Advisories

WDPN31 PGTW 070300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (KROVANH) 
WARNING NR 024//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 26.2N 132.1E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 232 NM EAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: 
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A SHALLOW, BUT 
SYMMETRIC, MOSTLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH 
FLARING SHALLOW CONVECTION WRAPPING AROUND THE NORTHERN SEMICIRCLE. 
THE PAST TWO HOURS OF HIMAWARI-9 ANIMATED VISIBLE SATELLITE IMAGERY 
SHOWS SOME SIGNATURE OF A MORE COMPACT LLCC ORBITING WITHIN THE 
BROADER CYCLONIC ROTATION. WATER VAPOR IMAGERY REVEALS THAT UPPER-
LEVEL OUTFLOW REMAINS LIMITED TO A WEAK WESTWARD CHANNEL PRIMARILY 
SUPPORTED BY SOUTHEASTERLY VERTICAL WIND SHEAR (VWS). A LACK OF MID-
LEVEL MOISTURE SURROUNDING THE VORTEX IS ALSO EVIDENT IN THE WATER 
VAPOR IMAGERY. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE 
BASED ON THE MOSTLY EXPOSED LLCC IN THE ANIMATED MSI. THE INITIAL 
INTENSITY OF 30 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON A 
CONSENSUS OF THE AGENCY DVORAK FIXES AND CIMSS OBJECTIVE INTENSITY 
ESTIMATES. THE ENVIRONMENT IS CHARACTERIZED AS MARGINALLY UNFAVORABLE 
FOR FURTHER DEVELOPMENT DUE TO THE PRESENCE OF SURROUNDING DRY AIR, 
LOW-MODERATE VWS, AND WEAK OUTFLOW ALOFT.

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

CURRENT STEERING MECHANISM: WESTERN FLANK OF A SUBTROPICAL RIDGE
CENTERED SOUTHEAST OF JAPAN

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T1.5 - 25 KTS
   KNES: T1.0 - 25 KTS
   CIMSS SATCON: 36 KTS AT 062140Z
   CIMSS ADT: 34 KTS AT 062340Z
   CIMSS AIDT: 30 KTS AT 062340Z
   CIMSS D-MINT: 27 KTS AT 062251Z
   CIMSS D-PRINT: 27 KTS AT 070020Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY
UNFAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: WEAK WESTWARD
   OTHER FACTORS: SURROUNDING DRY AIR MASS

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   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: TROPICAL DEPRESSION (TD) 22W HAS TURNED POLEWARD 
ON A NORTHEASTWARD TRACK OVER THE PAST 6 HOURS AS A SUBTROPICAL RIDGE 
CENTERED SOUTHEAST OF JAPAN BUILDS WESTWARD AND ASSERTS CONTROL OVER 
THE STEERING ENVIRONMENT. THE TRACK IS FORECAST TO CONTINUE TURNING 
POLEWARD OVER THE NEXT 12 HOURS, RESULTING IN A NEARLY DUE NORTH 
TRAJECTORY THROUGH TAU 36. AFTER TAU 36, THE TRACK TURNS NORTHEASTWARD 
TOWARD SOUTHERN HONSHU THROUGH THE REMAINDER OF THE FORECAST PERIOD. 
THE CURRENT INTENSITY OF 30 KTS IS EXPECTED TO PERSIST THROUGH TAU 36 
PRIMARILY DUE TO THE SURROUNDING PRESSURE GRADIENT. AFTER TAU 36, A 
STEADY DECREASE IN INTENSITY IS FORECAST AS VWS INCREASES AND THE 
SURROUNDING PRESSURE GRADIENT RELAXES. DISSIPATION OF TD 22W IS 
EXPECTED BY TAU 60, JUST BEFORE THE SYSTEM REACHES SOUTHERN HONSHU.

MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN GENERALLY GOOD AGREEMENT 
ABOUT THE POLEWARD TRAJECTORY AND NORTHEASTWARD TURN TOWARD SOUTHERN 
HONSHU. NOTABLY, ALL OF THE GFS-BASED TRACKERS (ENSEMBLE MEAN, HAFS-A, 
AND AI SOLUTIONS), WITH THE EXCEPTION OF THE GFS DETERMINISTIC 
SOLUTION, DEPICT A SIGNIFICANTLY FASTER NORTHEASTWARD TRAJECTORY AFTER 
TAU 36. THIS MAY BE ATTRIBUTABLE TO THE GFS TRACKERS JUMPING FROM THE 
VORTEX OF 22W TO A WEAK MID-LATITUDE CYCLONE THAT IS EXPECTED TO 
EMERGE OFF OF NORTHEASTERN HONSHU AROUND TAU 36. EXCLUDING THE 
AFOREMENTIONED SOLUTIONS AS OUTLIERS, THE CROSS-TRACK AND ALONG-TRACK 
SPREAD REMAINS SMALL THROUGHOUT THE FORECAST PERIOD. THE JTWC TRACK 
FORECAST IS PLACED CLOSE TO THE MEAN OF THE REMAINDER OF GUIDANCE WITH 
HIGH CONFIDENCE. MODEL INTENSITY GUIDANCE IS IN GOOD AGREEMENT ABOUT 
THE INTENSITY REMAINING AT OR BELOW 30 KTS, WITH THE NOTABLE 
EXCEPTIONS OF GFS-BASED COAMPS-TC AND HAFS-A, WHICH BOTH DEPICT A 
PERIOD OF INTENSIFICATION THROUGH TAU 36. GIVEN THE UNCERTAIN BEHAVIOR 
OF THE GFS SOLUTIONS AND THE EXPECTED ENVIRONMENTAL CONDITIONS, THE 
JTWC FORECAST ALIGNS WITH THE REMAINDER OF GUIDANCE THAT DEPICTS 
DISSIPATION AROUND TAU 60.

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