000
WTPZ44 KNHC 230855
TCDEP4
 
HURRICANE HILARY DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP092011
200 AM PDT FRI SEP 23 2011
 
HILARY HAS CONTINUED TO INTENSIFY. THE SATELLITE APPEARANCE OF THE
CYCLONE IS QUITE IMPRESSIVE...WITH THE HURRICANE MAINTAINING A
WELL-DEFINED 10 N MI WIDE EYE AND A RATHER SYMMETRIC CENTRAL DENSE
OVERCAST SURROUNDED BY A THICK RING OF VERY COLD CLOUD TOPS. DVORAK
T-NUMBERS FROM TAFB AND SAB AT 0600 UTC WERE 6.5 AND SUPPORT AN
INITIAL INTENSITY OF 125 KT. SOME ADDITIONAL STRENGTHENING IS
POSSIBLE IN THE SHORT TERM AS HILARY REMAINS IN A NEARLY IDEAL
ENVIRONMENT OF LIGHT SHEAR AND OVER VERY WARM WATERS. HOWEVER...
EYEWALL REPLACEMENT CYCLES...WHICH ARE NEARLY IMPOSSIBLE TO
TIME...ARE LIKELY TO INFLUENCE THE INTENSITY WITHIN A DAY OR SO.
ONLY A SLOW DECREASE IN STRENGTH IS EXPECTED THROUGH THE REST OF
THE FORECAST PERIOD AS WATERS ONLY GRADUALLY COOL AND THE SHEAR
REMAINS FAIRLY LOW. THE OFFICIAL FORECAST IS SIMILAR TO THE
PREVIOUS ONE AND IS IN VERY GOOD AGREEMENT WITH THE VARIOUS
INTENSITY CONSENSUS AIDS.

HILARY HAS JOGGED A BIT TO THE LEFT DURING THE LAST 6 HOURS...WITH
THE LONGER-TERM MOTION ESTIMATE OF 280/10. THE RECENT CHANGE IN THE
TRACK TOWARD THE WEST SEEMS TO BE IN RESPONSE TO THE HURRICANE
MOVING UNDERNEATH A MID-LEVEL RIDGE EXTENDING FROM NORTHERN MEXICO
WESTWARD INTO THE SUBTROPICAL EASTERN PACIFIC. GLOBAL MODELS ARE IN
GOOD AGREEMENT THAT THIS FEATURE WILL STEER HILARY ON A GENERAL
WESTWARD TO WEST-NORTHWESTWARD COURSE FOR THE NEXT SEVERAL DAYS.
THE OFFICIAL FORECAST HAS BEEN ADJUSTED A BIT TO THE SOUTH THROUGH
96 HOURS TO ACCOUNT FOR RECENT TRENDS AND ON THE ASSUMPTION OF A
STRONGER RIDGE THROUGH THAT TIME...IN BEST AGREEMENT WITH THE
RELIABLE GFS/ECWMF MODELS. TOWARD THE END OF THE PERIOD...THE MODEL
GUIDANCE BEGINS TO DIVERGE DUE TO THE DEPICTION OF A SHORTWAVE
TROUGH DIGGING SOUTHEASTWARD OVER THE SOUTHWESTERN UNITED STATES.
THIS FEATURE COULD WEAKEN THE RIDGE ENOUGH TO CAUSE HILARY TO SLOW
DOWN AND TURN MORE NORTHWEST OR PERHAPS EVEN NORTH. THE NHC
FORECAST HAS BEEN SHIFTED A BIT TO THE RIGHT AT DAY 5 BUT REMAINS
WELL LEFT OF THE MULTI-MODEL CONSENSUS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  23/0900Z 16.0N 101.9W  125 KT 145 MPH
 12H  23/1800Z 16.2N 103.2W  130 KT 150 MPH
 24H  24/0600Z 16.5N 104.8W  125 KT 145 MPH
 36H  24/1800Z 16.9N 106.4W  115 KT 135 MPH
 48H  25/0600Z 17.2N 107.9W  110 KT 125 MPH
 72H  26/0600Z 17.9N 111.0W  100 KT 115 MPH
 96H  27/0600Z 18.8N 113.7W   95 KT 110 MPH
120H  28/0600Z 20.5N 115.0W   85 KT 100 MPH
 
$$
FORECASTER KIMBERLAIN