Tropical Storm AERE Advisory 7月4日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (AERE) WARNING
NR 018//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
SUMMARY:
   INITIAL POSITION: 32.8N 129.4E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 23 NM SOUTHWEST OF SASEBO, JAPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 13 KTS
   SIGNIFICANT WAVE HEIGHT: 10 FEET
SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A FULLY
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH WEAKENING
CONVECTION SHEARED WELL TO THE SOUTHEAST OVER WESTERN KYUSHU, UNDER
THE INFLUENCE OF PERSISTENT NORTHWESTERLY UPPER-LEVEL FLOW. THE
INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE SUPPORTED BY THE
RJTD AND PGTW POSITION FIXES, ANIMATED RADAR DATA FROM JMA SHOWING
THE LOW LEVEL RAIN BANDS, AND IN THE CENTER OF THE EXPOSED LLCC IN
ANIMATED SHORTWAVE INFRARED SATELLITE IMAGERY. THE INITIAL
INTENSITY OF 25 KNOTS IS ASSESSED WITH MEDIUM CONFIDENCE. SURFACE
OBSERVATIONS FROM THE REGION INDICATE LIGHT WINDS OF LESS THAN 10
KNOTS, BUT MSLP READINGS FROM NAGASAKI AND FUKUE INDICATE PRESSURES
OF 1000MB, WHICH SUPPORTS A 997MB ASSESSED CENTRAL PRESSURE. THE
WIND PRESSURE RELATIONSHIP ALONE WOULD SUGGEST A 30-35 KNOT
INTENSITY, HOWEVER A PREVIOUS PARTIAL ASCAT-C PASS FROM 041314Z
SHOWED MAXIMUM WINDS OF ONLY 15-20 KNOTS, THUS THE INITIAL
INTENSITY REMAINS SET AT 25 KNOTS. ANIMATED WATER VAPOR IMAGERY
INDICATES THE UPPER-LEVEL LOW THAT PREVIOUSLY WAS ENSCONCED OVER
THE SYSTEM HAS MOVED AWAY AND HAS BEEN REPLACED BY A SHARP
UPPER-LEVEL TROUGH, THE AXIS OF WHICH IS CURRENTLY MOVING OVER THE
SYSTEM, INDUCING NORTHWESTERLY, CONVERGENT FLOW OVER THE SYSTEM.
THE ENVIRONMENT IS BECOMING STEADILY LESS FAVORABLE, WITH MODERATE
TO HIGH VWS AND LAND INTERACTION ADDING TO THE ALREADY UNFAVORABLE
SUBSIDENCE ALOFT.
INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND
RADII).
CURRENT STEERING MECHANISM: NORTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE TO THE SOUTHEAST.
AGENCY DVORAK AND AUTOMATED FIXES:
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   CIMSS SATCON: 47 KTS AT 041733Z
   CIMSS ADT: 45 KTS AT 041740Z
FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 20-25 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: WEAK EQUATORWARD
ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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: THE FORECAST EVOLUTION OF TD 05W IS COMPLEX.
IN THE NEAR-TERM (NEXT 24 HOURS), THE SYSTEM IS FORECAST TO TRACK
EAST-NORTHEASTWARD ALONG THE NORTHERN PERIPHERY OF THE STR SLIDING
WESTWARD ALONG THE 25TH PARALLEL, TD 05W WILL MOVE AT A RELATIVELY
QUICK PACE, CROSSING NORTHERN KYUSHU AND THE INLAND SEA BEFORE
EMERGING BACK OVER WATER SOUTH OF TOKYO BY TAU 36. AT THIS POINT
THINGS GET COMPLICATED. GLOBAL MODELS SUGGEST A WEAK BAROCLINIC LOW
WILL DEVELOP IN THE VICINITY OF TOKYO AROUND TAU 24 AT THE TAIL END
OF A 500MB TROUGH AND MOVE OFFSHORE. BY TAU 36, THE VORTICITY
ASSOCIATED WITH TD 05W OR ITS REMNANTS ARE EXPECTED TO MERGE WITH
THIS LOW PRESSURE AREA. INITIALLY THE BAROCLINIC ENERGY ASSOCIATED
WITH THE 500MB SHORTWAVE TROUGH WILL GIVE A BOOST TO TD 05W,
ALLOWING FOR REINTENSIFICATION OF THE SYSTEM.  SIMULTANEOUSLY IN
THE UPPER LEVELS, A HIGH-AMPLITUDE RIDGE EXTENDS NORTH FROM JAPAN
INTO THE SEA OF OKHOTSK, LEADING TO DEVELOPMENT OF A CUTOFF LOW
OVER TD 05W. ULTIMATELY THIS FORMS A REX BLOCK WITH TD 05W LYING
UNDERNEATH THE WARM-CORE CUTOFF LOW TO THE SOUTH WITH A UPPER-LEVEL
ANTICYCLONE TO THE NORTH OVER THE SEA OF OKHOTSK. THIS PATTERN IS
EXPECTED TO REMAIN IN PLACE THROUGH AT LEAST TAU 72, AND TD 05W
WILL BECOME QUASI-STATIONARY TO THE EAST OF HONSHU DURING THIS
TIMEFRAME UNDER THE INFLUENCE OF A WEAK STEERING PATTERN. BY TAU 96
THE REX BLOCK BEGINS TO BREAK DOWN, WITH THE STR TO THE EAST
BUILDING AND REORIENTING TO A MORE NORTH-SOUTH AXIS, EJECTING TD
05W TO THE NORTH-NORTHWEST. TD 05W IS FORECAST TO INTENSIFY TO A
PEAK OF 35 KNOTS AS IT MOVES EAST OF HONSHU, THEN SLOWLY WEAKEN
THROUGH THE END OF THE FORECAST PERIOD. THE SYSTEM WILL BEGIN
SUBTROPICAL TRANSITION BY TAU 48 AS IT MOVES UNDER THE UPPER-LEVEL
CUTOFF LOW, AND FULLY TRANSITION TO A GALE-FORCE SUBTROPICAL LOW NO
LATER THAN TAU 96.
MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS IN
RELATIVELY GOOD AGREEMENT THROUGH 72 AS THE SYSTEM TRACKS ALONG THE
NORTHERN EDGE OF THE STR. MODEL SPREAD IS 145NM AT TAU 72 WITH THE
JGSM MARKING THE SOUTHERN EDGE OF THE ENVELOPE AND NAVGEM THE
NORTHERN. WHILE THE GUIDANCE AGREES ON THE OVERALL SCENARIO IN THE
LONG-RANGE FORECAST, AVAILABLE GUIDANCE SHOWS SIGNIFICANT
DISAGREEMENT IN BOTH THE TIMING OF THE EJECTION NORTHWARD AND THE
DIRECTION OF MOTION ONCE TD 05W MOVES POLEWARD. CROSS-TRACK SPREAD
INCREASES TO 280NM WHILE ALONG-TRACK SPREAD INCREASES TO 350NM BY
TAU 120, WITH THE ECMWF, ITS ENSEMBLE AND NAVGEM RACING THE SYSTEM
NORTHWARD AT OVER 20 KNOTS WHILE THE REMAINDER OF THE GUIDANCE
SUGGESTS A WEAKER STEERING GRADIENT WITH THE SYSTEM MOVING POLEWARD
AT A MUCH SLOWER PACE. INTENSITY GUIDANCE IS IN GOOD AGREEMENT
THOUGH TAU 36 AS THE SYSTEM MOVES OVER LAND, BUT ONCE THE SYSTEM IS
BACK OVER WATER AND BEGINS TO UNDERGO SUBTROPICAL TRANSITION, THE
GUIDANCE SHOWS INCREASING UNCERTAINTY. ALL MODELS AGREE ON
INTENSIFICATION BUT DIFFER IN THE AMOUNT, DEPENDENT UPON THE DEGREE
OF INTERACTION WITH THE UPPER-LEVEL TROUGH AND LOW. SHIPS SUGGEST
DISSIPATION AFTER TAU 48, WHILE COAMPS-TC AND HWRF BRING THE
INTENSITY UP TO 45 KNOTS AT TAU 48 WITH SLOW WEAKENING THEREAFTER.
THE JTWC FORECAST IS WITHIN 5 KNOTS OF THE CONSENSUS MEAN THROUGH
THE FORECAST PERIOD. CONFIDENCE IS HIGH THROUGH TAU 72, BUT MEDIUM
IN THE EXTENDED PERIOD.
FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: HIGH
   INTENSITY 72-120 HR: MEDIUM//
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