Tropical Storm MEARI Advisory 8月13日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (MEARI) WARNING NR
007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 33.0N 136.7E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 203 NM SOUTHWEST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE LOW
LEVEL CIRCULATION (LLC) OF TS 09W REMAINS DECOUPLED AND FULLY
EXPOSED, WITH THE MAIN CONVECTION SHEARED SOUTH- TO SOUTHWESTWARD
OF THE LLC. THE EIR LOOP ALSO INDICATES SUBSIDENCE AND CONVERGENCE
ALONG THE NORTHERN HALF OF THE SYSTEM, INHIBITING CONVECTIVE
DEVELOPMENT AND INTENSIFICATION. THE INITIAL POSITION IS ASSESSED
WITH HIGH CONFIDENCE BASED ON THE EXPOSED LLC THAT LINED UP
PERFECTLY WITH A 121802Z GPM 89GHZ MICROWAVE LLC FEATURE. THE
INITIAL INTENSITY OF 35KTS IS HEDGED SLIGHTLY HIGHER THAN THE
AGENCY AND OBJECTIVE DVORAK CURRENT INTENSITY ESTIMATES AND
EXTRAPOLATED FROM RECENT SCATTEROMETRY PASSES TO REFLECT THE
SUSTAINED 6-HR EIR SIGNATURE.
INITIAL WIND RADII BASIS: SCATTEROMETER DATA.
CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF THE LOW- TO
MID-LAYER REFLECTION OF THE SUBTROPICAL RIDGE (STR) TO THE EAST.
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   CIMSS SATCON: 42 KTS AT 121701Z
   CIMSS ADT: 35 KTS AT 121740Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 20-25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG EQUATORWARD
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 MEARI WILL BEGIN TO TRACK MORE
NORTHEASTWARD AS IT ROUNDS THE NORTHWESTERN EDGE OF THE STEERING
STR, DRAG ACROSS THE SOUTHERN COAST OF HONSHU THROUGH TOKYO THEN
EXIT BACK INTO THE PACIFIC OCEAN JUST AFTER TAU 12. THE VWS IS
EXPECTED TO RELAX AND ALLOW A SLIGHT INTENSIFICATION TO A PEAK OF
40KTS AT TAUS 12 TO 24. AFTERWARD, COOLING SST AND ENTRY INTO THE
BAROCLINIC ZONE WILL GRADUALLY WEAKEN THE CYCLONE. BY TAU 36, THE
SYSTEM WILL BEGIN EXTRA-TROPICAL TRANSITION AND BY TAU 48, WILL
TRANSFORM INTO A 30-KT COLD CORE LOW. THERE IS A DISTINCT
POSSIBILITY THAT TS MEARI WILL DISSIPATE OR FALL BELOW JTWC WARNING
CRITERIA AFTER ITS PASSAGE OVER LAND.
MODEL DISCUSSION: NUMERICAL MODELS ARE IN VERY RIGHT AGREEMENT WITH
GRADUAL AND EVEN SPREAD TO 100NM BY TAU 48, LENDING HIGH CONFIDENCE
IN THE JTWC TRACK FORECAST. THERE IS, HOWEVER, LOW CONFIDENCE IN THE
INTENSITY FORECAST DUE TO THE POTENTIAL EARLY DISSIPATION.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   INTENSITY 0 - 72 HR: LOW//
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