ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION TWENTY-ONE-E DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP212006 200 AM PDT TUE NOV 14 2006 SATELLITE IMAGERY THIS MORNING INDICATES THAT THE TROPICAL DEPRESSION IS NEAR TROPICAL STORM STRENGTH. A SMALL AREA OF PERSISTENT CONVECTION HAS FORMED NEAR THE CENTER AT THE END OF A BAND THAT WRAPS IN FROM NORTHWEST TO SOUTHWEST TO SOUTHEAST OF THE CENTER. SATELLITE INTENSITY ESTIMATES ARE 30 KT FROM TAFB AND SAB...AND 25 KT FOR AFWA. BASED ON THAT...THE SYSTEM WILL REMAIN A DEPRESSION FOR THIS ADVISORY. THE CYCLONE HAS SLOWED ITS FORWARD MOTION TO 300/5. IT IS EMBEDDED IN AN AREA OF WEAK STEERING CURRENTS AS A SERIES OF MID/UPPER-LEVEL WESTERLY TROUGHS CROSS NORTHERN MEXICO...AND A MID/UPPER-LEVEL RIDGE AMPLIFIES WEST OF THE DEPRESSION. THE LARGE-SCALE MODELS FORECAST THIS COMBINATION OF FEATURES TO CREATE A LIGHT NORTHERLY MID-LEVEL FLOW NEAR THE DEPRESSION DURING THE NEXT 24-48 HR. SHOULD THIS VERIFY...THE DEPRESSION WOULD MAKE LITTLE PROGRESS TOWARD THE NORTHWEST...AND INDEED THE GFDL CALLS A LOOPING TRACK DURING THIS PERIOD. STARTING IN ABOUT 72 HR...A MID/UPPER-LEVEL SHORTWAVE TROUGH WILL DROP SOUTHWARD NEAR CLARION ISLAND AND BECOME A CUT-OFF LOW. THIS WOULD ALLOW THE TROPICAL CYCLONE TO ACQUIRE A FASTER NORTHWESTWARD OR NORTHWARD MOTION...WITH THE GFDL FORECASTING THE SYSTEM TO REACH CABO CORRIENTES MEXICO IN 96-108 HR. THE OFFICIAL FORECAST CALLS FOR A SLOWER NORTHWESTWARD MOTION THAN THE PREVIOUS PACKAGE FOR THE FIRST 72 HR...FOLLOWED BY A SLIGHTLY FASTER MOTION. IF CURRENT MODEL TRENDS CONTINUE...THE TRACK MAY HAVE TO BE ADJUSTED SOUTHWARD IN SUBSEQUENT ADVISORIES. THE DEPRESSION IS CURRENTLY IN AN AREA OF LIGHT VERTICAL WIND SHEAR WHICH SHOULD ALLOW STRENGTHENING. LARGE-SCALE MODELS FORECAST A GENERALLY FAVORABLE SHEAR ENVIRONMENT SOUTH OF 15N NEAR THE FORECAST TRACK FOR THE NEXT SEVERAL DAYS. THE GFDL MODEL FORECASTS THE SYSTEM TO BECOME A MAJOR HURRICANE IN 96 HR...WHILE THE SHIPS MODEL FORECAST IT TO PEAK JUST UNDER HURRICANE STRENGTH IN 60-72 HR. THE NEW INTENSITY FORECAST CALLS FOR MORE STRENGTHENING THAN PREVIOUSLY...BUT IS STILL BELOW THE SHIPS AND GFDL GUIDANCE. THERE ARE TWO CONCERNS ABOUT THE INTENSITY FORECAST. FIRST...THE ENVIRONMENT IS FAVORABLE ENOUGH THAT THERE IS A 40-50 PERCENT CHANCE OF RAPID STRENGTHENING DURING THE NEXT 24 HR ACCORDING TO THE INDEX ATTACHED TO THE SHIPS MODEL. SECOND...ANY MOTION THAT DELAYS THE CYCLONE REACHING THE STRONGER SHEAR NORTH OF 15N WOULD ALLOW IT MORE TIME IN A FAVORABLE ENVIRONMENT. THUS...THE SYSTEM COULD GET CONSIDERABLY STRONGER THAN FORECAST HERE. FORECAST POSITIONS AND MAX WINDS INITIAL 14/0900Z 13.0N 104.6W 30 KT 12HR VT 14/1800Z 13.2N 105.0W 40 KT 24HR VT 15/0600Z 13.6N 105.5W 45 KT 36HR VT 15/1800Z 13.9N 105.8W 50 KT 48HR VT 16/0600Z 14.4N 106.1W 55 KT 72HR VT 17/0600Z 15.5N 106.5W 55 KT 96HR VT 18/0600Z 16.5N 107.0W 50 KT 120HR VT 19/0600Z 17.5N 108.0W 45 KT $$ FORECASTER BEVEN NNNN
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Page last modified: Tuesday, 14-Nov-2006 08:50:04 UTC