Western Pacific:TY 20W(MINDULLE):now Typhoon CAT 4 peaking within 12/24h//North Indian:TC 03B(GULAB) slowly intensifying while approaching India,25/15utc

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TYPHOON 20W IS FORECAST TO CONTINUE TRACKING SLOWLY NORTHWESTWARD THROUGH 48H, IN A COMPETING STEERING ENVIRONMENT. THE STRENGTHENING SUBTROPICAL RIDGE(STR) CENTERED NEAR GUAM IS CREATING A TIGHTENING GRADIENT ON THE SOUTHEAST SIDE OF THE CIRCULATION, TENDING TO PUSH THE SYSTEM TO THE NORTH. HOWEVER, THE RIDGE EXTENDING EAST FROM THE STR CENTERED NEAR SHANGHAI IS BLOCKING MUCH IN THE WAY OF POLEWARD MOVEMENT FOR THE TIME BEING. THE NET RESULT WILL BE A SLOW DRIFT TO THE NORTHWEST THROUGH ABOUT 36H, WITH THE POSSIBILITY OF SHORT PERIOD OF QUASI-STATIONARY MOTION IN THE NEXT 24 HOURS. A SERIES OF MID-LATITUDE TROUGHS TRANSITING TO THE NORTH WILL ERODE THE NORTHERN RIDGE, SUCH THAT BY 48H, THE PRIMARY STEERING MECHANISM WILL SHIFT TO THE STRONG STR TO THE EAST. TY 20W WILL EJECT NORTHWARD AFTER 48H, THEN TURN NORTHEASTWARD AND ACCELERATE TO THE SOUTHEAST OF HONSHU, NOT ROUNDING THE RIDGE AXIS AS MUCH AS TURNING NORTHEAST AHEAD OF AN APPROACHING DEEP MID-LATITUDE TROUGH. THE SYSTEM HAS ABOUT ANOTHER 12 TO 24 HOURS TO FURTHER INTENSIFY BEFORE IT MOVES OVER THE COLD EDDY IN ITS PATH. THE SLOW FORWARD TRACK SPEEDS WILL ONLY SERVE TO ACCENTUATE THE UPWELLING OF COOLER WATERS, WHICH WILL SERVE TO PUT A BRAKE ON INTENSIFICATION AFTER 24H. IN THE NEAR-TERM, THE SYSTEM SHOULD BE ABLE TO PUSH BACK THE WEAK NORTHWESTERLY FLOW CURRENTLY IMPINGING ON THE NORTHWEST SIDE OF THE SYSTEM, AND IMPROVE THE OVERALL OUTFLOW. THE SYSTEM IS EXPECTED TO PEAK AT 130 KNOTS/CAT 4 "SUPER TYPHOON" AT 24H. THEN THE SYSTEM WILL STEADILY WEAKEN AS IT STRUGGLES AGAINST DECREASED OCEAN HEAT CONTENT, DECREASED OUTFLOW ALOFT AND INCREASING MID-LEVEL SHEAR. ONCE THE SYSTEM STARTS TO ACCELERATE TO THE NORTHEAST, SSTS REMAIN HIGH ENOUGH TO SUPPORT A BRIEF PERIOD OF STEADY INTENSITY TO 96H AS THE SYSTEM ONCE AGAIN TAPS INTO ROBUST POLEWARD OUTFLOW INTO THE BASE OF A STRONG MID-LATITUDE TROUGH, BUT BY 96H INCREASING SHEAR WILL BEGIN TO TAKE A TOLL, AND THE SYSTEM WILL BEGIN TO WEAKEN ONCE MORE.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TYPHOON 20W HAS UNDERGONE A SHORT PERIOD OF RAPID INTENSIFICATION OVER THE PAST SIX HOURS, WITH THE APPEARANCE OF A WELL DEFINED BUT VERY SMALL EYE IN THE EIR IMAGERY. HOWEVER, SUBSEQUENT ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE SYSTEM STRUGGLING TO MAINTAIN THE EYE AND EYEWALL STRUCTURE, PARTICULARLY ON THE NORTHWEST SIDE, WITH THE EYE WINKING IN AND OUT. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE EYE FEATURE EVIDENT AT THE 1200Z HOUR. THE INITIAL INTENSITY OF 115 KNOTS/CAT 4 IS ASSESSED WITH MEDIUM CONFIDENCE, ON THE HIGH END OF AGENCY CURRENT INTENSITY ESTIMATES FROM PGTW AND KNES. WHILE THE SATCON HAS COME UP TO A MORE REALISTIC 91 KNOTS, THE ADT STILL REFUSES TO ACKNOWLEDGE THE PRESENCE OF THE EYE, AND THUS LAGS THE REMAINDER OF THE INTENSITY ESTIMATES TO A MASSIVE DEGREE. A 250821Z SMAP FIX OF 107 KNOTS (1-MIN CONVERSION), PRIOR TO DEVELOPMENT OF A SOLID AND DEFINED EYE FEATURE, PROVIDED ADDITIONAL SUPPORT TO THE INITIAL INTENSITY. OVERALL, THE ENVIRONMENT REMAINS FAVORABLE WITH LOW VERTICAL WIND SHEAR AND STRONG POLEWARD AND EQUATORWARD OUTFLOW. THE OUTFLOW IN THE NORTHWEST SECTOR HOWEVER IS BEING IMPINGED UPON BY SOME NORTHWESTERLY FLOW ALOFT, WHICH MAY ALSO BE ENTRAINING SOME MID-LEVEL DRY AIR INTO THE WEST SIDE OF THE SYSTEM. SSTS REMAIN WARM (30C) AND OHC LEVELS HIGH FOR NOW, BUT THE SYSTEM WILL SHORTLY MOVE OVER A COLD EDDY WITH RELATIVELY LOW OHC, WHICH LIES ALONG THE FORECAST TRACK.

MODEL DISCUSSION: TRACK GUIDANCE REMAINS IN MODERATE AGREEMENT, WITH 290 KM SPREAD AT 72H BETWEEN THE ECMWF ENSEMBLE ON THE LEFT AND JGSM ON THE RIGHT. CROSS-TRACK SPREAD INCREASES TO A MODEST 390 KM BY 120H, BUT ALONG TRACK SPREAD INCREASES DRAMATICALLY AFTER 96H, UP TO 740 KM BY 120H. THE DUE TO THE UNCERTAINTY IN THE TIMING OF THE EROSION OF THE BLOCKING RIDGE TO THE NORTH AND THE EJECTION OF TY 20W TO THE NORTH, AND THE SUBSEQUENT TIMING OF THE RECURVE AND ACCELERATION TO THE NORTHEAST, THERE IS OVERALL LOW CONFIDENCE IN THE TRACK FORECAST. INTENSITY GUIDANCE REMAINS MIXED, WITH RIPA STILL BEING TRIGGERED AND THE SHIPS GUIDANCE INDICATING ADDITIONAL INTENSIFICATION TO 135 KNOTS/CAT 4 OR HIGHER. THE COAMPS-TC, HWRF AND GFS MEANWHILE INDICATE EITHER IMMEDIATE WEAKENING OR WEAKENING AFTER A SHORT INCREASE TO 12H. THE JTWC FORECAST LIES ABOVE THE CONSENSUS MEAN, BUT BELOW THE SHIPS AND RIPA GUIDANCE WITH MEDIUM CONFIDENCE.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TROPICAL CYCLONE 03B IS FORECAST TO CONTINUE TRACKING WESTWARD THROUGH THE DURATION OF THE FORECAST PERIOD, ALONG THE SOUTHERN PERIPHERY OF THE EXTENSION OF THE DEEP SUBTROPICAL RIDGE TO THE NORTH. THE SYSTEM IS EXPECTED TO MAKE LANDFALL ALONG THE INDIAN COASTLINE NORTH OF VISHAKHAPATNAM AROUND 30H. WHILE AN UPPER-LEVEL CYCLONE OVER MYANMAR CONTINUES TO RUN INTERFERENCE FOR THE SYSTEM, BLOCKING THE STRONGEST OF THE NORTHEASTERLY FLOW ALOFT, THE SYSTEM IS STILL HAVING TO BATTLE SOME LOW TO MODERATE VERTICAL WIND SHEAR. CURRENTLY, THE MODERATELY STRONG DIVERGENT OUTFLOW TO THE WEST IS OFFSETTING THE SHEAR, AND THIS GENERAL PATTERN IS EXPECTED TO CONTINUE FOR THE NEXT 24 HOURS OR SO. THIS WILL ALLOW FOR SLOW BUT STEADY INTENSIFICATION TO A PEAK OF 50 KNOTS BY LANDFALL. ONCE ASHORE, THE SYSTEM WILL RAPIDLY DISSIPATE OVER THE RUGGED TERRAIN TO THE NORTHWEST OF VISHAKHAPATNAM.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A CONSOLIDATING SYSTEM WITH A SMALL CENTRAL CORE OF FLARING CONVECTION HAVING DEVELOPED OVER THE PAST FEW HOURS. A 251049Z SSMIS 89GHZ MICROWAVE IMAGE SHOWED A BAND OF FAIRLY INTENSE CONVECTION WRAPPING IN FROM THE NORTHWEST, ALONG THE SOUTHERN SIDE OF THE CIRCULATION. THE COLORIZED VERSION OF THE SAME MICROWAVE IMAGE SHOWED WHAT APPEARED TO BE A WEAK MICROWAVE EYE, THOUGH THIS FEATURE WAS VERY CLEARLY NOT EVIDENT IN THE LOWER 36GHZ IMAGERY. ANALYSIS OF THE LOW LEVEL SPIRAL BANDS EVIDENT IN THE COLORIZED 89GHZ IMAGE LENT MEDIUM CONFIDENCE TO THE INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED AT 40 KNOTS WITH MEDIUM CONFIDENCE, HEDGED SLIGHTLY ABOVE THE PGTW CURRENT INTENSITY ESTIMATE OF T2.5 (35 KNOTS) IN LIGHT OF THE HIGHER ADT AND SATCON ESTIMATES, WHICH HOWEVER HAVE BEEN RUNNING MUCH HIGHER OVER THE PAST 24 HOURS WHEN COMPARED TO SCATTEROMETER DATA. THE ENVIRONMENT IS MARGINALLY FAVORABLE FOR INTENSIFICATION, WITH MODERATE WESTWARD, DIVERGENT OUTFLOW AND WARM SSTS. HOWEVER, THE SHARP UPSTREAM EDGE OF THE CONVECTIVE STRUCTURE IN BOTH THE EIR AND THE MICROWAVE IMAGERY SUGGESTS SOME MODERATE EAST-NORTHEAST SHEAR, THOUGH THE CIMSS ANALYSIS INDICATES ONLY 10-15 KNOTS OF SHEAR.

MODEL DISCUSSION: TRACK GUIDANCE HAS COME INTO BETTER AGREEMENT OVER THE PREVIOUS RUN, WITH ALL MODELS EXCEPT THE UKMET AND ENSEMBLE CONVERGING AROUND A DUE WEST TRACK WITH LANDFALL IN 24-30 HOURS. THE JTWC FORECAST LIES WITHIN THE TIGHTEST GROUPING OF MODELS, CLOSE TO THE CONSENSUS MEAN WITH HIGH CONFIDENCE. THE INTENSITY GUIDANCE REMAINS MIXED, WITH HWRF AND GFS INDICATING A STEADY WEAKENING TREND FROM 00H WHILE THE SHIPS AND COAMPS-TC GUIDANCE INDICATE INTENSIFICATION THROUGH 24H WITH MARKED WEAKENING THEREAFTER. THE JTWC FORECAST LIES ABOVE THE CONSENSUS MEAN, CLOSE TO THE SHIPS GUIDANCE WITH MEDIUM CONFIDENCE.

JTWC IS ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLEINTS ON BOTH 20W AND 03B.

CURRENT INTENSITY IS 105KNOTS/CAT 3 AND IS FORECAST TO PEAK AT 120KNOTS/CAT 4 BY 27/00UTC.

HU 18L(SAM). 25/1620UTC.

HU 18L(SAM). TRACK AND INTENSITY GUIDANCE.

25/1615UTC.