000 WTPZ43 KNHC 310849 TCDEP3 HURRICANE JIMENA DISCUSSION NUMBER 11 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP132009 200 AM PDT MON AUG 31 2009 THE SMALL EYE OF JIMENA HAS BECOME A LITTLE LESS DISTINCT IN INFRARED SATELLITE IMAGERY. AN EARLIER SSMIS MICROWAVE OVERPASS ALSO SHOWED A SOMEWHAT LESS DEFINED EYE...BUT WITH A WELL-DEFINED OUTER BAND. THIS MAY BE A SIGN THAT AN EYE-WALL REPLACEMENT HAS STARTED...HOWEVER THERE HAVE BEEN NO RECENT MICROWAVE IMAGES TO CORROBORATE THIS. DUE TO THE RECENT SATELLITE TRENDS...DVORAK DATA-T NUMBER HAVE DECREASED SLIGHTLY...BUT A BLEND OF THE OBJECTIVE AND SUBJECTIVE CURRENT INTENSITY ESTIMATES SUGGESTS MAINTAINING AN INITIAL INTENSITY OF 125 KT. JIMENA IS MOVING NORTHWESTWARD OR 310/7 KT. A MID-LEVEL RIDGE OVER MEXICO AND AN UPPER-LEVEL LOW NEAR THE WEST COAST OF THE CENTRAL BAJA PENINSULA ARE THE FEATURES THAT WILL PLAY A ROLE IN STEERING THE HURRICANE. THE 0000 UTC MODELS HAVE COME INTO BETTER AGREEMENT ON THE FUTURE TRACK OF JIMENA. NEARLY ALL OF THE MODELS KEEP THE UPPER-LOW INTACT LONG ENOUGH TO TURN THE HURRICANE NORTH-NORTHWESTWARD. THE OUTLIER TO THIS SOLUTION IS THE UKMET WHICH CONTINUES TO SHOW A WEST-NORTHWESTWARD MOTION. THE CANADIAN AND ECMWF MODELS HAVE SHIFTED EASTWARD AND ARE NOW IN MUCH BETTER AGREEMENT WITH THE REMAINDER OF THE GUIDANCE IN PREDICTING A TRACK NEAR OR OVER THE BAJA PENINSULA IN A COUPLE OF DAYS. THE NEW NHC TRACK FORECAST IS ESSENTIALLY AN UPDATE TO THE PREVIOUS ADVISORY... AND IS NEAR THE MULTI-MODEL CONSENSUS. THE HURRICANE IS EXPECTED TO REMAIN OVER VERY WARM WATER AND IN A LOW SHEAR ENVIRONMENT DURING THE NEXT 24 HOURS. THE OFFICIAL FORECAST SHOWS LITTLE CHANGE IN STRENGTH DURING THAT TIME...HOWEVER FLUCTUATIONS COULD OCCUR AS THE RESULT OF AN EYEWALL REPLACEMENT. IN ABOUT 48 HOURS...WESTERLY SHEAR IS FORECAST TO INCREASE. THAT COMBINED WITH POSSIBLE LAND INTERACTION SHOULD BEGIN TO WEAKEN THE HURRICANE. THE OFFICIAL INTENSITY FORECAST IS A BLEND OF THE AVAILABLE GUIDANCE AND INDICATES THAT JIMENA COULD REMAIN A VERY DANGEROUS HURRICANE AS IT MOVES NEAR THE SOUTHERN BAJA PENINSULA. BASED ON THE CURRENT FORECAST...A HURRICANE WARNING MAY BE REQUIRED LATER THIS MORNING FOR A PORTION OF THE SOUTHERN BAJA PENINSULA. INTERESTS ELSEWHERE IN CENTRAL AND SOUTHERN BAJA CALIFORNIA AND THE WESTERN PORTION OF MAINLAND MEXICO SHOULD CONTINUE TO MONITOR THE PROGRESS OF JIMENA. ADDITIONAL WATCHES OR WARNINGS MAY BE REQUIRED FOR PORTIONS OF THESE AREAS LATER TODAY. A U.S. AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO INVESTIGATE JIMENA AROUND 1800 UTC TODAY. DATA FROM THE AIRCRAFT SHOULD PROVIDE A BETTER ASSESSMENT OF THE INTENSITY AND SIZE OF THE HURRICANE. FORECAST POSITIONS AND MAX WINDS INITIAL 31/0900Z 17.5N 107.9W 125 KT 12HR VT 31/1800Z 18.5N 108.7W 125 KT 24HR VT 01/0600Z 20.1N 109.8W 125 KT 36HR VT 01/1800Z 22.1N 110.8W 115 KT 48HR VT 02/0600Z 24.1N 111.5W 100 KT 72HR VT 03/0600Z 27.2N 112.7W 50 KT...INLAND 96HR VT 04/0600Z 28.5N 113.3W 30 KT...INLAND 120HR VT 05/0600Z 29.5N 114.0W 25 KT...REMNANT LOW $$ FORECASTER BROWN