WDPN32 PGTW 192100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 05W (FIVE) WARNING 
NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 14.2N 130.0E
   INITIAL INTENSITY: 25 KTS
   GEOGRAPHIC REFERENCE: 748 NM SOUTH OF KADENA AB
   MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 16 KTS
   SIGNIFICANT WAVE HEIGHT: 10 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A BROAD,
ELONGATED AND RATHER DISORGANIZED LOW LEVEL CIRCULATION CENTER
(LLCC). AN UPSTREAM OUTAGE HAS RESULTED IN A LIMITED AMOUNT OF
MICROWAVE IMAGERY THAT WOULD ENABLE A PEAK UNDER THE CIRRUS CANOPY,
BUT THE ANIMATED PROXY VISIBLE IMAGERY SUGGESTS THE EASTERN LOBE OF
THE ELONGATED CIRCULATION IS JUST VISIBLE TO THE EAST OF THE MAIN
AREA OF CONVECTION. AN EARLIER SCATTEROMETER PASS INDICATED A
SIMILAR SET UP WITH THE PRIMARY LLCC ON THE EASTERN EDGE OF THE
CONVECTIVE MASS. HOWEVER, WITH THE LACK OF MICROWAVE IMAGERY, THE
INITIAL POSITION IS ASSESSED WITH LOW CONFIDENCE. THE
AFOREMENTIONED SCATTEROMETER DATA INDICATED NON-FLAGGED WINDS UP TO
20-25 KNOTS, MAINLY LIMITED TO THE SOUTHERN PORTION OF THE
CIRCULATION. ALONG WITH AGENCY DVORAK CURRENT INTENSITY ESTIMATES
OF T1.5 TO T2.0, THE INITIAL INTENSITY IS SET AT 25 KNOTS WITH
MEDIUM CONFIDENCE. ANALYSIS REVEALS A MARGINALLY FAVORABLE
ENVIRONMENT VERY WARM SSTS (30-31C), AND LOW TO MODERATE NORTHERLY
VERTICAL WIND SHEAR (VWS). OUTFLOW IS FAIRLY STRONG TO POLEWARD,
ENHANCED BY EASTWARD FLOW INTO A STRONG TUTT-CELL LOCATED NEAR 23N
143E. THE MAIN HINDRANCE TO DEVELOPMENT IN THE NEAR-TERM WILL BE
THE DISORGANIZED NATURE OF THE LLCC.

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

CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED TO THE SOUTH OF HONSHU. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T1.5 - 25 KTS
   RJTD: T1.5 - 25 KTS
   KNES: T2.0 - 30 KTS

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 10-15 KTS
   SST: 30-31 CELSIUS
   OUTFLOW: STRONG POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: MEDIUM
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING
MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY.

FORECAST DISCUSSION: TD 05W (FIVE) IS FORECAST TO CONTINUE TRACKING
TOWARDS THE WEST-NORTHWEST, ALONG THE SOUTHERN SIDE OF THE LARGE
STR, FOR THE NEXT 36 HOURS. TRACK SPEEDS ARE EXPECTED TO SLOW DOWN
THROUGH THE SAME TIME PERIOD AS THE STEERING GRADIENT WEAKENS IN
RESPONSE TO THE DEVELOPMENT OF A SECONDARY RIDGE WHICH PUSHES IN
OVER THE SOUTHERN PHILIPPINES, WHICH EFFECTIVELY PUTS TD 05W INTO A
RELATIVELY WEAK STEERING PATTERN. BY TAU 48, THE SYSTEM WILL SLOW
TO A ITS SLOWEST FORWARD SPEED AS THE STEERING PATTERN BEGINS TO
REORIENT. THE PASSAGE OF A MID-LATITUDE TROUGH OVER KOREA WILL
ERODE AND PUSH THE STR CURRENTLY NEAR HONSHU, OFF TO THE EAST,
WHILE AT THE SAME TIME, THE RIDGE TO THE SOUTHEAST CONTINUES TO
BUILD. THESE TWO RIDGES ARE EXPECTED TO MERGE INTO A ROUGHLY
NORTH-SOUTH ORIENTED RIDGE COMPLEX, CENTERED ROUGHLY ON 135E, BY
TAU 72. IN RESPONSE, TD 05W WILL TRACK NORTHWARD THROUGH TAU 96.
AFTER TAU 96, ANOTHER RIDGE IS EXPECTED TO BUILD EASTWARD FROM A
CENTER OVER CENTRAL CHINA, CUTTING OFF INTO A BUBBLE-HIGH OVER
KOREA BY THE END OF THE FORECAST PERIOD, WHICH WILL ALLOW TD 05W TO
SHIFT TO A MORE NORTH-NORTHWESTWARD TRACK BY THE END OF THE
FORECAST PERIOD, PASSING THROUGH THE SOUTHERN RYUKYU ISLANDS BY TAU
120. IN TERMS OF INTENSITY, DUE TO THE LACK OF A WELL-ORGANIZED
LLCC AT PRESENT, THE SYSTEM IS EXPECTED TO ONLY SLOWLY INTENSIFY
THROUGH THE FIRST 24-36 HOURS. AROUND TAU 48, NORTHEASTERLY SHEAR
IS EXPECTED TO PUT A CRIMP ON THINGS FOR A BIT, KEEPING THE SYSTEM
AT TROPICAL STORM STRENGTH THROUGH TAU 72. HOWEVER, AFTER THIS
POINT, SHEAR IS EXPECTED TO DECREASE SHARPLY, COINCIDING WITH
VORTEX ALIGNMENT AND MOVEMENT OVER A POCKET OF VERY WARM AND HIGH
OHC WATERS, WHICH WILL FUEL A PERIOD OF MORE AGGRESSIVE
INTENSIFICATION THROUGH THE END OF THE FORECAST PERIOD, PEAKING AT
95 KNOTS AT TAU 120. 

MODEL DISCUSSION: DETERMINISTIC MODELS ARE IN GENERAL AGREEMENT ON
THE OVERALL TRACK SCENARIO BUT DO EXHIBIT FAIRLY LARGE CROSS- AND
ALONG-TRACK SPREADS. OF THE CONSENSUS MEMBERS, THE UKMET ENSEMBLE
MEAN IS THE EXTREME OUTLIER TO THE WEST, TAKING THE SYSTEM INTO FAR
SOUTHERN TAIWAN. THE GFS MARKS THE EASTERN OUTLIER, MOVING THE
SYSTEM NORTHWARD TO A POINT ABOUT 90NM WEST OF OKINAWA BY TAU 120.
THE REMAINDER OF THE AVAILABLE GUIDANCE LIES IN A SMALLER ENVELOPE
ROUGHLY CENTERED ON ISHIGAKIJIMA. ENSEMBLE GUIDANCE DEPICTS A
FAIRLY WIDE SPREAD, BETWEEN THE LUZON STRAIT TO NORTH OF OKINAWA,
THOUGH THE ENSEMBLE MEANS (EPS, GEFS, UKMET AND CMC) AND THE
SUPER-ENSEMBLE MEAN, ARE CLOSELY ALIGNED POINTING TO A TRACK JUST
NORTHEAST OF ISHIGAKIJIMA. THE TIGHT GROUPING OF ENSEMBLE MEANS AND
DETERMINISTIC GUIDANCE LENDS HIGH CONFIDENCE TO THE JTWC TRACK
FORECAST, THOUGH SOME MOVEMENT OF THE TRACK NORTH OR SOUTH OF THE
CURRENT FORECAST IS CERTAINLY LIKELY AS THE LLCC CONTINUES TO
CONSOLIDATE. INTENSITY GUIDANCE IS LIMITED DUE TO THE UPSTREAM
OUTAGE BUT OVERALL IS SPLIT. THE HWRF AND COAMPS-TC ARE VERY
AGGRESSIVE, PEAKING THE SYSTEM AS A SUPER-TYPHOON IN THE EAST CHINA
SEA BY TAU 120. THE HAFS-A AND CMC MEANWHILE KEEP THE SYSTEM WEAK,
PEAKING AT JUST 55 KNOTS AT TAU 120. THE REMAINDER OF THE GUIDANCE
LIES IN THE MIDDLE. THE JTWC FORECAST IS BELOW THE CONSENSUS MEAN
THOUGH TAU 72 BY ABOUT 5-10 KNOTS, THEN TRACKS THE MEAN THROUGH THE
REMAINDER OF THE FORECAST. CONFIDENCE IS LOW IN THE INTENSITY
FORECAST, DUE TO THE LACK OF RELIABLE INTENSITY GUIDANCE AND THE
DISORGANIZED NATURE OF THE CIRCULATION AT PRESENT. 

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: HIGH
   TRACK 72-120 HR: HIGH
   INTENSITY 0 - 72 HR: LOW
   INTENSITY 72-120 HR: LOW//
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