000 WTPZ45 KNHC 050858 TCDEP5 TROPICAL STORM NORBERT DISCUSSION NUMBER 6 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP152008 200 AM PDT SUN OCT 05 2008 THE OVERALL CLOUD PATTERN ASSOCIATED WITH NORBERT HAS GRADUALLY IMPROVED DURING THE PAST FEW HOURS. SATELLITE IMAGERY SHOWS THAT CONVECTIVE BANDS HAVE DEVELOPED OVER THE SOUTH AND SOUTHEASTERN PORTION OF THE STORM. DVORAK INTENSITY ESTIMATES FROM TAFB AND SAB HAVE INCREASED TO 45 AND 35 KT...RESPECTIVELY. THEREFORE...THE INITIAL INTENSITY IS RAISED TO 40 KT. THE CENTER POSITION HAS BEEN ADJUSTED SLIGHTLY SOUTH OF THE EARLIER ESTIMATES BASED ON RECENT MICROWAVE IMAGERY. THE INITIAL MOTION ESTIMATE IS 270/6. NORBERT IS EXPECTED TO MOVE SLOWLY WEST TO WEST-NORTHWESTWARD DURING THE NEXT SEVERAL DAYS...TO THE SOUTH OF A NARROW MID-LEVEL RIDGE. LATE IN THE FORECAST PERIOD AS A TROUGH BEGINS TO DIG SOUTHWARD ALONG THE WEST COAST OF THE UNITED STATES...THE RIDGE IS FORECAST TO GRADUALLY WEAKEN. THIS SHOULD ALLOW NORBERT TO TURN MORE TOWARD THE NORTHWEST. IN GENERAL...THE FORECAST GUIDANCE AGREES WITH THIS SCENARIO...BUT AT VARYING SPEEDS. THE HWRF AND UKMET ARE FASTER AND MOVE NORBERT IN THE VICINITY OF THE SOUTHERN BAJA PENINSULA IN 4-5 DAYS...WHILE THE GFDL...ECMWF...AND NOGAPS ARE SOMEWHAT SLOWER. THE GFS CONTINUES TO BE MUCH SLOWER ON ITS WESTWARD PROGRESSION OF THE STORM AS IT PREDICTS SOME INTERACTION BETWEEN NORBERT AND THE DISTURBANCE TO THE EAST. THE OFFICIAL FORECAST LEANS TOWARD THE 00Z ECMWF AND NOGAPS SOLUTIONS...BUT REMAINS A LITTLE SLOWER THAN THE MODEL CONSENSUS. SHEAR IS FORECAST TO BECOME LIGHT AS NORBERT REMAINS OVER SSTS GREATER THAN 28C FOR THE NEXT SEVERAL DAYS. THEREFORE... STRENGTHENING IS EXPECTED AND THE OFFICIAL FORECAST FOLLOWS THE GUIDANCE WHICH UNANIMOUSLY CALL FOR NORBERT TO REACH HURRICANE STATUS IN ABOUT 36-48 HOURS. THE NEW FORECAST IS CLOSEST TO THE SHIPS AND LGEM GUIDANCE AND IS A LITTLE BELOW THE GFDL AND MUCH MORE AGGRESSIVE HWRF MODEL. IT SHOULD BE NOTED...THAT THERE IS SOME POTENTIAL FOR RAPID INTENSIFICATION DURING THE NEXT DAY OR SO AS THE SHIPS RI INDEX INDICATES THAT THE CHANCE OF A 30 KT OR GREATER INCREASE IN INTENSITY IS ABOUT 3 TIMES THE SAMPLE MEAN. FORECAST POSITIONS AND MAX WINDS INITIAL 05/0900Z 14.2N 101.4W 40 KT 12HR VT 05/1800Z 14.3N 102.3W 50 KT 24HR VT 06/0600Z 14.6N 103.5W 60 KT 36HR VT 06/1800Z 15.0N 104.7W 65 KT 48HR VT 07/0600Z 15.4N 105.8W 70 KT 72HR VT 08/0600Z 16.2N 108.0W 75 KT 96HR VT 09/0600Z 17.5N 110.2W 75 KT 120HR VT 10/0600Z 19.5N 112.0W 75 KT $$ FORECASTER BROWN