Tropical Storm JIMENA

ZCZC MIATCDEP3 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM JIMENA DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP132009
200 AM PDT SAT AUG 29 2009
 
ENHANCED INFRARED SATELLITE IMAGERY INDICATES THAT THE CENTER IS
LIKELY EMBEDDED IN A SMALL MASS OF DEEP CONVECTION TO -80C...WITH A
WELL-DEFINED CURVED BAND ARCING OUTWARD IN THE NORTHERN SEMICIRCLE. 
OVERALL...THE CLOUD PATTERN HAS EXHIBITED INCREASED ORGANIZATION
DURING THE LAST SEVERAL HOURS. DVORAK T-NUMBERS OF T 2.5 AND T 3.0
FROM SAB AND TAFB...RESPECTIVELY. THEREFORE...THE DEPRESSION IS
BEING UPGRADED TO TROPICAL STORM JIMENA WITH A 35 KT INITIAL
INTENSITY.
 
JIMENA CONTINUES TO MOVE ON A GENERAL WESTERLY COURSE...WITH A
SOMEWHAT UNCERTAIN INITIAL MOTION ESTIMATE OF 280/10. MODEL
GUIDANCE SHOWS A MID-LEVEL RIDGE COVERING CENTRAL/WESTERN MEXICO
WHICH SHOULD STEER JIMENA ON A WESTWARD TO WEST-NORTHWESTWARD
COURSE DURING THE NEXT 36-48 HOURS WITH SOME DECREASE IN FORWARD
SPEED. THEREAFTER...GLOBAL MODELS DEPICT AN AMPLIFYING LONGWAVE
TROUGH OVER THE EAST PACIFIC ALONG 135 WEST WHICH SHOULD CAUSE THE
MID-LEVEL RIDGE OVER MEXICO TO SHIFT EASTWARD.  THIS CHANGE IN THE
STEERING FLOW SHOULD FORCE JIMENA TO MOVE ON A MORE NORTHWESTERLY
COURSE BEYOND 48 HOURS.  IT SHOULD BE NOTED THAT MODEL SPREAD IS
RATHER LARGE TOWARD THE END OF THE FORECAST PERIOD...AS MODELS
DIFFER ON THE STRENGTH OF SUBTROPICAL RIDGE TO THE NORTH OF THE
CYCLONE. IN ONE CAMP...THE HWRF/GFDL CONTINUE TO FAVOR LESS RIDGING
TO THE NORTH...RESULTING IN A TRACK RIGHT OF THE MODEL CONSENSUS. 
IN THE OTHER CAMP...THE UKMET/ECMWF/CANADIAN MODELS KEEP A MORE
ROBUST RIDGE TO THE NORTH OF JIMENA AND THEREFORE TRACK THE CYCLONE
MUCH FARTHER WEST.  THE OFFICIAL FORECAST TRACK IS A COMPROMISE
BETWEEN THE TWO EXTREMES...NEARLY IN BETWEEN THE PREVIOUS PACKAGE
AND THE UPDATED MODEL CONSENSUS.
 
JIMENA IS FORECAST TO ENCOUNTER A LIGHT SHEAR ENVIRONMENT AND VERY
WARM SEA SURFACE TEMPERATURES ALONG THE FORECAST TRACK OVER THE
NEXT FEW DAYS.  THEREFORE...STRENGTHENING IS EXPECTED AND THE
OFFICIAL FORECAST FOLLOWS THE MODEL CONSENSUS...CALLING FOR JIMENA
TO BECOME A HURRICANE IN 36-48 HOURS.  BY 96 HOURS...JIMENA SHOULD
BE TRAVERSING COOLER WATERS...AND A GENERAL WEAKENING IS FORECAST.
THE OFFICIAL INTENSITY FORECAST IS SLIGHTLY HIGHER THAN THE
SHIPS MODEL GUIDANCE BUT LOWER THAN THE GFDL/HWRF RUNS WHICH MAKE
JIMENA A MAJOR HURRICANE.
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      29/0900Z 14.1N 102.3W    35 KT
 12HR VT     29/1800Z 14.4N 103.5W    40 KT
 24HR VT     30/0600Z 14.9N 104.8W    50 KT
 36HR VT     30/1800Z 15.4N 106.1W    60 KT
 48HR VT     31/0600Z 16.4N 107.3W    75 KT
 72HR VT     01/0600Z 19.5N 110.0W    80 KT
 96HR VT     02/0600Z 23.0N 112.5W    75 KT
120HR VT     03/0600Z 25.5N 114.0W    60 KT
 
$$
FORECASTER KIMBERLAIN
 
NNNN