WDPN31 PGTW 292100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (JANGMI) WARNING NR 
011//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.7N 130.8E
   INITIAL INTENSITY: 50 KTS
   GEOGRAPHIC REFERENCE: 611 NM SOUTH-SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 26 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
GRADUALLY CONSOLIDATING, LARGE CIRCULATION WITH DEEP CONVECTION
FORMING EAST OF THE CENTER, WHICH BOASTS A 60-70 NM AREA OF LIGHT
WINDS. A 291113Z GMI PASS REVEALED A STILL-BROAD, FRAGMENTED INNER
CORE, BUT RECENT EIR IMAGERY SHOWS A DEEPENING OF THE CLOUD LAYER
ON THE POLEWARD SIDE OF THE CIRCULATION. TS 06W IS CURRENTLY
BATTLING THE SUPPRESSIVE EFFECTS OF DRY MID-HIGH-LEVEL AIR
IMPINGING ON THE CIRCULATION DUE TO NORTHEASTERLY VERTICAL WIND
SHEAR (VWS). HOWEVER, DEEP CONVECTION IS NOW EXPANDING INTO THE
UPSTREAM SIDE OF THE SHEAR, HINTING THAT THE TROPICAL STORM IS
BEGINNING TO OVERCOME THE NEGATIVE EXTERNALITIES AND WILL INTENSIFY
MORE QUICKLY IN SHORT ORDER. THE SYSTEM IS ALSO MOVING OVER WATERS
OF HIGH OCEAN HEAT CONTENT (OHC) AND VERY WARM SEA SURFACE
TEMPERATURE (SST). WITHOUT A SUCCESSFUL ASCAT PASS IN THE PAST 36
HOURS, OSCAT-3 AT 291511Z PROVIDED VALUABLE INSIGHT INTO THE
SURFACE WIND SPEEDS, SHOWING 45 KTS SURROUNDING THE CENTER AND A
TIGHTENING OF THE CORE. TS 06W HAS BECOME BETTER ORGANIZED SINCE
THE PASS, AND THEREFORE THE INITIAL INTENSITY IS RAISED TO 50 KTS
WITH HIGH CONFIDENCE, IN LINE WITH MAJORITY OF SUBJECTIVE DVORAK
FIXES OF T3.0 AND THE RISING OBJECTIVE ESTIMATES FROM CIMSS. THE
INITIAL POSITION IS ASSESSED WITH MEDIUM CONFIDENCE AS DEEP
CONVECTION OSCURES THE LOW-LEVEL CIRCULATION CENTER (LLCC).

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: MID LEVEL SUBTROPICAL RIDGE (STR)
CENTERED OVER THE MARIANA ISLANDS

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T3.0 - 45 KTS
   KNES: T3.0 - 45 KTS
   CIMSS SATCON: 51 KTS AT 291800Z
   CIMSS ADT: 39 KTS AT 291800Z
   CIMSS AIDT: 37 KTS AT 291800Z
   CIMSS D-MINT: 44 KTS AT 291658Z
   CIMSS D-PRINT: 48 KTS AT 291800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE EQUATORWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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: STEERED BY STR TO THE EAST, TS 06W WILL
CONTINUE ON A NORTHWESTWARD TRAJECTORY FOR THE NEXT 24 HOURS. A
MID-LEVEL TROUGH PASSING THE YANGTZE DELTA WILL ERODE THE NORTHERN
EXTENSION OF THE STR AND INDUCE A MORE POLEWARD TRACK FROM TAU 36
TO TAU 72, WITH THE SYSTEM PASSING VERY NEAR AND TO THE WEST OF
OKINAWA. AFTER ROUNDING THE STR AXIS, THE MID-LATITUDE WESTERLIES
WILL EXERT A STRONGER STEERING INFLUENCE. THE STORM WILL ACCELERATE
TOWARDS THE EAST AND STRADDLE THE SOUTHERN COAST OF MAINLAND JAPAN.
BASED ON THE RECENT TRENDS IN THE EIR IMAGERY, THE SYSTEM IS POISED
TO INTENSIFY MORE QUICKLY. THE FORECAST CALLS FOR A FASTER RATE OF
INTENSIFICATION TO A PEAK OF 80 KTS. AFTER TAU 48, JANGMI WILL
WEAKEN AS IT TRAVERSES OVER COOLER SST AND LOW OHC. WEST OF
OKINAWA, WESTERLY VWS OF 20-25 KTS WILL ENTRAIN DRY AIR ALOFT INTO
THE CIRCULATION AND DEGRADE THE WESTERN SIDE OF THE INNER CORE.
INTERACTION WITH THE WARMER WATERS OF THE KUROSHIO CURRENT AND THE
RIGHT ENTRANCE QUADRANT OF A JET STREAK EXTENDING FROM THE REPUBLIC
OF KOREA TO NORTHERN HONSHU WILL MODERATE THE RATE OF WEAKENING,
BUT IT WILL NOT BE ENOUGH TO OVERCOME THE UNDERMINING EFFECTS OF
DRY AIR AND SHEAR. AS TS 06W FURTHER GAINS LATITUDE, THE WIND FIELD
WILL SIGNIFICANTLY EXPAND. SUBSTANTIAL BAROCLINIC FORCING WILL
CAUSE THE SYSTEM TO UNDERGO RAPID EXTRATROPICAL TRANSITION WITH
STORM-FORCE WINDS AT TAU 120.

MODEL DISCUSSION: MODELS ARE TIGHTLY CLUSTERED FOR THE ENTIRETY OF
THE FORECAST PERIOD. NOTABLY, THE HAFS-A MODEL IS THE WESTERN
OUTLIER FOR THIS FORECAST CYCLE. THE PHYSICS-BASED MODELS SPAN THE
WESTERN SIDE OF THE SPREAD, WHILE THE AI-MODELS ARE FURTHER EAST.
MOST OF THE GUIDANCE HAS NOT CHANGED MUCH IN THE PAST 6 HOURS, AND
A STRONG MAJORITY KEEPS TS 06W WEST OF OKINAWA. THE TRACKS AT TAU
72 FROM THE AIFS AND EXPERIMENTAL GOOGLE DEEPMIND MODELS SHIFTED
EASTWARD BY 30 NM. THROUGH TAU 72, THE FORECAST TRACK IS LAID ON
THE EASTERN SIDE OF THE TIGHT CLUSTERING OF THE GFS, ECMWF,
COAMPS-TC, AND GALWEM MODELS. FOR TAU 96 AND TAU 120, THE TRACK
LEANS TOWARDS THE PHYSICS-BASED MODELS, WHICH ARE CLOSER IN
PROXIMITY TO THE SOUTHERN COAST OF HONSHU. THERE IS A QUITE A BIT
OF UNCERTAINTY IN TIMING AT THE LATER FORECAST POINTS BECAUSE THE
ALONG-TRACK SPREAD INCREASES SUBSTANTIALLY TO 260 NM AT TAU 120.
THE AI MODELS ARE FASTER, EJECTING THE STORM 200 NM EAST OF THE
KANTO PLAIN WHILE THE GFS STILL HAS IT PASSING SURUGA BAY. THE
INTENSITY FORECAST IS SET CLOSE TO THE HAFS-A, GOOGLE DEEPMIND, AND
COAMPS-TC MODELS AT TAU 12. THE INTENSITY AIDS DIVERGE FROM TAU 24
TO TAU 48, RANGING FROM THE 70 KTS OF HAFS-A TO THE 80-85 KTS OF
DEEPMIND AND COAMPS-TC. WHILE THE RAPID INTENSIFICATION AIDS HAVE
TRIGGERED AND SHOW A PEAK OF 90-105 KTS, THEY HAVE BEEN DISCOUNTED
AS UNREALISTIC, GIVEN THE SIZE AND STRUCTURE OF THE TS 06W. THE
FORECAST THEN SHOWS A GRADUAL WEAKENING TREND BUT KEEPS THE
INTENSITY AT STORM FORCE THROUGH TAU 120, CONSISTENT WITH THE GFS
AND ECMWF GLOBAL MODELS.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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