WTCN31 CWHX 180000 CANADIAN HURRICANE INFORMATION STATEMENT ISSUED BY THE CANADIAN HURRICANE CENTRE OF ENVIRONMENT CANADA AT 8.00 PM EDT WEDNESDAY 17 SEPTEMBER 2003. THE NEXT STATEMENT WILL BE ISSUED BY 2.00 AM EDT ...ISABEL CONTINUING NORTHWESTWARD AND EXPECTING TO MAKE LANDFALL THURSDAY AFTERNOON IN EASTERN NORTH CAROLINA... ...REMNANTS EXPECTED IN ONTARIO AND QUEBEC ON FRIDAY AND SATURDAY... 1. CURRENT POSITION, STRENGTH, CENTRAL PRESSURE AND MOTION AT 8.00 PM EDT... HURRICANE ISABEL WAS LOCATED NEAR LATITUDE 31.8 N AND LONGITUDE 73.7 W... ABOUT 225 NAUTICAL MILES OR 420 KM SOUTH SOUTHEAST OF CAPE HATTERAS. MAXIMUM SUSTAINED WINDS ARE ESTIMATED AT 90 KNOTS... 167 KM/H... AND CENTRAL PRESSURE AT 958 MB. ISABEL IS MOVING NORTH NORTHWEST AT 12 KNOTS...22 KM/H. 2. FORECAST POSITION, CENTRAL PRESSURE AND STRENGTH. DATE TIME LAT LON MSLP MAX WIND EDT MB KTS KMH SEP 17 8.00 PM 31.8N 73.7W 958 90 167 SEP 18 8.00 AM 33.9N 75.4W 952 95 176 SEP 18 8.00 PM 36.5N 77.3W 970 70 130 SEP 19 8.00 AM 39.5N 79.0W 980 50 93 SEP 19 8.00 PM 43.7N 78.2W 987 40 74 POST-TROPICAL SEP 20 8.00 AM 49.0N 76.8W 985 30 56 POST-TROPICAL SEP 20 8.00 PM 54.6N 75.1W 983 30 56 POST-TROPICAL 3. PUBLIC WEATHER IMPACTS AND WARNINGS SUMMARY THE REMNANTS OF ISABEL ARE EXPECTED TO IMPACT THE WEATHER OVER ONTARIO AND QUEBEC ON FRIDAY AND SATURDAY. RAIN WILL LIKELY BEGIN EARLY ON FRIDAY OVER SOUTHERN ONTARIO AND SPREAD INTO SOUTHWESTERN QUEBEC DURING THE DAY. THE RAIN WILL LIKELY EXTEND INTO THE LAKE HURON/GEORGIAN BAY AREA AS WELL. RAINFALL AMOUNTS WITH THE REMAINS OF ISABEL ARE EXPECTED TO BE IN THE RANGE OF 30 TO 50 MM WITH LOCALLY HIGHER AMOUNTS POSSIBLE. STRONG SOUTHEAST WINDS GUSTING FROM 60 TO 80 KM/H WILL BE MOST PREVALENT OVER SOUTHERN QUEBEC AND EASTERN ONTARIO. SPECIAL WEATHER STATEMENTS HAVE BEEN ISSUED BY ENVIRONMENT CANADA ONTARIO REGION THIS AFTERNOON FOR SOUTHERN, CENTRAL AND NORTHEASTERN ONTARIO FOR THE POTENTIAL OF HEAVY RAINS IN THESE AREAS ON FRIDAY. 4. MARINE WEATHER IMPACTS AND WARNINGS SUMMARY NO WARNINGS ISSUED AT THIS TIME. HOWEVER GALE FORCE SOUTHERLY WINDS ARE LIKELY ON FRIDAY OVER LAKE ONTARIO. STRONG WEST TO NORTHWEST WINDS ARE EXPECTED ACROSS THE GREAT LAKES ON SATURDAY IN THE WAKE OF ISABEL. MODERATE SURF CONDITIONS ALONG THE ATLANTIC COAST OF NOVA SCOTIA WILL PRESIST THROUGH FRIDAY. SWELL OF 2 TO 3 METRES IS EXPECTED IN THE VICINITY OF THE GULF OF MAINE ESPECIALLY WITH THE EBBING TIDE. NO WIND IMPACTS EXPECTED OVER MARITIME WATERS WITH THIS SYSTEM. 5. TECHNICAL DISCUSSION A. ANALYSIS THE EYE OF ISABEL FIXED FROM SATELITTE IMAGERY. THE MOTION OVER THE PAST SEVERAL HOURS HAS BEEN FAIRLY CONSISTENT WITH A TRACK TOWARD THE NORTHWEST. THE SPEED OF ISABEL HAS INCREASED SLIGHTLY SINCE 1800Z THIS AFTERNOON AND THIS TREND WILL CONTINUE DURING THE NEXT 24 HOURS. B. PROGNOSTIC THIS FORECAST IS ESSENTIALLY AN UPDATE OF PREVIOUS TRACK WITH A SLIGHT SHIFT TO THE RIGHT AFTER 36 HOURS BASED ON THE LATEST GUIDANCE. DURING THE PRE-LANDFALL PERIOD..INTENSITY CHANGES WILL BE GOVERNED BY THE ENVIRONMENTAL FLOW AROUND ISABEL. SSTS ARE SUFFICIENTLY WARM TO SUPPORT A STRONG HURRICANE. A HIGH-LEVEL TROUGH WILL DIG SOUTHEASTWARD OVER FLORIDA DURING THE NEXT 24 HOURS. THIS WILL TEND TO ENHANCE OUTFLOW..PARTICULARLY ON THE NORTHWEST SIDE OF THE STORM AND MAY PROMOTE SOME REINTENSIFICATION. THE 500 MB ENVIRONMENTAL FLOW AROUND ISABEL WILL REMAIN WEAK PRIOR TO LANDFALL. THE HIGH NORTH OF ISABEL WILL CONTINUE TO MOVE NORTHWARD TONIGHT WHICH WILL MITIGATE THE DRY AIR INFLUENCE AND THERE MAY BE AN INTENSIFICATION PERIOD THEREAFTER LEADING UP TO LANDFALL THURSDAY AFTERNOON. THE POST-LANDFALL EXTRATROPICAL TRANSITION FORECAST REMAINS PROBLEMATIC. THERE IS GENERAL AGREEMENT AMONG MODELS THAT THE 500 MB SHORT WAVE TROUGH THAT WILL PROGRESS FROM WESTERN CANADA WILL JUST BARELY MERGE WITH THE STORM OVER PENNSYLVANIA ON FRIDAY. ISABEL'S REMNANTS MAY SIMPLY MERGE INTO THE BASE OF THIS TROUGH WITHOUT VIGOROUS TRANSITION..I.E. A DEEPENING REMNANT LOW. A CLOSER LOOK AT MODELLED PV FIELDS FROM GFDL AND NOGAPS LAST NIGHT DID NOT SHOW THE WRAP-UP OF THE TROUGH AND STORM PV FIELDS WHICH IS NECESSARY FOR A STRONG EXTRATROPICAL TRANSITION. ON THE OTHER HAND..IN THE UPPER LEVELS THERE WILL BE A MERGING OF THE NORTHERN TROUGH WITH A TROUGH OVER THE SOUTHEASTERN STATES. IN FACT.. THE REMNANT LOW OVER SOUTHERN ONTARIO WILL LIKELY BE IN THE LEFT EXIT REGION OF A MERIDIONAL JET OVER PENNSYLVANIA AND NEW YORK. GIVEN THIS ..WE WILL STICK WITH THE THEME THAT THERE WILL BE SOME WEAK REDEVELOPMENT OF THE STORM REMNANTS OVER SOUTHERN ONTARIO. ULTIMATELY THE LOW WILL LIKELY DEEPEN OVER HIGHER LATITUDES. DURING THE EXTRATROPICAL TRANSITION EXPECT THE STRONGEST WINDS TO BE EAST OF THE LOW TRACK AND THE HEAVIER RAINFALLS TO THE WEST. THIS CAN BE USED AS A RULE OF THUMB IN THE FORECASTS OVER THE COMING DAYS WITH RESPECT TO THE TRACK OF THE LOW. AT THIS TIME MODEL CONSENSUS IS FOR A TRACK OVER LAKE ONTARIO. END..SZETO/FOGARTY