WDPN31 PGTW 010300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 06W (JANGMI) WARNING NR 020//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 24.5N 127.3E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 123 NM SOUTH-SOUTHWEST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 36 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS THE PREVIOUSLY 
EXPOSED LOW-LEVEL MESOVORTICES IN THE VERY BROAD CORE OF THE SYSTEM 
HAVE BECOME INCREASINGLY OBSCURED BY THE SHALLOWING CONVECTION. 
ANIMATED WATER VAPOR IMAGERY REVEALS A WEDGE OF SIGNIFICANTLY DRIER 
AIR TO THE WEST THAT HAS INTRUDED INTO THE CENTRAL CORE OVER THE PAST 
6 HOURS. THE ANIMATED SATELLITE IMAGERY ALSO PRESENTS A VIGOROUS 
POLEWARD OUTFLOW CHANNEL SUPPORTED BY A FINGER OF THE POLAR FRONT JET 
POSITIONED OVER HONSHU. A 312154Z WSFM 37 GHZ MICROWAVE IMAGE CONFIRMS 
THE DISORGANIZED CENTRAL REGION AND A LACK OF DEEP CONVECTION, 
PARTICULARLY IN THE SOUTHWEST QUADRANT. THE INITIAL POSITION IS PLACED 
WITH MEDIUM CONFIDENCE BASED ON THE ANIMATED MSI AND MICROWAVE 
IMAGERY. THE INITIAL INTENSITY OF 65 KTS IS ASSESSED WITH LOW 
CONFIDENCE DUE TO THE SPREAD IN INTENSITY ESTIMATES AND A LACK OF 
RECENT WIND SPEED DATA. THE ENVIRONMENT IS ASSESSED AS MARGINAL AS THE 
SYSTEM APPROACHES THE 26 C SEA SURFACE TEMPERATURE ISOTHERM AND DRY 
AIR ENTRAINMENT FROM THE WEST IS INCREASING. MEANWHILE, LOW VERTICAL 
WIND SHEAR (VWS) AND A ROBUST POLEWARD OUTFLOW CHANNEL ARE SEEMINGLY 
UNABLE TO OVERCOME THOSE DETRIMENTAL FACTORS.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE CENTERED NEAR IWO TO.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   RJTD: T3.5 - 55 KTS
   RCTP: T4.0 - 65 KTS
   KNES: T4.0 - 65 KTS
   CIMSS ADT: 33 KTS AT 010000Z
   CIMSS AIDT: 54 KTS AT 010000Z
   CIMSS D-MINT: 64 KTS AT 312156Z
   CIMSS D-PRINT: 55 KTS AT 010000Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 5-10 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: MODERATE DRY AIR ENTRAINMENT FROM THE WEST.

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: LOW
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TYPHOON (TY) 06W (JANGMI) CONTINUES ON A 
GENERALLY NORTHWARD TRAJECTORY AS IT WORKS ITS WAY AROUND THE STEERING 
RIDGE AXIS OVER THE NEXT 12 HOURS. THE CLOSEST POINT OF APPROACH TO 
KADENA AB IS EXPECTED AT 011000Z AS THE STILL-BROAD CENTER SKIRTS THE 
WESTERN COAST OF OKINAWA. AFTER TAU 12 THE STEERING STR TO THE EAST 
BEGINS TO MIGRATE SOUTH AND TY 06W APPROACHES THE MIDLATITUDE 
WESTERLIES, SETTING UP A STRONG GRADIENT STEERING SCENARIO THAT WILL 
ACCELERATE THE SYSTEM ON A NORTHEASTWARD TRACK. TY JANGMI IS FORECAST 
TO SKIRT THE SOUTHEASTERN COASTS OF KYUSHU AND HONSHU BEFORE THE 
CENTER PASSES OVER THE YOKOSUKA-TOKYO BAY AREA AROUND 030600Z. 
EXTRATROPICAL TRANSITION IS EXPECTED TO BEGIN AROUND TAU 48 AS THE 
SYSTEM ACCELERATES NORTHEASTWARD, BECOMING FULLY EXTRATROPICAL BY TAU 
72. THE EFFECTS OF DRY AIR ENTRAINMENT AND COOLER SST HAVE ALREADY
TRIGGERED THE WEAKENING TREND FOR 06W, AND AN IMMINENT INCREASE IN
NORTHWESTERLY WIND SHEAR AFTER TAU 12 WILL SUPPORT FURTHER WEAKENING 
DESPITE A ROBUST POLEWARD OUTFLOW CHANNEL. THAT SAID, BAROCLINIC 
FORCING DURING AND AFTER EXTRATROPICAL TRANSITION SHOULD ALLOW THE 
REMNANTS THE SYSTEM TO MAINTAIN A BROAD AREA OF GALE FORCE WINDS AS IT 
TRANSITS NORTHEASTWARD. 

MODEL DISCUSSION: MODEL TRACK GUIDANCE REMAINS IN TIGHT AGREEMENT
IN THE RECURVING AND ACCELERATING TRACK WITH 100 NM CROSS-TRACK
SPREAD AT TAU 72, EXCLUDING JGSI AND JENI AS SOUTHERN OUTLIERS IN
THE LATER TAUS. THE ALONG-TRACK SPREAD AT TAU 72 IS SIMILARLY IMPROVED 
IN THE LATEST MODEL RUN, DOWN TO 60 NM, EXCLUDING EC-AIFS AS A NOTABLY 
FAST OUTLIER. THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE MULTI-
MODEL CONSENSUS WITH HIGH CONFIDENCE. MODEL INTENSITY GUIDANCE IS IN 
GOOD AGREEMENT ABOUT THE GRADUAL WEAKENING TREND THROUGHOUT THE 
FORECAST PERIOD WITH A NOTABLE EXCEPTION OF THE DECAY SHIPS SOLUTIONS, 
WHICH SUGGEST A MUCH STEEPER WEAKENING TREND. THE JTWC INTENSITY 
FORECAST IS PLACED WITH HIGH CONFIDENCE SLIGHTLY ABOVE THE MULTI-MODEL 
CONSENSUS TO OFFSET THE SHIPS MODELS.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   INTENSITY 00-72 HR: HIGH//
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