Advisories

WDPN31 PGTW 062100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (KROVANH) 
WARNING NR 023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.8N 131.6E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 209 NM EAST OF KADENA AB
   MOVEMENT PAST 6 HOURS: EASTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A SHALLOW, 
BUT SYMMETRIC PARTIALLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) 
WITH FLARING SHALLOW CONVECTION WRAPPING AROUND TO THE EASTERN SIDE OF 
THE CORE. THE FLARING CONVECTION HAS REMAINED SHALLOW AND UNABLE TO 
PERSIST AROUND THE CORE OVER THE PAST 6 HOURS. ANIMATED WATER VAPOR 
IMAGERY REVEALS THAT UPPER-LEVEL OUTFLOW HAS BEEN 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 PARTIALLY EXPOSED LLCC IN 
EIR. THE INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH HIGH CONFIDENCE 
BASED ON A COMBINATION OF THE AGENCY DVORAK FIXES AND CIMSS OBJECTIVE
INTENSITY ESTIMATES. DESPITE WARM SEA SURFACE TEMPERATURES, THE 
ENVIRONMENT IS CHARACTERIZED AS MARGINAL FOR FURTHER DEVELOPMENT DUE 
TO THE PRESENCE OF DRY AIR, LOW-MODERATE VWS, AND WEAK OUTFLOW ALOFT.

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: T1.5 - 25 KTS
   RJTD: T2.0 - 30 KTS
   RCTP: T2.0 - 30 KTS
   KNES: T1.5 - 25 KTS
   CIMSS SATCON: 38 KTS AT 061810Z
   CIMSS ADT: 34 KTS AT 061810Z
   CIMSS AIDT: 30 KTS AT 061810Z
   CIMSS D-MINT: 32 KTS AT 061723Z
   CIMSS D-PRINT: 28 KTS AT 061810Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: WEAK WESTWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT FROM THE WEST

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 CONTINUED ON AN 
EAST-NORTHEASTWARD TRACK OVER THE PAST 6 HOURS UNDER THE STEERING 
INFLUENCE OF THE NER TO THE SOUTH. A POLEWARD TURN IS IMMINENT AS A 
SUBTROPICAL RIDGE CENTERED SOUTHEAST OF JAPAN BUILDS INTO THE AREA AND 
TAKES CONTROL OF THE STEERING ENVIRONMENT. THE LATEST FEW FRAMES OF 
EIR SUGGEST THAT THE TURN NORTH-NORTHEASTWARD HAS ALREADY STARTED. THE 
NORTH-NORTHEASTWARD TRACK IS FORECAST TO CONTINUE THROUGH TAU 36, THEN 
TURN NORTHEASTWARD THROUGH THE REMAINDER OF THE FORECAST PERIOD. THE 
CURRENT INTENSITY OF 30 KTS IS EXPECTED TO PERSIST THROUGH TAU 36 
PRIMARILY AS A RESULT OF THE SURROUNDING PRESSURE GRADIENT. AFTER TAU 
36, A STEADY DECREASE IN INTENSITY IS EXPECTED 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 HAS COLLAPSED TO A MAXIMUM
CROSS-TRACK SPREAD OF 60 NM THROUGH TAU 60, LENDING HIGH CONFIDENCE TO 
THE JTWC TRACK FORECAST. 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 TO 40 KTS AROUND TAU 48. GIVEN 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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