000 WTPZ45 KNHC 062053 TCDEP5 TROPICAL STORM NORBERT DISCUSSION NUMBER 12 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP152008 200 PM PDT MON OCT 06 2008 SATELLITE IMAGERY SUGGEST THAT NORBERT CONTINUES TO GRADUALLY BECOME BETTER ORGANIZED...AND BOTH OBJECTIVE AND SUBJECTIVE DVORAK INTENSITY ESTIMATES HAVE INCREASED SINCE THIS MORNING. THE OFFICIAL FORECAST IS INCREASED TO 60 KT AND NORBERT IS NEARING HURRICANE STRENGTH. THE INTENSITY FORECAST AND THE ASSOCIATED REASONING ARE UNCHANGED FROM THE EARLIER PACKAGE. NORBERT IS EXPECTED TO BE WITHIN A FAVORABLE ENVIRONMENT FOR STRENGTHENING AND ALL OF THE AVAILABLE GUIDANCE CALLS FOR THE CYCLONE TO REACH AT LEAST CATEGORY ONE INTENSITY IN A COUPLE OF DAYS. THE HWRF REMAINS SOMEWHAT OF AN OUTLIER...ALBEIT A LITTLE WEAKER THAN BEFORE...AND SHOWS NORBERT BECOMING A MAJOR HURRICANE. THE REMAINING INTENSITY MODELS ARE LOWER...AND A CONSENSUS OF THESE MODELS IS THE BASIS FOR THE OFFICIAL FORECAST. BY DAYS 4 AND 5...NORBERT IS FORECAST TO BE APPROACHING COOLER WATERS AND A MORE STABLE AIR MASS. THEREFORE...SOME WEAKENING IS SHOWN BEYOND 72 HOURS. HOWEVER...MUCH UNCERTAINTY REMAINS IN THE TRACK FORECAST...ESPECIALLY IN TERMS OF FORWARD SPEED...AT THESE EXTENDED RANGES AND NORBERT COULD REACH LESS FAVORABLE CONDITIONS SOONER OR LATER THAN SHOWN HERE. NORBERT CONTINUES ON A GENERAL WESTWARD TO WEST-NORTHWESTWARD HEADING OR 290/7. THIS GENERAL MOTION IS EXPECTED TO CONTINUE FOR THE NEXT 2 DAYS AS A MID-LEVEL RIDGE REMAINS TO THE NORTH. THEREAFTER...A LARGE TROUGH IS FORECAST TO DIG SOUTHWARD ALONG THE WEST COAST OF THE UNITED STATES WHICH SHOULD RESULT IN A NORTHWARD TURN IN 3-4 DAYS. THERE ARE STILL SOME DIFFERENCES AMONG THE VARIOUS TRACK MODELS BEYOND 72 HOURS AND THE MODELS HAVE NOT DEMONSTRATED GOOD RUN-TO-RUN CONSISTENCY. THE GFS REMAINS THE SOUTHERN OUTLIER AND NEVER GETS NORBERT FAR ENOUGH NORTH TO RESPOND TO THE TROUGH. CONVERSELY...THE UKMET AND NOGAPS SHOW NORBERT ACCELERATING NORTH-NORTHEASTWARD AHEAD OF THE TROUGH. THE OFFICIAL FORECAST IS AGAIN SHIFTED A LITTLE SOUTH EARLY IN THE FORECAST PERIOD AND WEST LATE IN THE FORECAST PERIOD. FORECAST POSITIONS AND MAX WINDS INITIAL 06/2100Z 14.5N 105.3W 60 KT 12HR VT 07/0600Z 14.7N 106.3W 65 KT 24HR VT 07/1800Z 15.1N 107.7W 70 KT 36HR VT 08/0600Z 15.7N 109.0W 75 KT 48HR VT 08/1800Z 16.5N 110.4W 80 KT 72HR VT 09/1800Z 18.5N 112.5W 80 KT 96HR VT 10/1800Z 21.0N 113.5W 75 KT 120HR VT 11/1800Z 24.0N 112.5W 60 KT $$ FORECASTER RHOME