WDPN33 PGTW 181500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 25W (NEOGURI) 
WARNING NR 001//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 23.0N 162.9E
   INITIAL INTENSITY: 30 KTS
   GEOGRAPHIC REFERENCE: 1417 NM EAST-SOUTHEAST OF YOKOSUKA, JAPAN
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL
DEPRESSION 25W (NEOGURI) WITH DEEP CENTRAL CONVECTION OBSCURING THE
LOW-LEVEL CIRCULATION CENTER (LLCC). CIRRUS FILAMENTS ARE EXPANDING
OUTWARD IN ALL DIRECTIONS, HINTING AT GOOD DIVERGENCE ALOFT. AN
181042Z METOP-C ASCAT IMAGE SHOWS AN ASYMMETRIC WIND FIELD WITH THE
STRONGEST WINDS (30 KTS) CONFINED TO THE EASTERN SEMICIRCLE.
ENVIRONMENTAL ANALYSIS INDICATES THAT 25W IS IN A FAVORABLE
ENVIRONMENT CHARACTERIZED BY MODERATE RADIAL OUTFLOW, LOW (5-10 KTS)
VERTICAL WIND SHEAR, AND WARM (29-30 C) SEA SURFACE TEMPERATURES.
THE VORTEX CENTER APPEARS TO BE FENDING OFF THE DRY AIR THAT IS
ENTIRELY SURROUNDING THE SYSTEM. THE INITIAL POSITION AND INTENSITY
ARE BOTH PLACED WITH HIGH CONFIDENCE BASED ON THE MENTIONED METOP-C
ASCAT IMAGE.

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

CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A SUBTROPICAL
RIDGE (STR) TO THE NORTH

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   RJTD: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   CIMSS D-MINT: 29 KTS AT 180923Z
   CIMSS D-PRINT: 33 KTS AT 181200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: MODERATE RADIAL

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   INITIAL INTENSITY: HIGH
   INITIAL WIND RADII: NOT APPLICABLE

3. FORECAST REASONING.

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

FORECAST DISCUSSION: 25W IS FORECAST TO TRACK NORTHWESTWARD, ALONG
THE SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE THROUGH TAU 72.
NEAR TAU 72, AN INCOMING UPPER-LEVEL TROUGH IS EXPECTED TO BREAK
DOWN THE RIDGE, ALLOWING FOR A BRIEF TURN NORTHWARD. HOWEVER, A
SECOND SUBTROPICAL RIDGE WILL QUICKLY FOLLOW BEHIND THE FIRST AND
POTENTIALLY INHIBIT THE SYSTEM FROM RECURVING. THE JTWC FORECAST
SLOWS THE TRACK SPEED NEAR THE END OF THE FORECAST, WHICH IS RIGHT
AROUND THE INFLECTION POINT OF THE SYSTEM EITHER RECURVING OR
BEGINNING A WESTWARD TRACK, ALONG THE SOUTHERN PERIPHERY OF THE
RIDGE. REGARDING INTENSITY, 25W IS FORECAST TO STEADILY INTENSIFY
THROUGH TAU 96 TO A PEAK OF AROUND 80 KTS. THE ENVIRONMENT IS
EXPECTED TO REMAIN OVERALL CONDUCIVE WITH LOW SHEAR AND WARM SST. 

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN MODERATE
AGREEMENT THROUGH TAU 72, WITH A 243 NM CROSS-TRACK SPREAD AT THAT
TIME. AFTERWARD, MODELS GREATLY DIVERGE AND BIFURCATE AS SOME
MODELS RECURVE (GFS) AND SOME MODELS FAIL TO RECURVE (ECMWF). AS A
RESULT, THE JTWC TRACK FORECAST IS PLACED WITH MEDIUM CONFIDENCE
THROUGH TAU 72 AND LOW CONFIDENCE THEREAFTER. INTENSITY GUIDANCE IS
IN VERY POOR AGREEMENT WITH ECMWF AND AI MODELS DEPICTING
INTENSIFICATION WHILE GFS AND HAFS-A DEPICT LITTLE TO NO FURTHER
DEVELOPMENT. OF NOTE, GFS HAS BEEN INITIALIZING VERY POORLY FOR THE
SYSTEM, SHOWING A MUCH WEAKER VORTEX THAN IS CURRENTLY APPARENT IN
REAL TIME. THE JTWC INTENSITY FORECAST IS PLACED WITH LOW
CONFIDENCE THROUGHOUT THE FORECAST PERIOD.

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