Tropical Storm IN-FA Advisory Fr, 23.07.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 09W (IN-FA) WARNING NR 028//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 24.1N 125.3E
   INITIAL INTENSITY: 75 KTS
   GEOGRAPHIC REFERENCE: 198 NM SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 35 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND A 222236Z SSMIS
SERIES SHOWS THE EYE OF TY 09W WEAKENING OVER THE POLEWARD
SEMICIRCLE. ANIMATED WATER VAPOR IMAGERY SHOWS INCREASING PRESSURE
ON THE OUTFLOW OVER THE NORTHWESTERN QUADRANT. THE HWRF-P COUPLED
MODEL SHOWS INCREASING COOLING OF THE SEA SURFACE AROUND THE CORE
DUE TO THE CHURNING CAUSED BY THE RELATIVELY SLOW MOVEMENT OF THE
SYSTEM. THE UPWELLING, SUPPRESSED OUTFLOW, AND DISSIPATION OF ENERGY
INDICATED BY THE EXPANSIVE EYE SEEM TO BE ACTING AS BRAKING
MECHANISMS ON THE INTENSITY OF THE SYSTEM. THE CURRENT INTENSITY
ASSESSMENT IS BASED ON MULTIPLE AGENCY DVORAK ESTIMATES AND AN ADT
EVALUATION OF 74KTS. TY 09W IS UNDERWAY ON ITS NORTHWESTERLY LEG
THROUGH TAU 48 AND IS STEERING ALONG THE SOUTHWESTERN PERIPHERY OF A
DEEP LAYER RIDGE.
INITIAL WIND RADII BASIS: PERSISTENCE.
CURRENT STEERING MECHANISM: THE SOUTHWESTERN PERIPHERY OF A
DEEP-LAYERED SUBTROPICAL RIDGE (STR) CENTERED JUST OFF THE EAST
COAST OF NORTH KOREA.
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T4.5 - 77 KTS
   RJTD: T5.0 - 90 KTS
   RCTP: T4.5 - 77 KTS
   KNES: T4.5 - 77 KTS
   CIMSS ADT: 74 KTS AT 222340Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 0-5 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD
ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: LOW
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: PRESSURE FALLS REPORTED OVER THE SOUTHERN
SENKAKU ISLANDS VERIFY THE APPROACH OF TYPHOON IN-FA. THE SYSTEM
HAS CLOCKED A LITTLE MORE TO THE RIGHT DURING THE PAST SIX HOURS
AND IS NOW EXPECTED TO TRACK BETWEEN ISHIKAKIJIMA AND MIYAKOJIMA
DURING THE NEXT 24 HOURS. ONCE CLEARING THE RYUKUS, COOLER WATERS ON
COUPLED WITH INCREASING VERTICAL WIND SHEAR WILL PUT THE SYSTEM ON A
WEAKENING TREND THROUGH THE DURATION OF ITS TRACK INTO EASTERN
CHINA. IT IS EXPECTED TO COME ASHORE AT SEVERE TROPICAL STORM
STRENGTH.
MODEL DISCUSSION: TRACK GUIDANCE HAS COME INTO SHARPER FOCUS
REGARDING A LEFT TURN NORTH OF THE 28TH LATITUDE AND LANDFALL SOUTH
OF SHANGHAI. IT HAS, HOWEVER, CLOCKED A LITTLE MORE TO THE
NORTH-NORTHWEST OVER THE PAST TWO CYCLES AND FIXES ARE VERIFYING
THAT TREND. THE ECMWF ENSEMBLE MEAN CONTINUES TO LOCK INTO THE
LANDFALL SCENARIO WHICH MATCHES THE JTWC FORECAST, WHILE THE GEFS
ENSEMBLE IS SHOWING AN INCREASING AMOUNT OF MEMBERS STAYING
OFF-SHORE AND TRACKING TOWARDS THE YELLOW SEA. INTENSITY GUIDANCE
SHOWS A MODERATE INTENSIFICATION DURING THE NEXT 24-36 HOURS, THEN
A SHARP DECAY AS THE SYSTEM MAKES ITS WESTWARD BEND. THE INTENSITY
FORECAST STAYS ON THE HIGH SIDE OF THE ENSEMBLE MEAN DURING THE
FIRST 24 HOURS THEN COMES INTO THE MEAN AT TAU 72.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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