Explored Core Sound in eastern North Carolina yesterday by circumnavigating Hawkers Island. The forecast was for winds of 9-11 knots. Isolated thunder storms were a 10% possibility. On the trip to the coast I noticed that the temperature was 8 degrees warmer than 40 miles inland. That's unusual; normally coastal temps are 7-8 degrees cooler in the summer. Raising the mast in winds over 10 mph can be hard if the wind blows across the beam of the boat. Although the shrouds make controlling the mast easy in a fore/aft plane they do nothing to counteract a sideways force while raising. Therefore I positioned the back of the trailer into the wind. This pushes the mast forward when lifting it & makes it easier to get the forestay pin into its hole. The 8-9 knot winds lasted only 1/2 hour, just enough time to motor through the swing bridge. As I glanced back I noticed long low dark narrow cloud systems coming across the barrier islands from the ocean. Quickly clearing the cockpit of gear that could get underfoot in a squall I put on a vest-type PFD. A few minutes later a squall blocked my view of the ramp but I got only a few drops. Three hours later I turned the corner on Hawkers Island & started to sail SE. Winds were only 5-6 knots instead of the forecasted 9-11. Sometimes thunderstorm downdrafts can counteract prevailing winds but these were low quick moving clouds in the direction of the prevailing winds. Passing the HQ of the Cape Lookout National Seashore, a large water rope formed just off a spoil-bank. 200-300 feet high & leaning forward approx. 70 degrees it moved across the Sound & passed out of sight. It had a small foot, no more than 50-60' across & could have been easily avoided under power if it was closer. I had seen a large, clear air dust devil hit a fire camp in Montana & suck sleeping bags & foam pads a couple of hundred feet in to the air but this was a first on the water (excluding low flying jet water vortices). Low winds & signs of atmospheric instability prompted me to lower the sails & motor. As I completed furling the sails, an island 2 miles away was blanketed by a "white wall". I had only a few minutes to close the hatch & get the rain gear out before the rain wall hit. Generally lasting only 5-10 minutes the white squalls are easily handled but they can cause problems. Visibility is limited so you can no longer steer by marks or shorelines unless they are less than 1/2 mile away. The force of the rain beats the wave crests down so the waves aren't useful as a tool to maintain your heading. By this time I was in a known channel so any grounding would be a soft one. After the squall there were 15 minutes of 8 knot winds. Wow! Raised the sail; got to sail back to the ramp although the last 2 miles were in winds of 5-6 again. Mike, Fionulla, M-15