene’s track over the next few days will be the pressure pattern and winds in the upper atmosphere.

Source: NOAA

Irene will turn northward into a weak spot between two high pressure ridges, one over the Atlantic and one over the southwest U.S. This is visualized on the forecast chart above for early Sunday. Helping pull Irene northward will be a large upper air storm (low pressure) over northeast Canada. The precise track will be determined by the strength of the pressure fields at any given time and that is what the various computer forecast models try to figure out.

The strength of the storm is controlled by many factors. One of those is the temperature of the water the storm travels over. Warm water is the “fuel” for the storm and the warmer the water the higher the octane so to speak.

The map above shows the sea surface temperatures in the Atlantic and Caribbean basins. The temperature scale is at the bottom of the image. The orange and red shadings in the expected path of the storm indicate that water temperatures at the surface are around 30 degrees celsius, roughly the low-mid 80s fahrenheit. This is the perfect range for sustaining and strengthening the storm.

The latest forecast track for Irene (11:00 pm Tuesday) still has the storm passing fairly close to the Mid Atlantic coast over the weekend.

The margin of error at this time for the storm’s weekend position is still rather large. You will want to keep up with developments on wbaltv.com and tune in for the latest with Tony and Tom on WBAL TV-11.

John Collins

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