ZCZC MIATCDAT1 ALL TTAA00 KNHC DDHHMM TROPICAL STORM KATE DISCUSSION NUMBER 19 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT TUE SEP 30 2003 KATE IS UNDERGOING SOME SIGNIFICANT VERTICAL SHEAR...DUE IN PART TO THE CYCLONE SLOWING ITS FORWARD SPEED AND ALSO TURNING MORE NORTHWARD NOW. CONVECTIVE CLOUD TOPS HAVE WARMED SIGNIFICANTLY AND THE OVERALL CLOUD PATTERN HAS BECOME QUITE RAGGED IN APPEARANCE. THERE REMAINS ...HOWEVER...A RATHER WELL-DEFINED LOW-/MID-LEVEL CIRCULATION AS NOTED IN NIGHTTIME VISIBLE IMAGERY. THE INITIAL INTENSITY IS LOWERED TO 55 KT BASED ON A CONSENSUS DVORAK SATELLITE INTENSITY ESTIMATE OF T3.5...OR 55 KT...FROM TAFB...SAB...AND AFWA. THE INITIAL MOTION ESTIMATE IS 015/07...EVEN THOUGH THE PAST 6-HOUR MOTION WAS 035/10. ALL OF THE GLOBAL MODELS AGREE ON KATE BECOMING NEARLY STATIONARY WITHIN THE NEXT 12 HOURS...AND THE LAST FEW SATELLITE POSITION ESTIMATES SUGGEST THAT THIS MAY ALREADY BE OCCURRING. AFTER THAT...HOWEVER...THERE IS A SIGNIFICANT BIFURCATION IN THE NHC MODEL GUIDANCE WITH HALF THE MODELS TAKING KATE EASTWARD...WHILE THE OTHER HALF TAKE THE CYCLONE WESTWARD. THE UKMET AND MEDIUM AND DEEP BAM MODELS TAKE KATE EASTWARD...WHILE THE GFS...NOGAPS...CANADIAN...GFDL...AND GFDN MODELS MOVE KATE WESTWARD. THE UKMET KEEPS KATE AS A RELATIVELY WEAK CYCLONE...WHICH DOES NOT APPEAR LIKELY GIVEN THE TENACITY WITH WHICH THIS CYCLONE HAS FOUGHT OFF SOME HOSTILE SHEAR CONDITIONS...INDICATING THAT KATE IS A VERY DEEP AND WELL-ORGANIZED SYSTEM. AS SUCH...KATE IS EXPECTED TO SLOW AND THEN TURN WESTWARD BY 24 HOURS AS IS UNDERGOES SOME BINARY INTERACTION WITH A MID-/UPPER-LEVEL LOW LOCATED ABOUT 350 NMI WEST OF THE CYCLONE. AS THE UPPER-LOW DROPS SOUTHWARD ... KATE IS EXPECTED TO TURN WESTWARD UNDER THE INFLUENCE OF INCREASING DEEP-LAYERED EASTERLY FLOW. THE OFFICIAL FORECAST TRACK IS TO THE LEFT OF THE PREVIOUS FORECAST TRACK...AND ALSO FASTER AFTER 72 HOURS....WHICH IS SIMILAR TO THE GFDL...GFS AND NOGAPS MODELS. KATE MAY WEAKEN A LITTLE MORE IN THE NEXT 12 HOURS OR SO AS THE COMBINATION OF SOUTHWESTERLY FLOW ON THE EAST SIDE OF THE UPPER-LOW TO THE WEST MAINTAINS SOME SHEAR ON THE SLOW-MOVING CYCLONE. HOWEVER...BY 24-36 HOURS...THE UPPER-LEVEL FLOW IS FORECAST BY ALL THE GLOBAL AND REGIONAL MODELS TO BECOME LIGHT TO MODERATE EASTERLY WHICH WOULD FAVOR ADDITIONAL STRENGTHENING. IN FACT...BY 96 TO 120 HOURS...A SMALL ANTICYCLONE IS FORECAST BY ALL THE MODELS TO RESIDE NEAR 35N 50W...WHICH WOULD FAVOR EVEN MORE STRENGTHENING THAN WHAT THE OFFICIAL FORECAST IS INDICATING. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE SHIPS INTENSITY MODEL THROUGH 72 HOURS ...AND THEN MUCH HIGHER THAN SHIPS BASED ON THE LOWER LATITUDE FORECAST KEEPING KATE OVER WARMER WATER AND ALSO UNDER LITTLE OR NO SHEAR CONDITIONS. THE GFDL MODEL IS SIMILAR IN THAT IT BRINGS KATE UP TO 80-85 KT IN 48-60 HOURS AND THEN HOLDS IT STEADY AFTER THAT. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 30/0900Z 31.1N 34.7W 55 KT 12HR VT 30/1800Z 31.9N 34.8W 55 KT 24HR VT 01/0600Z 32.1N 35.7W 60 KT 36HR VT 01/1800Z 32.3N 36.6W 65 KT 48HR VT 02/0600Z 32.4N 38.0W 70 KT 72HR VT 03/0600Z 32.6N 41.4W 70 KT 96HR VT 04/0600Z 33.5N 45.5W 70 KT 120HR VT 05/0600Z 35.0N 50.0W 70 KT NNNN
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Page last modified: Monday, 07-Feb-2005 16:49:59 UTC