000 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