Hurricane HOWARD
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TROPICAL STORM HOWARD DISCUSSION NUMBER 20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
8 AM PDT SAT SEP 04 2004
EARLIER AMSU-B AND TRMM MICROWAVE PASSES AT 04/1029Z AND 04/1200Z
RESPECTIVELY DEPICTED THAT HOWARD HAD DECOUPLED SOUTH OF THE DEEP
CONVECTION LAST NIGHT. BASED ON THESE FIXES...THE TRACK HAS BEEN
ADJUSTED A LITTLE TO THE WEST OF THAT FROM THE PREVIOUS ADVISORY.
SATELLITE CURRENT INTENSITY ESTIMATES REMAINED UNCHANGED...
HOWEVER...FIX POSITIONS WHERE PLACED IN THE CONVECTION. BASED SOLEY
ON THE EARLIER MICROWAVE PASSES...THE INITIAL INTENSITY IS
DECREASED TO 60 KT. SEA SURFACE TEMPERATURE ANALYSIS INDICATES THAT
HOWARD HAS MOVED OVER A COOL TONGUE OF SEAS SURFACE TEMPS LESS THAN
24 DEGREES CELSIUS. WATER VAPOR REVEALS UPPER SOUTHWESTERLY SHEAR
OVER THE SYSTEM AS WELL...FURTHER JUSTIFYING A WEAKENING TREND.
SHIPS DISSIPATES THE TROPICAL CYCLONE IN 36 HOURS...AND THE GFDL
MODEL DECREASES THE INTENSITY TO 25 KT IN 48 HOURS. THE FORECAST
INTENSITY CALLS FOR WEAKENING TO A REMNANT LOW IN 48 HOURS...WITH
THE LOW DISSIPATING BY DAY 5.
INITIAL MOTION IS 330 DEGREES AT 9 KT. THE MAJORITY OF THE MODELS
NOW DEPICT A NORTHWEST TO WEST-NORTHWEST MOTION THROUGH 48
HOURS...WITH DISSIPATION IN 72 HOURS. THE NOGAPS...WHICH MAINTAINS
A STRONG TROPICAL CYCLONE THROUGH DAY 4...IS THE OUTLIER WITH A
NORTHWARD MOVEMENT OVER THE NEXT COUPLE OF DAYS. THE OFFICIAL
FORECAST IS ADJUSTED TO THE LEFT OF THE PREVIOUS FORECAST AND
AGREES WITH THE GUNA AND CONU.
FORECASTER ROBERTS/PASCH
FORECAST POSITIONS AND MAX WINDS
INITIAL 04/1500Z 23.7N 117.6W 55 KT
12HR VT 05/0000Z 24.7N 118.0W 45 KT
24HR VT 05/1200Z 25.6N 118.6W 35 KT
36HR VT 06/0000Z 26.3N 119.2W 25 KT...DISSIPATING
48HR VT 06/1200Z 26.5N 120.0W 20 KT...REMNANT LOW
72HR VT 07/1200Z 26.5N 121.5W 20 KT...REMNANT LOW
96HR VT 08/1200Z 26.5N 122.5W 20 KT...REMNANT LOW
120HR VT 09/1200Z...DISSIPATED
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