WDPN33 PGTW 190300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 25W (NEOGURI) WARNING NR 
003//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.7N 161.4E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 392 NM NORTHWEST OF WAKE ISLAND
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 08 KTS
   SIGNIFICANT WAVE HEIGHT: 13 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A NEARLY
FULLY OBSCURED LOW-LEVEL CIRCULATION CENTER (LLCC) ASSOCIATED WITH
TROPICAL STORM (TS) 25W (NEOGURI). CIRRUS FILAMENTS INDICATING GOOD
RADIAL OUTFLOW CAN BE OBSERVED ON THE EDGES OF THE SPIRAL BANDS OF
DEEP CONVECTION. DESPITE SURROUNDING SIGNIFICANT DRY AIR, THE
SYSTEM CONTINUES TO CONSOLIDATE STRUCTURALLY, AS WITNESSED BY THE
ANALYSIS OF 850 MB VORTICITY SIGNATURE. ENVIRONMENTAL CONDITIONS
REMAIN FAVORABLE FOR FURTHER DEVELOPMENT, INCLUDING WARM (29-30 C)
SEA SURFACE TEMPERATURES AND LOW (5-10 KTS) VERTICAL WIND SHEAR.
THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON
CONVECTIVE BANDING PATTERNS IN THE ANIMATED EIR IMAGERY AND AN
181751Z F18 SSMIS MICROWAVE PASS. THE INITIAL INTENSITY OF 40 KTS
IS ASSESSED WITH MEDIUM CONFIDENCE, BASED ON DVORAK FIXES AND
OBJECTIVE ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: PERSISTENCE AND A PARTIAL 182309Z METOP-C
ASCAT PASS

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T3.0 - 45 KTS
   CIMSS SATCON: 50 KTS AT 181954Z
   CIMSS ADT: 41 KTS AT 182030Z
   CIMSS AIDT: 41 KTS AT 182030Z
   CIMSS D-MINT: 51 KTS AT 181953Z
   CIMSS D-PRINT: 51 KTS AT 190040Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   INITIAL INTENSITY: MEDIUM
   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 25W IS EXPECTED TO CONTINUE TRACKING
NORTHWESTWARD UNDER THE INFLUENCE OF A DEEP-LAYER STR TO THE
NORTHEAST. AROUND TAU 72, A PASSAGE OF AN UPPER-LEVEL TROUGH WILL
DISRUPT THE STEERING PATTERN, CAUSING THE SYSTEM TO SLOW AND TURN
NORTHWARD. SIMULTANEOUSLY, A NEW STR IS EXPECTED TO BUILD TO THE
WEST-NORTHWEST OF TS NEOGURI, POTENTIALLY HALTING THE RECURVING
MOTION. UNDER THIS SCENARIO, AROUND TAU 120, TS 25W COULD FURTHER 
SLOW DOWN AND BEGIN A WESTWARD TRACK ALONG THE SOUTHEASTERN EDGE OF A 
BUILDING RIDGE. ALTERNATIVELY, TS 25W MAY CONTINUE RECURVING AND 
TRANSITING ALONG THE WESTERN PERIPHERY OF THE RIDGE TO THE EAST-
NORTHEAST, WHICH CAN OCCUR, IF THIS STR REMAINS THE DOMINANT STEERING 
FEATURE IN THE AREA. INTENSITY GUIDANCE STRONGLY INDICATES 
INTENSIFICATION THROUGH TAU 72, WITH PERSISTENT MODEL GUIDANCE. THE 
JTWC FORECASTS A PEAK INTENSITY OF 115 KTS, EXPECTED TO BE REACHED AT 
TAU 96. FAVORABLE ENVIRONMENTAL CONDITIONS, PARTICULARLY WARM SEA 
SURFACE TEMPERATURES, ARE EXPECTED TO PERSIST THROUGHOUT THE FORECAST 
PERIOD. HOWEVER, AS THE SYSTEM TRACKS NORTHWARD AND SLOWS DOWN WITHIN 
A WEAK OR COMPETING STEERING ENVIRONMENT, STORM-INDUCED UPWELLING AND 
DECREASING OCEAN HEAT CONTENT WILL LIKELY IMPACT ITS INTENSIFICATION 
POTENTIAL.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE REMAINS IN GOOD
AGREEMENT THROUGH TAU 72, WITH A CROSS-TRACK SPREAD OF 25 NM AT TAU
12, EXPANDING TO 110 NM AT TAU 72. AFTER TAU 72, THE GUIDANCE
DIVERGES SIGNIFICANTLY, WITH A BIFURCATION SCENARIO. MOST MODELS
PREDICT RECURVATURE, WHILE ECMWF, GALWEM, ECMWF ENSEMBLE, AS WELL
AS UKMET ENSEMBLE INDICATE STALLED MOTION FOLLOWED BY A POSSIBLE
WESTWARD TRACK. INTENSITY GUIDANCE IS IN FAIR AGREEMENT DURING THE
INITIAL STAGES OF THE FORECAST, BUT UNCERTAINTY INCREASES WITH
TIME. THE LEAST AGGRESSIVE MODELS INCLUDE HAFS AND DETERMINISTIC
GFS, WHILE THE MOST AGGRESSIVE REMAIN NAVGEM AND GFS-DRIVEN COAMPS-
TC, ALL CONSISTENT WITH PREVIOUS FORECAST. THE JTWC SHORT-TERM 
INTENSITY PREDICTION IS ASSESSED NEAR THE HIGHER END OF THE MULTI-
MODEL CONSENSUS, WITH MEDIUM CONFIDENCE. LONG-TERM INTENSITY GUIDANCE 
SHOWS A SPREAD OF 55 KTS IN PEAK INTENSITY, REFLECTING IMPROVING, BUT 
STILL LOW CONFIDENCE IN THE FORECAST BEYOND TAU 72.

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