Hurricane HERNAN

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HURRICANE HERNAN DISCUSSION NUMBER   9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   EP092008
200 PM PDT FRI AUG 08 2008
 
THE RAGGED EYE FEATURE FROM THIS MORNING HAS PERSISTED INTO THE
AFTERNOON...AND LATEST SATELLITE IMAGERY INDICATES THAT THE EYE IS
BECOMING BETTER DEFINED. DVORAK SATELLITE CLASSIFICATIONS REFLECT
THIS INCREASING ORGANIZATION...WITH TAFB AND SAB COMING IN WITH
T4.5 AND T4.0...RESPECTIVELY. ON THIS BASIS...THE INITIAL INTENSITY
IS SET AT 75 KT. LIGHT EASTERLY SHEAR AND OTHER FAVORABLE FACTORS
PREDICTED ALONG THE FORECAST TRACK SHOULD GIVE HERNAN THE
OPPORTUNITY TO INTENSIFY FURTHER DURING THE NEXT 24 TO 36 HOURS. 
HOWEVER...BETWEEN 36 AND 48 HOURS...HERNAN SHOULD REACH SUB-26C
SSTS AND BEGIN A GRADUAL WEAKENING. THE OFFICIAL INTENSITY FORECAST
LIES SLIGHTLY ABOVE ALL OBJECTIVE AIDS AS WELL AS THE PREVIOUS
ADVISORY.
 
THE HEADING IS 275/10...A MOTION WHICH HAS REMAINED NEARLY UNCHANGED
DURING THE PAST DAY OR SO. NEARLY ALL OF THE TRACK GUIDANCE TURNS
HERNAN MORE TOWARD THE NORTHWEST VERY SOON...LIKELY IN RESPONSE TO
A PRONOUNCED MID- TO UPPER-LEVEL TROUGH LYING WELL NORTHWEST OF THE
HURRICANE.  HOWEVER...WATER VAPOR CLOUD-TRACKED WINDS SHOW A SMALL
MID-LEVEL RIDGE AXIS LYING DIRECTLY NORTH OF HERNAN...WHICH HAS
BEEN GUIDING IT ON A MORE WESTERLY COURSE. THIS FEATURE SEEMS TO BE
UNDER-REPRESENTED IN THE GLOBAL MODEL FIELDS AND PERHAPS THIS IS
WHY THE MODEL GUIDANCE HAS BEEN EXHIBITING A NORTHWARD BIAS WITH
HERNAN.  CONSEQUENTLY...THE NEW OFFICIAL FORECAST REMAINS ON THE
SOUTHERN EDGE OF THE GUIDANCE ENVELOPE. IN 24 TO 48 HOURS...MODEL
GUIDANCE IS IN GOOD AGREEMENT ON THE MID-LEVEL RIDGE BUILDING
WESTWARD WITH THE HURRICANE AS THE MID- TO UPPER-LEVEL TROUGH TO
THE NORTH LIFTS OUT.  THIS SHOULD ALLOW THE TRACK TO BEND MORE
TOWARD THE WEST AND PERHAPS EVEN TO THE WEST-SOUTHWEST LATE IN THE
PERIOD...AS A WEAKER HERNAN BECOMES STEERED BY THE LOW- TO
MID-LEVEL FLOW.
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      08/2100Z 14.8N 120.9W    75 KT
 12HR VT     09/0600Z 15.0N 122.3W    85 KT
 24HR VT     09/1800Z 15.4N 124.0W    85 KT
 36HR VT     10/0600Z 16.1N 125.7W    75 KT
 48HR VT     10/1800Z 16.7N 127.4W    65 KT
 72HR VT     11/1800Z 17.0N 130.5W    45 KT
 96HR VT     12/1800Z 17.0N 133.0W    35 KT
120HR VT     13/1800Z 16.5N 135.0W    25 KT
 
$$
FORECASTER KIMBERLAIN/BROWN
 
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