951 ABNT30 KNHC 301304 TWSAT MONTHLY TROPICAL WEATHER SUMMARY NATIONAL WEATHER SERVICE MIAMI FL 8 AM EST SUN NOV 30 1997 FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO... ...NO TROPICAL CYCLONES FORMED DURING THE MONTH OF NOVEMBER... ...SUMMARY OF TROPICAL CYCLONE ACTIVITY DURING 1997... TROPICAL CYCLONE ACTIVITY IN THE ATLANTIC HURRICANE BASIN WAS WELL BELOW NORMAL DURING 1997. ONLY SEVEN TROPICAL STORMS FORMED AND JUST THREE OF THOSE REACHED HURRICANE STRENGTH. IN CONTRAST...THE LONG-TERM ANNUAL AVERAGES FOR TROPICAL STORMS AND HURRICANES ARE 10 AND 6...RESPECTIVELY. THE YEARLY TOTALS ALSO REPRESENT A LARGE DECREASE FROM THE RECORD PACE OF 1995 AND 1996...AND ARE MORE IN LINE WITH THE NUMBERS OF SYSTEMS OBSERVED DURING THE PRECEDING FOUR YEARS. SEVERAL OTHER ASPECTS OF THE ACTIVITY HELP CHARACTERIZE THE 1997 SEASON. THERE WERE NO TROPICAL STORMS OR HURRICANES DURING THE MONTH OF AUGUST FOR THE FIRST TIME SINCE 1961. IN FACT...THERE WAS ONLY ONE NAMED SYSTEM DURING THE AUGUST-SEPTEMBER PERIOD...AN OCCURRENCE LAST NOTED IN 1929. ONLY ONE NAMED SYSTEM WAS OBSERVED SOUTH OF 20N LATITUDE. THIS IS CONSISTENT WITH THE RELATIVELY SMALL ROLE PLAYED BY TROPICAL WAVES IN THE DEVELOPMENT OF TROPICAL CYCLONES THIS YEAR. THE WAVES CONTRIBUTED TO THE FORMATION OF JUST ONE HURRICANE...ONE TROPICAL STORM...AND THIS SEASONS ONLY TROPICAL DEPRESSION (WHICH FORMED AND DISSIPATED EAST OF THE LESSER ANTILLES IN JULY). THE TROPICAL CYCLONES WERE RELATIVELY SHORT-LIVED AND WEAK. ONLY HURRICANES DANNY AND ERIKA LASTED MORE THAN FIVE DAYS AND ERIKA WAS THE ONLY MAJOR HURRICANE...THAT IS...THE ONLY ONE TO REACH CATEGORY 3 ON THE SAFFIR/SIMPSON HURRICANE SCALE. DANNY WAS THE ONLY SYSTEM TO MAKE LANDFALL. IN ADDITION TO THESE SYSTEMS...THE NATIONAL HURRICANE CENTER HAS CONCLUDED FROM A REANALYSIS OF DATA THAT AN EARLY SEASON CYCLONE... ORIGINALLY CLASSIFIED AS AN EXTRATROPICAL GALE...SHOULD BE DESIGNATED AN UNNUMBERED SUBTROPICAL STORM. IT ORIGINATED IN THE FINAL DAYS OF MAY FROM AN AREA OF THUNDERSTORMS OVER THE STRAITS OF FLORIDA. THE SYSTEM GRADUALLY STRENGTHENED AND ACCELERATED TOWARD THE NORTHEAST. IT IS NOW ESTIMATED FROM SATELLITE PICTURES TO HAVE BECOME A SUBTROPICAL DEPRESSION AND THEN A SUBTROPICAL STORM ABOUT 100-200 MILES OFF THE U.S. SOUTHEAST COAST EARLY ON 1 JUNE. RECONNAISSANCE AIRCRAFT DATA SUGGEST THAT THE SUBTROPICAL STORM WAS AT ITS STRONGEST ON THE EVENING OF THE 1ST WHEN THE SYSTEM WAS CENTERED OFF THE NORTH CAROLINA OUTER BANKS. THE CYCLONE BECAME EXTRATROPICAL ABOUT 24 HOURS LATER WHILE MOVING EASTWARD...WELL TO THE SOUTH OF NOVA SCOTIA. SUMMARY TABLE: NAME CLASS DATES MAX. MIN. U.S. DIRECT WIND PRESS. DAMAGE DEATHS (MPH) (MB) ($MIL.) -------------------------------------------------------------------- ----- SUBTROPICAL STORM JUN 1-2 50 1003 0 0 ANA TROPICAL STORM JUN 30-JUL 4 45 1000 0 0 BILL HURRICANE JUL 11-13 75 986 0 0 CLAUDETTE TROPICAL STORM JUL 13-16 45 1003 0 0 DANNY HURRICANE JUL 16-26 80 984 100 4 ERIKA HURRICANE SEP 3-15 125 946 0 0 FABIAN TROPICAL STORM OCT 4-8 40 1004 0 0 GRACE TROPICAL STORM OCT 16-17 45 999 0 0 TROPICAL STORM ANA WAS THE FIRST OF FOUR NAMED SYSTEMS TO REACH THEIR MAXIMUM INTENSITY IN JULY...PUTTING THE SEASONS PACE AHEAD OF NORMAL TEMPORARILY. ANA FORMED ON THE LAST DAY OF JUNE FROM A FRONTAL LOW OFFSHORE OF THE U.S. SOUTHEASTERN STATES. IT DEVELOPED IN AN ENVIRONMENT OF RATHER STRONG WINDS AT UPPER LEVELS WHICH ACCELERATED THE SYSTEM TOWARD THE NORTHEAST. ALTHOUGH THE SYSTEM BECAME A TROPICAL STORM WITH 45 MPH WINDS ON 1 JULY...THE STRONG UPPER-LEVEL WINDS PREVENTED FURTHER STRENGTHENING. ANA LOST ITS TROPICAL CHARACTERISTICS AND BECAME EXTRATROPICAL OVER THE WESTERN ATLANTIC ON 4 JULY. IT THEN DISSIPATED. HURRICANE BILL ALSO FORMED OFF THE U.S. SOUTHEAST COAST IN JULY...ON THE 11TH. IT ORIGINATED FROM AN UPPER-LEVEL LOW PRESSURE SYSTEM. BILL MOVED SWIFTLY NORTHEASTWARD AHEAD OF A FRONTAL SYSTEM AND BECAME A HURRICANE ON THE 12TH...JUST BEFORE BECOMING ABSORBED BY THE FRONT SEVERAL HUNDRED MILES SOUTH OF NEWFOUNDLAND. THE FRONTAL SYSTEM THAT SWEPT HURRICANE BILL TO THE NORTHEAST WAS ALSO THE INITIATING DISTURBANCE FOR TROPICAL STORM CLAUDETTE. LIKE ANA AND BILL...CLAUDETTE ALSO CAME TO LIFE OVER THE SOUTHWESTERN ATLANTIC. IT TRANSFORMED FROM A FRONTAL LOW INTO A TROPICAL DEPRESSION ON 13 JULY AND REACHED TROPICAL STORM STRENGTH LATE THAT DAY. THE FIRST USE OF THE NOAA G-IV JET TO OBTAIN ATMOSPHERIC MEASUREMENTS OF A TROPICAL CYCLONE OCCURRED DURING CLAUDETTE. THE DATA CONFIRMED THAT CLAUDETTE DEVELOPED IN AN ENVIRONMENT OF RATHER STRONG WIND SHEAR. THUNDERSTORM ACTIVITY WAS RATHER SPORADIC IN THIS ENVIRONMENT AND MAXIMUM WINDS NEVER EXCEEDED ABOUT 45 MPH. ON THE 16TH...THE SYSTEM DEGENERATED INTO AN EXTRATROPICAL LOW PRESSURE SYSTEM. DANNY FORMED FROM A WEAK LOW PRESSURE AREA OF NON-TROPICAL ORIGIN OVER THE NORTHERN GULF OF MEXICO. IT BECAME A SLOW-MOVING HURRICANE THAT MADE LANDFALL WITH CATEGORY ONE INTENSITY NEAR THE MOUTH OF THE MISSISSIPPI RIVER ON 18 JULY AND JUST SOUTHEAST OF MOBILE ON THE 19TH. DANNY DROPPED ENORMOUS AMOUNTS OF RAIN...TO NEARLY 40 INCHES... OVER EXTREME SOUTHERN ALABAMA. AFTER CROSSING THE COAST AND WEAKENING BELOW STORM STRENGTH...THE CYCLONE MOVED OVER THE SOUTHEASTERN UNITED STATES FOR FOUR DAYS AS A WEAK...YET WELL DEFINED ON SATELLITE IMAGES...DEPRESSION. HEAVY RAINS ALONG ITS PATH PRODUCED SIGNIFICANT INLAND FLOODING...ESPECIALLY IN SOUTH CAROLINA AND NORTH CAROLINA. WHEN THE CYCLONE NEARED THE VIRGINIA COAST...IT BEGAN INTENSIFYING AND WAS ONCE AGAIN A TROPICAL STORM WHEN IT EMERGED FROM THE MID-ATLANTIC COAST. DANNY THEN TURNED TOWARD SOUTHEASTERN NEW ENGLAND AND THE CENTER PASSED WITHIN 30 MILES OF NANTUCKET ISLAND ON 24 JULY. TROPICAL STORM-FORCE WINDS OCCURRED OVER THAT ISLAND AND THE CAPE COD AREA. THE STORM THEN TURNED AWAY FROM LAND AND EVENTUALLY MERGED WITH A FRONT OVER THE NORTH ATLANTIC ON THE 26TH. FOUR DEATHS ARE DIRECTLY ATTRIBUTED TO DANNY...ONE OFFSHORE ALABAMA...ONE RELATED TO A TORNADO IN SOUTH CAROLINA...AND TWO IN FLOODING IN CHARLOTTE...NORTH CAROLINA. MOST OF THE $100 MILLION IN DAMAGE RESULTING FROM DANNY OCCURRED IN ALABAMA. ERIKA FORMED FROM A TROPICAL WAVE OVER THE CENTRAL TROPICAL ATLANTIC OCEAN ON 3 SEPTEMBER. THE CYCLONE GRADUALLY INTENSIFIED WHILE MOVING TOWARD THE WEST-NORTHWEST TO NORTHWEST. IT REACHED HURRICANE STRENGTH AND BECAME AN INCREASED THREAT TO THE NORTHEASTERN LEEWARD ISLANDS ON THE 5TH...BUT THEN TURNED TOWARD THE NORTH AND THE STRONGEST PART OF ITS CIRCULATION PASSED JUST TO THE NORTHEAST OF THOSE ISLANDS. ERIKA WAS BY FAR THE STRONGEST TROPICAL CYCLONE OF THE YEAR IN THE ATLANTIC WITH MAXIMUM WINDS OF 125 MPH ESTIMATED ON THE 8TH AND 9TH...WHEN THE HURRICANE WAS CENTERED SEVERAL HUNDRED MILES TO THE SOUTHEAST OF BERMUDA. OVER THE FOLLOWING FEW DAYS...THE TRACK OF ERIKA BECAME EASTWARD AND THE SYSTEM WEAKENED. IT STILL BROUGHT TROPICAL STORM CONDITIONS...HOWEVER...WITH HURRICANE FORCE GUSTS...TO SOME OF THE AZORES ISLANDS ON 15 SEPTEMBER. ERIKA THEN BECAME EXTRATROPICAL AND MOVED TOWARD THE NORTHEAST. THE LAST TWO TROPICAL CYCLONES OF THE YEAR...FABIAN AND GRACE... OCCURRED IN OCTOBER. BOTH FORMED OVER THE SOUTHWEST ATLANTIC... MOVED TOWARD THE EAST TO NORTHEAST...REACHED TROPICAL STORM STRENGTH...AND WERE SHORT-LIVED. FABIAN ORIGINATED FROM A TROPICAL WAVE THAT PRODUCED ABOUT 5 INCHES OF RAIN OVER PORTIONS OF THE LESSER ANTILLES ON 29 SEPTEMBER. THE ASSOCIATED AREA OF LOW- PRESSURE THEN TURNED TOWARD THE NORTH AND BECAME ORGANIZED INTO A TROPICAL DEPRESSION SEVERAL HUNDRED MILES TO THE NORTH OF PUERTO RICO ON THE 4TH. THE CYCLONE BECAME A WEAK TROPICAL STORM A DAY LATER BUT THUNDERSTORM ACTIVITY WAS FLEETING AND FABIAN LOST ITS TROPICAL CHARACTERISTICS ON THE 8TH. GRACE FORMED FROM ONE OF SEVERAL LOW LEVEL CYCLONIC CIRCULATIONS THAT SPUN UP ALONG A FRONTAL TROUGH EXTENDING EAST-NORTHEASTWARD FROM THE WESTERN CARIBBEAN SEA TO THE CENTRAL ATLANTIC OCEAN. THE TROUGH BROUGHT UNSETTLED WEATHER TO THE AREA FOR ABOUT A WEEK AND... ON 15 OCTOBER...GALE FORCE WINDS WERE ASSOCIATED WITH A LOW THAT WAS THEN LOCATED JUST NORTH OF THE DOMINICAN REPUBLIC. THAT LOW BECAME TROPICAL STORM GRACE THE FOLLOWING DAY...WHEN THUNDERSTORM ACTIVITY DEVELOPED NEAR THE CIRCULATION CENTER. GRACE NEVER COMPLETELY BECAME INDEPENDENT OF THE FRONTAL CIRCULATION AND...EARLY ON THE 17TH...ITS THUNDERSTORMS RAPIDLY DISSIPATED AND THE SYSTEM RETURNED TO EXTRATROPICAL STATUS. AVILA...LAWRENCE...MAYFIELD...PASCH...RAPPAPORT