000
WTPZ44 KNHC 110846
TCDEP4
TROPICAL STORM CARLOS DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP042009
200 AM PDT SAT JUL 11 2009
 
IT NOW APPEARS THAT THE CENTER OF CARLOS IS EMBEDDED BENEATH A
CENTRAL DENSE OVERCAST...AND A NEW CONVECTIVE BAND TO THE SOUTHEAST
OF THE CENTER IS TAKING SHAPE.  DVORAK INTENSITY ESTIMATES HAVE
INCREASED TO 3.5 AND 3.0 FROM TAFB AND SAB...RESPECTIVELY...AND THE
LATEST ADT ESTIMATE FROM UW-CIMSS IS 3.9.  GIVEN THE RANGE OF
ESTIMATES...THE INITIAL INTENSITY IS RAISED TO A CONSENSUS OF 55
KT.
 
CARLOS IS LOCATED TO THE SOUTH OF A WESTWARD-EXPANDING MID-LEVEL
RIDGE AND IS MOVING AT 275/11.  THE DYNAMICAL GUIDANCE CONTINUES TO
BE TIGHTLY CLUSTERED AROUND A WEST TO WEST-NORTHWESTWARD MOTION AS
THE RIDGE IMPEDES A NORTHWARD COMPONENT TO THE MOTION. HOWEVER...THE
MODELS HAVE INCREASED THE FORWARD MOTION A BIT...AND THE NEW
OFFICIAL FORECAST IS JUST A LITTLE FASTER THAN THE PREVIOUS
FORECAST.  THE NEW FORECAST IS CLOSE TO THE MODEL CONSENSUS BUT
STILL A LITTLE SLOWER THAN SOME OF THE GUIDANCE...SPECIFICALLY THE
GFS...GFDL...AND HWRF.
 
THE KEY PROBLEM FOR THE INTENSITY FORECAST IS THE SHORT-TERM RATE OF
STRENGTHENING.  THE SHIPS RAPID INTENSITY INDEX NOW INDICATES A 63%
CHANCE OF RAPID INTENSIFICATION OVER THE NEXT 24 HOURS.  THE
OFFICIAL FORECAST MAKES CARLOS A HURRICANE WITHIN THE NEXT 12 HOURS
AND IS SUPPORTED BY NEARLY ALL THE INTENSITY GUIDANCE.  WITH THE RI
INDEX SO HIGH...HOWEVER...IT IS POSSIBLE THAT CARLOS COULD
INTENSIFY QUICKER DURING THE NEXT 24 HOURS THAN IS SHOWN IN THE
FORECAST.  VERTICAL SHEAR IS EXPECTED TO REMAIN LIGHT...AND OCEAN
TEMPERATURES WILL REMAIN SUFFICIENTLY WARM THROUGH 96 HOURS TO
ALLOW FURTHER STRENGTHENING BEYOND 24 HOURS.  BY DAY 5...THERE ARE
SOME INDICATIONS THAT CARLOS COULD COME UNDER THE INFLUENCE OF
STRONG SOUTHWESTERLY UPPER-LEVEL WINDS BETWEEN IT AND HAWAII...SO
THE OFFICIAL FORECAST SHOWS SLIGHT WEAKENING AT THAT TIME.  THIS IS
SUPPORTED BY NEARLY ALL OF THE INTENSITY GUIDANCE...AND MOST
ACTUALLY SHOW MORE WEAKENING THAN INDICATED HERE.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      11/0900Z 10.5N 116.3W    55 KT
 12HR VT     11/1800Z 10.6N 118.0W    65 KT
 24HR VT     12/0600Z 10.9N 120.4W    70 KT
 36HR VT     12/1800Z 11.1N 122.9W    75 KT
 48HR VT     13/0600Z 11.4N 125.4W    80 KT
 72HR VT     14/0600Z 12.0N 130.4W    85 KT
 96HR VT     15/0600Z 12.5N 135.5W    85 KT
120HR VT     16/0600Z 13.5N 140.5W    80 KT
 
$$
FORECASTER BERG