000 WTPZ45 KNHC 081432 TCDEP5 HURRICANE NORBERT DISCUSSION NUMBER 19 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP152008 800 AM PDT WED OCT 08 2008 NORBERT UNDERWENT RAPID INTENSIFICATION OVERNIGHT...AND THE CYCLONE NOW HAS AN IMPRESSIVE SATELLITE PRESENTATION CONSISTING OF A WELL-DEFINED EYE SURROUNDED BY A RING OF VERY DEEP CONVECTION. THE INITIAL INTENSITY IS INCREASED TO 110 KT BASED ON A COMPROMISE BETWEEN THE SUBJECTIVE DVORAK ESTIMATES OF 102 KT AND OBJECTIVE DVORAK ESTIMATES NEAR 125 KT. WITH THE LARGE-SCALE ENVIRONMENT EXPECTED TO REMAIN FAVORABLE FOR ANOTHER DAY OR SO...INTENSITY WILL BE LARGELY CONTROLLED BY THE INNER-CORE STRUCTURAL EVOLUTION IN THE SHORT-TERM. FORECASTING SUCH INNER-CORE CHANGES IS DIFFICULT BUT GUIDANCE SUGGEST THAT NORBERT COULD GET A LITTLE STRONGER...PERHAPS REACHING CATEGORY 4 STRENGTH. IN ABOUT 36-48 HOURS...VERTICAL SHEAR IS FORECAST TO INCREASE AND SSTS GRADUALLY DECREASE ALONG THE FORECAST TRACK. ADDITIONALLY...NORBERT COULD BE NEGATIVELY IMPACTED BY RELATIVELY STABLE AIR TO ITS NORTHWEST. STILL...NORBERT COULD APPROACH BAJA CALIFORNIA AS A HURRICANE...AND INTERESTS OVER THE CENTRAL AND SOUTHERN PORTIONS OF THE PENINSULA SHOULD MONITOR THE PROGRESS OF THIS SYSTEM. NORBERT CONTINUES TO MOVE AROUND A STRONG RIDGE OVER THE SOUTHWESTERN UNITED STATES RESULTING IN A WEST-NORTHWEST HEADING... OR 290 DEGREES AT 8 KNOTS. A GRADUAL TURN TOWARD THE NORTHWEST IS EXPECTED DURING THE NEXT TWO DAYS AS THE CYCLONE REACHES THE WESTERN PERIPHERY OF THE RIDGE. THEREAFTER...A TURN TOWARD THE NORTH AND NORTHEAST WITH AN INCREASE IN FORWARD SPEED IS EXPECTED AS A LARGE MID-LATITUDE TROUGH DEVELOPS OVER THE WESTERN UNITED STATES AND ADJACENT PACIFIC. WHILE ALL OF THE DYNAMICAL MODELS FORECAST THIS TROUGH TO DEVELOP...THEY DISAGREE SOMEWHAT ON NORBERT'S STRENGTH...AND HENCE ITS VERTICAL DEPTH...WHEN IT REACHES THE TROUGH. MOST OF THE TRACK MODEL SHOW A DEEP CYCLONE RESPONDING TO THE TROUGH BY ACCELERATING NORTHEASTWARD IN ABOUT 3 DAYS. HOWEVER...THE GFS AND THE ECMWF MODELS STILL SHOW NORBERT RAPIDLY BECOMING A SHALLOW SYSTEM AS IT NEARS THE BAJA PENINSULA RESULTING IN A REDUCTION IN FORWARD SPEED OR EVEN STALLING IN THE VICINITY OF BAJA CALIFORNIA. SINCE THESE HIGHLY-RESPECTED MODELS CANNOT BE IGNORED...THE OFFICIAL FORECAST IS A LITTLE SLOWER THAN THE DYNAMICAL MODEL CONSENSUS AT DAY 4. FORECAST POSITIONS AND MAX WINDS INITIAL 08/1500Z 16.3N 110.6W 110 KT 12HR VT 09/0000Z 16.8N 111.5W 115 KT 24HR VT 09/1200Z 17.7N 112.6W 115 KT 36HR VT 10/0000Z 19.0N 113.3W 110 KT 48HR VT 10/1200Z 20.6N 113.3W 100 KT 72HR VT 11/1200Z 24.5N 111.5W 85 KT...INLAND 96HR VT 12/1200Z 30.0N 107.5W 35 KT...INLAND 120HR VT 13/1200Z...DISSIPATED $$ FORECASTER RHOME