ZCZC MIATCDAT2 ALL TTAA00 KNHC DDHHMM HURRICANE KARL DISCUSSION NUMBER 7 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT SAT SEP 18 2004 KARL HAS RAPIDLY INTENSIFIED OVER THE PAST 6 HOURS OR SO BASED ON THE APPEARANCE OF A SMALL BUT DISTINCT 10 NMI DIAMETER EYE IN INFRARED SATELLITE IMAGERY. THE INITIAL INTENSITY OF 75 KT IS BASED ON A BLEND OF DVORAK SATELLITE INTENSITY ESTIMATES OF 90 KT...77 KT ...AND 65 KT...FROM TAFB...SAB...AND AFWA...RESPECTIVELY. THE INITIAL MOTION IS 310/13. THERE REMAINS NO SIGNIFICANT CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING. THE NHC MODEL GUIDANCE REMAINS QUITE CONSISTENT ON A GENERAL NORTHWESTWARD MOTION FOR THE NEXT 36-48 HOURS AS KARL MOVES AROUND THE SOUTHWEST PERIPHERY OF THE DEEP-LAYER SUBTROPICAL RIDGE TO THE NORTH. BY 72 HOURS...A STRONG HIGH AMPLITUDE RIDGE IS FORECAST BY ALL THE GLOBAL MODELS TO DEVELOP OVER THE NORTHEASTERN U.S. AND EASTERN CANADA...WHICH CAUSES A STRONG MID-TROPOSPHERIC TROUGH TO DIG SOUTHWARD OVER THE CENTRAL ATLANTIC TO THE NORTH AND NORTHWEST OF KARL. THE LARGE TROUGH IS EXPECTED TO ERODE THE SUBTROPICAL RIDGE TO THE NORTH OF KARL...WHICH ALLOW THE HURRICANE TO TURN NORTH-NORTHEASTWARD...AND POSSIBLY EVEN BEGIN RECURVATURE TO THE NORTHEAST. THE OFFICIAL FORECAST IS JUST A TAD TO THE LEFT OF THE PREVIOUS TRACK AND IS CLOSE TO THE NHC MODEL CONSENSUS. THE OUTFLOW PATTERN OVER KARL REMAINS QUITE IMPRESSIVE...ALTHOUGH THE CONVECTIVE CLOUD PATTERN IS ELONGATED SLIGHTLY NORTHEAST- SOUTHWEST. HOWEVER...THE OUTFLOW HAS CONTINUED TO EXPAND OUTWARD IN THE WESTERN SEMICIRCLE...SUGGESTING THAT ANY RESTRICTION THAT HAS CREATED THE ASYMMETRIC CLOUD PATTERN SHOULD GRADUALLY WEAKEN. KARL IS EXPECTED TO CONTINUE TO RAPIDLY INTENSIFY FOR THE NEXT 12 TO 18 HOURS DUE TO THE SMALL INNER-CORE WIND FIELD...GOOD OUTFLOW PATTERN ...AND WARM SSTS OF AT LEAST 28C. AFTER THAT...THE INTENSITY TREND IS EXPECTED TO BE A LITTLE LESS ROBUST AND IS LEVELED OFF BY 72 HOURS WHEN INCREASING SOUTHWESTERLY SHEAR IS FORECAST TO BEGIN AFFECTING THE HURRICANE. THE OFFICIAL INTENSITY FORECAST IS A LITTLE HIGHER THAN SHIPS THROUGH 24 HOURS...AND THEN MUCH LOWER AFTER THAT...SINCE THE SHIPS MODEL BRINGS KARL UP TO 125 KT IN 72H. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 18/0900Z 14.9N 38.6W 75 KT 12HR VT 18/1800Z 15.8N 40.3W 90 KT 24HR VT 19/0600Z 16.8N 42.4W 100 KT 36HR VT 19/1800Z 18.1N 44.1W 105 KT 48HR VT 20/0600Z 19.7N 45.3W 110 KT 72HR VT 21/0600Z 23.0N 46.5W 110 KT 96HR VT 22/0600Z 26.5N 47.0W 100 KT 120HR VT 23/0600Z 31.0N 45.5W 90 KT $$ NNNN
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Page last modified: Saturday, 18-Sep-2004 08:53:41 UTC