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TROPICAL STORM JIMENA DISCUSSION NUMBER 54
NWS CENTRAL PACIFIC HURRICANE CENTER HONOLULU HI EP132015
ISSUED BY NWS NATIONAL HURRICANE CENTER MIAMI FL
500 PM HST TUE SEP 08 2015
THERE HAVE NOT BEEN MANY CHANGES WITH JIMENA OVER THE PAST SEVERAL
HOURS WITH THE CENTER MOSTLY EXPOSED TO THE WEST OF A BLOB OF
CONVECTION. ALTHOUGH THE SATELLITE PRESENTATION IS NOT VERY
IMPRESSIVE...AN EARLIER ASCAT-B PASS SURPRISINGLY SHOWED MAXIMUM
WINDS OF ABOUT 50 KT. ASSUMING SOME SPIN DOWN OF THE VORTEX SINCE
THEN LEADS TO AN INITIAL INTENSITY ESTIMATE OF 45 KT FOR THIS
ADVISORY.
MODEL GUIDANCE SHOWS SHEAR INCREASING TO RATHER HIGH VALUES OVER THE
NEXT DAY OR SO...LIKELY CAUSING A DECREASE IN STRENGTH. THE ONE
CAVEAT IS THAT JIMENA IS EXPECTED TO BE MOVING OVER WARMER WATERS
AND INTO A MORE MOIST ATMOSPHERE ALOFT AS WELL...WHICH COULD TEMPER
THE WEAKENING RATE. THE OFFICIAL FORECAST FOLLOWS THE TREND OF THE
INTENSITY CONSENSUS AND THE PREVIOUS OFFICIAL FORECAST SHOWING SLOW
WEAKENING...ALTHOUGH THE VALUES ARE HIGHER BECAUSE OF THE INITIAL
INTENSITY. REMNANT LOW STATUS IS LIKELY IN A COUPLE OF DAYS DUE TO
THE PERSISTENT STRONG SHEAR.
VISIBLE IMAGES INDICATE THE CYCLONE HAS TURNED WEST-SOUTHWESTWARD
AND IS MOVING ABOUT 7 KT. THIS GENERAL MOTION IS LIKELY FOR THE
NEXT DAY OR SO...FOLLOWED BY A TURN TO THE WEST WHILE THE STORM
MOVES AROUND A RIDGE TO THE NORTH. JIMENA...OR ITS REMNANTS...
SHOULD TURN NORTHWESTWARD AWAY FROM THE HAWAIIAN ISLANDS AND
ACCELERATE IN A FEW DAYS AHEAD OF A MID-LATITUDE TROUGH. THE TROUGH
SHOULD THEN ABSORB THE LOW BY DAY 5. OVERALL THE MODELS ARE IN GOOD
AGREEMENT ON THIS SYNOPTIC PATTERN AND THE OFFICIAL FORECAST IS
SHIFTED A LITTLE TO THE SOUTH BASED ON THE LATEST CONSENSUS
GUIDANCE.
FORECAST POSITIONS AND MAX WINDS
INIT 09/0300Z 26.0N 153.9W 45 KT 50 MPH
12H 09/1200Z 25.7N 155.1W 40 KT 45 MPH
24H 10/0000Z 25.3N 156.7W 35 KT 40 MPH
36H 10/1200Z 25.1N 158.3W 30 KT 35 MPH
48H 11/0000Z 25.1N 159.6W 30 KT 35 MPH...POST-TROP/REMNT LOW
72H 12/0000Z 25.5N 161.5W 30 KT 35 MPH...POST-TROP/REMNT LOW
96H 13/0000Z 28.0N 163.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
120H 14/0000Z...DISSIPATED
$$
FORECASTER BLAKE
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