ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION ELEVEN-E DISCUSSION NUMBER 1 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP112009 800 AM PDT SAT AUG 22 2009 THE TROPICAL DISTURBANCE LOCATED ABOUT 1350 MILES EAST-SOUTHEAST OF THE HAWAIIAN ISLANDS HAS MAINTAINED A VIGOROUS CIRCULATION DURING THE LAST 24 HOURS...WITH PULSES OF DEEP CONVECTION COINCIDING WITH THE DIURNAL NOCTURNAL MAXIMUM. HOWEVER...MORE RECENTLY A DEEP CONVECTIVE CLUSTER HAS PERSISTED FOR SOME TIME OVER THE WESTERN SEMICIRCLE...EVEN PARTIALLY COVERING WHAT WAS EARLIER AN EXPOSED CIRCULATION CENTER. ADDITIONALLY...AN EXPANDING CIRRUS CANOPY IS EVIDENT IN SATELLITE IMAGERY...SUGGESTIVE OF A BETTER ESTABLISHED UPPER-LEVEL OUTFLOW. SINCE THE DEEP CONVECTION HAS BEEN PERSISTENT AND THERE HAS BEEN A FURTHER INCREASE IN ORGANIZATION...THIS SYSTEM CAN NOW BE CLASSIFIED AS A TROPICAL DEPRESSION. BASED UPON DVORAK T-NUMBERS FROM TAFB AND SAB OF 2.0 AND AND EARLIER QUIKSCAT PASS...THE INITIAL INTENSITY IS SET AT 30 KT. THE INITIAL MOTION ESTIMATE IS 275/09. GLOBAL MODELS SHOW THE DEPRESSION TO THE SOUTH OF A MID- TO UPPER-LEVEL SUBTROPICAL RIDGE OVER THE CENTRAL NORTH PACIFIC...WHICH SHOULD STEER THE CYCLONE ON A GENERAL WESTERLY COURSE FOR THE NEXT FEW DAYS. AROUND 72 HOURS AND BEYOND...A MID- TO UPPER-LEVEL CYCLONE NORTH OF HAWAII SHOULD LIFT NORTHEAST AHEAD OF A DEEP TROUGH FORECAST TO DIG OVER THE EASTERN PACIFIC. THESE TWO FEATURES SHOULD TEMPORARILY WEAKEN SUBTROPICAL RIDGING NORTH OF THE DEPRESSION...WHICH SHOULD CAUSE IT TO MOVE ON A SLOWER FORWARD SPEED TO THE WEST. THE OFFICIAL FORECAST FOLLOWS SUIT BY SHOWING A SLOWER-MOVING CYCLONE TOWARD THE END OF THE PERIOD. ON THE CURRENT TRACK...THE DEPRESSION SHOULD PASS 140W AND ENTER THE CENTRAL PACIFIC HURRICANE CENTER AREA OF RESPONSIBILITY IN APPROXIMATELY 24 HOURS. THE DEPRESSION REMAINS EMBEDDED IN A MODEST EASTERLY SHEAR ENVIRONMENT...AND LITTLE CHANGE IN THE SHEAR IS EXPECTED FOR THE NEXT SEVERAL DAYS. EVEN THOUGH SEA SURFACE TEMPERATURES REMAIN SUFFICIENTLY WARM ALONG THE FORECAST TRACK...THE SHEAR IS EXPECTED TO HAMPER DEVELOPMENT AND THE INTENSITY GUIDANCE SHOWS LITTLE TO NO INTENSIFICATION IN THE SHORT-TERM. BEYOND 72 HOURS...THERE IS SOME INDICATION THAT THE SHEAR COULD DECREASE...WHICH COULD LEAVE SOME OPPORTUNITY FOR STRENGTHENING. THE OFFICIAL INTENSITY FORECAST IS CONSERVATIVE AND INCREASES THE INTENSITY ON DAYS 4 AND 5...IN BEST AGREEMENT WITH THE INTENSITY MODEL CONSENSUS ICON AND LGEM. FORECAST POSITIONS AND MAX WINDS INITIAL 22/1500Z 13.6N 136.9W 30 KT 12HR VT 23/0000Z 13.7N 138.1W 30 KT 24HR VT 23/1200Z 14.1N 139.6W 35 KT 36HR VT 24/0000Z 14.6N 141.2W 35 KT 48HR VT 24/1200Z 15.0N 142.9W 40 KT 72HR VT 25/1200Z 15.5N 146.0W 45 KT 96HR VT 26/1200Z 15.5N 149.0W 50 KT 120HR VT 27/1200Z 15.5N 151.5W 60 KT $$ FORECASTER KIMBERLAIN/AVILA/READ NNNN
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Page last modified: Thursday, 31-Dec-2009 12:09:22 UTC