000 WTPZ45 KNHC 052041 TCDEP5 TROPICAL STORM NORBERT DISCUSSION NUMBER 8 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP152008 200 PM PDT SUN OCT 05 2008 AN EARLIER QUIKSCAT PASS AT 1252 UTC CONFIRMED THAT NORBERT'S INTENSITY WAS NEAR 50 KT AT THAT TIME. THE INITIAL INTENSITY IS HELD AT THAT VALUE SINCE THE CLOUD PATTERN HAS NOT CHANGED SIGNIFICANTLY DURING THE LAST SEVERAL HOURS AND DVORAK INTENSITY ESTIMATES REMAIN 45 KT FROM BOTH SAB AND TAFB. NORBERT IS FORECAST TO BE OVER WARM WATERS AND WITHIN A RELATIVELY LOW VERTICAL SHEAR ENVIRONMENT FOR THE NEXT COUPLE OF DAYS...AND SUCH AN ENVIRONMENT SHOULD ALLOW INTENSIFICATION. HOWEVER...THERE CONTINUES TO BE CONSIDERABLE SPREAD AMONG THE VARIOUS INTENSITY MODELS WITH THE GFDL AND HWRF FORECASTING NORBERT TO BECOME A MAJOR HURRICANE WHILE THE SHIPS AND LGEM MODELS SHOW CONSIDERABLY LESS STRENGTHENING. THE OFFICIAL FORECAST IS A LITTLE HIGHER THAN BEFORE BUT IS STILL SLIGHTLY BELOW THE INTENSITY MODEL CONSENSUS. VISIBLE SATELLITE IMAGERY SUGGEST THAT THE LOW-LEVEL CENTER IS A LITTLE FARTHER SOUTH THAN PREVIOUSLY ESTIMATED YIELDING AN INITIAL MOTION ESTIMATE OF 275/8. THE SHORT-TERM TRACK WILL BE GOVERNED BY A NARROW MID-LEVEL RIDGE WHICH EXTENDS WESTWARD FROM MEXICO TO THE NORTH OF NORBERT. SINCE MOST OF THE DYNAMICAL MODELS NOW FORECAST THIS RIDGE TO REMAIN LARGELY IN PLACE...A CONTINUED WEST- NORTHWESTWARD HEADING IS EXPECTED FOR THE NEXT 2-3 DAYS. BY DAYS 4 AND 5...GLOBAL MODELS SHOW LARGE DIFFERENCES IN THE EVOLUTION OF THE SYNOPTIC PATTERN RESULTING IN CONSIDERABLE SPREAD IN THE TRACK GUIDANCE...ESPECIALLY IN TERMS OF FORWARD SPEED. SINCE THE GUIDANCE HAS NOT DEMONSTRATED GOOD RUN-TO-RUN CONSISTENCY...ONLY SMALL CHANGES ARE MADE TO THE PREVIOUS OFFICIAL FORECAST AT THE EXTENDED TIME RANGES. FORECAST POSITIONS AND MAX WINDS INITIAL 05/2100Z 14.4N 103.1W 50 KT 12HR VT 06/0600Z 14.6N 104.1W 60 KT 24HR VT 06/1800Z 14.9N 105.3W 65 KT 36HR VT 07/0600Z 15.3N 106.4W 70 KT 48HR VT 07/1800Z 15.9N 107.8W 80 KT 72HR VT 08/1800Z 17.5N 110.0W 80 KT 96HR VT 09/1800Z 19.5N 112.0W 70 KT 120HR VT 10/1800Z 22.5N 114.0W 60 KT $$ FORECASTER RHOME