WDPN31 PGTW 090300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (KROVANH) 
WARNING NR 032//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 33.6N 134.4E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 122 NM EAST-SOUTHEAST OF IWAKUNI, JAPAN
   MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
DEPRESSION (TD) 22W TURNING SHARPLY NORTHEASTWARD. THE LOW-LEVEL
CIRCULATION CENTER (LLCC) IS PARTIALLY EXPOSED, WITH DEEP
CONVECTION FLARING ALONG THE NORTHERN PERIPHERY AND OUTFLOW ALOFT
VENTING INTO A JET STREAM OVER THE SEA OF JAPAN AND HONSHU. A
STRONG UPPER-LEVEL RIDGE SOUTHEAST OF HONSHU IS IMPARTING HIGH
SOUTHERLY VERTICAL WIND SHEAR (VWS) ACROSS THE SYSTEM. IN ADDITION,
DRY AIR ENTRAINMENT INTO THE CIRCULATION AND INTERACTION WITH THE
RUGGED TERRAIN OF HONSHU ARE INCREASING. THESE FACTORS INDICATE A
HIGHLY UNFAVORABLE ENVIRONMENT FOR INTENSIFICATION. THE LLCC HAS
MADE LANDFALL NEAR CAPE MUROTO, WHERE AN EXPOSED COASTAL SURFACE
OBSERVATION AT AN ELEVATION OF 185 METERS REPORTED A 1-MINUTE MEAN
EQUIVALENT WIND SPEED OF 46 KTS. AVAILABLE 081830Z AND 082130Z
SCATTEROMETER DATA INDICATED WINDS OF UP TO 30 KTS OVER OPEN WATER
AND NEAR THE MOUTH OF THE BUNGO CHANNEL. BASED ON THESE DATA AND
AFTER ACCOUNTING FOR THE ELEVATED AND EXPOSED NATURE OF THE MUROTO
OBSERVATION, THE INITIAL INTENSITY HAS BEEN HELD AT 30 KTS WITH
MEDIUM CONFIDENCE. JAPAN'S DENSE NETWORK OF SURFACE OBSERVATIONS
AND RADAR IMAGERY SUPPORT THE CONTINUED IDENTIFICATION OF THE LLCC
AND THE INITIAL POSITION WITH MEDIUM CONFIDENCE.

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

CURRENT STEERING MECHANISM: MID-LATITUDE WESTERLIES ALONG THE
NORTHWESTERN FLANK OF A SUBTROPICAL RIDGE (STR) POSITIONED
SOUTHEAST OF HONSHU

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: NO CURRENT ESTIMATE
   RJTD: T1.0 - 25 KTS
   CIMSS SATCON: 37 KTS AT 081930Z
   CIMSS ADT: 33 KTS AT 082340Z
   CIMSS AIDT: 41 KTS AT 082340Z
   CIMSS D-MINT: 29 KTS AT 082221Z
   CIMSS D-PRINT: 34 KTS AT 082340Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 20-25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT AND LAND INTERACTION

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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 WILL ACCELERATE NORTHEASTWARD UNDER THE
STEERING INFLUENCE OF THE MID-LATITUDE WESTERLIES, TRACKING ALONG
THE NORTHWESTERN FLANK OF THE LOW- TO MID-LEVEL STR CENTERED AT 30N
150E. AFTER TAU 12, THE LLCC MAY BECOME DIFFICULT TO LOCATE AS IT
UNRAVELS INTO A STATIONARY FRONT DRAPED OVER HONSHU BEFORE IT CAN
RE-EMERGE OVER THE OPEN WESTERN PACIFIC EAST OF THE KANTO PLAIN.
THE ENVIRONMENT WILL REMAIN HIGHLY UNFAVORABLE FOR INTENSIFICATION.
VWS WILL INCREASE TO 30-40 KTS BY TAU 12 AS THE UPPER-LEVEL FLOW
ASSOCIATED WITH THE RIDGE STRENGTHENS. FURTHERMORE, THE SHALLOW,
COMPACT VORTEX WILL INTERACT WITH ADDITIONAL TERRAIN AND THE
STATIONARY FRONT. THESE FACTORS WILL LEAD TO RAPID DISSIPATION OF
TD 22W BY TAU 24, WITH ITS REMNANTS BECOMING ABSORBED INTO THE
FRONTAL ZONE. WHILE THE FORECAST DEPICTS STEADY WEAKENING,
LOCALIZED TERRAIN-ENHANCED WINDS MAY OCCUR IN FAVORED CHANNELS AND
COASTAL AREAS, INCLUDING THE MOUTH OF THE KII CHANNEL AND THE
WATERS OFFSHORE OF CAPE SHIONOMISAKI, DURING THE NEXT 24 HOURS.

MODEL DISCUSSION: MODEL GUIDANCE AGREES ON A CONTINUED
NORTHEASTWARD TO EAST-NORTHEASTWARD MOTION THROUGH TAU 12. HOWEVER,
SOME CROSS-TRACK SPREAD EXISTS, WITH THE ENVELOPE INCREASING TO 70
NM AT TAU 12 AND 80 NM AT TAU 24. THE JTWC FORECAST TRACK IS PLACED
SLIGHTLY SOUTH OF THE CONSENSUS BUT NORTH OF THE ECMWF SOLUTION AT
TAU 12. BY TAU 24, MOST MODEL SOLUTIONS EJECT THE SYSTEM EAST OF
THE KANTO PLAIN. THE TRACK FORECAST FAVORS AN INLAND REMNANT-VORTEX
SCENARIO AND KEEPS THE SYSTEM OVER LAND. THIS SCENARIO IS MOST
CONSISTENT WITH THE REMNANT LOW-LEVEL VORTICITY SIGNATURE AS THE
LLCC DISSIPATES. NO DISCERNIBLE CLOSED SURFACE CIRCULATION IS
DEPICTED EAST OF THE KANTO PLAIN IN THE AVAILABLE MODEL SURFACE
WIND FIELDS. INSTEAD, THE MODELS DEPICT AN OPEN TROUGH THAT THE
TRACKERS CONTINUE TO FOLLOW. THE INTENSITY AIDS UNIFORMLY DEPICT A
WEAKENING TREND DURING THE NEXT 24 HOURS. THE JTWC INTENSITY
FORECAST IS CONSISTENT WITH THIS TREND, SHOWING DISSIPATION NO
LATER THAN TAU 24.

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