WDIO31 PGTW 121500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 03A (THREE) WARNING NR 002// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 22.0N 65.6E INITIAL INTENSITY: 35 KTS GEOGRAPHIC REFERENCE: 185 NM SOUTH-SOUTHWEST OF KARACHI, PAKISTAN MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 03 KTS SIGNIFICANT WAVE HEIGHT: 14 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC), UNDER CIRRUS BLOWOFF EMANATING FROM DEEP CONVECTIVE ACTIVITY SHEARED TO THE WEST. TC 03A HAS PEAKED, WITH THE EARLIER POINT SOURCE ALOFT WHICH HAD ALLOWED FOR A MESOSCALE REDUCTION IN THE SHEAR, HAVING DISSIPATED, REPLACED BY THE SEASONAL STRONG TROPICAL EASTERLY JET (TEJ) ASSOCIATED FLOW PATTERN. A 121200Z F16 SSMIS 91GHZ MICROWAVE IMAGE REVEALED THE LLCC, DEVOID OF ANY SIGNIFICANT CONVECTION, AND LENT HIGH CONFIDENCE TO THE INITIAL POSITION. THE INITIAL INTENSITY REMAINS SET AT 35 KNOTS BASED IN LARGE PART ON THE CIMSS ADT ESTIMATE, ABOVE THE SUBJECTIVE DVORAK INTENSITY ESTIMATES. THE ENVIRONMENT HAS BECOME EVER MORE HOSTILE, WITH SHEAR DRAMATICALLY INCREASING TO ROUGHLY 30 KNOTS, MORE THAN SUFFICIENT TO OFFSET ANY DOWNSTREAM DIVERGENCE ALOFT AND THE WARM SSTS, AND THE FIRST HINTS OF A NOSE OF MID-LEVEL DRY AIR PUNCHING IN FROM THE EAST. THE SYSTEM LIES IN A WEAK STEERING PATTERN AND IS DRIFTING RATHER AIMLESSLY TO THE NORTH. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: WEAK STEERING PATTERN IN A COL REGION BETWEEN A SUBTROPICAL RIDGE (STR) OVER THE SAUDI PENINSULA, AN EXTENSION OF THE STR EXTENDING FROM CENTRAL CHINA TO AFGHANISTAN AND A NEAR EQUATORIAL RIDGE (NER) CENTERED SOUTHWEST OF SOUTHERN INDIA. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.0 - 30 KTS KNES: T1.5 - 25 KTS DEMS: T1.5 - 25 KTS CIMSS ADT: 35 KTS AT 121215Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY UNFAVORABLE VWS: 25-30 KTS SST: 28-29 CELSIUS OUTFLOW: MODERATE EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TRAPPED BETWEEN A SERIES OF LOW TO MID-LEVEL RIDGES DESCRIBED ABOVE, TC 03A WILL EXHIBIT ERRATIC MOVEMENT THROUGH THE DURATION OF THE FORECAST. MEAN MOTION IS EXPECTED TO BE NORTH-NORTHWESTWARD AS THE RIDGE EXTENSION TO THE NORTH RECEDES AND WEAKENS, AND THE NER PUSHES NORTH TO 10N, MOVING TC 03A NORTHWARD AS WELL. BUT SIGNIFICANT DEPARTURES FROM THIS FORECAST ARE POSSIBLE DUE TO THE LACK OF A STRONG STEERING MECHANISM. NOW THAT THE SYSTEM HAS LOST THE PROTECTION OF THE UPPER-LEVEL POINT SOURCE AND IS EXPOSED TO THE FULL FORCE OF THE TEJ WINDS ALOFT, IT IS FORECAST TO SLOWLY SUCCUMB TO THE INFLUENCE OF MODERATE TO HIGH VWS AND AN INFLUX OF MID-LEVEL DRY AIR PUSHING SOUTH OUT OF PAKISTAN. HOWEVER, DUE TO THE STRONG LOW-LEVEL SOUTHWESTERLY MONSOONAL FLOW ALONG THE SOUTHERN FLANK OF THE SYSTEM FEEDING STRONG VORTICITY INTO THE CIRCULATION, IT WILL TAKE SOME TIME FOR THE SYSTEM TO SPIN DOWN BELOW GALE FORCE, EXPECTED TO OCCUR NO LATER THAN TAU 36, POTENTIALLY AS EARLY AS TAU 24. MODEL DISCUSSION: TRACK GUIDANCE IS IN GENERAL AGREEMENT ON A SLOW DRIFT TO THE NORTHWEST THROUGH THE FORECAST PERIOD, WITH GFS TAKING THE SYSTEM FURTHEST TO THE WEST WHILE THE ECMWF FURTHEST EAST. THE JTWC FORECAST CLOSELY TRACKS THE ECMWF WITH LOW CONFIDENCE DUE TO THE VAGARIES ASSOCIATED WITH WEAK STEERING PATTERNS. INTENSITY GUIDANCE IS IN RELATIVELY GOOD AGREEMENT, WITH ALL BUT THE COAMPS-TC INDICATING A NEAR-TERM INTENSIFICATION TO 40 KNOTS FOLLOWED BY SLOW BUT STEADY WEAKENING. THE JTWC FORECAST LIES BELOW THE GUIDANCE THROUGH TAU 24 AND LIES ALONG THE CONSENSUS MEAN THEREAFTER. CONFIDENCE IN THE INTENSITY FORECAST IS MEDIUM. FORECAST CONFIDENCE: TRACK 0 - 72 HR: LOW INTENSITY 0 - 72 HR: MEDIUM// NNNN