Western Pacific: 09W(IN-FA) Cat1 Typhoon forecast to landfall South of Shanghai, 11W(NEPARTAK) still subtropical//Eastern Pacific & Atlantic: TCFA issued for Invest 98E & Invest 90L, 25/03utc updates

JTWC HAS BEEN ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON 09W AND 11W. SATELLITE BULLETINS WERE DISCONTINUED FOR 10W AT 24/15UTC.

09W(IN-FA). WARNING 36 ISSUED AT 25/03UTC.THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TYPHOON 09W WILL TURN MORE WESTWARD AFTER 12H AND MAKE LANDFALL JUST SOUTH OF SHANGHAI, TRACK INLAND, THEN RECURVE NORTHEASTWARD AFTER 72H IF IT MAINTAINS ITS LOW LEVEL STRUCTURE. THE DEGRADING ENVIRONMENT CAUSED BY COOLING SSTS AND LAND INTERACTION WILL GRADUALLY THEN RAPIDLY WEAKEN THE SYSTEM DOWN TO 25KNOTS BY 120H AS IT APPROACHES THE YELLOW SEA.

09W(IN-FA).SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS FEEDER BAND CONVECTIVE TOPS CONTINUED TO WARM UP AND UNRAVEL; HOWEVER THE CENTRAL DENSE OVERCAST FEATURE REMAINS INTACT AND MAINTAINED A LARGE 75KM RAGGED EYE. THE INITIAL INTENSITY IS PLACED WITH HIGH CONFIDENCE BASED ON THE EYE THAT WAS COINCIDED WITH AN LOW LEVEL CENTER FEATURE IN A CMA COMPOSITE RADAR LOOP. THE INITIAL INTENSITY OF 65KNOTS/CAT 1 IS ASSESSED WITH HIGH CONFIDENCE BASED ON OVERALL ASSESSMENT OF AGENCY AND AUTOMATED DVORAK FIXES TO REFLECT THE DETERIORATING CONVECTIVE STAGE BUT MAINTAINED THE TYPHOON INTENSITY.

TY 09W(IN-FA). 25/0457UTC.

09W(IN-FA).MODEL DISCUSSION: NUMERICAL MODELS DIVERGE SIGNIFICANTLY AFTER LANDFALL, SPREADING OUT TO OVER 480KM BY 72H THEN DIVERGE SIGNIFICANTLY AFTERWARD, LENDING HIGH CONFIDENCE TO THE JTWC TRACK FORECAST UP TO 72H ONLY. THE SPREAD NARROWS DOWN TO UNDER 370KM BY 120H BUT ALONG-TRACK SPEEDS WIDELY VARY.

11W(NEPARTAK). WARNING 7 ISSUED AT 25/03UTC.THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: SUBTROPICAL SYSTEM 11W WILL CONTINUE ON ITS CURRENT TRACK MORE NORHTWESTWARD UNDER THE SUBTROPICAL RIDGE. THE MARGINAL ENVIRONMENT WILL SUSTAIN THE CURRENT INTENSITY FOR UP TO 24HRS AS STRONG OUTFLOW AND WARM SSTS OFFSET THE STRONG VERTICAL WIND SHEAR(VWS). AFTERWARD, THE CYCLONE WILL WEAKEN TO TROPICAL DEPRESSION INTENSITY AND STRUGGLE TO MAINTAIN ITS CORE AS THE LARGE LOW LEVEL CIRCULATION BECOMES MORE IRREGULAR AND UNWIELDY UNDER VERY STRONG VWS. ADDITIONALLY, AN UPPER LEVEL LOW WILL STACK OVER THE SYSTEM AFTER 48H AND CAUSE SUBSIDENCE ALOFT AND STREAM COLD DRY AIR IN THE LOWER LEVELS. SHOULD 11W MAINTAIN ITS CORE, IT WILL MAKE LANDFALL OVER HONSHU NEAR 60H IN THE VICINITY OF IWAKI AND CROSS INTO THE SEA OF JAPAN (SOJ) SHORTLY AFTER 72H. THE UNUSUALLY WARM SOJ MAY REVIVE IT 30KNOTS. THERE IS NOW A DISTINCT POSSIBILITY THAT THE SYSTEM WILL DISSIPATE IN THE NEAR TERM UNDER THE INTENSE VWS AND THE ANTICIPATED NEGATIVE EFFECTS OF THE UPPER LEVEL LOW.

11W(NEPARTAK).SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE LOW LEVEL CIRCULATION (LLC) IS NOW FULLY EXPOSED. IT IS WEAK AND RAGGED WITH THE MAIN CONVECTION SHEARED OVER 185KM NORTHEASTWARD. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE LLC IN THE MSI LOOP. THE INITIAL INTENSITY OF 35 KNOTS IS ASSESSED WITH LOW CONFIDENCE BASED ON THE PGTW DVORAK THAT IS BASED ON SUBTROPICAL METHOD.

11W(NEPARTAK).MODEL DISCUSSION: NUMERICAL MODELS DIVERGE SIGNIFICANTLY ACROSS- AND ALONG-TRACK SPREADING OUT TO OVER 700KM BY 48H AND OVER 1280KM BY 120H. ECMF OFFERS A TRUNCATED SOLUTION, TERMINATING THE FORECAST TRACK AT 36HRS. THESE VARYING SOLUTIONS MAY INDICATE THE MODELS ARE HAVING DIFFICULTY TRACKING MULTIPLE WEAK VORTICES.

EASTERN PACIFIC. INVEST 98E. TROPICAL CYCLONE FORMATION ALERT ISSUED AT 25/01UTC.AN AREA OF CONVECTION (INVEST 98E) HAS PERSISTED NEAR 131.2N 130.3W, APPROXIMATELY 3055 KM EAST-SOUTH EAST OF HONOLULU, HAWAII. ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A 242227Z AMSR2 PARTIAL MICROWAVE PASS DEPICT AN EXPOSED LOW LEVEL CIRCULATION (LLC) WITH CONSOLIDATING AND DEEPENING CONVECTION DISPLACED TO THE NORTHWEST. UPPER AIR ANALYSIS INDICATES 98E IS LOCATED IN AN AREA FAVORABLE FOR DEVELOPMENT WITH WEAK VERTICAL WIND SHEAR (05-10KTS) AND WARM SEA SURFACE TEMPERATURES(29-30 C). MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1009 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS HIGH.

INVEST 98E. GUIDANCE.

ATLANTIC. INVEST 90L. TROPICAL CYCLONE FORMATION ALERT ISSUED AT 24/15UTC.

INVEST 90L. GUIDANCE.

25/00UTC.

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