WDPN33 PGTW 182100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 25W (NEOGURI) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.5N 162.3E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 348 NM NORTHWEST OF WAKE ISLAND
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 10 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A FULLY
OBSCURED LOW-LEVEL CIRCULATION (LLCC) ASSOCIATED WITH TROPICAL STORM 
(TS) 25W (NEOGURI). DEEP-LAYER CENTRAL CONVECTION AND MODERATE RADIAL 
OUTFLOW INDICATE STRONG DIVERGENCE ALOFT AND CONTINUOUS STRUCTURAL 
DEVELOPMENT OF THE SYSTEM, DESPITE SIGNIFICANT AMOUNT OF DRY AIR 
SURROUNDING THE CURRENT PERIMETER OF THE WIND FIELD. ADDITIONAL 
ENVIRONMENTAL ANALYSIS REVEALS CONDITIONS FAVORABLE FOR DEVELOPMENT 
WITH WARM (29-30 C) SEA SURFACE TEMPERATURES AND LOW (5-10 KTS) 
VERTICAL WIND SHEAR. THE INITIAL POSITION IS PLACED WITH HIGH 
CONFIDENCE BASED ON TRACING OF THE CONVECTIVE BANDING WRAP SEEN IN 
THE ANIMATED EIR SATELLITE IMAGERY, AS WELL AS AN 181751Z F18 SSMIS 
MICROWAVE SUITE. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH 
MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK FIXES AND OBJECTIVE 
ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: AN 181042Z METOP-C ASCAT PASS

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   RJTD: T2.5 - 35 KTS
   RCTP: T2.5 - 35 KTS
   KNES: T3.0 - 45 KTS
   CIMSS SATCON: 38 KTS AT 181504Z
   CIMSS ADT: 34 KTS AT 181730Z
   CIMSS AIDT: 37 KTS AT 181730Z
   CIMSS D-MINT: 43 KTS AT 181752Z
   CIMSS D-PRINT: 56 KTS AT 181900Z

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

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TS 25W IS FORECAST TO CONTINUE TRACKING
NORTHWESTWARD UNDER THE INFLUENCE OF A DEEP-LAYER STR LOCATED TO
THE NORTH. AROUND TAU 72, A PASSING UPPER-LEVEL TROUGH IS EXPECTED
TO DISRUPT THE STEERING PATTERN, ALLOWING TS NEOGURI TO SLOW DOWN
AND TURN NORTHWARD. BETWEEN TAU 72 AND THE END OF THE CURRENT 
FORECAST PERIOD, ANOTHER STR IS EXPECTED TO BUILD TO THE WEST-
NORTHWEST AND POTENTIALLY STOP THE SYSTEM FROM RECURVING. IN SUCH 
SCENARIO, TS 25W MAY SLOW DOWN FURTHER AND BEGIN A WESTWARD TRACK 
ALONG THE SOUTHEASTERN PERIPHERY OF THE NEWLY BUILT RIDGE AROUND TAU 
120 OR BEYOND. IN TERMS OF INTENSITY, ALL AVAILABLE GUIDANCE 
INDICATES INTENSIFICATION THROUGH TAU 72, HOWEVER RATE OF 
INTENSIFICATION CARRIES MODERATE UNCERTAINTY, WHICH INCREASES WITH 
TIME, RESULTING IN LOW CONFIDENCE ASSESSMENT FOR TAUS BETWEEN 72 AND 
120. CURRENT JTWC FORECAST PEAK INTENSITY IS ASSESSED AT 95 KTS AND 
IS EXPECTED TO BE REACHED AROUND TAU 96. ENVIRONMENTAL CONDITIONS ARE 
EXPECTED TO BE FAVORABLE THROUGHOUT THE FORECAST PERIOD, PARTICULARLY 
AS THE SYSTEM TRANSITS THROUGH AN AREA OF WARM SEA SURFACE 
TEMPERATURES TO THE WEST. ADDITIONALLY, THE FURTHER NORTH THE SYSTEM 
TRACKS, IN ANY OF THE SCENARIOS, THE MORE SIGNIFICANT THE IMPACTS 
WILL BE FROM THE STORM-INDUCED UPWELLING AND THE ASSOCIATED 
DECREASING AVAILABLE OCEAN HEAT CONTENT.  

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE REMAINS IN GOOD
AGREEMENT THROUGH TAU 72 WITH CROSS-TRACK SPREAD OF 40 NM AT TAU
12, EXPANDING TO 130 NM AT TAU 72. AFTERWARDS, GUIDANCE BEGINS TO
INTRODUCE SIGNIFICANT UNCERTAINTY, ESPECIALLY NEAR TAU 120 AND
BEYOND, WITH BIFURCATION SCENARIO, AS SOME MODELS PREDICT RECURVATURE 
(GFS) AND SOME MODELS SIGNIFICANTLY SLOWING DOWN AND EVENTUALLY 
TURNING WESTWARD (ECMWF). AVAILABLE INTENSITY GUIDANCE INDICATES FAIR 
AGREEMENT THROUGH THE INITIAL PHASES OF THE FORECAST, WHICH DECREASES 
WITH TIME. THE LEAST AGGRESSIVE MODELS ARE CURRENTLY HAFS AND 
DETERMINISTIC GFS, WHILE THE MOST AGGRESSIVE ARE NAVGEM AND GFS 
DRIVEN COAMPS-TC, JOINED BY NUMEROUS RAPID INTENSIFICATION (RI) AIDS 
(RIDE, FRIA, RICN, RIPA). THEREFORE JTWC SHORT-TERM INTENSITY 
FORECAST IS ASSESSED NEAR THE HIGHER END OF THE MULTI-MODEL 
CONSENSUS, WITH MEDIUM CONFIDENCE. OF NOTE, LONG TERM INTENSITY 
GUIDANCE IS ASSESSED WITH LOW CONFIDENCE, AS WITNESSED BY A 75 KTS 
PEAK INTENSITY SPREAD BETWEEN THE MOST CONSERVATIVE GFS AND MOST 
AGGRESSIVE GFS-DRIVEN COAMPS-TC.


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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