000 WTPZ45 KNHC 252044 TCDEP5 HURRICANE DARBY DISCUSSION NUMBER 12 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP052010 200 PM PDT FRI JUN 25 2010 DARBY REMAINS A WELL-ORGANIZED HURRICANE WITH VISIBLE IMAGERY SHOWING A DISTINCT EYE AND AN IMPRESSIVE OUTFLOW PATTERN. DVORAK SATELLITE CLASSIFICATIONS FROM TAFB AND SAB AT 1800 UTC WERE T5.5...102 KT. SINCE THAT TIME...THE SYSTEM HAS BECOME BETTER ORGANIZED WITH DEEPER CONVECTION IN THE EYEWALL. THUS...THE INITIAL INTENSITY IS NUDGED UPWARD TO 105 KT. EASTERLY SHEAR IS FORECAST BY ALL OF THE GLOBAL MODELS TO INCREASE OVERNIGHT WHICH SHOULD LIMIT FUTURE STRENGTHENING. THIS SHEAR WILL LIKELY PERSIST FOR SEVERAL DAYS AND CAUSE DARBY TO GRADUALLY WEAKEN. MOST OF THE INTENSITY GUIDANCE IS IN REASONABLE AGREEMENT ON THIS SCENARIO... AND THE NHC FORECAST IS BASICALLY AN UPDATE OF THE PREVIOUS ADVISORY. THE INITIAL MOTION OF THE TROPICAL CYCLONE IS TOWARD THE WEST-NORTHWEST OR 285/5. A MID-TROPOSPHERIC RIDGE OVER MEXICO IS FORECAST BY ALL OF THE GLOBAL MODELS TO WEAKEN DURING THE NEXT 24 HOURS...WHICH SHOULD CAUSE DARBY TO SLOW DOWN AND BECOME NEARLY STATIONARY. THEREAFTER...THE MODELS HAVE WILDLY DIVERGENT SOLUTIONS...WITH THE HWRF CONTINUING A WESTWARD MOTION OF DARBY AND THE ECMWF/UKMET SHOWING AN EASTWARD MOTION. MOST OF THIS DISAGREEMENT IS CAUSED BY THE HANDLING OF THE SYSTEM OVER THE NORTHWESTERN CARIBBEAN...AND WHETHER THE MUCH-SMALLER DARBY GETS CAUGHT UP IN WESTERLY FLOW SOUTH OF MEXICO. IT IS BEST TO STAY CLOSE TO THE MODEL CONSENSUS FOR NOW...AND THE NHC FORECAST IS CLOSE TO THE PREVIOUS ONE...A LITTLE WEST OF THE DYNAMICAL MODEL CONSENSUS. DARBY IS THE EARLIEST SECOND MAJOR HURRICANE FORMATION IN THE EASTERN PACIFIC SINCE RELIABLE RECORDS BEGAN IN 1971...ECLIPSING OF THE PREVIOUS RECORD OF HURRICANE DANIEL ON JUNE 30 1978. FORECAST POSITIONS AND MAX WINDS INITIAL 25/2100Z 13.6N 101.5W 105 KT 12HR VT 26/0600Z 13.7N 102.3W 105 KT 24HR VT 26/1800Z 13.5N 103.3W 100 KT 36HR VT 27/0600Z 13.4N 103.8W 90 KT 48HR VT 27/1800Z 13.5N 104.2W 80 KT 72HR VT 28/1800Z 14.0N 103.5W 65 KT 96HR VT 29/1800Z 14.3N 102.7W 55 KT 120HR VT 30/1800Z 14.6N 102.0W 45 KT $$ FORECASTER BLAKE