WDPN31 PGTW 272100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 06W (JANGMI) WARNING 
NR 003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 11.7N 136.7E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 156 NM NORTH-NORTHWEST OF YAP
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 15 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A
GRADUALLY CONSOLIDATING LOW LEVEL CIRCULATION CENTER (LLCC) WITH
SUSTAINED CONVECTION EXPANDING OVER THE NORTHERN SEMICIRCLE. THE
SYSTEM IS EXPANSIVE WITH A BROAD LLCC. THOUGH ASCAT DID NOT PROVIDE
WIND SPEED DATA OF THE STORM CENTER FOR THE PAST 24 HOURS, A 271501Z 
OSCAT-3 PASS REVEALED AN AREA MEASURING 140 NM IN DIAMETER OF MOSTLY 
CALM WINDS ASSOCIATED WITH THE LLCC. THE PASS SHOWED A PATCH OF 30-35 
KT WINDS IN THE SW QUADRANT, THOUGH THIS IS DISCOUNTED AS UNRELIABLE 
DUE TO RAIN ATTENUATION. MORE THAN LIKELY, 25-30 KT WINDS SPAN THE SW 
AND NE QUADRANTS BETWEEN 70 NM AND 240 NM FROM THE CENTER. 
ENVIRONMENTAL ANALYSIS INDICATES FAVORABLE CONDITIONS CHARACTERIZED BY 
LOW VERTICAL WIND SHEAR, VERY WARM SST AND HIGH OHC OF 125-150 KJ PER 
CM2, AND PLENTY OF DEEP LAYER MOISTURE. THE INITIAL POSITION IS 
ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE WIND MINIMUM OBSERVED IN 
THE OSCAT-3 PASS. THE INITIAL INTENSITY IS SET AT 30 KTS WITH MEDIUM 
CONFIDENCE BASED ON THE SAME PASS AND ALIGNS WITH THE SUBJECTIVE T2.0 
FIX FROM RJTD AND RCTP AND THE RISING OBJECTIVE ESTIMATES FROM CIMSS.

INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).

CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A LOW- TO
MID-LEVEL RIDGE TO THE EAST AND SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   KNES: T1.5 - 25 KTS
   CIMSS SATCON: 31 KTS AT 271643Z
   CIMSS ADT: 33 KTS AT 271730Z
   CIMSS AIDT: 35 KTS AT 271730Z
   CIMSS D-MINT: 26 KTS AT 271644Z
   CIMSS D-PRINT: 24 KTS AT 271830Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TD 06W IS BEING STEERED TOWARDS THE NNW BY THE
COMBINATION OF A LOW-MID LEVEL RIDGE EAST OF THE MARIANA ISLANDS
AND A RIDGE SE OF THE DEPRESSION. AS THE SYSTEM DEEPENS, A DEEP
LAYER RIDGE TO THE EAST WILL MEANDER WESTWARD AND BECOME THE
DOMINANT STEERING MECHANISM, WHILE AN ANTICYCLONE OVER SE CHINA
SHIFTS TOWARDS THE SW. THE MOVEMENT OF THESE FEATURES WILL NUDGE
THE SYSTEM MOTION TO THE NW. JANGMI WILL BEGIN TO ROUND THE AXIS OF
AND ENTER A WEAKNESS IN THE SUBTROPICAL RIDGE AT THE END OF THE
FORECAST PERIOD. THE PROXIMITY OF THE SYSTEM TO OKINAWA WILL DEPEND
ON THE TIMING AND STRENGTH OF A LOW-MID LEVEL TROUGH PASSING OVER
HONSHU. EVEN IF 06W AVOIDS A DIRECT LANDFALL ON THE RYUKYU ISLANDS,
THE SIGNIFICANT SIZE OF THE STORM WILL GENERATE IMPACTS THAT WILL
BE FELT FAR FROM THE CENTER. ENVIRONMENTAL CONDITIONS WILL BE
FAVORABLE FOR CONTINUED DEVELOPMENT THROUGH TAU 72. INITIALLY, TD
06W WILL INTENSIFY AT OR NEAR THE CLIMATOLOGICAL RATE OF ONE T-NUMBER
PER DAY. MORE RAPID INTENSIFICATION WILL COMMENCE AT TAU 36 WHEN
THE INNER CORE BECOMES ESTABLISHED. THE SYSTEM WILL ACHIEVE A PEAK
INTENSITY OF AT LEAST 95 KTS BETWEEN TAU 72 AND TAU 96, WHICH IS
NOT EXPLICITLY SHOWN IN THE FORECAST GRAPHIC. TOWARDS TAU 96, TD 06W
WILL APPROACH THE 26 DEGREE CELSIUS ISOTHERM, WHICH WILL INDUCE
WEAKENING. MORE SUBSTANTIAL WEAKENING WILL OCCUR AT TAU 120 DUE TO
THE PREVAILING COOL SST AND A DRIER ENVIRONMENT.

MODEL DISCUSSION: MODELS ARE IN TIGHT AGREEMENT THROUGH TAU 24 WITH A 
CROSS TRACK SPREAD OF 80 NM. THIS SPREAD INCREASES TO 200 NM AT TAU 72 
AND 450 NM AT TAU 120. THREE DISTINCT CLUSTERS OF MODELS BECOME 
APPARENT AT TAU 72. THE UKMET AND NAVGEM ARE THE WESTERN OUTLIERS, 
WHICH TAKE THE SYSTEM CLOSER TO MIYAKOJIMA. THE GFS, ECMWF, AND THEIR 
ENSEMBLE MEANS BRING THE SYSTEM VERY CLOSE TO OR DIRECTLY OVER 
OKINAWA. THE AI-BASED MODELS ARE FURTHER EAST BUT HAVE NOTABLY SHIFTED 
WESTWARD COMPARED TO THE PREVIOUS FORECAST. THE JTWC FORECAST TRACK IS 
PLACED NEAR THE CENTER OF THE SPREAD THROUGH TAU 72 WITH HIGH 
CONFIDENCE AND THEN LEANS TOWARDS THE EASTERN SIDE OF THE MIDDLE 
GROUPING OF THE PHYSICS-BASED MODELS WITH MEDIUM CONFIDENCE. THE 
INTENSITY FORECAST IS SET WITH MEDIUM CONFIDENCE CLOSE TO COAMPS-TC, 
WHICH MORE REALISTICALLY DEPICTS A SLOWER INITIAL RATE OF DEVELOPMENT. 
THE GFS AND THE EXPERIMENTAL GOOGLE DEEPMIND MODELS MAX THE SYSTEM AT 
95 KTS, WHILE HWRF IS THE MOST AGGRESSIVE AT 100 KTS. HAFS-A IS 
NOTABLY THE WEAKEST AT 70 KTS. VIRTUALLY ALL RELIABLE INTENSITY AIDS 
DEPICT WEAKENING AT TAU 96 AS THE SYSTEM APPROACHES OKINAWA. THE 
FORECAST CALLS FOR 90 KTS AT TAU 72 TO 96 BUT DOES NOT SHOW THE PEAK 
WHICH WILL TAKE PLACE BETWEEN THESE POINTS.

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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