WDPN31 PGTW 012100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 22W (GONI) WARNING 
NR 020//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 22W (GONI), LOCATED APPROXIMATELY 87 NM
WEST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 
18 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
(EIR) SATELLITE IMAGERY DEPICTS LOW LEVEL BANDING FEATURES
THAT WRAP INTO A PARTIALLY OBSCURED LOW LEVEL CIRCULATION
CENTER (LLCC). FURTHERMORE, THE EIR LOOP REVEALS THAT THE LOW
LEVEL CONVECTION HAS BECOME DECOUPLED FROM THE UPPER AND MID 
LEVEL CONVECTION AND THAT AN OVERALL WEAKENING TREND HAS TAKEN 
PLACE OVER THE PAST 6 HOURS. THE INITIAL POSITION IS PLACED
WITH FAIR CONFIDENCE BASED ON THE POSITION OF THE LOW LEVEL
CIRCULATION FEATURE PRESENT IN THE EIR AND COMPOSITE RADAR
LOOPS. THE INITIAL INTENSITY OF 55 KTS IS PLACED BETWEEN
MULTI-AGENCY DVORAK CURRENT INTENSITY ESTIMATES OF T5.5 (PGTW,
102 KTS) AND T2.5 (35 KTS, KNES) AND IS IN AGREEMENT WITH THE
SCATTEROMETRY DATA FROM A PARTIAL 011303Z ASCAT-A PASS AND 
THE OVERALL CONVECTIVE WEAKENING. TS GONI IS TRACKING ALONG
THE SOUTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE
(STR) POSITIONED TO THE NORTHWEST AND THROUGH AN UNFAVORABLE
ENVIRONMENT WITH HIGH (25-30 KTS) VERTICAL WIND SHEAR (VWS),
AND ONLY WEAK POLEWARD OUTFLOW ALOFT. 
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TS GONI WILL TRACK WESTWARD ALONG THE SOUTHERN PERIPHERY
OF THE STEERING RIDGE THROUGH TAU 72. THE ENVIRONMENT WILL 
IMPROVE SLIGHTLY AS VWS BECOMES MODERATE (15-20 KTS) AND WILL
LEAD TO A GRADUAL INTENSIFICATION TO 55 KTS BY TAU 48. AFTER 
THIS TIME, SEA SURFACE TEMPERATURES (SST) ARE FORECAST TO 
DECREASE WHILE UPPER LEVEL OUTFLOW FURTHER WEAKENS. THIS WILL
LEAD TO A GRADUAL WEAKENING TO 50 KTS BY TAU 72. NUMERICAL 
MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT DURING THIS INITIAL
PORTION OF THE JTWC FORECAST WITH A MAXIMUM SPREAD IN MODEL
SOLUTIONS OF 215 NM AT TAU 72, AND LENDS GOOD CONFIDENCE IN
THE INITIAL PORTION OF THE JTWC FORECAST TRACK. 
   C. BEYOND TAU 72, TS GONI WILL BEGIN A WEST-SOUTHWESTWARD 
TRACK AS THE STEERING RIDGE BUILDS TO THE NORTH. BY TAU 96 TS 
GONI WILL MAKE LANDFALL ALONG THE COAST OF SOUTHERN VIETNAM NEAR
QUI NOHN. INTERACTION WITH THE UNDERLYING TERRAIN WILL CAUSE
THE SYSTEM TO BEGIN DISSIPATING OVER LAND, RESULT IN A
WEAKENING TO 35 KTS BY TAU 96 AND FULL DISSIPATION BY TAU 120. 
NUMERICAL MODEL TRACK GUIDANCE IS IN OVERALL FAIR AGREEMENT
FOR THIS FINAL PORTION OF THE FORECAST PERIOD WITH A MAXIMUM
SPREAD IN MODEL TRACK SOLUTIONS OF 290 NM AT TAU 120. THIS
FAIR AGREEMENT IN MODEL TRACK GUIDANCE LENDS OVERALL FAIR 
CONFIDENCE IN THE REMAINDER OF THE JTWC FORECAST TRACK.//
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