000
WTPZ45 KNHC 250852
TCDEP5
HURRICANE DARBY DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP052010
200 AM PDT FRI JUN 25 2010
 
DARBY HAS MAINTAINED A SMALL 10-N MI EYE FOR ABOUT THE PAST FIVE
HOURS BUT HAS DISPLAYED AN OBLONG CONVECTIVE PATTERN WITH THE
STRONGEST ACTIVITY LOCATED OVER THE SOUTHERN SEMICIRCLE.  DVORAK
ESTIMATES FROM TAFB AND SAB ARE BOTH T5.0...AND THE INITIAL
INTENSITY IS RAISED TO 90 KT.
 
ENVIRONMENTAL CONDITIONS APPEAR CONDUCIVE FOR SOME FURTHER
STRENGTHENING OVER THE NEXT DAY OR SO.  ANALYSES FROM UW-CIMSS
INDICATE THAT DARBY HAS MOVED INTO A FAVORABLE NORTH-SOUTH CORRIDOR
OF HIGHER SSTS AND SHOULD REMAIN OVER THOSE WATERS FOR ANOTHER 12
TO 24 HOURS.  IN ADDITION...VERTICAL SHEAR IS EXPECTED TO BE LOW
DURING THAT PERIOD.  THE NEW OFFICIAL INTENSITY FORECAST BRINGS
DARBY TO MAJOR HURRICANE STRENGTH IN 12 HOURS...WHICH IS ABOVE ALL
OF THE GUIDANCE EXPECT FOR SHIFOR.  THE SHIPS RI INDEX DOES
INDICATE A 1 IN 4 CHANCE OF A 30 KT INCREASE IN INTENSITY OVER THE
NEXT 24 HOURS...SO IT IS NOT OUT OF THE QUESTION FOR DARBY TO
STRENGTHEN MORE THAN INDICATED HERE.  GRADUAL WEAKENING IS EXPECTED
AFTER 24 HOURS DUE TO INCREASED VERTICAL SHEAR AND LOWER SSTS...AND
THE OFFICIAL FORECAST LIES CLOSE TO SHIPS AND LGEM.
 
THE TRACK FORECAST IS HEAVILY DEPENDENT ON THE EVOLUTION OF THE AREA
OF LOW PRESSURE CURRENTLY OVER THE WESTERN CARIBBEAN.  NEARLY ALL
OF THE GLOBAL MODELS SHOW DEVELOPMENT OF THIS SYSTEM BY THE TIME IT
GETS TO THE WESTERN GULF OF MEXICO IN A FEW DAYS...AND THESE MODELS
STALL DARBY BY DAY 2 FOLLOWED BY A NORTHEASTWARD ACCELERATION ON
DAYS 4 AND 5...MOST NOTABLY INDICATED BY THE ECMWF AND UKMET.  THE
OFFICIAL FORECAST FOLLOWS THIS GENERAL PATTERN...BUT DOES NOT
INDICATE A POSITION AS FAR TO THE EAST ON DAY 5 AS THE MODEL
CONSENSUS TVCN...WHICH IS BEING INFLUENCED BY THE ECMWF AND UKMET
OUTLIERS.  ON ANOTHER NOTE...THE GFS SHOWS ALMOST NO DEVELOPMENT OF
THE CARIBBEAN LOW AND THEREFORE KEEPS DARBY ON THE WESTERN SIDE OF
THE RATHER HELTER-SKELTER GUIDANCE ENVELOPE.  ESSENTIALLY...THE
STRONGER THE CARIBBEAN LOW GETS WHILE IN THE GULF OF MEXICO...THE
FARTHER TO THE EAST DARBY COULD BE LOCATED BY THE END OF THE
FORECAST PERIOD.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      25/0900Z 13.4N 100.7W    90 KT
 12HR VT     25/1800Z 13.5N 101.6W   100 KT
 24HR VT     26/0600Z 13.6N 102.6W    95 KT
 36HR VT     26/1800Z 13.4N 103.5W    90 KT
 48HR VT     27/0600Z 13.4N 103.7W    80 KT
 72HR VT     28/0600Z 13.6N 103.7W    70 KT
 96HR VT     29/0600Z 14.0N 103.0W    60 KT
120HR VT     30/0600Z 14.5N 102.0W    50 KT
 
$$
FORECASTER BERG