Advisories

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 THE 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//
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