999 
 WTPZ43 KNHC 031444
 TCDEP3
  
 TROPICAL STORM SONIA DISCUSSION NUMBER  10
 NWS NATIONAL HURRICANE CENTER MIAMI FL       EP182013
 700 AM PST SUN NOV 03 2013
 
 THE AREA OF DEEP CONVECTION THAT DEVELOPED OVERNIGHT IN ASSOCIATION
 WITH SONIA HAS EXPANDED THIS MORNING.  EARLY MORNING VISIBLE
 SATELLITE IMAGES SUGGEST THAT THE CENTER IS LOCATED JUST BENEATH 
 THE SOUTHEAST PORTION OF THE LARGE CONVECTIVE MASS.  BASED ON THE
 SLIGHTLY IMPROVED ORGANIZATION AND DVORAK T-NUMBERS OF 2.5 AND 3.0
 FROM SAB AND TAFB...RESPECTIVELY...THE INITIAL WIND SPEED IS
 INCREASED TO 40 KT.  THE RECENT STRENGTHENING APPEARS TO BE THE
 RESULT OF DECREASING SHEAR AS SONIA MOVED BENEATH AN UPPER-LEVEL
 RIDGE AXIS OVERNIGHT.  THIS RELAXATION IN SHEAR IS EXPECTED TO BE
 SHORT-LIVED AS SOUTHWESTERLY UPPER-LEVEL WINDS AHEAD OF A MID- TO
 UPPER-LEVEL TROUGH WILL CAUSE A SUBSTANTIAL INCREASE IN SHEAR
 TONIGHT....AND NO SIGNIFICANT ADDITIONAL STRENGTHENING IS EXPECTED.   
 SOME WEAKENING IS POSSIBLE AROUND THE TIME SONIA REACHES THE COAST
 AS THE SHEAR IS EXPECTED TO CAUSE THE LOW- AND MID-LEVEL CENTERS TO
 DECOUPLE.  SONIA IS FORECAST TO DISSIPATE SHORTLY AFTER LANDFALL
 OVER THE MOUNTAINS OF WESTERN MEXICO. 
 
 THE INITIAL MOTION IS STILL NORTHWARD OR 005 DEGREES AT 7 KT.  SONIA
 SHOULD TURN NORTH-NORTHEASTWARD VERY SOON AS DEEP LAYER
 SOUTHWESTERLY FLOW STRENGTHENS AHEAD OF A MID-LATITUDE TROUGH MOVING
 INTO THE SOUTHWESTERN UNITED STATES AND NORTHERN MEXICO.  SONIA
 SHOULD BEGIN TO ACCELERATE LATER TODAY AND MAKE LANDFALL ALONG THE
 COAST OF MAINLAND MEXICO MONDAY MORNING.  THE TRACK GUIDANCE IS IN
 GOOD AGREEMENT ON THIS SCENARIO AND NO SIGNIFICANT CHANGES WERE 
 REQUIRED FROM THE PREVIOUS NHC ADVISORY. 
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  03/1500Z 19.9N 109.8W   40 KT  45 MPH
  12H  04/0000Z 21.6N 109.1W   40 KT  45 MPH
  24H  04/1200Z 23.7N 107.6W   35 KT  40 MPH
  36H  05/0000Z 25.9N 106.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
  48H  05/1200Z...DISSIPATED
  
 $$
 FORECASTER BROWN