770 
 WTPZ45 KNHC 060232
 TCDEP5
 TROPICAL STORM NORBERT DISCUSSION NUMBER   9
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP152008
 800 PM PDT SUN OCT 05 2008
  
 DEEP CONVECTION HAS BEEN WAXING AND WANING AROUND THE LOW-LEVEL
 CIRCULATION CENTER THIS AFTERNOON AND EVENING...BUT THE OVERALL
 TREND HAS BEEN FOR IMPROVED ORGANIZATION. DVORAK SATELLITE
 INTENSITY ESTIMATES ARE T3.0/45 KT FROM BOTH TAFB AND SAB.
 HOWEVER...3-HR AVERAGE ODT/ADT ESTIMATES HAVE BEEN T3.8 TO T3.9. 
 ALSO...THERE WAS A 05/2317Z AMSU INTENSITY ESTIMATE OF 55 KT.
 THEREFORE...THE INITIAL INTENSITY HAS BEEN INCREASED TO 55 KT.
 
 THE INITIAL MOTION ESTIMATE IS 270/07. THE INITIAL POSITION WAS
 ADJUSTED SLIGHTLY TO THE SOUTH OR LEFT OF THE PREVIOUS TRACK BASED
 ON A 05/2022Z AMSR OVERPASS...WHICH REVEALED A TIGHT LOW-LEVEL
 CIRCULATION CENTER IN THE 37 GHZ CHANNEL ALONG 14N LATITUDE. OTHER
 THAN THE SLIGHT SOUTHWARD RELOCATION...THERE IS NO SIGNIFICANT
 CHANGE TO THE PREVIOUS FORECAST TRACK OR PHILOSOPHY. FOR THE NEXT
 96 HOURS...NORBERT IS EXPECTED TO GRADUALLY MOVE WEST-NORTHWESTWARD
 AND THEN TURN NORTHWESTWARD AROUND THE WESTERN PERIPHERY OF A
 SUBTROPICAL RIDGE SITUATED TO THE NORTH OF THE CYCLONE. AFTER
 THAT...A MID-LEVEL SHORTWAVE TROUGH IS FORECAST TO DROP SOUTHWARD
 ALONG THE U.S. WEST COAST AND INTO THE U.S. DESERT SOUTHWEST BY 120
 HOURS...WHICH SHOULD WEAKEN THE RIDGE AND ALLOW NORBERT TO TURN
 MORE TOWARD THE NORTH. THE OFFICIAL FORECAST TRACK IS SIMILAR TO
 THE PREVIOUS ADVISORY AND IS ALSO SIMILAR TO BUT FASTER THAN THE
 NHC MODEL CONSENSUS...TVCN.
  
 THE MODERATE EASTERLY SHEAR THAT HAS BEEN PLAGUING NORBERT FOR MANY
 DAYS NOW IS EXPECTED TO DECREASE SLIGHTLY AND SHIFT AROUND FROM THE
 SOUTHEAST OVER THE NEXT 72 HOURS. ALTHOUGH THE CYCLONE IS FORECAST
 TO REMAIN OVER 28C AND WARMER SSTS DURING THIS TIME...THE MID-LEVEL
 ENVIRONMENT IS FORECAST TO GRADUALLY BECOME LESS MOIST. THE RESULT
 IS THAT ONLY SLOW STRENGTHENING INTO A CATEGORY 1 OR 2 HURRICANE IS
 EXPECTED. THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE
 PREVIOUS ADVISORY AND THE SHIPS INTENSITY MODEL...BUT IS MUCH LOWER
 THAN THE HOT-TO-TROT HWRF MODEL...WHICH MAKES NORBERT A 119-KT
 CATEGORY 4 HURRICANE IN 2-3 DAYS. IN CONTRAST...THE USUALLY ROBUST
 GFDL MODEL BARELY BRINGS THE CYCLONE UP TO 70 KT IN 48 HOURS.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      06/0300Z 14.1N 103.7W    55 KT
  12HR VT     06/1200Z 14.3N 104.6W    60 KT
  24HR VT     07/0000Z 14.7N 105.7W    65 KT
  36HR VT     07/1200Z 15.1N 107.0W    70 KT
  48HR VT     08/0000Z 15.7N 108.3W    75 KT
  72HR VT     09/0000Z 17.3N 110.5W    80 KT
  96HR VT     10/0000Z 19.5N 112.5W    75 KT
 120HR VT     11/0000Z 23.0N 113.5W    65 KT
  
 $$
 FORECASTER STEWART