Tropical Storm IN-FA Advisory 7月26日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (IN-FA) WARNING NR
039//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 30.5N 121.6E
   INITIAL INTENSITY: 45 KTS
   GEOGRAPHIC REFERENCE: 42 NM SOUTH OF SHANGHAI, CHINA
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 20 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE SYSTEM
CONTINUED TO ERODE AS IT IS ABOUT TO MAKE 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 45KTS IS BASED ON OVERALL ASSESSMENT
OF AGENCY DVORAK AND AUTOMATED FIXES AND EXTRAPOLATED FROM NEARBY
WIND AND PRESSURE OBSERVATIONS AND CONSISTENT WITH THE DEGRADED EIR
SIGNATURE.
INITIAL WIND RADII BASIS: RECENT SCATTEROMETER DATA.
CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
NORTHEAST.
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T3.5 - 55 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T3.5 - 55 KTS
   KNES: T4.0 - 65 KTS
   CIMSS ADT: 43 KTS AT 251740Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 5-10 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: MODERATE 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 09W WILL CONTINUE NORTHWESTWARD AND MAKE
LANDFALL BY TAU 06, TRACK INLAND THEN RECURVE NORTHEASTWARD AFTER
TAU 48 AS IT ROUNDS THE WESTERN EDGE OF THE STR. LAND INTERACTION
WILL MOSTLY BE RESPONSIBLE FOR ITS GRADUAL DECAY DOWN TO 25KTS BY
TAU 120 AS IT REACHES THE 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.
MODEL DISCUSSION: NUMERICAL MODELS ARE IN FAIRLY GOOD AGREEMENT UP
TAU 72. AFTERWARD, THE MODELS WIDELY SPREAD ALONG AND ACROSS-TRACK,
LENDING MEDIUM CONFIDENCE IN THE JTWC TRACK FORECAST UP TO TAU 72
THEN LOW CONFIDENCE AFTERWARD. THERE IS LOW CONFIDENCE IN THE
INTENSITY FORECASTS DUE TO THE UNCERTAINTY IN THE TOPOGRAPHICAL
EFFECTS.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: LOW
   INTENSITY 72-120 HR: LOW//
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