950 
 WTPZ42 KNHC 182040
 TCDEP2
 TROPICAL DEPRESSION TWELVE-E DISCUSSION NUMBER   2
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP122007
 200 PM PDT TUE SEP 18 2007
  
 SATELLITE IMAGERY INDICATES THAT TROPICAL DEPRESSION TWELVE-E IS
 GETTING BETTER ORGANIZED...WITH A BAND OF CURVED CONVECTION FORMING
 NEAR THE CENTER.  SATELLITE INTENSITY ESTIMATES ARE 30 KT FROM TAFB
 AND SAB...SO THAT IS THE INITIAL INTENSITY FOR THIS ADVISORY. 
 HOWEVER...THE ORGANIZATION HAS IMPROVED SINCE THE ESTIMATES WERE
 MADE...AND THERE IS A CHANCE THIS INTENSITY IS A LITTLE
 CONSERVATIVE.  WHILE THE SYSTEM REMAINS UNDER LIGHT NORTHWESTERLY
 VERTICAL SHEAR...THE CIRRUS OUTFLOW IS IMPROVING EVEN IN THE
 NORTHWEST QUADRANT.
 
 THE INITIAL MOTION IS 295/10.  THE DEPRESSION REMAINS ON THE SOUTH
 SIDE OF OF A MID-LEVEL RIDGE EXTENDING WESTWARD FROM NORTHERN
 MEXICO.  THE DYNAMICAL MODELS FORECAST THIS RIDGE TO BREAK DURING
 THE NEXT THREE DAYS AS A LARGE DEEP-LAYER LOW MOVES SOUTHWARD OVER
 CALIFORNIA.  THIS SHOULD ALLOW THE DEPRESSION TO TURN NORTHWARD AND
 THEN NORTHEASTWARD BY THE END OF THE FORECAST PERIOD.  HOWEVER...
 THE LOW DOES NOT MOVE FAR ENOUGH SOUTH FOR ACCELERATION AFTER
 RECURVATURE...WITH THE GFDL SHOWING LITTLE MOTION AND THE HWRF
 MODEL SHOWING A SLOW EASTWARD MOTION.  THE FORECAST TRACK AGAIN
 CALLS FOR RECURVATURE AND DECELERATION DURING THE FORECAST PERIOD.
 IT IS SIMILAR TO THE PREVIOUS FORECAST FOR THE FIRST 72 HR AND THEN
 SHIFTED A LITTLE TO THE NORTHWEST THEREAFTER.
  
 THE LARGE-SCALE MODELS FORECAST THE CURRENT LIGHT SHEAR TO CONTINUE
 FOR 48-72 HR...FOLLOWED BY A SIGNIFICANT INCREASE IN THE SHEAR. 
 THIS...COMBINED WITH DRY AIR SEEN IN WATER VAPOR IMAGERY NORTHWEST
 OF THE CYCLONE AND MOTION OVER COOLER WATER AT ABOUT 72 HR...
 SUGGESTS GRADUAL STRENGTHENING THROUGH 72 HR FOLLOWED BY WEAKENING. 
 NONE OF THE GUIDANCE CURRENTLY FORECASTS THE DEPRESSION TO BECOME A
 HURRICANE...SO THE INTENSITY FORECAST WILL FOLLOW THAT IN CALLING
 FOR A PEAK INTENSITY OF 55 KT.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      18/2100Z 13.8N 108.4W    30 KT
  12HR VT     19/0600Z 14.5N 110.1W    35 KT
  24HR VT     19/1800Z 15.4N 112.2W    40 KT
  36HR VT     20/0600Z 16.2N 113.7W    45 KT
  48HR VT     20/1800Z 17.1N 114.6W    50 KT
  72HR VT     21/1800Z 19.0N 115.0W    55 KT
  96HR VT     22/1800Z 20.5N 114.5W    45 KT
 120HR VT     23/1800Z 21.5N 113.5W    30 KT
  
 $$
 FORECASTER BEVEN