Advisories

WDPN31 PGTW 161500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (DUJUAN) WARNING NR 
005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 16.5N 149.5E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 227 NM EAST-NORTHEAST OF SAIPAN
   MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 16 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS IMPROVED 
CONVECTIVE DEVELOPMENT AND STRUCTURAL CONSOLIDATION OF TROPICAL STORM 
(TS) 24W (DUJUAN), AS THE SYSTEM ACCELERATES NORTHEASTWARD. WHILE THE 
LOW-LEVEL CIRCULATION CENTER (LLCC) REMAINS SLIGHTLY ELONGATED, DEEP 
CONVECTION IS BUILDING NEARLY THROUGHOUT THE VICINITY OF THE VORTEX, 
WITH THE EXCEPTION OF THE NORTHWESTERN QUADRANT STILL DOMINATED BY A 
DRY AIR MASS. THE INITIAL POSITION IS ASSESSED WITH MEDIUM CONFIDENCE 
BASED ON THE WRAPPING OF THE SPIRAL BANDING INTO A CURRENTLY FULLY 
OBSCURED LLCC PRESENT IN THE SHORTWAVE INFRARED IMAGERY. ENVIRONMENTAL 
ANALYSIS DISCLOSES A CONDUCIVE DEVELOPMENT REGIME, SUPPORTED BY HIGHLY 
FAVORABLE, WARM (29-30 C) SEA SURFACE TEMPERATURES (SST), DUAL-CHANNEL 
POLEWARD AND EQUATORWARD OUTFLOW CHANNELS, AND BENIGN VERTICAL WIND 
SHEAR (VWS) OF 5-10 KTS. THESE STIMULATING PARAMETERS ARE CONCURRENTLY 
OFFSET BY THE CONTINUOUS ADVECTION OF DRY TROPOSPHERIC AIR ENTRAINING 
ALONG THE NORTHWESTERN FLANK. THE INITIAL INTENSITY DESIGNATION OF 35 
KTS IS ASSESSED WITH HIGH CONFIDENCE, BASED ON THE CONGRUENCE OF 
SUBJECTIVE SATELLITE DVORAK FIXES AND OBJECTIVE ESTIMATES LISTED 
BELOW.

INITIAL WIND RADII BASIS: A 160753Z SMOS WIND SPEED DATA

CURRENT STEERING MECHANISM: NORTHWARD EXTENSION OF AN ELONGATED
NEAR EQUATORIAL RIDGE (NER) CENTERED TO THE SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   CIMSS ADT: 33 KTS AT 161140Z
   CIMSS AIDT: 35 KTS AT 161140Z
   CIMSS D-PRINT: 41 KTS AT 161230Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: STRONG POLEWARD AND EQUATORWARD
   OTHER FACTORS: DRY AIR ENTRAINMENT FROM THE NORTHWEST

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 24W IS CURRENTLY TRANSITING ALONG A NORTH-
NORTHEASTWARD TRANSLATION VECTOR, GUIDED PRIMARILY BY THE STEERING 
FLOW 
OF THE ELONGATED NEAR-EQUATORIAL RIDGE (NER) ANCHORED TO THE 
SOUTHEAST. 
THE CO-LOCATED SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHEAST IS 
PROGNOSTICATED TO REORIENT EASTWARD AND RETROGRADE SLIGHTLY, AS AN 
UPPER-LEVEL TROUGH ADVANCES FROM THE WEST. AS SUCH, A PREVALENT 
NORTHWARD TRACK IS ANTICIPATED FOR THE COMING 12 HOURS, PRIOR TO THE 
SYSTEM ENCOUNTERING A BUILDING STEERING GRADIENT ASSOCIATED WITH THE 
SUBSEQUENT BUILDING SOUTHWESTERN FLANK OF THE AFOREMENTIONED STR, 
WHICH 
WILL DEVIATE THE TRAJECTORY NORTHWESTWARD THROUGH TAU 72. SUBSEQUENT 
TO 
TAU 72, TS DUJUAN WILL NAVIGATE THE WESTERN PERIPHERY OF THE RIDGE 
AXIS 
PRIOR TO VEERING NORTHWARD, CULMINATING IN A RAPID NORTHEASTWARD 
ACCELERATION IN CLOSE PROXIMITY TO THE EASTERN SEABOARD OF HONSHU, 
JAPAN. TRACK PROGNOSIS UNCERTAINTY PERSISTS AT MODERATE LEVELS, 
PRINCIPALLY STEMMING FROM THE TEMPORAL PROGRESSION OF THE RECURVATURE 
STEPS. IN TURN, THE PROXIMITY TO THE COAST OF HONSHU WILL VARY 
DIRECTLY 
WITH THE COMPLEX STEERING HAND-OFF BETWEEN STEERING MECHANISMS AND THE 
RATE OF STR EXPANSION. INTENSITY OUTLOOKS PROJECT GRADUAL 
INTENSIFICATION, SUPPORTED BY COHERENT THERMODYNAMIC CONDITIONS. 
SEVERAL RAPID INTENSIFICATION AIDS TRIGGERED DURING THIS MODEL RUN, 
INCREASING THE POTENTIAL FOR FASTER DEVELOPMENT. SIMULTANEOUSLY, 
INTERMEDIATE TAUS 36 TO 48 WILL EXHIBIT AN INTENSIFICATION PLATEAU AS 
DRY-AIR ADVECTION AGGRESSIVELY ENTRAINS INTO THE CENTRAL VORTEX CORE, 
IN CONJUNCTION WITH THE TEMPORARILY REDUCED UPPER-LEVEL OUTFLOW. 
SUBSEQUENTLY, TS 24W WILL RESUME INTENSIFICATION, PEAKING AT 70-75 KTS 
BETWEEN TAUS 72 AND 96. IN THE LATER TAUS, ENSEMBLE SOLUTIONS PROJECT 
MID-LEVEL DRY AIR ENTIRELY ENVELOPING THE VORTEX STRUCTURE, 
TERMINATING 
SIGNIFICANT DEVELOPMENT, JUST PRIOR TO THE ONSET OF INTERACTION WITH 
THE BAROCLINIC ZONE AND STRONG UPPER-LEVEL FLOW TO THE NORTH. WHILE 
RESTRUCTURING VWS PROFILES ESCALATE TO 15-20 KTS AFTER TAU 72, THESE 
DYNAMIC IMPEDIMENTS ARE SOMEWHAT MITIGATED AS THE CYCLONE INTEGRATES 
INTO A HIGHLY VENTILATED POLEWARD EXHAUST CHANNEL INDUCED BY THE JET 
STREAK OVER JAPAN.

MODEL DISCUSSION: NUMERICAL WEATHER PREDICTION TRACK GUIDANCE 
DEMONSTRATES IMPROVED CONSISTENCY ACROSS THE CURRENT FORECAST 
TIMELINE, 
EXHIBITING A 140 NM CROSS-TRACK DISPERSION AT TAU 24 WHICH ENLARGES TO 
ONLY A 150 NM ENVELOPE NEAR THE WESTERN RECURVATURE AXIS BEYOND TAU 
96. 
THE OFFICIAL JTWC TRACK PROJECTION ALIGNS CLOSE TO THE EASTERN 
PERIPHERY OF THE MULTI-MODEL CONSENSUS GUIDANCE, BIASING TOWARDS 
EXPERIMENTAL AI GUIDANCE. INTENSITY MODEL CONSENSUS REMAINS WELL-
ALIGNED REGARDING CONTINUOUS INTENSIFICATION UNTIL THE PEAK AROUND TAU 
72 OR SHORTLY THEREAFTER, TRANSITIONING TO AN INTENSITY PLATEAU 
AFTERWARDS. COAMPS-TC IS CURRENTLY IDENTIFIED AS THE PRIMARY 
DETERMINISTIC DYNAMICAL OUTLIER PROJECTING EXTREME SUSTAINED PEAKS OF 
115-120 KTS, ROOTED IN SIGNIFICANTLY SLOWER ALONG-TRACK PROPAGATION. 
THE MAJORITY OF THE REMAINING CONSENSUS SOLUTIONS GROUP NARROWLY 
WITHIN 
A 55-75 KTS INTENSITY SPECTRUM. ACCORDINGLY, THE OFFICIAL JTWC 
INTENSITY PROFILE CONVERGES ON THE MULTI-MODEL DYNAMICAL CONSENSUS 
WITH 
MEDIUM CONFIDENCE.

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