344 
 WTNT42 KNHC 312039
 TCDAT2
  
 TROPICAL STORM KATIA DISCUSSION NUMBER  11
 NWS NATIONAL HURRICANE CENTER MIAMI FL       AL122011
 500 PM AST WED AUG 31 2011
 
 KATIA IS NEAR THE THRESHOLD OF HURRICANE STATUS.  THE SYSTEM
 CONTINUES TO EXHIBIT PROMINENT CURVED CONVECTIVE BANDS AND DEEP
 CONVECTION IS BECOMING STRONGER OVER THE CENTER.  THE STORM ALSO
 HAS A FAIRLY SYMMETRIC AND WELL-ESTABLISHED UPPER-LEVEL OUTFLOW
 PATTERN.  DVORAK INTENSITY ESTIMATES FROM BOTH AGENCIES REMAIN AT
 55 KT...BUT AMSU INTENSITY ESTIMATES FROM THE UNIVERSITY OF
 WISCONSIN CIMSS ARE A LITTLE HIGHER.  THE INTENSITY IS SET AT 60 KT
 FOR THIS ADVISORY.  WEAK VERTICAL SHEAR AND MODESTLY WARM WATERS
 ARE LIKELY TO PREVAIL OVER THE NEXT FEW DAYS...SO CONTINUED
 INTENSIFICATION IS FORECAST.  A LARGE UPPER-LEVEL LOW TO THE
 NORTHWEST OF KATIA COULD CAUSE AN INCREASE IN SHEAR...AND INHIBIT
 INTENSIFICATION...LATE IN THE FORECAST PERIOD.  HOWEVER SOME OF THE
 GLOBAL MODELS...SUCH AS THE GFS...SUGGEST THAT THE OUTFLOW
 ANTICYCLONE OF KATIA WILL DOMINATE THE UPPER-LEVEL WIND PATTERN AND
 DISPLACE THE SHEARING FLOW ASSOCIATED WITH THE LOW.  IF THAT
 OCCURS...KATIA WOULD LIKELY BECOME A MAJOR HURRICANE BY DAY 4 OR 5. 
 THE OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ONE AND
 SLIGHTLY HIGHER THAN THE STATISTICAL-DYNAMICAL GUIDANCE.
 
 THE STORM CONTINUES TO MOVE WEST-NORTHWESTWARD ON THE SOUTH SIDE OF
 A SUBTROPICAL ANTICYCLONE.  THE TRACK FORECAST AND REASONING ARE
 ESSENTIALLY UNCHANGED.  AS KATIA NEARS THE SOUTHWEST SIDE OF THE
 ANTICYCLONE...A GRADUAL TURN TOWARD THE NORTHWEST WITH DECREASING
 FORWARD SPEED IS LIKELY.  THE CURRENT OFFICIAL TRACK FORECAST IS AN
 UPDATE OF THE PREVIOUS ONE AND ABOUT IN THE MIDDLE OF THE GUIDANCE
 ENVELOPE.  IT IS ALSO A LITTLE TO THE WEST OF THE GFS AND ECMWF
 SOLUTIONS.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INIT  31/2100Z 14.6N  42.6W   60 KT  70 MPH
  12H  01/0600Z 15.1N  44.9W   65 KT  75 MPH
  24H  01/1800Z 15.8N  47.7W   75 KT  85 MPH
  36H  02/0600Z 16.6N  50.0W   85 KT 100 MPH
  48H  02/1800Z 17.7N  52.0W   90 KT 105 MPH
  72H  03/1800Z 20.0N  55.5W   95 KT 110 MPH
  96H  04/1800Z 22.0N  58.5W  100 KT 115 MPH
 120H  05/1800Z 23.5N  61.0W  105 KT 120 MPH
  
 $$
 FORECASTER PASCH