Show Selection: |
#287373 (Received by flhurricane at: 10:49 AM 11.Aug.2009) TCDAT2 TROPICAL DEPRESSION TWO DISCUSSION NUMBER 2 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022009 1100 AM AST TUE AUG 11 2009 THE DEPRESSION IS A LITTLE THIN ON DEEP CONVECTION AT THE MOMENT...BUT IT STILL HAS A SMALL WELL-DEFINED LOW-LEVEL CIRCULATION. AN 1114 UTC ASCAT PASS INDICATED THAT MAXIMUM WINDS ARE 25 KT...LIMITED TO THE WESTERN SIDE OF THE CIRCULATION...AND THE INITIAL INTENSITY IS HELD AT THAT INTENSITY FOR THIS ADVISORY. IN GENERAL...THE NUMERICAL GUIDANCE IS NOT ALL THAT AGGRESSIVE IN SHOWING INTENSIFICATION OF THIS SYSTEM. SEA SURFACE TEMPERATURES ALONG THE FORECAST TRACK WILL BE MARGINALLY WARM...AND THE DEPRESSION WILL HAVE TO ENDURE SOME DRY AIR IN THE MID-LEVELS. NONETHELESS...VERTICAL SHEAR IS EXPECTED TO BE LIGHT ENOUGH DURING THE FIRST FOUR DAYS OR SO TO ALLOW SOME SLOW STRENGTHENING. THE SYSTEM COULD MOVE FAR ENOUGH NORTH BY DAY 5 THAT IT BEGINS TO FEEL THE EFFECTS OF UPPER-LEVEL WESTERLY WINDS...AND THE OFFICIAL FORECAST INDICATES SOME WEAKENING BY THEN. IT MUST BE STATED AGAIN THAT IF THE DEPRESSION TAKES A MORE SOUTHERN TRACK...IT WOULD STAY AWAY FROM THE INCREASING SHEAR AND COULD POSSIBLY BECOME STRONGER THAN INDICATED HERE. THE DEPRESSION IS MOVING AT 275/11. LITTLE CHANGE TO THIS MOTION IS EXPECTED OVER THE NEXT 3 DAYS DUE TO A MID-LEVEL SUBTROPICAL RIDGE FORECAST TO PERSIST NORTH OF THE DEPRESSION. BY DAYS 4 AND 5...A WEAKNESS IS EXPECTED TO DEVELOP IN THE RIDGE OVER THE CENTRAL ATLANTIC AND CAUSE THE SYSTEM TO TURN SLIGHTLY TO THE WEST- NORTHWEST. THE NEW OFFICIAL FORECAST IS SHIFTED A LITTLE TO THE SOUTH BUT STILL LIES NORTH AND EAST OF THE GFDL...HWRF...AND THE MODEL CONSENSUS TVCN. FORECAST POSITIONS AND MAX WINDS INITIAL 11/1500Z 14.6N 29.6W 25 KT 12HR VT 12/0000Z 14.7N 31.3W 30 KT 24HR VT 12/1200Z 14.8N 33.6W 35 KT 36HR VT 13/0000Z 14.9N 35.8W 35 KT 48HR VT 13/1200Z 15.1N 38.2W 40 KT 72HR VT 14/1200Z 16.0N 43.0W 45 KT 96HR VT 15/1200Z 17.5N 47.5W 50 KT 120HR VT 16/1200Z 20.0N 52.0W 45 KT $$ FORECASTER BERG |