WOCN31 CWHX 301200 TROPICAL STORM HERMINE INFORMATION STATEMENT ISSUED BY THE CANADIAN HURRICANE CENTRE OF ENVIRONMENT CANADA AT 9.00 AM ADT MONDAY 30 AUGUST 2004. THE NEXT STATEMENT WILL BE ISSUED BY 3.00 PM ADT ... TROPICAL STORM HERMINE FORECAST TO MERGE WITH TROPICAL DEPRESSION GASTON ON TUESDAY JUST PRIOR TO BRINGING RAIN INTO ATLANTIC CANADA. 1. CURRENT POSITION, STRENGTH, CENTRAL PRESSURE AND MOTION AT 9.00 AM ADT... TROPICAL STORM HERMINE WAS LOCATED NEAR LATITUDE 35.5 N AND LONGITUDE 71.8 W... ABOUT 580 NAUTICAL MILES OR 1070 KM SOUTHWEST OF YARMOUTH . MAXIMUM SUSTAINED WINDS ARE ESTIMATED AT 45 KNOTS... 83 KM/H... AND CENTRAL PRESSURE AT 1000 MB. HERMINE IS MOVING NORTH AT 18 KNOTS... 33 KM/H. THE REMNANTS OF TROPICAL DEPRESSION GASTON ARE LOCATED NEAR RAYLEIGH- DURHAM NORTH CAROLINA WITH MAXIMUM WINDS LESS THAN 60 KM/H. 2. FORECAST POSITION, CENTRAL PRESSURE AND STRENGTH DATE TIME LAT LON MSLP MAX WIND ADT MB KTS KMH AUG 30 9.00 AM 35.5N 71.8W 1000 45 83 AUG 30 9.00 PM 39.2N 70.6W 1000 45 83 AUG 31 9.00 AM 41.8N 68.1W 1002 40 74 AUG 31 9.00 PM 43.3N 64.5W 1004 35 65 SEP 01 9.00 AM 44.4N 60.2W 1004 35 65 SEP 01 9.00 PM 45.4N 52.6W 1004 35 65 SEP 02 9.00 AM 45.9N 40.5W 1004 35 65 3. PUBLIC WEATHER IMPACTS AND WARNINGS SUMMARY TROPICAL DEPRESSION GASTON WILL BECOME ABSORBED INTO TROPICAL STORM HERMINE ON TUESDAY AND THE TWO SYSTEMS WILL COMBINE TO BRING PERIODS OF HEAVY RAIN TO MUCH OF ATLANTIC CANADA TUESDAY AND WEDNESDAY... AT TIMES HEAVY. RAINFALL AMOUNTS OF 50 MM OR MORE SHOULD BE EXPECTED IN MANY AREAS. THE ATLANTIC STORM PREDICTION CENTRE HAS ISSUED RAINFALL WARNINGS FOR PORTIONS OF ATLANTIC CANADA. 4. MARINE WEATHER IMPACTS AND WARNINGS SUMMARY STRONG TO GALE FORCE WINDS ARE PREDICTED IN THE VICINITY OF HERMINE AS IT PASSES THROUGH MARITIME WATERS TUESDAY AND EARLY WEDNESDAY AND THROUGH NEWFOUNDLAND WATERS WEDNESDAY AND WEDNESDAY NIGHT. GALE WARNINGS ARE IN EFFECT FOR SOUTHWESTERN MARITIME WATERS AND THESE WARNINGS MAY BE EXTENDED TO OTHER WATERS SOUTH OF ATLANTIC CANADA FOR TUESDAY AND WEDNESDAY. 5. TECHNICAL DISCUSSION A. ANALYSIS SATELLITE PICTURES SHOW AN AREA OF WELL ORGANIZED CONVECTION AROUND TROPICAL DEPRESSION GASTON LOCATED OVER NORTH CAROLINA. MEANWHILE TROPICAL STORM HERMINE IS LOCATED ON THE NORTH SIDE OF THE AREA OF CONVECTION AND IS BEING MAINTAINED UNDER WEAK VERTICAL SHEAR. B. PROGNOSTIC A CHALLENGING FORECAST PROBLEM EXISTS WITH THE MERGING OF TWO TROPICAL SYSTEMS AS THEY MOVE UNDER INCREASING SHEAR. IT IS STILL DIFFICULT TO KNOW WHETHER A BINARY INTERACTION WILL OCCUR BETWEEN THESE SYSTEMS... BUT IF IT DOES IT WILL NOT BE A TYPICAL FUJIWHARA EFFECT SINCE THE SHEAR WILL PREVENT A CYCLONIC DANCE. SINCE HERMINE IS THE DOMINANT FEATURE WITH TROPICAL STORM FORCE WINDS WE ARE TREATING IT AS THE MAIN FEATURE FOR TRACKING. THE CANADIAN MODELS AND GFS STRUGGLE TO IDENTIFY BOTH FEATURES AND WE BELIEVE THAT THEIR SOLUTION IS A BLEND OF THE TWO. THE GFS RAIN PATTERN CARRIES TWO FEATURES... BOTH SOUTH OF ATLANTIC CANADA... SO WE MAINTAIN A TRACK SOUTH OF NOVA SCOTIA AND NEWFOUNDLAND WITH ULTIMATE DEVELOPMENT OF A SUBSTANTIAL EXTRATROPICAL LOW WELL EAST OF NEWFOUNDLAND WEDNESDAY NIGHT AND THURSDAY. C. PUBLIC WEATHER THE CONVERGENCE OF THE TWO SYSTEMS SHOULD ENHANCE THE POTENTIAL FOR HIGHER RAINFALL AMOUNTS AND WE ARE CONCERNED THAT THERE WILL BE WIDESPREAD AMOUNTS OF 50 MM THROUGH NOVA SCOTIA. THE SPEED AT WHICH THE SYSTEM PASSES WILL BE A SIGNIFICANT FACTOR IN DETERMINING THE RAINFALL. RULE OF THUMB GUIDANCE FROM CORE RAINFALL AMOUNTS SUGGEST THAT AMOUNTS IN EXCESS OF 100 MM ARE NOT OUT OF THE QUESTION. D. MARINE WEATHER WE ARE MAINTAINING HERMINE AS A GALE CENTRE EVEN AFTER IT MAKES THE TRANSITION TO EXTRATROPICAL. PREDICTED WIND RADII (NM) TIME GALES STORMS HURRICANE NE SE SW NW NE SE SW NW NE SE SW NW 30/12Z 50 50 40 40 0 0 0 0 0 0 0 0 31/00Z 50 50 40 40 0 0 0 0 0 0 0 0 31/12Z 50 50 40 30 0 0 0 0 0 0 0 0 01/00Z 50 50 20 10 0 0 0 0 0 0 0 0 01/12Z 50 50 10 0 0 0 0 0 0 0 0 0 02/00Z 50 50 0 0 0 0 0 0 0 0 0 0 02/12Z 50 50 0 0 0 0 0 0 0 0 0 0 END ROUSSEL/BOWYER $$$^^