407 
 WTPZ42 KNHC 241442
 TCDEP2
 TROPICAL STORM NORA DISCUSSION NUMBER   7
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP172009
 800 AM PDT THU SEP 24 2009
  
 NORA IS BEGINNING TO BE AFFECTED BY WESTERLY VERTICAL WIND SHEAR.
 RECENT TRMM DATA INDICATED THAT THE LOW-LEVEL CENTER WAS NEAR THE
 WESTERN EDGE OF THE CONVECTIVE MASS...WHICH HAS INCREASED OVER THE
 LAST FEW HOURS. IN ADDITION...ANALYSES FROM CIMSS AT THE UNIVERSITY
 OF WISCONSIN SHOW 10-15 KT OF WEST-SOUTHWESTERLY SHEAR.  USING A
 BLEND OF SATELLITE INTENSITY ESTIMATES...THE INITIAL INTENSITY IS
 HELD AT 45 KT. 
 
 NORA HAS LIKELY PEAKED IN INTENSITY...AS THE CYCLONE SHOULD
 ENCOUNTER INCREASING WESTERLY SHEAR DUE TO AN UPPER-LEVEL TROUGH TO
 ITS NORTHWEST.  STATISTICAL AND DYNAMICAL MODEL GUIDANCE IS IN
 AGREEMENT IN SHOWING STEADY WEAKENING DUE TO THE SHEAR AND COOLER
 WATERS ALONG THE FORECAST TRACK.  THE INTENSITY FORECAST HAS BEEN
 ADJUSTED DOWNWARD BASED ON THESE FACTORS...TO A TROPICAL DEPRESSION
 IN 36 HOURS AND TO A REMNANT LOW IN A FEW DAYS.
 
 MICROWAVE FIXES HAVE HELPED LOCATE THE CENTER...RESULTING IN A MORE
 CONFIDENT INITIAL MOTION OF 290/4. THE STRONG SHEAR WILL LIKELY
 DECOUPLE THE CIRCULATION...WITH THE LOW-LEVEL CENTER TURNING MORE
 TOWARD THE WEST OR WEST-SOUTHWEST OVER THE NEXT COUPLE OF DAYS AS
 SHOWN BY MOST OF THE DYNAMICAL MODELS.  THEREAFTER...THE REMNANTS
 OF NORA IS FORECAST TO TURN WEST-NORTHWEST WITH A REDUCTION IN
 FORWARD SPEED DUE TO A BREAK IN THE SUBTROPICAL RIDGE. THIS
 FORECAST IS SIMILAR TO BUT SLIGHTLY SOUTH OF THE PREVIOUS
 FORECAST...TRENDING TOWARD THE MODEL CONSENSUS.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      24/1500Z 17.3N 120.0W    45 KT
  12HR VT     25/0000Z 17.4N 120.9W    40 KT
  24HR VT     25/1200Z 17.2N 122.4W    35 KT
  36HR VT     26/0000Z 17.1N 123.6W    30 KT
  48HR VT     26/1200Z 17.2N 125.1W    25 KT
  72HR VT     27/1200Z 18.0N 128.0W    20 KT...REMNANT LOW
  96HR VT     28/1200Z 18.5N 130.5W    20 KT...REMNANT LOW
 120HR VT     29/1200Z 19.0N 132.5W    20 KT...REMNANT LOW
  
 $$
 FORECASTER CANGIALOSI/BEVEN