ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM HURRICANE JOHN DISCUSSION NUMBER 6 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP112006 200 PM PDT TUE AUG 29 2006 JOHN HAS UNDERGONE RAPID INTENSIFICATION TODAY AND A PINHOLE EYE IS NOW EVIDENT ON SATELLITE IMAGERY. 24 HOURS AGO THE CYCLONE WAS A 40 KT TROPICAL STORM AND THE INITIAL INTENSITY FOR THIS ADVISORY IS SET AT 100 KT. IT SHOULD BE NOTED THAT BOTH TAFB AND SAB DVORAK CLASSIFICATIONS WERE LIMITED TO DATA T-NUMBERS OF 5.0 OR 90 KT DUE TO RESTRICTIONS IN THE TECHNIQUE...BUT RAW DATA T-NUMBERS GIVE ESTIMATES CLOSER TO 6.0 OR 115 KT. THERE ARE NO APPARENT ENVIRONMENTAL CONDITIONS WHICH SHOULD INHIBIT ADDITIONAL INTENSIFICATION AS INDICATED BY THE SHIPS GUIDANCE. THIS IS REFLECTED IN THE OFFICIAL FORECAST WHICH MAKES JOHN A CATEGORY FOUR HURRICANE WITHIN 12 HOURS...AND MAINTAINS JOHN AS A STRONG HURRICANE THROUGH 5 DAYS. THE INITIAL MOTION IS 290/9. A WEST-NORTHWEST TO NORTHWEST MOTION IS EXPECTED TO CONTINUE THROUGH 72 HOURS...AS THE HURRICANE IS STEERED ALONG THE SOUTHWESTERN PERIPHERY OF A MID- TO UPPER-LEVEL RIDGE BUILDING ACROSS NORTHERN MEXICO. BOTH THE GFDL AND FSU SUPERENSEMBLE GUIDANCE ARE TO THE EAST OF THE MODEL CONSENSUS AND STILL FORECAST THE WESTERN EXTENT OF THE RIDGE TO BE FARTHER EAST ALLOWING THE HURRICANE TO MOVE NORTHWESTWARD CLOSER TO THE WEST COAST OF MEXICO AND EVENTUALLY TOWARD THE BAJA PENINSULA. ON THE OTHER HAND...THE GFS AND NOGAPS MODELS ARE TO THE WEST OF THE MODEL CONSENSUS AND TAKE THE HURRICANE ON A MORE WEST-NORTHWEST TO WEST TRACK RESULTING FROM A STRONGER RIDGE TO ITS NORTH. THE OFFICIAL FORECAST TRACK IS SLIGHTLY NORTH OF THE PREVIOUS ADVISORY AND FOLLOWS THE DYNAMICAL MODEL CONSENSUS CONU CLOSELY. THE CONTINUED STRENGTHENING OF JOHN AND A COUPLE OF SHIP REPORTS HAVE RESULTED IN AN EXPANSION OF THE WIND RADII. THIS HAS PROMPTED THE GOVERNMENT OF MEXICO TO ADJUST THE WATCHES AND WARNINGS ONCE AGAIN. FORECAST POSITIONS AND MAX WINDS INITIAL 29/2100Z 14.4N 99.7W 100 KT 12HR VT 30/0600Z 15.0N 101.1W 115 KT 24HR VT 30/1800Z 16.0N 103.0W 120 KT 36HR VT 31/0600Z 17.3N 104.8W 120 KT 48HR VT 31/1800Z 18.8N 106.8W 115 KT 72HR VT 01/1800Z 21.0N 110.5W 110 KT 96HR VT 02/1800Z 22.0N 113.0W 100 KT 120HR VT 03/1800Z 22.0N 116.0W 90 KT $$ FORECASTER MAINELLI/PASCH NNNN
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Page last modified: Monday, 11-Sep-2006 11:28:43 UTC