Tropical Storm MUIFA Advisory So, 11.09.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (MUIFA) WARNING NR 019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 22.6N 124.5E
   INITIAL INTENSITY: 110 KTS
   GEOGRAPHIC REFERENCE: 295 NM SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 32 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A 20NM
ROUND EYE WITH CORE CONVECTION RAPIDLY CYCLING WITHIN THE EYEWALL.
DESPITE LINGERING OVER A SLIGHTLY COOLER (27-28C) POOL OF WATER
FROM STY 12W, TY 14W HAS CONTINUED TO STEADILY STRENGTHEN. ANIMATED
RADAR IMAGERY SHOWS SPIRAL BANDING WRAPPING TIGHTLY INTO A COMPLETE
EYEWALL SURROUNDING A SYMMETRIC EYE. THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON THE EIR IMAGERY AND HOURLY RJTD RADAR
FIXES. THE INITIAL INTENSITY OF 110 KTS IS ASSESSED WITH HIGH
CONFIDENCE BASED ON AN AVERAGE OF THE KNES, RJTD AND PGTW FIXES,
AND IS ALSO SUPPORTED BY THE CIMSS ADT ESTIMATE. THE 34-KNOT WIND
RADII HAVE BEEN ADJUSTED BASED ON A 101738Z AMSR2 WINDSPEED IMAGE
AS WELL AS CURRENT SURFACE OBSERVATIONS FROM ISHIGAKI-JIMA, WHICH ARE
LESS THAN 20 KNOTS AT THIS TIME. UPPER-LEVEL CONDITIONS REMAIN
FAVORABLE WITH RADIAL OUTFLOW AND LOW VERTICAL WIND SHEAR.
INITIAL WIND RADII BASIS: AMSR2 WINDSPEED IMAGE AND SURFACE
OBSERVATIONS
CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE
POSITIONED TO THE EAST AND NORTH-NORTHEAST
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T6.0 - 115 KTS
   RJTD: T5.5 - 102 KTS
   KNES: T5.5 - 102 KTS
   CIMSS ADT: 109 KTS AT 102330Z
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: HIGH
   INITIAL WIND RADII: MEDIUM
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, SKIRTING THE EASTERN COAST OF CHINA.
MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN TIGHT AGREEMENT
THROUGH TAU 72 LENDING HIGH CONFIDENCE TO THE JTWC TRACK FORECAST.
MODEL SPREAD VARIES FROM 75NM AT TAU 48 TO 100NM 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 ECMWF 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 110-120 KNOTS. 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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