Advisories

WDPN31 PGTW 060900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15E (NOLO) WARNING NR 063//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 25.6N 171.1E
   INITIAL INTENSITY: 105 KTS
   GEOGRAPHIC REFERENCE: 448 NM NORTHEAST OF WAKE ISLAND
   MOVEMENT PAST 6 HOURS: WESTWARD AT 17 KTS
   SIGNIFICANT WAVE HEIGHT: 44 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A PARTIALLY
CLEAR, WARM (17 C), 25 NM DIAMETER EYE FEATURE OF TYPHOON (TY) NOLO
(15E) SURROUNDED BY FAIRLY SYMMETRICAL SPIRAL BANDS OF DEEP
CONVECTION. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON THE VISIBLE IMAGERY SHOWING A WELL-DEFINED EYE, WHILE THE
INITIAL INTENSITY OF 105 KTS IS ASSESSED WITH HIGH CONFIDENCE
BASED ON THE DVORAK ESTIMATES AND OBJECTIVE AIDS LISTED BELOW,
SUPPORTED BY OBSERVED PERSISTENT CLOUD TOP TEMPERATURES (-70 C)
AND WARM (17 C) CENTER OF THE TYPHOON. AS THE SYSTEM TRANSLATES
INTO A BROAD AREA OF DRY AIR TO THE WEST AND NORTHWEST, SOME
EROSION OF THE NORTHWESTERN PORTION OF THE INNER EYEWALL CAN BE
OBSERVED IN THE 060632Z WSFM MWI 89 GHZ MICROWAVE IMAGE.
ENVIRONMENTAL ANALYSIS REVEALS MARGINALLY FAVORABLE CONDITIONS,
CHARACTERIZED BY WARM (28-29 C) SEA SURFACE TEMPERATURES (SST),
ESTABLISHED MODERATE POLEWARD OUTFLOW CHANNEL, OFFSET BY INCREASING
LOW TO MODERATE (15-20 KTS) VERTICAL WIND SHEAR AND DRY MID-LEVEL
AIR ENVELOPING THE SYSTEM.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: DEEP-LAYER SUBTROPICAL RIDGE (STR)
CENTERED TO THE NORTHWEST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T6.0 - 115 KTS
   RCTP: T5.5 - 102 KTS
   PHFO: T5.5 - 102 KTS
   CIMSS ADT: 109 KTS AT 060530Z
   CIMSS AIDT: 100 KTS AT 060530Z
   CIMSS D-MINT: 104 KTS AT 060213Z
   CIMSS D-PRINT: 116 KTS AT 060600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE POLEWARD

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: LOW

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TY 15E WILL MAINTAIN A PREDOMINANTLY WESTWARD
TO WEST-NORTHWESTWARD TRACK OVER THE NEXT 48 HOURS, PROPAGATING
ALONG THE SOUTHERN STEERING FLANK OF A ROBUST STR. BEYOND TAU 48,
AN INDUCED STEERING WEAKNESS DEVELOPS WITHIN THE WESTERN BOUNDARY
OF THE STR, TRIGGERING A POLEWARD TRACK SHIFT AND REDIRECTION INTO
THE STEERING BREAK CREATED BETWEEN THE STR PERIPHERY AND A LOW- TO
MID-LEVEL ANTICYCLONIC CELL EXPANDING OVER JAPAN. FORWARD
TRANSLATIONAL VELOCITY IS PROGNOSTICATED TO SLOW SIGNIFICANTLY
DURING THIS RECURVATURE DRIFT, GOVERNED BY COMPETING STEERING
INFLUENCES AND THE ABSENCE OF A DEEP DYNAMIC LONGWAVE TROUGH TO
ENTRAIN THE CORE. THERMODYNAMICALLY, THE SYSTEM IS EXPECTED TO
GRADUALLY WEAKEN THROUGH TAU 48, RESULTING FROM A GRADUAL INCREASE
IN VWS AND COINCIDENT WITH AN INCREASING DRY MID-LEVEL ENVIRONMENT.
AROUND TAU 48, VWS IS EXPECTED TO BRIEFLY DECREASE, WHICH COMBINED
WITH IMPROVING AND ROBUST POLEWARD OUTFLOW OVER HIGHLY SUPPORTIVE
THERMAL OCEAN WATERS WILL RESULT IN THE SYSTEM RECONSOLIDATING AND
POTENTIALLY SLIGHTLY INTENSIFYING. POST-TAU 48 HOWEVER, YET AGAIN
RAPIDLY INCREASING VWS AND CONTINUOUS DRY AIR ENTRAINMENT WILL
RESULT IN BEGINNING OF THE DECAY PHASE, AS THE SYSTEM ROUNDS THE
AXIS OF THE STR NOW CENTERED TO ITS EAST.

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE DEMONSTRATES STRONG
TRACK COHERENCE THROUGH TAU 36, AS WITNESSED BY A 90 NM CROSS-TRACK
SPREAD, WITH MINIMAL ALONG-TRACK DISPERSION. AFTERWARDS,
RECURVATURE TRACK DISPERSION RESULTS IN AN INCREASE OF THE
CROSS-TRACK ENVELOPE TO 380 NM AROUND TAU 96. ALL AVAILABLE MODELS
PORTRAY THE RECURVATURE SCENARIO AT THIS STAGE, WITH ECMWF OFFERING
THE WIDEST TURN, WHILE DETERMINISTIC GFS, ENSEMBLE GFS, JGSM, AS
WELL AS EXPERIMENTAL AI-DERIVED CONSENSUS PROJECT A SLIGHTLY FASTER
AND SHARPER RIDGE AXIS ROUNDING MOTION. THE OFFICIAL JTWC TRACK IS
PLACED CONGRUENTLY WITH THE PREVIOUS PROGNOSIS, AND LAID ON THE
EASTERN SIDE OF THE MULTI-MODEL CONSENSUS, HEDGING TOWARDS THE
SHARPER TURN. IN TERMS OF INTENSITY PROJECTION, THE LONG TERM
CONFIDENCE REMAINS LOW, AS THE SPREAD ENVELOPE IS AT THE ORDER OF
45-55 KTS. ALL MULTI-MODEL DYNAMICAL CONSENSUS MEMBERS PREDICT
SIMILAR SCENARIO, WITH INITIALLY SLOW WEAKENING, FOLLOWED BY A BRIEF
PERIOD OF MINOR RECONSOLIDATION BEGINNING BETWEEN TAU 48 AND TAU
60, FOLLOWED BY A SYSTEMIC DECAY TREND AFTERWARDS

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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