Tropical Storm MUIFA Advisory 9月11日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (MUIFA) WARNING NR 018//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 22.2N 125.0E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 300 NM SOUTH-SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 07 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A 10NM
OBLONG EYE WITH CORE CONVECTION RAPIDLY CYCLING WITHIN THE EYEWALL.
A 101738Z AMSR2 89GHZ COLOR COMPOSITE MICROWAVE IMAGE AND RADAR
IMAGERY REVEAL TIGHLY CURVED BANDING WRAPPING INTO A WELL-DEFINED
EYE WITH A SMALL BREAK IN THE EYEWALL OVER THE SOUTH QUADRANT. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EIR
IMAGERY AND AMSR2 IMAGE. THE INITIAL INTENSITY OF 100 KTS IS
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE PGTW AND RJTD DVORAK
ESTIMATES. HOWEVER, A 101738Z AMSR2 WINDSPEED IMAGE INDICATES LOWER
MAXIMUM SUSTAINED WINDS OF 81-82 KNOTS. ADDING ADDITIONAL
UNCERTAINTY TO THE INITIAL INTENSITY IS THE CONTINUED LACK OF ADT
ESTIMATES DUE TO THE HIMAWARI-8 DATA PROBLEMS. UPPER-LEVEL
CONDITIONS REMAIN FAVORABLE WITH RADIAL OUTFLOW AND LOW VERTICAL
WIND SHEAR.
INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK, WHICH CORRESPONDS
FAIRLY WELL TO THE AMSR2 WINDSPEED IMAGE
CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE
POSITIONED TO THE EAST AND NORTH-NORTHEAST
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T5.5 - 102 KTS
   RJTD: T5.5 - 102 KTS
   CIMSS SATCON: 90 KTS AT 101712Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE RADIAL
ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: LOW
3. FORECAST REASONING.
SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.
FORECAST DISCUSSION: TY 14W IS TRACKING SLOWLY POLEWARD ALONG THE
WESTERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR) DUE TO
THE PRESENCE OF AN EXTENSION OF THE STR EXTENDING FROM SHIKOKU
ISLAND WESTWARD TO SHANGHAI. A NEARLY-STATIONARY SHORT-WAVE TROUGH
IS POSITIONED OVER NORTHEAST CHINA WITH A WIND MAXIMUM OVER THE
LEADING EDGE OF THE TROUGH PUSHING INTO SOUTH KOREA. THIS SHORTWAVE
TROUGH IS WEAK WITH NEUTRAL TEMPERATURE ADVECTION AND PVA WELL TO
THE NORTH OF THE SYSTEM, THEREFORE, NOT DYNAMIC ENOUGH TO BREAK
DOWN THE STR TO THE NORTH. CONSEQUENTLY, TY 14W IS FORECAST TO
CONTINUE ITS SLOW TREK NORTHWARD THROUGH TAU 72. THE SYSTEM WILL
CONTINUE TO STEADILY INTENSIFY THROUGH TAU 24 WITH A PEAK INTENSITY
OF 120 KNOTS THEN STEADY WEAKENING AS THE SYSTEM BECOMES EMBEDDED
WITHIN BROAD UPPER-LEVEL TROUGHING EXTENDING FROM SOUTHEAST CHINA.
POLEWARD OUTFLOW IS ALSO EXPECTED TO DEGRADE AS THE UPPER-LEVEL
TROUGH WEAKENS AND THE STR BUILDS OVER WESTERN JAPAN AND THE EAST
CHINA SEA, SHIFTING THE JET FURTHER NORTH OVER NORTH KOREA. AFTER
TAU 72, TY 14W WILL ACCELERATE NORTH-NORTHWESTWARD AS THE STR
STRENGTHENS.
MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT
THROUGH TAU 72 LENDING HIGH CONFIDENCE TO THE JTWC TRACK FORECAST.
MODEL SPREAD VARIES FROM 40NM AT TAU 48 TO 55NM AT TAU 72. THE
PROBABILISTIC GUIDANCE (EPS AND GEFS) ALSO SHOWS GOOD AGREEMENT
WITH THE BULK OF THE SOLUTIONS SUPPORTING THE JTWC TRACK FORECAST.
AFTER TAU 72, THE MODELS DIVERGE WITH INCREASING UNCERTAINTY IN THE
EXACT TRACK. GFS AND NAVGEM DRIVE THE SYSTEM OVER EASTERN CHINA
WHILE THE REMAINING GUIDANCE SKIRTS THE COAST THUS MEDIUM
CONFIDENCE. THERE IS MEDIUM CONFIDENCE IN THE JTWC INTENSITY
FORECAST WITH RELIABLE GUIDANCE IN FAIR AGREEMENT. HWRF INDICATES A
PEAK OF 100 KNOTS WHILE COAMPS-TC (GFS AND NAVGEM VERSIONS) IS
AROUND 110-115 KNOTS. ALTHOUGH LIMITED RAPID INTENSIFICATION
GUIDANCE (RI45) TRIGGERED, THE EPS AND GEFS ENSEMBLES INDICATE VERY
LOW (10 PERCENT) TO NIL PROBABILITY OF RAPID INTENSIFICATION. AFTER
TAU 72, THE INTENSITY GUIDANCE IS IN FAIR AGREEMENT WITH LOW
CONFIDENCE IN THE JTWC INTENSITY FORECAST DUE TO THE INCREASING
INTERACTION WITH LAND AND INTERACTION WITH THE UPPER-LEVEL TROUGH.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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