Tropical Storm KULAP Advisory Mi, 28.09.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (KULAP) WARNING NR
010//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 32.1N 145.3E
   INITIAL INTENSITY: 60 KTS
   GEOGRAPHIC REFERENCE: 339 NM EAST-SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS TS 19W HAS
BECOME BETTER CONSOLIDATED AND ORGANIZED WITH DEEP CONVECTION
WRAPPING INTO A PERSISTENT CLOUD STRUCTURE, WHICH IS OBSCURING THE
LOW LEVEL CIRCULATION CENTER (LLCC). AN EARLIER 271930Z SSMIS 91GHZ
MICROWAVE IMAGE DEPICTS FORMATIVE DEEP CONVECTIVE BANDS OVER THE
NORTHWEST QUADRANT WRAPPING INTO THE LLCC. THE INITIAL POSITION IS
PLACED WITH HIGH CONFIDENCE BASED ON A BULLSEYE ASCAT PASS. A
280036Z METOP-C ASCAT IMAGE SHOWS A SWATH OF 55-60 KNOT WINDS OVER
THE SOUTHEASTERN SEMICIRCLE WITH SLIGHTLY WEAKER WINDS OVER THE
WESTERN QUADRANTS. THE INITIAL INTENSITY OF 60 KTS IS ASSESSED WITH
HIGH CONFIDENCE BASED ON THE METOP-C ASCAT PASS. ALONG WITH A BLEND
OF THE AGENCY DVORAK INTENSITIES FROM PGTW T3.5, RJTD T3.5, AND
KNES AT T3.5.
INITIAL WIND RADII BASIS: PERSISTENCE
CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED TO THE EAST
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T3.5 - 55 KTS
   RJTD: T3.5 - 55 KTS
   KNES: T3.5 - 55 KTS
   CIMSS ADT: 51 KTS AT 272340Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 20-25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD
ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: HIGH
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TS 19W CONTINUES TO TRACK AROUND THE OUTER
PERIPHERY OF THE DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED TO THE
EAST AND HAS CONTINUED TO ACCELERATE TOWARD THE NORTHEAST.
ADDITIONALLY, A DEEP SHORTWAVE TROUGH UPSTREAM IS EXPECTED TO ERODE
AND WEAKEN THE STR TO THE EAST, WHICH WILL ULTIMATELY ALLOW 19W TO
CONTINUE TO ACCELERATE NORTHEASTWARD. BY TAU 24, THE SYSTEM WILL
INTENSIFY TO A MAXIMUM WIND SPEED OF 70 KNOTS, AS STRONG SHEAR IS
OFFSET BY VERY STRONG DIVERGENT POLEWARD OUTFLOW ALOFT. AFTER TAU 24,
AS THE SYSTEM BEGINS TO INTERACT WITH THE DEEP SHORTWAVE TROUGH, THE
SYSTEM WILL ALSO INDUCE WARM AIR ADVECTION WHICH WILL AMPLIFY AND
DEEPEN THE SHORTWAVE UPPER-LEVEL TROUGH. AS THIS OCCURS THE TROUGH
WILL BECOME NEGATIVELY TILTED WHICH WILL ALLOW 19W TO BEGIN TO
UNDERGO EXTRA-TROPICAL TRANSITION (ETT). BY TAU 36, THE SYSTEM WILL
COMPLETE EXTRA-TROPICAL TRANSITION (ETT) AS IT GAINS FRONTAL
CHARACTERISTICS AND BECOMES A WARM SECLUSION TYPE EXTRA-TROPICAL
LOW, WHILE DECREASING ITS INTENSITY SLIGHTLY DUE TO COOLER SEA
SURFACE TEMPERATURE VALUES (25-26C) AND STRONG VERTICAL WIND SHEAR.
MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE ARE IN VERY GOOD
AGREEMENT WITH ONLY A GRADUAL SPREAD TO 200NM MODEL TRACK SOLUTIONS
BY TAU 36. THIS IS LIKELY DUE TO HOW NUMERICAL MODELS ARE HANDLING
LARGE SCALE DEEP SHORTWAVE UPPER LEVEL TROUGHS. BECAUSE OF THIS, SOME
INTERACTIONS WITH 19W ARE BEHAVING DIFFERENTLY. OVERALL, THE JTWC
TRACK FORECAST IS ASSESSED WITH HIGH CONFIDENCE, WITH THE JTWC
TRACK FORECAST REMAINING CLOSE TO THE MULTI-MODEL CONSENSUS. THE
INTENSITY FORECAST IS ASSESSED WITH MEDIUM CONFIDENCE WITH A BLEND
BETWEEN THE HWRF AND GFS NUMERICAL MODEL GUIDANCE. THEREFORE, THE
JTWC INTENSITY FORECAST REMAINS CLOSE TO THE MULTI-MODEL CONSENSUS
FOR THE NEXT 12 HOURS, BEFORE REMAINING ABOVE THE CONSENSUS THROUGH
OUT THE FORECAST PERIOD.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: MEDIUM//
NNNN
NNNN