Tropical Storm NEPARTAK Advisory wo, 28-07

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 11W (NEPARTAK)
WARNING NR 019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 39.1N 141.6E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 80 NM SOUTH-SOUTHEAST OF MISAWA, JAPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 13 KTS
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY, SYNOPTIC DATA, AND FIXES
FROM RJTD AND PGTW INDICATE THAT TROPICAL DEPRESSION 11W (NEPARTAK)
CAME ASHORE OVER MIYAGI PREFECTURE AT APPROXIMATELY 272300Z, NEAR
THE TOWN OF MINAMISANRIKU. THE CURRENT POSITION SPLITS THE FIXES
FROM PGTW AND RJTD FIXES AND IS NORTH OF A LINE OF RADAR FIXES FROM
THE JMA. THE CLOUD FIELDS SURROUNDING THE CORE EXPANDED AND BECAME
LESS ORGANIZED AS THE SYSTEM TRACKED INLAND, MAKING POSITIONING LESS
PRECISE THAN DESIRED. IMAGERY ALSO SHOWS THE SYSTEM ACCELERATING
AND TAKING A MORE POLEWARD TRACK OVER THE PAST 12 HOURS. THE
INTENSITY ASSESSMENT IS BASED ON A SLIGHT DROP AFTER THE SYSTEM
MADE LANDFALL AT 35 KNOTS AND AGREES WITH THE RJTD DVORAK ESTIMATE
OF 30KTS. SURFACE REPORTS DO NOT REFLECT ANY DESTRUCTIVE WINDS.
SOME DEEP CONVECTION PERSISTS OVER THE NORTHERN SEMICIRCLE BUT THE
MOST RECENT FRAMES INDICATE THAT THE HEAVIEST CONVECTIVE CLOUDS ARE
COLLAPSING.
INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).
CURRENT STEERING MECHANISM: A HIGH AMPLITUDE RIDGE EXTENDING
NORTHWESTWARD FROM THE SUBTROPICAL HIGH EXTENDS OVER THE SOUTHERN
KURILS, FORCING THE SYSTEM TOWARDS THE SEA OF JAPAN.
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: NO CURRENT ESTIMATE
   RJTD: T2.0 - 30 KTS
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 0-5 KTS
   SST: OVER LAND
   OUTFLOW: WEAK RADIAL
ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   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: TROPICAL DEPRESSION 11W (NEPARTAK) HAS MADE
LANDFALL AND IS NOW HEADING ACROSS NORTHERN HONSHU TOWARDS THE
SEA OF JAPAN. THE LOW LEVEL CIRCULATION CETNER (LLCC) REMAINS
VERTICALLY STACKED WITH AN UPPER LEVEL CYCLONE AND IS MOVING IN
TANDEM TOWARDS THE SEA OF JAPAN. AMSU RADIAL HEIGHT CROSS SECTIONS
CONTINUE TO SUPPORT THE ASSESSMENT THAT TROPICAL DEPRESSION 11W IS A
SUB-TROPICAL SYSTEM. THE SUBTROPICAL HIGH IS ANCHORED NEAR 39N
170E. THERE IS AN EXPANSIVE LOW-TO-MID-LEVEL RIDGE EXTENDING FROM
THE SYSTEM CENTER ACROSS THE SOUTHERN KURILS THAT IS EXPECTED TO
FORCE THE SYSTEM WESTWARD INTO THE SEA OF JAPAN. WHETHER OR NOT THE
LOW LEVEL CIRCULATION CENTER SURVIVES THE TRIP OVER THE ROUGH
TERRAIN OF THE JAPANESE ALPS REMAINS UNCERTAIN, BUT A NUMBER OF
VORTEX TRACKERS AND ENSEMBLE MEMBERS CARRY THE SYSTEM INTO THE SEA
OF JAPAN (SOJ). THE FARTHER NORTH THE LLCC EMERGES, THE MORE
QUICKLY IT WILL DISSIPATE OVER WATER. SEA SURFACE TEMPERATURES FALL
PRECIPITOUSLY NORTH OF THE 40TH LATITUDE AND WILL NOT SUPPORT THE
SYSTEM.  NO MATTER WHERE THE VORTEX EMERGES INTO THE SOJ,
IT WILL ENCOUNTER GREATER THAN 25 KNOTS OF VERTICAL WIND SHEAR.
MODEL DISCUSSION: THE JTWC TRACK FORECAST STAYS CLOSE TO CONSENSUS
WHILE THE INTENSITY FORECAST DROPS THE INTENSITY QUICKER THAN
GUIDANCE DUE TO EXPECTED DECAY ON THE OVERLAND TRACK. SOME MODELS
AND ENSEMBLE MEMBERS SHOW THE VORTEX SURVIVING INTO THE SOJ THROUGH
TAU 48, BUT DUE TO THE COOLER WATERS AND HIGH VERTICAL WINDSHEAR,
EVEN IF THE LLCC PERSISTS IT WILL NOT BE ABLE TO RE-GENERATE TO OVER
20 KNOTS.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM//
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