Tropical Storm KRISTY
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TROPICAL STORM KRISTY DISCUSSION NUMBER 3
NWS NATIONAL HURRICANE CENTER MIAMI FL EP112012
800 PM PDT WED SEP 12 2012
THE LAST FEW VISIBLE IMAGES AND THE BD-CURVE INFRARED ENHANCEMENT
INDICATE THAT KRISTY HAS BECOME A LITTLE BETTER ORGANIZED DURING
THE PAST FEW HOURS. DEEP CONVECTION HAS BECOME MORE CONCENTRATED
NEAR THE CENTER AND BANDING IS IMPROVING...PARTICULARLY OVER THE
EASTERN AND SOUTHERN PORTIONS OF THE SYSTEM. SUBSEQUENTLY...THE
INITIAL INTENSITY IS RAISED TO 45 KT...AND THIS AGREES WITH A BLEND
OF THE SUBJECTIVE AND OBJECTIVE SATELLITE INTENSITY ESTIMATES.
SATELLITE-DERIVED WINDS FROM UW-CIMSS REVEAL A QUITE IMPRESSIVE
OUTFLOW PATTERN OVER THE TROPICAL STORM. THIS WIND ANALYSIS
CONTRADICTS THE GFS-BASED SHIPS MODEL SOLUTION...WHICH INDICATES
15-20 KT OF NORTHWESTERLY SHEAR THAT IS LIKELY JUST THE STRONG
OUTFLOW OF THE CYCLONE IN THE NORTHERN SEMICIRCLE. KRISTY SHOULD
STRENGTHEN DURING THE NEXT 36-48 HOURS BEFORE ENCOUNTERING MUCH
COOLER SEA SURFACE TEMPERATURES. THE FORECAST INDICATES A PEAK
INTENSITY OF 60 KT AT THE 36 HOUR PERIOD. HOWEVER...FURTHER
STRENGTHENING TO A LOW-END HURRICANE IS POSSIBLE...AS INDICATED BY
THE SHIPS AND THE HWRF MODELS. SIGNIFICANT WEAKENING IS EXPECTED TO
OCCUR AFTER THAT...AND KRISTY SHOULD DEGENERATE TO A REMNANT LOW
AROUND DAY 4...IF NOT SOONER. THE NHC INTENSITY FORECAST IS
ADJUSTED A BIT HIGHER THAN THE PREVIOUS FORECAST...AND IS BASED
PRIMARLY ON THE IVCN MODEL CONSENSUS.
THE INITIAL MOTION ESTIMATE IS 285/8. THE GLOBAL MODELS AND THE HWRF
MODEL ALL SHOW THAT A MID-LEVEL RIDGE EXTENDING WESTWARD FROM THE
GULF OF MEXICO TO THE EASTERN PACIFIC SHOULD STEER KRISTY GENERALLY
TOWARD THE WEST-NORTHWEST DURING THE NEXT SEVERAL DAYS. ONLY THE
GFDL MODEL INDICATES A MORE NORTHWARD TRACK OVER THE SOUTHERN
PORTION OF BAJA CALIFORNIA IN 48-72 HOURS. IN PREVIOUS YEARS...THIS
PARTICULAR MODEL HAS EXHIBITED A NORTH OR RIGHT-OF-TRACK BIAS FOR
TROPICAL CYCLONES LOCATED SOUTH OF MEXICO. THE OFFICIAL TRACK
FORECAST IS ADJUSTED TO THE LEFT OF THE PREVIOUS ONE AND IS CLOSE
TO THE TVCE CONSENSUS...WHICH LIES BETWEEN THE GFS AND THE ECMWF.
FORECAST POSITIONS AND MAX WINDS
INIT 13/0300Z 18.0N 107.4W 45 KT 50 MPH
12H 13/1200Z 18.5N 108.4W 50 KT 60 MPH
24H 14/0000Z 19.2N 110.0W 55 KT 65 MPH
36H 14/1200Z 20.0N 111.4W 60 KT 70 MPH
48H 15/0000Z 21.1N 113.2W 60 KT 70 MPH
72H 16/0000Z 23.5N 116.7W 45 KT 50 MPH
96H 17/0000Z 25.0N 120.0W 30 KT 35 MPH...POST-TROP/REMNT LOW
120H 18/0000Z 25.5N 121.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
$$
FORECASTER ROBERTS
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