Azores Islands brace for Gordon; Helene not a threat

The Azores Islands are bracing for the arrival of Hurricane Gordon, which is expected to rip through the islands tonight as a Category 1 hurricane with 75 mph winds. Gordon is under about 20 knots of shear, and will be moving over cool waters of 22-23 C this afternoon, so a decrease in intensity from its current 85 mph winds is likely before the storm moves through the Azores. Hurricane force winds extend out 40 miles from the center, and the islands of the Azores are widely scattered enough that Gordon may not bring hurricane force winds to any of the islands. The first place to feel Gordon's effects will be the northwesternmost islands of Corvo and Flores. The link for today's weather conditions on Flores can be found here. About 4,000 people live on these two islands, about 2% of the total population of the Azores. Gordon now appears to be moving slightly south of due east, which may mean the more southern islands will feel the worst of Gordon.

Gordon's rapid forward speed near 30 mph may allow the storm to make it all the way to Spain or Portugal on Wednesday night as a tropical storm, making it only the second tropical cyclone ever to hit the Iberian Peninsula (Tropical Depression Vince of 2005 was the first). It it more likely, though, that Gordon will arrive as a powerful extratropical storm with 50 mph winds.

Hurricane Helene
Hurricane Helene remains a powerful Category 3 hurricane, but we are now confident that this storm presents no threat to land. Beginning with yesterday morning's computer model runs, all of the reliable models have been consistently been predicting that the next trough of low pressure moving over the Atlantic will be strong enough to turn Helene northwards, then recurve her out to sea. My confidence in this forecast is high, because the NOAA P-3 and Gulfstream IV jet have been probing Helene for the past two days as part of a research mission into how dry Saharan air affects hurricane intensification (the SALEX project). The computer models have had the advantage of having this high-quality data available for their runs. Given this factor, plus the high degree of unanimity of the models in turning Helene northeast over multiple runs, we can be confident that Helene poses no threat to the U.S., Bermuda, or Canada.


Figure 1. Current satellite image of Helene, updated every 1/2 hour.

Helene is over warm waters of about 28C, and under about 5-10 knots of wind shear. These conditions favor intensification for another two days, and Helene could be the first Category 4 hurricane in the Atlantic this year.

The rest of the tropical Atlantic
A non-tropical area of low pressure a few hundred miles east of Cape Hatteras, North Carolina, has a slight chance of development as it drifts slowly east. Most of the computer models are forecasting that a tropical storm will develop later this week in the region between Africa and the Lesser Antilles Islands.

I'll have an update Wednesday morning.
Jeff Masters