143 
 WTPZ45 KNHC 181449
 TCDEP5
 HURRICANE RICK DISCUSSION NUMBER  13
 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP202009
 800 AM PDT SUN OCT 18 2009
  
 SATELLITE IMAGERY SUGGESTS THAT RICK APPARENTLY PEAKED BETWEEN 0200
 AND 0400 UTC THIS MORNING. SINCE THAT TIME...THE WARM EYE
 TEMPERATURE HAS FLUCTUATED BETWEEN 10 AND 13 DEGREES
 CELSIUS WHILE THE CONVECTIVE TOPS HAVE WARMED SLIGHTLY...ESPECIALLY
 IN THE WESTERN SEMICIRCLE. A 1230 UTC SSMIS PASS SHOWED A WEAKENING
 OF THE SOUTHERN EYEWALL AND FRAGMENTS OF A DEVELOPING OUTER
 RING.  IF THE INNER EYEWALL WEAKENS FURTHER...RICK COULD WEAKEN MORE
 QUICKLY THAN INDICATED HERE. GIVEN THAT THE OBJECTIVE ADVANCED
 DVORAK INTENSITY 3-HOUR TREND SUGGESTS SLIGHT WEAKENING...THE
 INITIAL INTENSITY IS LOWERED TO 150 KT FOR THIS ADVISORY. 
  
 NO SIGNIFICANT CHANGES ARE MADE TO THE INTENSITY FORECAST...AS THE
 CYCLONE IS STILL EXPECTED TO MOVE INTO AN ENVIRONMENT OF INCREASING
 SHEAR IN ABOUT 48 HOURS. THE VERTICAL SHEAR SHOULD CONTINUE TO
 AFFECT THE SYSTEM THROUGH DAY 5 AS IT MOVES NORTHEASTWARD OVER THE
 BAJA PENINSULA AND INTO MAINLAND MEXICO. THE OFFICIAL FORECAST IS
 BASED ON THE ICON INTENSITY CONSENSUS THROUGH 48 HOURS...THEN
 HEDGES MORE TOWARD THE LGEM AND DECAY SHIPS GUIDANCE.
  
 THE INITIAL MOTION IS ESTIMATED TO BE 295/12...AS RICK IS EMBEDDED
 WITHIN AN EAST-SOUTHEASTERLY STEERING FLOW PRODUCED BY A MID- TO
 UPPER-LEVEL RIDGE EXTENDING FROM THE SOUTHWESTERN U.S. TO CENTRAL
 MEXICO. THE LARGE-SCALE MODELS CONTINUE TO INDICATE THAT THIS RIDGE
 WILL WEAKEN AND SHIFT EASTWARD IN RESPONSE TO A SHORTWAVE TROUGH
 MOVING INTO CALIFORNIA IN 36 TO 48 HOURS. THIS CHANGE IN THE
 SYNOPTIC STEERING PATTERN SHOULD CAUSE RICK TO TURN NORTHWARD. BY
 48 HOURS AND BEYOND RICK SHOULD TURN NORTHEASTWARD AS THE TROUGH
 DIGS SOUTH OVER NORTHWESTERN MEXICO. WITH THE EXCEPTION OF THE HWRF
 AND THE UKMET...ALL OF THE DYNAMICAL MODELS ARE BEGINNING TO
 INDICATE A SHARPER TURN TOWARD THE NORTHEAST. CONSEQUENTLY...THE
 OFFICIAL FORECAST TRACK IS NUDGED SLIGHTLY TO THE RIGHT AFTER 48
 HOURS BUT REMAINS ALONG THE LEFT EDGE OF THE MODEL GUIDANCE.
  
 ALTHOUGH A GRADUAL WEAKENING TREND IS FORECAST DURING THE NEXT FEW
 DAYS...RICK IS STILL EXPECTED TO BE A POWERFUL HURRICANE AS IT
 APPROACHES THE SOUTHWESTERN COAST OF BAJA CALIFORNIA.  INTERESTS IN
 THAT AREA AND ALONG THE COAST OF CENTRAL MEXICO SHOULD CLOSELY
 FOLLOW THE PROGRESS OF THIS EXTREMELY DANGEROUS HURRICANE OVER THE
 NEXT SEVERAL DAYS.
  
 FORECAST POSITIONS AND MAX WINDS
  
 INITIAL      18/1500Z 15.8N 108.3W   150 KT
  12HR VT     19/0000Z 16.5N 109.8W   150 KT
  24HR VT     19/1200Z 17.6N 111.1W   140 KT
  36HR VT     20/0000Z 18.6N 111.7W   125 KT
  48HR VT     20/1200Z 19.9N 111.6W   110 KT
  72HR VT     21/1200Z 23.0N 110.0W    85 KT...INLAND OVER BAJA
  96HR VT     22/1200Z 25.5N 107.5W    70 KT...INLAND
 120HR VT     23/1200Z...DISSIPATED
  
 $$
 FORECASTER ROBERTS/BRENNAN
  
 

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