WDPN31 PGTW 060900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (KROVANH) 
WARNING NR 021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.5N 130.2E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 143 NM EAST-SOUTHEAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: EASTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
DEPRESSION 22W (KROVANH) WITH A MOSTLY EXPOSED LOW-LEVEL
CIRCULATION CENTER (LLCC) WITH WEAK FLARING CONVECTION ALONG THE
SOUTHERN SEMICIRCLE. THE LLCC APPEARS TO BE FURTHER SEPARATING FROM
THE CONVECTION DUE TO THE MODERATE EASTERLY CURRENTLY SHEAR
IMPACTING THE SYSTEM. THE INITIAL POSITION IS PLACED WITH HIGH
CONFIDENCE BASED ON THE ANIMATED MSI. THE INITIAL INTENSITY OF 30
KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED PRIMARILY ON THE
AGENCY DVORAK CI ESTIMATES OF T2.0 FROM ALL AGENCIES. ENVIRONMENTAL
ANALYSIS INDICATES THAT 22W IS IN A MARGINAL ENVIRONMENT
CHARACTERIZED BY MODERATE POLEWARD OUTFLOW ALOFT, 15-20 KTS
EASTERLY SHEAR, DRY AIR ENTRAINMENT, AND WARM (29-30 C) SEA SURFACE
TEMPERATURES.

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

CURRENT STEERING MECHANISM: THE NORTHERN PERIPHERY OF AN ELONGATED
NEAR EQUATORIAL RIDGE (NER) POSITIONED TO THE SOUTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   CIMSS SATCON: 42 KTS AT 060456Z
   CIMSS ADT: 37 KTS AT 060540Z
   CIMSS AIDT: 36 KTS AT 060540Z
   CIMSS D-MINT: 30 KTS AT 060514Z
   CIMSS D-PRINT: 28 KTS AT 060540Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT FROM THE WEST

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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 22W IS FORECAST TO TRACK GENERALLY EASTWARD
TO EAST-NORTHEASTWARD THROUGH TAU 12 ALONG THE NORTHERN PERIPHERY
OF THE NER TO THE SOUTH. AFTER TAU 12, THE SYSTEM IS EXPECTED TO
MAKE A POLEWARD TURN AS IT RUNS INTO THE SUBTROPICAL RIDGE CENTERED
TO THE SOUTHEAST OF JAPAN. THE POLEWARD TRACK IS THEN FORECAST TO
PERSIST THROUGH TAU 48. FOLLOWING TAU 48, THE TRAJECTORY IS
EXPECTED TO BECOME MORE NORTHEASTWARD AS THE SYSTEM TRACKS ALONG
THE NORTHWESTERN EXTENT OF THE RIDGE. 22W IS FORECAST TO SKIRT THE
SOUTHERN COAST OF JAPAN AFTER TAU 60 WITH THE REMNANT VORTEX
TRACKING ALONG THE COAST, SOUTH OF KYOTO, AROUND TAU 72.  IN TERMS
OF INTENSITY, 22W IS FORECAST TO MAINTAIN ITS CURRENT INTENSITY OF
30 KTS THROUGH TAU 36 UNDER THE EFFECTS OF THE MARGINAL
ENVIRONMENT. AFTER TAU 36, SOUTHERLY SHEAR AND DRY AIR ENTRAINMENT
WILL INCREASE, CAUSING 22W TO WEAKEN AS IT APPROACHES JAPAN.
DISSIPATION IS FORECAST TO OCCUR AT AROUND TAU 72, AS THE SHALLOW
AND ELONGATED VORTEX ACCELERATES NORTHEASTWARD. 

MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT THROUGH
TAU 48 WITH A CROSS-TRACK SPREAD OF 70 NM AND THE ONLY OUTLIER
BEING HAFS-A, WHICH TRACKS THE VORTEX SIGNIFICANTLY QUICKER TO THE
NORTHEAST. AFTER TAU 48, THE ALONG-TRACK SPREAD QUICKLY INCREASES.
THE JGSM AND NAVGEM ARE AMONG THE SLOWEST TO ROUND THE RIDGE WHILE
THE GFS AND ECMWF ARE MUCH FASTER. THE JTWC TRACK FORECAST IS
PLACED NEAR THE CONSENSUS THROUGH TAU 48 AND THEN CLOSER TO THE
ECMWF DETERMINISTIC TRACKER THROUGH TAU 72 WITH MEDIUM CONFIDENCE.
INTENSITY GUIDANCE IS SLIGHTLY SPLIT, WITH THE COAMPS-TC AND HAFS-A
BOTH SHOWING A SLIGHT INTENSIFICATION TO AROUND 40 KTS AT TAU 72.
HOWEVER, IT IS WORTH NOTING THAT THE HAFS-A IN PARTICULAR SHOWS A
SIGNIFICANTLY DIFFERENT TRACK. IT HAS A MUCH FASTER TRACK SPEED AND
JUMPS THE VORTEX INTO THE DEVELOPING FRONTAL BOUNDARY NORTHEAST OF
JAPAN. THE REMAINDER OF GUIDANCE SHOWS A GRADUAL WEAKENING TREND.
THE JTWC INTENSITY FORECAST IS PLACED CLOSER TO THE GFS AND GOOGLE
DEEPMIND ENSEMBLE MEAN THROUGHOUT THE FORECAST PERIOD WITH MEDIUM
CONFIDENCE.

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