Western Pacific: the cyclonic pair 09W & 11W still monitored, Eastern Pacific/Atlantic: Tropical Cyclone Formation Alerts re-issued, 26/03utc updates

JTWC HAS BEEN ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON 09W AND 11W.

TS 09W(IN-FA). WARNING 40 ISSUED AT 26/03UTC.THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TS 09W WILL CONTINUE WEST-NORTHWESTWARD INTO THE CHINESE INTERIOR THEN RECURVE NORTHEASTWARD AFTER 48H AS IT ROUNDS THE WESTERN EDGE OF THE SUBTROPICAL RIDGE. LAND INTERACTION WILL MOSTLY BE RESPONSIBLE FOR ITS GRADUAL DECAY DOWN TO 25KNOTS BY 120H AS IT REACHES THE TIP OF SHANDONG PENINSULA AND POISED TO MAKE AN EXIT INTO THE GULF OF POHAI. THERE IS, HOWEVER, A POSSIBILITY THAT THE SYSTEM WILL DISSIPATE OVER LAND.

09W(IN-FA).SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM CONTINUED TO ERODE AS IT MADE LANDFALL JUST SOUTH OF SHANGHAI. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON A DEFINED LOW LEVEL CIRCULATION FEATURE IN A CMA COMPOSITE RADAR LOOP. THE INITIAL INTENSITY OF 40KNOTS IS BASED ON EXTRAPOLATION FROM RECENT AGENCY DVORAK AND AUTOMATED FIXES AND EXTRAPOLATED FROM NEARBY WIND AND PRESSURE OBSERVATIONS AND CONSISTENT WITH THE DEGRADED METSAT SIGNATURE.

09W(IN-FA).MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIRLY GOOD AGREEMENT UP 72H. AFTERWARD, THE MODELS WIDELY SPREAD ALONG AND ACROSS-TRACK, LENDING MEDIUM CONFIDENCE IN THE JTWC TRACK FORECAST UP TO 72H THEN LOW CONFIDENCE AFTERWARD. THERE IS LOW CONFIDENCE IN THE INTENSITY FORECASTS DUE TO THE UNCERTAINTY IN THE TOPOGRAPHICAL EFFECTS.

STS 11W(NEPARTAK). WARNING 11 ISSUED AT 26/03UTC. THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: SUBTROPICAL CYCLONE 11W WILL CONTINUE TO TRACK NORTHWESTWARD UNDER THE STEERING SUBTROPICAL RIDGE ON A PINWHEEL PATTERN AROUND AN UPPER LEVEL LOW TO THE SOUTHWEST, MAKING LANDFALL OVER NORTHERN HONSHU NEAR KESENNUMA, JAPAN, NEAR 48H. THE MARGINAL ENVIRONMENT - STRONG VERTICAL WIND SHEAR OFFSET BY STRONG POLEWARD OUTFLOW AND WARM SST - WILL FUEL A SLIGHT INTENSIFICATION TO 40KNOTS AT 24-36H. AFTERWARD, THE UPPER LEVEL LOW WILL COME INTO CLOSE PROXIMITY OF 11W AND PROMOTE SUBSIDENCE ALOFT AND INDUCE THE INFLOW OF COLD DRY AIR IN THE LOWER LEVELS. THESE PLUS THE TOPOGRAPHICAL EFFECTS AFTER LANDFALL WILL GRADUALLY ERODE THE SYSTEM DOWN TO 25KNOTS BY THE TIME IT EXITS INTO THE SEA OF JAPAN (SOJ) BEFORE 96H. THE COOLER SSTS IN THE SOJ FOLLOWED BY A SECONDARY LANDFALL INTO HOKKAIDO AFTER THE SYSTEM RECURVES NORTHEASTWARD AROUND THE STR AXIS WILL FURTHER ERODE 11W TO DISSIPATION BY 96H.

11W(NEPARTAK).SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS A SUBTROPICAL SYSTEM WITH A BROAD, LONG SWATH OF CONVECTION CURLING INTO AN ELONGATED, NARROW, AND PARTLY EXPOSED LOW LEVEL CIRCULATION (LLC). THE MULTIPLE VORTICES OBSERVED PRIOR TO THIS WARNING CYCLE HAVE COALESCED INTO THIS LLC, WHICH WAS THE CENTROID THAT WAS BEING TRACKED BY JTWC. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE ON THIS LLC WHICH WAS PARTIALLY CAPTURED BY A 252320Z ASCAT PASS. THE INITIAL INTENSITY OF 35KNOTS IS BASED ON PATCHES OF 35-KT WIND BARBS DEPICTED IN THE ASCAT PASS OVER 220KM NORTHEASTWARD FROM THE LLC UNDER THE SWATH OF CONVECTION. ALTHOUGH NOT REPRESENTATIVE OF THE STORM POSITION, THE INITIAL INTENSITY IS SUPPORTED BY THE PGTW DVORAK AND THE ADT AUTOMATED FIXES.

11W(NEPARTAK).MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT BUT GIVEN THE BROAD COMPLEXITY OF A SUBTROPICAL CYCLONE AND THE UNCERTAINTY OF A LAND PASSAGE, THERE IS MEDIUM CONFIDENCE IN THE JTWC TRACK AND INTENSITY FORECASTS UP TO 72H, THEN LOW CONFIDENCE AFTERWARD.

EASTERN PACIFIC. INVEST 98E. TROPICAL CYCLONE FORMATION ALERT RE-ISSUED AT 26/01UTC.N AREA OF CONVECTION PREVIOUSLY LOCATED NEAR 13.1N 130.3W IS NOW LOCATED NEAR 13.2N 136.5W, APPROXIMATELY 2430 KM EAST- SOUTHEAST OF HONOLULU, HAWAII. ANIMATED MULTISPECTRAL SATELLITE IMAGERY AND A 252203Z ATM 88 GHZ MICROWAVE PASS DEPICT AN IRREGULAR LOW LEVEL CIRCULATION (LLC) WITH DEEPENING CONVECTION TO THE NORTH AND ALONG A FRAGMENTED SOUTHERN BAND. A 251822Z ASCAT-B IMAGE SHOWS AN ELONGATED CIRCULATION WITH 25 KNOT WIND BARBS IN THE NORTHERN SEMI-CIRCLE, LIKELY ASSOCIATED WITH THUNDERSTORM ACTIVITY, AND LOWER WIND BARBS ELSEWHERE. ENVIRONMENTAL ANALYSIS INDICATES INVEST 98E IS LOCATED IN AN AREA FAVORABLE FOR DEVELOPMENT WITH GOOD POLEWARD OUTFLOW ALOFT, WEAK VERTICAL WIND SHEAR (10-15KTS) AND WARM SEA SURFACE TEMPERATURES (28-29C). MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 20 TO 25 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1004 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS HIGH.

INVEST 98E. GUIDANCE.

ATLANTIC. INVEST 90L. TROPICAL CYCLONE FORMATION ALERT RE-ISSUED AT 25/15UTC.

INVEST 90L. GUIDANCE.

26/03UTC.

26/00UTC.

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