WDXS31 PGTW 140300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 11S (FREDDY) WARNING NR 023// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 15.4S 92.5E INITIAL INTENSITY: 85 KTS GEOGRAPHIC REFERENCE: 1277 NM EAST-SOUTHEAST OF DIEGO GARCIA MOVEMENT PAST 6 HOURS: WESTWARD AT 09 KTS SIGNIFICANT WAVE HEIGHT: 30 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS DEEP CONVECTION WRAPPING INTO A RAGGED, CLOUD-FILLED EYE. DEEP CONVECTION IN ENHANCED INFRARED SATELLITE IMAGERY IS CONCENTRATED IN THE DOWN-SHEAR RIGHT QUADRANT, WHICH IS INDICATIVE OF THE CONTINUED PRESENCE OF EASTERLY VERTICAL WIND SHEAR. A 132310Z SSMIS 91GHZ MICROWAVE IMAGE REVEALS A 20 NM MICROWAVE EYE, LENDING HIGH CONFIDENCE IN THE INITIAL POSITION. THE INITIAL INTENSITY OF 85 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON A BLEND OF CIMSS SATCON, ADT, ATMS, SSMIS, AND INTERAGENCY DVORAK ESTIMATES. A 131548Z METOP-C ASCAT IMAGE WAS USED TO ADJUST THE INITIAL WIND RADII. INITIAL WIND RADII BASIS: SCATTEROMETER DATA CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE SOUTH AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T5.0 - 90 KTS KNES: T5.0 - 90 KTS DEMS: T5.0 - 90 KTS APRF: T4.5 - 77 KTS CIMSS SATCON: 85 KTS AT Z CIMSS ADT: 84 KTS AT 132330Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL VWS: 15-20 KTS SST: 27-28 CELSIUS OUTFLOW: WEAK WESTWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TROPICAL CYCLONE 11S IS FORECAST TO TRACK WESTWARD THROUGH THE FORECAST PERIOD ALONG THE NORTHERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) TO THE SOUTH. THE SYSTEM HAS GONE THROUGH SEVERAL WEAKENING AND INTENSIFICATION CYCLES, AND THIS TREND IS EXPECTED TO CONTINUE THROUGH THE FORECAST PERIOD. TC 11S HAS SLIGHTLY WEAKENED IN RESPONSE TO EASTERLY VERTICAL WIND SHEAR (15 TO 20 KNOTS), BUT THIS SHEAR IS EXPECTED TO WEAKEN OVER THE NEXT 12 TO 24 HOURS. AFTER THIS TIME, THE SYSTEM WILL REINTENSIFY TO A PEAK OF 110 KNOTS BY TAU 72. AFTER TAU 72, SEA SURFACE TEMPERATURES ARE EXPECTED TO COOL SLIGHTLY ALONG THE FORECAST TRACK, WITH VERTICAL WIND SHEAR ONCE AGAIN INCREASING, RESULTING IN ANOTHER WEAKENING PHASE. MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH THE FORECAST PERIOD WITH AN 85 NM CROSS-TRACK SPREAD AT TAU 72 AND 275 NM BY TAU 120. THERE IS HIGH CONFIDENCE IN THE FORECAST TRACK THROUGH TAU 72. THEREAFTER, THE NAVGEM IS THE SOUTHERNMOST OUTLIER, SO THE FORECAST TRACK IS PLACED SLIGHTLY NORTH OF CONSENSUS WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE AGREES ON SLIGHT WEAKENING THROUGH TAU 24 FOLLOWED BY INTENSIFICATION THROUGH TAU 72. GIVEN THE MODERATELY LARGE SPREAD IN SOLUTIONS REGARDING PEAK INTENSITY, THERE IS MEDIUM CONFIDENCE IN THE JTWC INTENSITY FORECAST THROUGH TAU 72 AND LOW CONFIDENCE BEYOND. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN