ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM TROPICAL STORM ANDRES DISCUSSION NUMBER 14 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 2 AM PDT FRI MAY 23 2003 AFTER LOOKING QUITE DISORGANIZED YESTERDAY AFTERNOON...ANDRES HAS MADE A CONSIDERABLE COMEBACK THIS MORNING. THE LOW-LEVEL CENTER HAS DISAPPEARED UNDER A PERSISTENT CONVECTIVE BURST WITH TOPS COLDER THAN -80C...AND TWO RECENT SSM/I OVERPASSES SUGGEST THAT THE CONVECTION IS TRYING TO WRAP AROUND THE NORTH SIDE OF THE CENTER. SATELLITE INTENSITY ESTIMATES ARE 30 KT...35 KT...AND 45 KT FROM TAFB...AFWA...AND SAB RESPECTIVELY. THE INITIAL INTENSITY IS SET AT 40 KT BASED ON THE IMPROVED APPEARANCE DURING THE PAST 6 HR. THE INITIAL MOTION IS 280/18. ANDRES IS EMBEDDED IN LOW/MID LEVEL EASTERLY FLOW SOUTH OF A STRONG SUBTROPICAL RIDGE...WHILE A LARGE MID/UPPER-LEVEL TROUGH COVERS THE AREA WEST OF 135W. THE RIDGE SHOULD KEEP THE CYCLONE ON A GENERAL WEST TO WEST-NORTHWEST TRACK THROUGH 24-36 HR. BEYOND THAT TIME...THE TROUGH COULD TURN ANDRES MORE NORTHWARD IF IT IS WELL-ENOUGH DEVELOPED...AS IS SUGGESTED BY THE BAMD AND BAMM. HOWEVER...THE CURRENT EXPECTATION IS THAT ANDRES WILL BE WEAK AND BE STEERED BY THE LOW-LEVEL FLOW. THE OFFICIAL FORECAST THEREFORE CALLS FOR A WESTWARD MOTION AFTER 36 HR WITH A DECREASE IN FORWARD SPEED. THIS IS IN BEST AGREEMENT WITH THE NOGAPS. TO DEAL WITH THE EASY PART OF THE INTENSITY FORECAST...ANDRES SHOULD CROSS THE 26C ISOTHERM IN 24-30 HR. AFTER THAT TIME...COOLER WATER AND SHEAR FROM THE TROUGH SHOULD CAUSE THE SYSTEM TO STEADILY WEAKEN. THE TRICKY PART IS WHAT MAY HAPPEN BEFORE ANDRES REACHES THE COOLER WATER. THE INTENSITY FORECAST CALLS FOR LITTLE CHANGE IN STRENGTH...BASED PARTLY ON THE SHIPS MODEL...PARTLY ON THE EXPECTATION OF CONTINUED SHEAR...AND PARTLY ON THE WAY ANDRES FELL APART YESTERDAY AFTER LOOKING SIMILAR TO HOW IT DOES NOW. HOWEVER...THE STORM IS MOVING OUT OF WESTERLY AND NORTHWESTERLY UPPER-LEVEL FLOW INTO AN AREA OF SOUTHERLY TO SOUTHWESTERLY FLOW. WHILE HARDLY IDEAL...THIS BRINGS UP AN ALTERNATE SCENARIO THAT THE SHEAR MAY DECREASE OVER ANDRES FOR 12-24 HR AND ALLOW SOME STRENGTHENING BEFORE THE CYCLONE REACHES COOLER WATER. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 23/0900Z 12.4N 123.3W 40 KT 12HR VT 23/1800Z 12.8N 125.7W 40 KT 24HR VT 24/0600Z 13.4N 128.7W 40 KT 36HR VT 24/1800Z 13.8N 131.1W 35 KT 48HR VT 25/0600Z 14.1N 133.3W 30 KT 72HR VT 26/0600Z 14.5N 137.5W 25 KT...DISSIPATING 96HR VT 27/0600Z 14.5N 141.5W 20 KT...REMNANT LOW 120HR VT 28/0600Z 14.5N 145.5W 20 KT...REMNANT LOW NNNN
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Page last modified: Monday, 07-Feb-2005 16:49:55 UTC