PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE WILMINGTON NC
700 AM EDT MON MAY 21 2001

...WATERSPOUTS...

FAIR WEATHER WATERSPOUTS ARE A UNIQUE WEATHER PHENOMENON THAT
OCCURS OVER A BODY OF WATER. THEY ARE DEFINED AS AN INTENSE
VERTICAL COLUMN OR VORTEX OF LOW PRESSURE THAT DEVELOPS ON THE
WATER SURFACE AND EXTENDS UPWARD TO A CLOUD BASE...USUALLY
CUMULUS CONGESTUS...RATHER THAN DESCENDING DOWN FROM THE BASE OF
A CLOUD AS IS THE CASE WITH TORNADOES. 

WATERSPOUTS CAN BECOME EXTREMELY DANGEROUS WITH MAXIMUM BRIEF
WIND SPEEDS OF HURRICANE FORCE OR GREATER. AS A RESULT...THEY HAVE
BEEN SEEN CAPSIZING AND SINKING VESSELS AS LARGE AS SHRIMP BOATS.
THEIR AVERAGE LIFE CYCLE RANGES FROM 2 TO 20 MINUTES AS THEY TRAVEL
AT AN AVERAGE SPEED BETWEEN 10 AND 15 KNOTS. 

WATERSPOUTS GENERALLY OCCUR DURING THE SUMMER MONTHS...ALTHOUGH
THEY CAN FORM AS EARLY AS MID-SPRING OR AS LATE AS MID-AUTUMN.  THEIR
FORMATION IS ENHANCED BY UNSTABLE CONDITIONS OFTEN CREATED BY
WARM WATER TEMPERATURES AND HIGH HUMIDITIES IN THE FIRST FEW
THOUSAND FEET OF THE ATMOSPHERE ABOVE THE WATER SURFACE. WINDS
ARE USUALLY LIGHT AND VARIABLE WITH AN EXTREMELY WEAK VERTICAL
WIND SHEAR. RESEARCH HAS ALSO SHOWN THAT MOST WATERSPOUTS OCCUR
WHEN THE SURFACE PRESSURE IS BETWEEN 1010 AND 1015 MB AND THE AIR
TEMPERATURE IS BETWEEN 80 AND 85 DEGREES. 

THERE ARE 5 STAGES TO WATERSPOUT DEVELOPMENT. STAGE 1 CONSISTS OF A
DARK SPOT WHICH IS A CIRCULAR LIGHT COLORED DISC ON THE WATER
SURFACE. ALTHOUGH NOT VISILE TO THE MARINER AT SEA LEVEL...THE
PRESENCE OF A DARK SPOT AND AN ASSOCIATED FUNNEL CLOUD OVERHEAD
INDICATE THAT A COMPLETE FUNNEL IS PRESENT. STAGE 2 ILLUSTRATES A
SPIRAL PATTERN EMINATING FROM THE DARK SPOT. STAGE 3 EVOLVES INTO A
SPRAY RING WHICH IS A DENSE SWIRLING RING OF SEA SPRAY THAT APPEARS
AROUND THE DARK SPOT. WHEN THE WIND SPEEDS REACH CLOSE TO 40
MPH...THE WIND BEGINS TO DISPERSE THE SPRAY UPWARD IN A CIRCULAR
PATTERN KNOWN AS THE SPRAY VORTEX. STAGE 4 IS THE MATURE VORTEX
WHEREBY THE WATERSPOUT IS NOW COMPLETELY VISIBLE AND ACHEIVES
MAXIMUM ORGANIZATION AND INTENSITY. STAGE 5 IS THE DECAYING STAGE
WHEREBY THE FUNNEL AND SPRAY VORTEX DISSIPATE...FREQUENTLY INTO A
DOWNDRAFT OF RAIN SHOWERS.    

AS WITH ANY KIND OF WEATHER HAZARD OVER THE WATER...BOATER SAFETY
BEGINS BY STAYING INFORMED. ONE OF THE SPECIAL RADIOS THAT HAS
CONTINUOUS WEATHER BROADCASTS SHOULD ALWAYS BE ABOARD YOUR
BOAT AND SHOULD BE LISTENED TO REGULARLY.

THE PROTECTION OF YOUR CREW IS THE MOST IMPORTANT ASPECT DURING 
SEVERE WEATHER AT SEA. IF A WATERSPOUT APPROACHES...AND YOU ARE 
CAUGHT OUT IN THE OPEN WATERS...MAKE SURE YOU AND YOUR CREW ARE 
WEARING APPROVED FLOTATION DEVICES.

IF BOATING OUT ON THE OPEN WATER...AND A WATERSPOUT COMES YOUR
WAY...TRY TO ESCAPE IT BY GOING AT RIGHT ANGLES TO ITS PATH. IF ITS
ABOUT TO HIT YOUR BOAT...THE BEST BET MIGHT BE TO DIVE OVERBOARD
AND UNDERWATER...THUS AVOIDING THE WATERSPOUT ITSELF AND THE
FLYING DEBRIS IT CREATES. THIS SHOULD ONLY BE A DONE AS A LAST DITCH
EFFORT SINCE SCIENTISTS WHO HAVE STUDIED WATERSPOUTS ARE NOT
PREPARED TO SAY THAT ITS TOTALLY SAFE TO DIVE UNDERNEATH A
WATERSPOUT. 

THE NATIONAL WEATHER SERVICE IN WILMINGTON NC AND THE UNITED
STATES COAST GUARD WILL CONTINUE TO ISSUE STATEMENTS TO PROMOTE
NATIONAL SAFE BOATING WEEK FROM MAY 19 TO MAY 25...2001. A STATEMENT
ABOUT EFFECTIVE COMMUNICATIONS DURING DISTRESS WILL BE ISSUED
AROUND 7 AM EDT TUESDAY.

...BOAT SMART; BOAT SAFE; TAKE CONTROL...

$$