Hurricane GILMA

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HURRICANE GILMA DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP072012
200 AM PDT THU AUG 09 2012
 
YESTERDAY AFTERNOON...A SERIES OF MICROWAVE IMAGES FROM THE FNMOC
SATELLITE DATA TROPICAL CYCLONE PAGE INDICATED THAT THE EYEWALL OF
GILMA WAS PARTIALLY OPEN IN THE NORTH PORTION.  RECENTLY...A 0400
UTC SSMIS OVERPASS REVEALED A FULLY CLOSED EYEWALL...ALBEIT...A
LITTLE THIN IN THE NORTHWEST QUADRANT. BASED ON THE INNER CORE
IMPROVEMENT DURING THE PAST SEVERAL HOURS...AND A BLEND OF THE TAFB
AND SAB SATELLITE INTENSITY ESTIMATES...THE INITIAL INTENSITY IS
RAISED TO 70 KT.  THERE ARE NO CHANGES TO THE INTENSITY FORECAST
PHILOSOPHY. A WEAKENING TREND IS EXPECTED TO COMMENCE IN 24 HOURS
OR SO AS THE CYCLONE TRAVERSES A SHARP GRADIENT OF DECREASING SSTS
AND MOVES INTO A LESS FAVORABLE THERMODYNAMIC ENVIRONMENT.  THE
OFFICIAL NHC INTENSITY FORECAST IS BASICALLY A COMPROMISE OF THE
LGEM AND FLORIDA STATE SUPERENSEMBLE MODELS AND CALLS FOR GILMA TO
BECOME A REMNANT LOW IN 4 DAYS. 
 
THE INITIAL MOTION IS ESTIMATED TO BE 285/6.  A MID- TO UPPER-
TROPOSPHERIC LOW AND AN ASSOCIATED TROUGH EXTENDING
SOUTHWESTWARD FROM THE SOUTHERN TIP OF BAJA CALIFORNIA APPEARS TO
BE ERODING THE RIDGE SITUATED TO THE NORTH OF GILMA. 
CONSEQUENTLY...THIS SYNOPTIC FEATURE HAS CAUSED THE CYCLONE TO SLOW
ITS FORWARD SPEED DURING THE PAST 12 HOURS...AND THE LARGE-SCALE
MODELS INDICATE THAT THIS WEAKENED STEERING PATTERN WILL PERSIST
THROUGH THE ENTIRE FORECAST PERIOD.  A SUBSEQUENT TURN TOWARD THE
NORTHWEST IS ALSO EXPECTED LATER TODAY AS A RESULT OF THE
AFOREMENTIONED GROWING WEAKNESS IN THE RIDGE.  AROUND DAY 4...GILMA
IS FORECAST TO TURN BACK TOWARD THE WEST-NORTHWEST WITHIN THE
EASTERLY LOW-LEVEL FLOW AS A WEAK...SHALLOW SYSTEM.  THE NHC
FORECAST FOR THIS ADVISORY LIES BETWEEN THE PREVIOUS ONE AND THE
TVCE MULTI-MODEL CONSENSUS.

THE 34-KT AND 50-KT WIND RADII WERE SLIGHTLY ADJUSTED BASED ON A
0452 UTC ASCAT PASS. 

FORECAST POSITIONS AND MAX WINDS
 
INIT  09/0900Z 16.2N 118.6W   70 KT  80 MPH
 12H  09/1800Z 16.7N 119.2W   70 KT  80 MPH
 24H  10/0600Z 17.4N 119.9W   65 KT  75 MPH
 36H  10/1800Z 18.1N 120.5W   55 KT  65 MPH
 48H  11/0600Z 18.8N 121.0W   45 KT  50 MPH
 72H  12/0600Z 19.9N 121.7W   35 KT  40 MPH
 96H  13/0600Z 20.6N 122.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
120H  14/0600Z 20.6N 124.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 
$$
FORECASTER ROBERTS
 
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