WDPN31 PGTW 020900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (JANGMI) WARNING NR 
025//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 30.7N 130.7E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 153 NM SOUTH-SOUTHEAST OF SASEBO, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 20 KTS
   SIGNIFICANT WAVE HEIGHT: 30 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN
ACCELERATING, NEARLY FULLY EXPOSED LOW-LEVEL CIRCULATION CENTER
(LLCC) ASSOCIATED WITH TROPICAL STORM (TS) 06W (JANGMI). A MAJORITY
OF THE EXISTING DEEP CONVECTION IS NOW LOCATED POLEWARD AND
EASTWARD, WHILE MODERATE TO HIGH (20-25 KTS) VERTICAL WIND SHEAR 
HAS RESULTED IN A DECOUPLING OF THE CONVECTIVE STRUCTURE. ADDITIONAL
ENVIRONMENTAL ANALYSIS REVEALS A DRY AIR MASS POSITIONED TO THE WEST 
OF THE SYSTEM AND ASSOCIATED DRY AIR ENTRAINMENT PRIMARILY THROUGHOUT 
THE SOUTHWESTERN QUADRANT OF THE STORM. AS THE SYSTEM IS TRANSITING
DIRECTLY OVER THE WARM KUROSHIO CURRENT, THERE IS SOME RESIDUAL OCEAN 
HEAT CONTENT AVAILABLE FOR SUSTAINMENT. HOWEVER, THE SEA SURFACE
TEMPERATURES OUTSIDE OF THE WARM STREAM ARE ALREADY LOWER THAN 24
C. THE WIND FIELD IS BECOMING MORE ELONGATED, AS WITNESSED BY AN
EARLIER (020051Z METOP-C) ASCAT PASS. CONCURRENTLY, THE SYSTEM IS 
POSITIONED UNDERNEATH A PASSING UPPER LEVEL TROUGH, WHICH
SIGNIFICANTLY IMPROVES THE OUTFLOW POTENTIAL. THE INITIAL POSITION
IS PLACED WITH HIGH CONFIDENCE BASED ON THE ANIMATED MSI LOOP AND
AGENCY RADAR FIXES, WHILE THE INITIAL INTENSITY OF 50 KTS IS ALSO
ASSESSED WITH HIGH CONFIDENCE BASED ON OBJECTIVE AIDS AND AGENCY
FIXES LISTED BELOW.

INITIAL WIND RADII BASIS: A 020051Z METOP-C ASCAT PASS

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR)
CENTERED TO THE SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T3.0 - 45 KTS
   CIMSS SATCON: 45 KTS AT 020600Z
   CIMSS ADT: 37 KTS AT 020600Z
   CIMSS AIDT: 36 KTS AT 020600Z
   CIMSS D-MINT: 38 KTS AT 020455Z
   CIMSS D-PRINT: 37 KTS AT 020600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 24-25 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT FROM THE SOUTH AND WEST

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: TS 06W IS FORECAST TO CONTINUE TRACKING
NORTHEASTWARD UNDER THE INFLUENCE OF THE STR CENTERED TO THE
SOUTHEAST. THE LLCC WILL TRAVERSE THE WATERS NEAR THE SOUTHERN
COAST OF JAPAN, WITH THE STRONGEST WINDS EXPECTED PRIMARILY
THROUGHOUT THE EASTERN SEMICIRCLE. BRIEF LANDFALLS ARE POSSIBLE
OVER THE KII PENINSULA, NEAR SURUGA BAY AND NEAR TOKYO, JAPAN.
TRANSLATIONAL SPEED IS EXPECTED TO INCREASE, WHILE THE SYSTEM WILL
BEGIN ITS ETT WITHIN THE NEXT 6-12 HOURS. THE MAXIMUM INTENSITY IS
EXPECTED TO REMAIN NEAR 50 KTS, EVENTUALLY GRADUALLY WEAKENING TO
40 KTS BY THE END OF THE CURRENT FORECAST PERIOD, ONCE THE ETT IS
COMPLETED. AT THAT TIME, THE SYSTEM WILL BE POSITIONED DIRECTLY
UNDERNEATH A JET MAXIMUM, RESULTING IN DRAMATICALLY INCREASED VWS.
COLD SSTS AND CONTINUOUS DRY AIR ENTRAINMENT WILL FURTHER
ACCELERATE THE WEAKENING TREND.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN VERY GOOD
AGREEMENT IN REGARD TO THE TRACK, WITH CROSS-TRACK SPREAD OF ONLY
40 NM NEAR YOKOSUKA, JAPAN. SOME MODELS TAKE THE TRACK DIRECTLY
OVER THE CITY, WHILE THE MAJORITY ARE PLACED SLIGHTLY TO THE SOUTH AND
OVER WATER. THE JTWC OFFICIAL TRACK FORECAST IS LAID WITH HIGH 
CONFIDENCE AND NEAR THE MULTI-MODEL CONSENSUS. THE INTENSITY FORECAST 
IS ASSESSED WITH MEDIUM CONFIDENCE, AS THE STATISTICAL-DYNAMICAL 
MODELS PREDICT A MORE RAPID WEAKENING, WHILE MESOSCALE (HAFS AND 
COAMPS-TC) AND GLOBAL DETERMINISTIC (GFS) PREDICT MORE SIGNIFICANT 
WEAKENING ONLY AFTER THE SYSTEM COMPLETES THE ETT. THE JTWC FORECAST 
IS THEREFORE LAID SLIGHTLY HIGHER THAN THE CONSENSUS AVERAGE AND 
CLOSER TO THE MESOSCALE GUIDANCE.

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