Advisories

WDPN31 PGTW 081500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (KROVANH) 
WARNING NR 030//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 31.9N 133.1E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 153 NM SOUTH-SOUTHEAST OF IWAKUNI, JAPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
DEPRESSION 22W (KROVANH) WITH A FULLY EXPOSED LOW-LEVEL CIRCULATION
CENTER (LLCC) THAT IS NOW NEARLY COMPLETELY VOID OF DEEP CONVECTION. 
A 081115Z METOP-B ASCAT PASS REVEALED A DEFINED CENTER WITH 30-KNOT 
WINDS ALONG THE WESTERN AND EASTERN PORTIONS OF THE CIRCULATION. THE 
INITIAL POSITION AND INTENSITY ARE BOTH PLACED WITH HIGH CONFIDENCE 
BASED ON THE TIMELY ASCAT DATA. THE AGENCY DVORAK FIXES AND CIMSS 
INTENSITY ESTIMATES LISTED BELOW FURTHER SUPPORT THE INITIAL 
INTENSITY ASSESSMENT. ENVIRONMENTAL ANALYSIS INDICATES THAT 22W 
REMAINS PLACED WITHIN AN UNFAVORABLE ENVIRONMENT CHARACTERIZED BY 
STRONG POLEWARD OUTFLOW ALOFT AND WARM (28-29 C) SEA SURFACE 
TEMPERATURES GREATLY OFFSET BY MODERATE TO HIGH (20-25 KTS) SOUTHERLY 
VERTICAL WIND SHEAR AND EXTENSIVE DRY AIR ENTRAINMENT.

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

CURRENT STEERING MECHANISM: THE NORTHWESTERN FLANK OF THE
SUBTROPICAL RIDGE (STR) CENTERED SOUTHEAST OF JAPAN

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T1.0 - 25 KTS
   CIMSS ADT: 32 KTS AT 081210Z
   CIMSS AIDT: 35 KTS AT 081210Z
   CIMSS D-PRINT: 28 KTS AT 081210Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD
   OTHER FACTORS: SIGNIFICANT DRY AIR ENTRAINMENT

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: TD 22W HAS STARTED ON ITS NORTHEASTWARD TURN
OVER THE PAST 6 HOURS, WHICH IS EXPECTED TO BECOME MORE
EAST-NORTHEASTWARD OVER THE NEXT 12 HOURS AS THE SYSTEM CONTINUES
TO ROUND THE STR. NEAR TAU 12, THE SYSTEM WILL SKIRT THE SOUTHERN
COAST OF JAPAN, NEAR THE SHIKOKU AND KANSAI REGIONS WITH INCREASING
TRACK SPEEDS. 22W WILL BE HEAVILY IMPACTED BY THE STATIONARY
FRONTAL BOUNDARY THAT IS CURRENTLY DRAPED ACROSS HONSHU, CAUSING
THE CIRCULATION TO BECOME STRETCHED AND LIKELY MOVE UNPREDICTABLY.
IN TERMS OF INTENSITY, 22W IS FORECAST TO BEGIN WEAKENING AS IT
APPROACHES THE COAST DUE PRIMARILY TO SIGNIFICANTLY INCREASING
SOUTHWESTERLY VERTICAL WIND SHEAR (OVER 40 KTS). ONCE THE SYSTEM
BEGINS TO INTERACT WITH THE MOUNTAINOUS TERRAIN OF JAPAN, 22W WILL
QUICKLY WEAKEN WITH DISSIPATION EXPECTED TO OCCUR AROUND TAU 24.
EVEN THOUGH THE VORTEX ASSOCIATED WITH 22W LIKELY BECOMES ABSORBED
WITHIN THE FRONTAL BOUNDARY, LOCALIZED AREAS OF ENHANCED WINDS MAY
PERSIST IN AREAS SUCH AS WAKAYAMA BAY AND ISE BAY DUE TO TOPOGRAPHIC 
FUNNELING EFFECTS.

MODEL DISCUSSION: MODEL TRACK GUIDANCE AGREES ON THE
EAST-NORTHEASTWARD TURN THROUGH TAU 24 WITH MINIMAL CROSS-TRACK
SPREAD. HOWEVER, ALONG-TRACK SPREAD CONTINUES TO BE HIGH DUE TO
MODELS VARYING IN THE SPEED OF ADVANCE AROUND THE RIDGE. THE JTWC
TRACK FORECAST IS PLACED NEAR THE MULTI-MODEL CONSENSUS THROUGHOUT
THE SHORT FORECAST PERIOD WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE 
GENERALLY AGREES ON RAPID WEAKENING AFTER LANDFALL. SOME MODELS DO 
SHOW OFFSHORE WINDS REMAINING AROUND 30 KTS THROUGH TAU 24, THOUGH 
THE ACTUAL VORTEX OF 22W WASHES OUT OVER LAND. AS A RESULT, THE JTWC 
INTENSITY FORECAST IS PLACED SLIGHTLY BELOW THE CONSENSUS.

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